[top]
000
FXUS65 KTFX 101148
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
548 AM MDT FRI OCT 10 2008
.DISCUSSION...
TODAY THROUGH SUNDAY...AN UPPER LEVEL LOW OVER SOUTHERN IDAHO...WILL
CONTINUE TO DEEPEN THROUGH THE DAY...WITH MOST DYNAMICS WELL SOUTH
OF MONTANA. HOWEVER...ABUNDANT MOISTURE WILL MOVE NORTHWARD INTO
THE REGION THROUGH THE WEEKEND. A GOOD UPSLOPE SURFACE PATTERN WILL
CONTINUES EAST OF THE DIVIDE THROUGH SUNDAY...BETWEEN A DEEPENING
SURFACE LOW OVER UTAH AND A CANADIAN SURFACE HIGH OVER CENTRAL
ALBERTA. THUS...A WINTER STORM WARNING WILL REMAIN TODAY THROUGH
SUNDAY AFTERNOON FOR MOST OF SOUTHWEST MONTANA AND THE SOUTHERN HALF
OF NORTH CENTRAL MONTANA. SNOW IS EXPECTED TO BE HEAVY AT TIMES WITH
ACCUMULATIONS OF 15 TO 30 INCHES OVER THE MOUNTAINS AND
3 TO 6 INCHES ACROSS THE PLAINS AND VALLEYS BY SUNDAY EVENING.
THERE WILL BE SOME MELTING OF SNOW...DUE TO WARM GROUND...AT LOWER
ELEVATIONS. THE BEST CHANCE FOR HEAVY SNOW WILL BE SATURDAY AFTERNOON
AND SATURDAY NIGHT...AS THE UPPER LOW MOVES NORTHEAST INTO SOUTHEAST
MONTANA BY SUNDAY EVENING. IT WILL BE UNSEASONABLY COLD THROUGH
SUNDAY...WITH TEMPERATURES RUNNING SOME 20 TO 30 DEGREES BELOW
SEASONAL AVERAGE. HIGHWAYS WILL BECOME ICY AT LOWER
ELEVATIONS...ESPECIALLY DURING THE NIGHT AND MORNING HOURS ALONG
WITH SOME BLOWING SNOW THROUGH THE PASSES AND CANYONS. CONDITIONS
WILL IMPROVE FROM THE NORTHWEST AS AN UPPER LEVEL RIDGE OF HIGH
PRESSURE OVER THE WEST COAST...BUILDS INTO CENTRAL ALBERTA.
WILLIAMSON DC
SUNDAY NIGHT THROUGH WEDNESDAY NIGHT...A DEEP...UPPER LEVEL LOW
PRESSURE SYSTEM WILL CONTINUE TO MOVE SLOWLY EAST...MOVING ACROSS
THE MONTANA/DAKOTA BORDER SUNDAY NIGHT. HIGH PRESSURE WILL BUILD
ALOFT OVER THE ZONES AND THE THE AIRMASS WILL BEGIN A DRYING AND
WARMING TREND THAT WILL LAST INTO TUESDAY. AN UPPER LEVEL LOW
PRESSURE TROF WILL CROSS THE ROCKIES EARLY WEDNESDAY. THIS WILL BE A
RATHER FAST-MOVING SYSTEM AND THE CHANCE OF PRECIPITATION WILL
REMAIN LOW. HOWEVER...BREEZY CONDITIONS WILL REMAIN OVER THE AREA
UNTIL THIS SHORT WAVE MOVES INTO EASTERN MONTANA. THE WARMING TREND
WILL ALSO BE INTERRUPTED UNTIL ANOTHER HIGH PRESSURE RIDGE BEGINS TO
BUILD OVER THE AREA ON THURSDAY. ZELZER
THURSDAY AND FRIDAY...A DISTURBANCE IN A NORTHWEST FLOW MOVES EAST
OUT OF THE ZONES THURSDAY ALLOWING HIGH PRESSURE TO BUILD IN FROM
THE WEST. A ZONAL FLOW SETS UP AHEAD OF THE NEXT PACIFIC SYSTEM BY
FRIDAY. SAUCIER
&&
.AVIATION...
UPDATED 1145Z.
A DEEP UPPER LEVEL LOW PRESSURE TROF WILL REMAIN OVER THE AREA AND
KEEP THE AIRMASS COOL AND MOIST. PERIODS OF SNOW AND LOW CIGS WILL
CAUSE AREAS OF MVFR CONDITIONS ACROSS SOUTHWEST MONTANA AND PORTIONS
OF NORTH CENTRAL MONTANA. VFR CONDITIONS WILL PREVAIL OVER MUCH OF
NORTH CENTRAL MONTANA AND THE CANADIAN BORDER ALTHOUGH MVFR
CONDITIONS MAY DEVELOP AFTER 06Z FRIDAY. SURFACE FLOW WILL GENERALLY
REMAIN NORTHEAST AND BREEZY.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 34 23 34 21 / 60 60 60 40
CTB 38 21 34 17 / 30 30 30 10
HLN 38 25 34 25 / 60 60 50 50
BZN 38 26 36 25 / 100 80 80 80
WEY 33 19 30 16 / 90 90 80 80
DLN 33 20 30 17 / 80 60 50 80
HVR 44 25 39 18 / 20 30 30 10
LWT 34 22 30 17 / 80 80 80 80
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 6 PM MDT SUNDAY FOR MTZ008-012-014-
015-050>055.
&&
$$
SHORT TERM...WILLIAMSON DC
LONG TERM...ZELZER/SAUCIER
AVIATION...ZELZER
WEATHER.GOV/GREATFALLS
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000
FXUS65 KGGW 101017
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
417 AM MDT FRI OCT 10 2008
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH SUNDAY...
UPPER TROUGH DIGGING INTO THE GREAT BASIN WILL CONTINUE TO BRING
SOUTHWEST FLOW ALOFT TO MONTANA TODAY AND TONIGHT. MOISTURE
OVERRUNNING A FRONTAL BOUNDARY WELL SOUTH OF MONTANA HAS BROUGHT A
MIX OF RAIN AND SNOW TO SOUTHEAST MONTANA OVERNIGHT. THE
PRECIPITATION IS GENERALLY SOUTH OF WINNETT... JORDAN AND GLENDIVE
AT 10Z. THE PRECIPITATION WILL MAKE MINIMAL PROGRESS FURTHER NORTH
TODAY AS LOW LEVEL DRY AIR FROM THE NORTH KEEPS THE RAIN AND SNOW
SOUTH OF THE MISSOURI RIVER. WITH TEMPERATURES NEAR FREEZING AT
HIGHER ELEVATION SITES LIKE BIG SHEEP MOUNTAIN RAWS...WILL KEEP
WINTER STORM WARNING IN PLACE AS WET HEAVY SNOW IS STILL LIKELY IN
HIGHER ELEVATION AREAS.
THE OVERRUNNING MOISTURE WILL MOVE TO THE EAST THIS EVENING
ALLOWING A BREAK IN THE PRECIPITATION TONIGHT. MEANWHILE...A
CLOSED UPPER LOW WILL FORM AT THE BASE ON THE UPPER TROUGH OVER
NEVADA TODAY AND DEEPEN AS IT MOVES SLOWLY NORTHEAST TONIGHT AND
SATURDAY.
THE NEXT SURGE OF MOISTURE WILL MOVE NORTH SATURDAY AND WITH
TEMPERATURES COLD ENOUGH ALOFT...WIDESPREAD SNOW WILL DEVELOP FROM
SOUTH TO NORTH ACROSS NORTHEAST MONTANA SATURDAY AFTERNOON AND EVENING.
THE UPPER LOW WILL LIFT NORTHEAST ACROSS EASTERN MONTANA ON
SUNDAY. WITH GULF OF MEXICO MOISTURE FEEDING THIS SYSTEM...HEAVY
SNOW IS LIKELY ACROSS MOST OF NORTHEAST MONTANA SATURDAY NIGHT AND
SUNDAY. WILL MAINTAIN GOING WINTER STORM WATCH FOR NOW. NORTH
WINDS 15 TO 30 MPH WILL BLOW AND DRIFT ANY OF THE SNOW THAT FALLS.
FORECAST MODELS ARE HINTING AT A FOOT OR MORE OF SNOW FOR PARTS OF
THE FORECAST AREA FROM THIS STORM. FORRESTER
PREVIOUS SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH
SATURDAY...A BUSY FEW DAYS...WEATHER WISE...IN STORE FOR NORTHEAST
MONTANA. AN UPPER TROUGH DIGGING INTO THE GREAT BASIN WILL EJECT
WARMER MORE MOIST AIR OVER A POLAR AIRMASS IN PLACE OVER EASTERN
MONTANA. THIS OVERRUNNING WILL DRIVE A MIX OF RAIN AND SNOW ACROSS
THE SOUTHERN ZONES...MAINLY SOUTH OF HIGHWAY 200. HAVE UPGRADED
THE EXISTING WATCH FOR THE SOUTHERN ZONES TO A WINTER STORM
WARNING. NORTHERLY WINDS OF 15 TO 25 MPH WILL ACCOMPANY THE
STORM...HOWEVER GIVEN THE HEAVY WET NATURE TO THE SNOWFALL DO NOT
EXPECT MUCH IN THE WAY OF BLOWING AND DRIFTING. THESE WINDS MAY
ALSO REQUIRE A LAKE WIND ADVISORY FOR FORT PECK LAKE FRIDAY
AFTERNOON. BY FRIDAY EVENING THE LIFT GENERATED BY THE OVERRUNNING
WILL TAPER OFF...SUBSEQUENTLY TAPERING OFF THE RAIN AND SNOW. THIS
LULL WILL LAST INTO SATURDAY MORNING...BEFORE A SECOND MORE
POTENT/WET SYSTEM MOVES IN FROM THE SOUTH. COORDINATED A WATCH
WITH THE EXTENDED FORECASTER THAT STARTS SATURDAY AFTERNOON FOR
AREAS SOUTH OF THE MISSOURI RIVER. SIGNIFICANT SNOW ACCUMULATION
CAN BE EXPECTED ACROSS THE WHOLE OF NORTHEAST MONTANA WITH THIS
SECOND STORM SYSTEM. GILCHRIST
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...
STORM VORTEX WILL BEGIN LIFTING OUT OF NORTHEAST MONTANA SUNDAY
NIGHT. WRAP-AROUND ENERGY FROM THE NORTHERLY FLOW ON THE WEST
SIDE OF THE LOW WILL FOCUS QPF OVER THE NORTHERN ZONES FOR
ADDITIONAL TAPERING OFF SNOWFALL. RISING HEIGHTS FROM THE WEST
MONDAY WILL CUT OFF ANY REMAINING PRECIPITATION. THE POSITIVE
LEANING RIDGE WILL BE QUICKLY FLATTENED BY A QUICK-MOVING
SHORTWAVE ACROSS ALBERTA AND SASKATCHEWAN MONDAY NIGHT. THE 00Z
GFS SHORTWAVE IS MORE SHALLOW THAN THE 12/00Z ECMWF SHORTWAVE.
TUESDAY AND WEDNESDAY THE MODELS SEND ADDITIONAL WEAK SHORTWAVES
ACROSS CANADA...NOT NECESSARILY IN AGREEMENT WITH EACH OTHER. BUT
AROUND WEDNESDAY NIGHT OR THURSDAY AN UPPER RIDGE SLOWLY BUILDS UP
OVER THE WEST...MAINTAINING UPPER FLOW FROM THE NORTHWEST LOCALLY.
AFTER THE PASSAGE OF THE SUNDAY NIGHT STORM THE CONDITIONS WILL
GENERALLY DRY AND COOL...WITH THE POSSIBILITY OF WARMING TO NORMAL
BY THE END OF THE PERIOD. SCT
&&
.AVIATION...
A STORM SYSTEM EJECTING RAIN AND SNOW NORTHEAST ACROSS EASTERN
MONTANA AND THE WESTERN DAKOTAS WILL CONTINUE TO LIFT NORTH TODAY
BRING MVFR CEILINGS AND VISIBILITIES. KGDV AND KSDY WILL BE
AFFECTED THE MOST WITH POSSIBLE IFR CONDITIONS FROM SNOW/LOW
CEILINGS. HIGH PRESSURE TO THE NORTH WILL RESULT IN LESSER AMOUNTS
OF RAIN AND SNOW AFFECTING KOLF AND KGGW. MORNING NORTHEAST WINDS
OF 10KT WILL INCREASE THIS AFTERNOON TO 15-25KT BEFORE DIMINISHING
AROUND SUNSET. SCT
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR CENTRAL AND SOUTHEAST PHILLIPS-CENTRAL AND
SOUTHERN VALLEY-DANIELS-SHERIDAN-WESTERN ROOSEVELT-NORTHERN
PHILLIPS-SOUTHWEST PHILLIPS-NORTHERN VALLEY-EASTERN ROOSEVELT.
WINTER STORM WARNING UNTIL 6 PM MDT THIS AFTERNOON FOR PETROLEUM-
GARFIELD-DAWSON-PRAIRIE-WIBAUX.
WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY
AFTERNOON FOR PETROLEUM-GARFIELD-MCCONE-RICHLAND-DAWSON-PRAIRIE-
WIBAUX.
&&
$$
WEATHER.GOV/GLASGOW
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000
FXUS65 KMSO 101009
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
409 AM MDT FRI OCT 10 2008
.DISCUSSION...A COLD MOIST AIR MASS RESIDES OVER MUCH OF WESTERN
MONTANA AND NORTH-CENTRAL IDAHO FOLLOWING THE DEVELOPMENT OF A
CLOSED UPPER LOW OVER IDAHO. ENHANCEMENT OF CLOUDS AND PRECIP
CONTINUES TO OCCUR ACROSS WEST-CENTRAL MONTANA AND LEMHI COUNTY
THIS MORNING AS MOISTURE CIRCULATES INTO THE SAME AREAS WHERE
BETTER SYNOPTIC LIFT/FORCING WAS TAKING PLACE. WEATHER RADAR AND
SURFACE OBSERVATIONS INDICATE LIGHT SNOW OCCURRING OVER THE HIGHER
TERRAIN WITH SOME VALLEY LOCATIONS PICKING UP SNOW ALSO. A TIGHT
NORTHERLY SURFACE PRESSURE GRADIENT COUPLED WITH HEALTHY NORTHEAST
WINDS ALOFT WILL RESULT IN BREEZY CONDITIONS. THE UPPER LOW SYSTEM
AND BULK OF ITS ASSOCIATED MOISTURE/DYNAMICS WILL SAG SOUTH
SLIGHTLY TONIGHT...SAGGING BETTER SNOWFALL SOUTH OVER EASTERN LEMHI
COUNTY. HOWEVER...AS THE LOW SYSTEM TRACKS NORTHEAST AGAIN THROUGH
EASTERN IDAHO ON SATURDAY...THIS WILL PUSH BETTER MOISTURE AND
DYNAMICS BACK NORTH INTO SOUTHWEST MONTANA...INCLUDING THE BUTTE
AREA. NORTHERLY WINDS WILL CONTINUE THROUGH SATURDAY CAUSING SOME
BLOWING AND DRIFTING OF SNOW. NO CHANGES MADE TO THE WINTER
HIGHLIGHTS (BELOW). WHILE THE BEST PRECIPITATION ASSOCIATED WITH
THIS PATTERN REMAINS FOCUSED OVER EASTERN LEMHI COUNTY AND
SOUTHWEST MONTANA...CONDITIONS GRADUALLY DRY AS YOU MOVE FARTHER
NORTH AWAY FROM THE LOW SYSTEM.
MONDAY THROUGH THURSDAY...NO CHANGES MADE TO THE FORECAST DURING
THIS PERIOD. AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL DRY AND
WARM CONDITIONS MONDAY. THE UPPER RIDGE WEAKENS TUESDAY IN
RESPONSE TO A DISTURBANCE MOVING INTO THE PACIFIC NORTHWEST. LOW
CHANCES OF PRECIPITATION WILL BE INTRODUCED BACK INTO THE
FORECAST TUESDAY AND WEDNESDAY AS THE AFFECTS OF THIS NEXT
DISTURBANCE SWEEPS ACROSS THE REGION.
&&
.AVIATION...CLOUDS/SNOWFALL WILL REDUCE VISIBILITIES AND CEILINGS
ACROSS MUCH OF WEST-CENTRAL MONTANA AND LEMHI COUNTY TODAY AND
TONIGHT. MOUNTAINS AND PASSES WILL BE OBSCURED IN THESE AREAS. IN
GENERAL...CONDITIONS WILL BE IMPROVED FARTHER NORTH ACROSS
NORTHWEST MONTANA WITH ONLY MOUNTAIN TOPS MASKED BY CLOUDS AND
LIGHT PRECIPITATION TODAY.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WARNING UNTIL 6 PM MDT SATURDAY FOR BUTTE/BLACKFOOT
REGION.
WINTER WEATHER ADVISORY UNTIL NOON MDT TODAY FOR
BITTERROOT/SAPPHIRE MOUNTAINS.
ID...WINTER STORM WARNING UNTIL 6 PM MDT SATURDAY FOR EASTERN LEMHI
COUNTY.
&&
$$
MSJ
000
FXUS65 KTFX 100942
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
342 AM MDT FRI OCT 10 2008
.DISCUSSION...
TODAY THROUGH SUNDAY...AN UPPER LEVEL LOW OVER SOUTHERN IDAHO...WILL
CONTINUE TO DEEPEN THROUGH THE DAY...WITH MOST DYNAMICS WELL SOUTH
OF MONTANA. HOWEVER...ABUNDANT MOISTURE WILL MOVE NORTHWARD INTO
THE REGION THROUGH THE WEEKEND. A GOOD UPSLOPE SURFACE PATTERN WILL
CONTINUES EAST OF THE DIVIDE THROUGH SUNDAY...BETWEEN A DEEPENING
SURFACE LOW OVER UTAH AND A CANADIAN SURFACE HIGH OVER CENTRAL
ALBERTA. THUS...A WINTER STORM WARNING WILL REMAIN TODAY THROUGH
SUNDAY AFTERNOON FOR MOST OF SOUTHWEST MONTANA AND THE SOUTHERN HALF
OF NORTH CENTRAL MONTANA. SNOW IS EXPECTED TO BE HEAVY AT TIMES WITH
ACCUMULATIONS OF 15 TO 30 INCHES OVER THE MOUNTAINS AND
3 TO 6 INCHES ACROSS THE PLAINS AND VALLEYS BY SUNDAY EVENING.
THERE WILL BE SOME MELTING OF SNOW...DUE TO WARM GROUND...AT LOWER
ELEVATIONS. THE BEST CHANCE FOR HEAVY SNOW WILL BE SATURDAY AFTERNOON
AND SATURDAY NIGHT...AS THE UPPER LOW MOVES NORTHEAST INTO SOUTHEAST
MONTANA BY SUNDAY EVENING. IT WILL BE UNSEASONABLY COLD THROUGH
SUNDAY...WITH TEMPERATURES RUNNING SOME 20 TO 30 DEGREES BELOW
SEASONAL AVERAGE. HIGHWAYS WILL BECOME ICY AT LOWER
ELEVATIONS...ESPECIALLY DURING THE NIGHT AND MORNING HOURS ALONG
WITH SOME BLOWING SNOW THROUGH THE PASSES AND CANYONS. CONDITIONS
WILL IMPROVE FROM THE NORTHWEST AS AN UPPER LEVEL RIDGE OF HIGH
PRESSURE OVER THE WEST COAST...BUILDS INTO CENTRAL ALBERTA.
WILLIAMSON DC
SUNDAY NIGHT THROUGH WEDNESDAY NIGHT...A DEEP...UPPER LEVEL LOW
PRESSURE SYSTEM WILL CONTINUE TO MOVE SLOWLY EAST...MOVING ACROSS
THE MONTANA/DAKOTA BORDER SUNDAY NIGHT. HIGH PRESSURE WILL BUILD
ALOFT OVER THE ZONES AND THE THE AIRMASS WILL BEGIN A DRYING AND
WARMING TREND THAT WILL LAST INTO TUESDAY. AN UPPER LEVEL LOW
PRESSURE TROF WILL CROSS THE ROCKIES EARLY WEDNESDAY. THIS WILL BE A
RATHER FAST-MOVING SYSTEM AND THE CHANCE OF PRECIPITATION WILL
REMAIN LOW. HOWEVER...BREEZY CONDITIONS WILL REMAIN OVER THE AREA
UNTIL THIS SHORT WAVE MOVES INTO EASTERN MONTANA. THE WARMING TREND
WILL ALSO BE INTERRUPTED UNTIL ANOTHER HIGH PRESSURE RIDGE BEGINS TO
BUILD OVER THE AREA ON THURSDAY. ZELZER
THURSDAY AND FRIDAY...A DISTURBANCE IN A NORTHWEST FLOW MOVES EAST
OUT OF THE ZONES THURSDAY ALLOWING HIGH PRESSURE TO BUILD IN FROM
THE WEST. A ZONAL FLOW SETS UP AHEAD OF THE NEXT PACIFIC SYSTEM BY
FRIDAY. SAUCIER
&&
.AVIATION...
UPDATED 0455Z.
AN UPPER LEVEL TROUGH WILL CONTINUE TO DEEPEN OVER THE PACIFIC
NORTHWEST AND INTO THE GREAT BASIN THROUGH 06Z SATURDAY. THE MOIST
EASTERLY FLOW ALOFT WILL KEEP WIDESPREAD CLOUDINESS WITH SNOW OVER
CENTRAL (KGTF AND KLWT) AND SOUTHWEST (KHLN AND KBZN) MONTANA.
CONDITIONS THERE WILL REMAIN IN THE LOW VFR/HIGH MVFR RANGE WITH
MOUNTAIN OBSCURATION. HOWEVER...CONDITIONS OVERNIGHT AND THROUGH THE
EARLY MORNING MAY LOWER TO IFR LEVELS AT TIMES DUE TO CLOUDS AND
SNOW. ONLY MID AND HIGH CLOUDS WILL LINGER OVER NORTH CENTRAL
MONTANA (KCTB AND KHVR TERMINALS) THROUGH FRIDAY...BUT A FEW SHOWERS
MAY DEVELOP THERE FRIDAY EVENING. OVERALL...SURFACE WINDS WILL
GENERALLY REMAIN NORTHEASTERLY AND BREEZY. COULSTON
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 34 23 34 21 / 60 60 60 40
CTB 38 21 34 17 / 30 30 30 10
HLN 38 25 34 25 / 60 60 50 50
BZN 38 26 36 25 / 100 80 80 80
WEY 33 19 30 16 / 90 90 80 80
DLN 33 20 30 17 / 80 60 50 80
HVR 44 25 39 18 / 20 30 30 10
LWT 34 22 30 17 / 80 80 80 80
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 6 PM MDT SUNDAY FOR MTZ008-012-014-
015-050>055.
&&
$$
SHORT TERM...WILLIAMSON DC
LONG TERM...ZELZER/SAUCIER
AVIATION...ZELZER
WEATHER.GOV/GREATFALLS
[top]
000
FXUS65 KBYZ 100922
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
322 AM MDT FRI OCT 10 2008
.SHORT TERM...VALID FOR TDY AND SAT...
OVERALL PICTURE OF THE FORECAST IN TACT AND DID NOT CHANGE MUCH
OF. SNOW AND/OR RAIN AND SNOW HAVE BEEN OCCURRING ALL NIGHT OVER
A LARGE PART OF THE AREA. PRECIPITATION HAS BEEN PRIMARILY SNOW
OVER CENTRAL AND WESTERN ZONES...WITH RAIN OR A RAIN AND SNOW
MIXTURE OVER PARTS OF THE EAST. HIGHER ELEVATIONS HAVE ALREADY
ACCUMULATED SEVERAL INCHES BASED ON SNOTEL REPORTS. WARM GROUND
TEMPERATURES HAVE LIMITED ACCUMULATIONS A BIT OVER THE PLAINS.
SNOW ACCUMULATIONS SEEM TO BE ELEVATION DEPENDANT...WITH AREAS
ABOVE 35 HUNDRED FEET GETTING SNOW TO STICK...BUT THOSE BELOW
HAVING A HARDER TIME. BURSTS OF HEAVIER SNOW OVERCOMES THE WARMER
GROUND. STRONG AND DEEP ISENTROPIC LIFT SHOULD ALLOW FOR A
CONTINUATION OF THE SNOW TODAY. THIS DEEP LIFT WILL BE ENHANCED
BY SHORTWAVES EJECTING OUT OF DEEPENING UPPER LOW OVER NORTHEAST
NEVADA. ONE SUCH WAVE WAS MOVING OVER SOUTH CENTRAL MONTANA AT
THE MOMENT AND THE RADAR DATA WAS FILLING IN AGAIN. SHOULD SEE
SNOW ALL MORNING...WITH PERIODS OF MODERATE SNOW EARLY. THE NEXT
SHORTWAVE TO ENTER THE AREA BY LATE MORNING WAS MOVING INTO
SOUTHWEST WYOMING THIS HOUR. THIS WAVE WILL ENHANCE THE STRONG
LIFT AGAIN BY LATE MORNING AND CONTINUE THE LIFT INTO EARLY
EVENING. HOW MUCH SNOW ACCUMULATES OVER THE PLAINS WILL BE VERY
TRICKY AS GROUND STILL FAIRLY WARM AND EARLY OCTOBER SUN
ANGLE...NOT TO MENTION WET SNOW...CAN LIMIT ACCUMULATIONS. A
LAYER OF SNOW THIS MORNING WOULD HELP TO NOT HINDER
ACCUMULATIONS. WILL CARRY CURRENT ACCUMULATIONS.
THE DEEP UPPER LOW DIGS INTO SOUTHERN NEVADA TONIGHT AND THE
SHORTWAVE ENERGY OF THIS AFTERNOON LIFTS NORTH. THIS SHOULD TAPER
SNOW OFF A BIT TONIGHT...BUT NOT TOTALLY. SNOW RATES MAY BE AS
STRONG BUT COOLING TEMPERATURES SHOULD ALLOW FOR EASIER
ACCUMULATIONS. ISENTROPIC LIFT WILL CONTINUE TONIGHT AND THUS
SNOW WILL LIKELY ACCUMULATE FURTHER. THE UPPER LOW OVER NEVADA
THEN EJECTS INTO UTAH SATURDAY. THIS WILL SEND A STRONG SURGE OF
UPPER DIFLUENCE INTO SOUTHERN MONTANA AND NORTHERN WYOMING. THIS
POWERFUL FORCING WILL CONTINUE THROUGH EARLY SUNDAY AS THE LOW
MOVES TOWARD SOUTHEAST MONTANA. THIS LOOKS TO BE THE BEST
POTENTIAL FOR HEAVY SNOW ACROSS THE AREA. TIMING MAY BE SLOWED
FURTHER AS THE LOW CONTINUES TO EVOLVE. BUMPED ACCUMULATIONS UP A
BIT MORE SATURDAY NIGHT. MODELS HAVE BEEN CONSISTENTLY PUSHING
DYNAMIC FORCING INTO SOUTHEAST MONTANA SATURDAY NIGHT AND HAVE
BUMPED ACCUMULATIONS THERE AS WELL. SNOW TOTALS FOR SATURDAY
NIGHT ALONE SHOULD APPROACH 6 INCHES IN BILLINGS AND COULD REACH
A FOOT OVER SOUTHEAST MONTANA. THE FAVORED UPSLOPE AREAS WILL
ALSO BE HIT VERY HARD BY THIS STORM AS UPSLOPE WILL BE VERY DEEP.
RED LODGE LOOKS TO BE IN LINE TO GET NEARLY 2 FEET OF SNOW BY THE
TIME IT ENDS SUNDAY NIGHT. THE MOUNTAINS WILL GET SEVERAL FEET OF
NEW SNOW FROM THIS STORM AS WELL. WILL KEEP THE HIGHLIGHTS GOING.
THIS DANGEROUS SITUATION WILL STRETCH OUT FOR SEVERAL DAYS. A
MAJORITY OF THE LEAVES HAVE NOT DROPPED YET AND HEAVY WET SNOW
COULD EASILY TAKE TREE LIMBS DOWN...THUS RUNNING A GREAT RISK OF
EXTENSIVE POWER OUTAGES AS THE SNOW ACCUMULATES. HUMPHREY
.LONG TERM...VALID FOR SUN...MON...TUE...WED...THU...
MODELS CONTINUE TO BE QUITE CONSISTENT REGARDING THE WINTER STORM
SYSTEM. STORM IMPACT WILL CONTINUE THROUGH SUNDAY AS WRAP AROUND
PRECIPITATION REMAINS ENTRENCHED ACROSS THE REGION. CURRENT TRACK
OF LOW MOVING ACROSS THE EASTERN ZONES SEEM TO SPREAD PRECIPITATION
ACROSS THE CWA...BUT BEST SNOW CHANCES LOOK LIKE THE AREA WEST OF
A LINE FROM KSHR TO KBIL TO ROUNDUP RESULTING IN AN ADDITIONAL 2
OR 3 INCHES OF SNOWFALL INTO SUNDAY NIGHT. SOME SNOW SHOWERS WILL
LINGER INTO MONDAY MORNING...BUT WILL PROVIDE LITTLE OR NO ADDITIONAL
ACCUMULATION.
THE WEATHER TURNS WARMER AND APPEARS QUITE DRY FOLLOWING THE PASSAGE OF
THE STORM SYSTEM...AS THE PATTERN BECOMES ZONAL AND DOWNSLOPE FLOW COMES
INTO PLAY. TEMPS WILL CLIMB FROM 40S MONDAY...STAYING COOL DUE TO
EXPECTED SNOW COVER...TO THE 60S ON FRIDAY. GILSTAD
&&
.AVIATION...
RAIN AND SNOW MIX OF SHOWERS...OF VARYING INTENSITY...WILL
CONTINUE THROUGH THE DAY TODAY. RAIN WILL BE MIXED WITH THE SNOW
AT TIMES THROUGH THE DAY...HIGHER TERRAIN WILL SEE SNOW THROUGH
THE DAY. LOW CEILINGS ARE EXPECTED TO REMAIN IN PLACE THROUGH THE
DAY AND OVERNIGHT...RESULTING IN FLIGHT CONDITIONS RANGING FROM
IFR TO VLIFR ACROSS THE REGION. THE MOUNTAINS WILL BE OBSCURED
THOUGH SUNDAY NIGHT. GILSTAD
&&
.PRELIMINARY POINT TEMP/POPS...
TDY SAT SUN MON TUE WED THU
-------------------------------------------------------
BIL 034 026/033 026/034 023/043 028/053 032/053 033/054
+/S ++/S +8/S 31/B 10/B 11/B 11/B
LVM 034 020/032 020/036 022/046 027/053 032/053 033/054
+/S ++/S +8/S 31/N 10/B 11/B 21/B
HDN 037 025/034 026/038 022/046 027/054 031/054 032/055
+/S ++/S +8/S 31/B 10/B 11/B 11/B
MLS 039 026/037 026/038 024/046 029/055 032/055 033/056
+/O 89/S +7/S 31/B 11/B 11/B 21/U
4BQ 035 026/035 025/037 023/046 028/055 030/055 031/056
+/S ++/S +6/S 31/B 10/U 11/U 21/B
BHK 037 025/035 025/039 022/045 024/053 029/053 031/054
+/S 78/S +5/O 31/B 11/B 11/B 21/B
SHR 035 023/034 026/035 022/045 027/053 029/053 031/054
+/S ++/S +8/S 31/B 10/U 11/U 12/W
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WARNING IN EFFECT UNTIL 6 AM MDT MONDAY FOR
ZONES 28>42-56>58-63>68.
WY...WINTER STORM WARNING IN EFFECT UNTIL 6 AM MDT MONDAY FOR
ZONES 98-99.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KTFX 100504
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1055 PM MDT THU OCT 9 2008
...UPDATE TO AVIATION...
.DISCUSSION...
UPDATE FORTHCOMING. HAVE MADE RELATIVELY MINOR ADJUSTMENTS TO THE
POP GRIDS TONIGHT MAINLY TO BETTER ALIGN WITH NEIGHBORING OFFICES.
FIRST SIGNIFICANT WINTER STORM OF THE SEASON CONTINUES TO DEVELOP
OVER THE AREA. DEEP UPPER TROF SLOWLY MOVES OVER THE AREA FRIDAY.
OVERRUNNING PRECIPITATION...MAINLY SNOW...STILL LOOKING GOOD THROUGH
THE WEEKEND. EMANUEL
&&
.AVIATION...
UPDATED 0455Z.
AN UPPER LEVEL TROUGH WILL CONTINUE TO DEEPEN OVER THE PACIFIC
NORTHWEST AND INTO THE GREAT BASIN THROUGH 06Z SATURDAY. THE MOIST
EASTERLY FLOW ALOFT WILL KEEP WIDESPREAD CLOUDINESS WITH SNOW OVER
CENTRAL (KGTF AND KLWT) AND SOUTHWEST (KHLN AND KBZN) MONTANA.
CONDITIONS THERE WILL REMAIN IN THE LOW VFR/HIGH MVFR RANGE WITH
MOUNTAIN OBSCURATION. HOWEVER...CONDITIONS OVERNIGHT AND THROUGH THE
EARLY MORNING MAY LOWER TO IFR LEVELS AT TIMES DUE TO CLOUDS AND
SNOW. ONLY MID AND HIGH CLOUDS WILL LINGER OVER NORTH CENTRAL
MONTANA (KCTB AND KHVR TERMINALS) THROUGH FRIDAY...BUT A FEW SHOWERS
MAY DEVELOP THERE FRIDAY EVENING. OVERALL...SURFACE WINDS WILL
GENERALLY REMAIN NORTHEASTERLY AND BREEZY. COULSTON
&&
.PREV DISCUSSION...ISSUED 242 PM MDT THU OCT 9 2008
TONIGHT THROUGH SUNDAY...FORECAST AREA IS BENEATH THE INFLUENCE
OF A DEVELOPING UPPER LEVEL TROUGH. FORECAST CONTINUES TO LOOK
FAVORABLE FOR THE DEVELOPMENT OF A SIGNIFICANT EARLY SEASON WINTER
STORM. SHOWERS ARE ALREADY DEVELOPING ACROSS SOUTHERN PORTIONS OF
CENTRAL MONTANA. AS LOW LEVEL UPSLOPE FLOW STRENGTHENS AND A BROAD
AREA OF UPWARD VERTICAL MOTION MOVES ACROSS THE REGION AM EXPECTING
WIDESPREAD SNOW TO DEVELOP ACROSS THE SOUTHERN HALF OF MY CWA
TONIGHT. THE UPPER TROUGH WILL CONTINUE TO STRENGTHEN...BECOMING A
CUTOFF LOW OVER THE GREAT BASIN BY FRIDAY MORNING. THIS FEATURE IS
EXPECTED TO REMAIN IN THIS GENERAL AREA WITH A GRADUAL DRIFT TO
THE NORTHEAST THROUGH SATURDAY AFTERNOON. ABUNDANT MOISTURE WILL
BE PUMPED INTO CENTRAL AND SOUTHWEST MONTANA WITH LIGHT SNOW
CONTINUING ACROSS THE SOUTHERN HALF OF MY CWA THROUGH THE WEEKEND.
HAVE DECIDED TO ISSUE A WINTER STORM WARNING FOR THE ENTIRE
SOUTHERN HALF OF MY FORECAST AREA BEGINNING TONIGHT AND CONTINUING
CLEAR THROUGH SUNDAY AFTERNOON. ALTHOUGH SNOW AMOUNTS ARE NOT
EXPECTED TO BE ESPECIALLY HEAVY IN ANY 12 OR 24 HOUR PERIOD...AND
THERE WILL INITIALLY BE SOME MELTING DUE TO WARM GROUND
TEMPERATURES...BY THE END OF THE WEEKEND AM EXPECTING 3 TO 6
INCHES SNOWFALL OVER THE PLAINS...WITH 15 TO 30 INCHES OVER THE
MOUNTAINS. I AM ALSO EXPECTING THAT THERE COULD BE SOME DAMAGE TO
TREES SINCE THERE ARE STILL LEAVES HAVE NOT FALLEN IN SOME
LOCATIONS...AND ROADWAYS COULD BECOME QUITE SLICK AS MELTING SNOW
FREEZES ONCE TEMPERATURES FALL. MPJ
FOR MONDAY THROUGH TUESDAY...EXPECT A NICE WARMING TREND OVER THE
REGION...AS A WEAK UPPER LEVEL RIDGE TRIES TO REBUILD OVER THE
REGION. TEMPERATURES WILL WARM UP NICELY IN THE CUT BANK AREA...AS A
BROWN GROUND AND BREEZY WEST WIND DEVELOPS. HOWEVER...IN AREAS THAT
RECEIVE A SNOW COVER OVER SOUTHWEST AND CENTRAL MONTANA...IT WILL
TAKE A FEW DAYS FOR THE SNOW TO MELT AND TEMPERATURES WILL BE SLOWER
TO WARM UP. ANY PRECIP WILL BE CONFINED MAINLY TO THE WESTERN
MOUNTAINS ON TUESDAY. BRUSDA
WEDNESDAY AND THURSDAY...LATEST MODELS INDICATE A HIGH PRESSURE
BUILDING OVER THE PACIFIC NORTHWEST DURING THIS PERIOD. WEAK
DISTURBANCES WILL FLOW THROUGH BUT MOISTURE APPEARS LIMITED AT THIS
POINT SO KEPT SLIGHT CHANCE POPS ALONG THE DIVIDE. TEMPERATURES ARE
EXPECTED TO BE NEAR SEASONAL AVERAGES. JNS
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 26 37 23 34 / 60 30 50 40
CTB 24 37 21 34 / 20 30 30 30
HLN 30 39 25 34 / 60 60 50 50
BZN 29 38 26 36 / 90 100 80 70
WEY 22 33 19 30 / 60 80 70 80
DLN 25 33 20 30 / 80 70 60 50
HVR 24 44 25 39 / 20 20 30 30
LWT 26 36 22 30 / 90 70 80 80
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM MDT SUNDAY
FOR MTZ008-012-014-015-050>055.
&&
$$
SHORT TERM...EMANUEL/MPJ
LONG TERM...BRUSDA/JNS
AVIATION...COULSTON
WEATHER.GOV/GREATFALLS
000
FXUS65 KBYZ 100313
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
913 PM MDT THU OCT 9 2008
.SHORT TERM...VALID FOR FRI AND SAT...
NO MAJOR CHANGES TO THE GOING FORECAST. TWEAKED PRECIPITATION AND
SNOWFALL AMOUNTS SLIGHTLY IN A FEW LOCATIONS BASED ON CURRENT
TRENDS. STRONG ISENTROPIC FORCING OVER CENTRAL AND WESTERN ZONES
IS RESULTING IN LIGHT TO MODERATE SNOWFALL RATES THIS EVENING.
SOME HEAVIER BURSTS OF SNOW HAVE BEEN NOTED IN THE COOKE CITY AREA
EARLIER WITH A QUICK COUPLE OF INCHES. TEMPERATURES ARE HOVERING
IN THE LOW TO MID 30S IN THE WEST AND CENTRAL AND SOUTHEAST WHERE
STRONGEST FORCING IS LOCATED...WARMER TEMPERATURES NORTHEAST WHERE
FORCING AND DYNAMIC COOLING ARE NOT QUITE AS STRONG. WILL CONTINUE
TO SEE TEMPERATURES SLOWLY COOL INTO THE UPPER 20S AND LOWER 30S
OVERNIGHT...WITH MODELS AGREEING ON CONTINUED STRONG ISENTROPIC
LIFT ON THE 290-300K SURFACES KEEPING STEADY LIGHT TO MODERATE
PRECIPITATION GOING. OCCASIONAL PERIODS OF UPPER LEVEL DYNAMICS
WILL ENHANCE PRECIPITATION RATES RESULTING IN BRIEF HEAVY SNOWFALL
AT TIMES. ROAD SURFACE TEMPERATURES ARE SLOWLY FALLING INTO THE
30S ACROSS THE AREA WITH MID 30S IN THE BILLINGS AREA. SHOULD SEE
SNOW START TO STICK ON ROADWAYS AFTER MIDNIGHT FROM BILLINGS
WEST...AND AT ELEVATIONS ABOVE 4500 FEET IN THE EAST. BY MORNING
SNOW WILL LIKELY BE STICKING TO ROAD SURFACES ACROSS THE AREA.
EVEN SMALL ACCUMULATIONS OF HEAVY WET SNOW WILL CAUSE TREE AND
POWER LINE DAMAGE...AND SHOULD SEE SUFFICIENT ACCUMULATIONS BY LATE
TONIGHT TO START TO SEE THIS OCCUR. THIS IS COVERED WELL IN THE
CURRENT WARNING AND WILL ONLY UPDATE THE WARNING TO REFRESH
WORDING. CHAMBERS
.LONG TERM...VALID FOR SUN...MON...TUE...WED...THU...
THE WINTER STORMS IMPACT WILL CONTINUE INTO SUNDAY. GFS/ECMWF
CONSISTENT WITH UPPER LOW PROGRESSING FROM NORTHERN WYOMING INTO
EASTERN MONTANA ON SUNDAY. WRAP AROUND MOISTURE WILL REMAIN
ENTRENCHED ACROSS THE REGION. GIVEN THIS TRACK SOLUTION...THE
HEAVIEST SNOW WOULD LINGER FROM BILLINGS NORTHWESTWARD FOR YET
ANOTHER 3 OR 5 INCHES OF ADDITIONAL SNOWFALL INTO SUNDAY NIGHT. A
FEW SNOW SHOWERS COULD LINGER IN CYCLONIC FLOW AROUND THE SYSTEM
INTO MONDAY BUT NO ADDITIONAL ACCUMULATIONS BEFORE EVERYTHING
CLEARS OUT.
MOSTLY DRY PATTERN DEVELOPS FOR TUESDAY AND BEYOND AS FLOW BECOMES
MORE ZONAL AND DOWNSLOPE. HAVE LOWERED TEMPERATURES EARLY IN THE
WEEK IN ANTICIPATION OF A DEEPER SNOW COVER TO MELT OFF. FRIEDERS
&&
.AVIATION...
SNOW WILL CONTINUE THROUGHOUT THE NIGHT TONIGHT. LOCATIONS FROM
KMLS-KBHK STILL EXPERIENCING SOME LIGHT RAIN NOW BUT THIS IS
EXPECTED TO CHANGE OVER TO SNOW LATER THIS EVENING. THE SNOW WILL
BE HEAVY AT TIMES...MAINLY FROM A KMLS-KBIL-KLVM LINE AND AREAS
SOUTH. CONDITIONS WILL CONTINUE TO DETERIORATE THROUGHOUT THE
EVENING AND OVERNIGHT HOURS WITH LOWERING VISIBILITIES AND
CEILINGS. EXPECT IFR TO LIFR WITH SOME VLIFR CONDITIONS
THROUGHOUT THE NIGHT. THE MOUNTAINS WILL BE OBSCURED.
FOR KBIL...EXPECT VLIFR CONDITIONS TO BE PREDOMINANT THROUGH MUCH
OF THE NIGHT WITH A FEW BRIEF PERIODS OF IMPROVEMENT TO LIFR
EXPECTED. SIGNIFICANT IMPROVEMENT TO IFR LEVELS IS NOT LIKELY UNTIL
POSSIBLY MID MORNING FRIDAY WITH STRONG ISENTROPIC LIFT
CONTINUING...AND THOSE PERIODS WILL BE BRIEF. HOOLEY/CHAMBERS
&&
.PRELIMINARY POINT TEMP/POPS...
FRI SAT SUN MON TUE WED THU
-----------------------------------------------------------
BIL 027/034 026/033 026/034 023/043 028/053 032/053 033/054
++/S ++/S +8/S 31/B 10/B 11/B 11/B
LVM 022/033 019/032 019/036 022/046 027/053 032/053 033/054
++/S ++/S +8/S 31/N 10/B 11/B 21/B
HDN 028/037 026/034 026/038 022/046 027/054 031/054 032/055
++/S ++/S +8/S 31/B 10/B 11/B 11/B
MLS 031/039 026/037 026/038 024/046 029/055 032/055 033/056
++/S 89/S 97/S 31/B 11/B 11/B 21/U
4BQ 030/037 025/035 025/037 023/046 028/055 030/055 031/056
++/S ++/S +6/S 31/B 10/U 11/U 21/B
BHK 027/037 025/035 025/039 022/045 024/053 029/053 031/054
++/S 78/S 85/O 31/B 11/B 11/B 21/B
SHR 028/036 025/034 026/035 022/045 027/053 029/053 031/054
++/S ++/S +8/S 31/B 10/U 11/U 12/W
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WARNING IN EFFECT UNTIL 6 AM MDT MONDAY FOR
ZONES 28>42-56>58-63>68.
WY...WINTER STORM WARNING IN EFFECT UNTIL 6 AM MDT MONDAY FOR
ZONES 98-99.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KGGW 100301
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
901 PM MDT THU OCT 9 2008
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT...
SATELLITE CHANNELS SHOW ENHANCEMENT WITH 115KT JET STREAK MOVING
ENE ACROSS ND. MOISTURE/CLOUDS ARE ALSO TENDING TO INCREASE BEHIND
THIS FEATURE THOUGH...ACROSS WY AND E MT. MODELS SHOW ANOTHER
ASSOCIATED JET STREAK DEVELOPING LATER TONIGHT IN WY. THIS
ASSOCIATED WITH THE UPPER TROUGH OVER THE PACIFIC NW THAT IS
INTENSIFYING AS IT MOVES SE...FORECAST BY MODELS TO CLOSE OFF LATE
TONIGHT. THIS IS CAUSING UPPER FLOW TO TIGHTEN AND BACK OVER E MT.
EXPANDING REFLECTIVITY IN S PART OF OUR CWA ON 88D RADAR...BUT
RETURNS ARE WEAK AND TEMP/DEW POINT SPREADS 15-25F. MODELS
INDICATE AIRMASS TO MOISTEN UP ENOUGH AND UPPER LEVEL DYNAMICS
STRENGTHEN...TO BEGIN SOME SIGNIFICANT RAINFALL. THE DRY AIRMASS
AND RESULTING LOW WET BULB TEMPS MEAN THAT ONCE THE RAIN GETS
GOING WITH SOME INTENSITY IT SHOULD TURN TO SNOW LATE TONIGHT.
DRIER AIRMASS IN N HALF OF CWA...WITH A SURFACE HIGH CENTER IN S
AB. THIS WILL KEEP N HALF OF CWA GENERALLY DRY TONIGHT. MODELS
SEEM TO HAVE ONLY A FAIR HANDLE ON FEATURES FOR TONIGHT...BUT THE
ONGOING FORECAST IS REASONABLE...AND SO UPDATES IN AWAITING FOR
THE EXPECTED PRECIP SCENARIO TO GET GOING. SIMONSEN
PREVIOUS SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH
SATURDAY...A BUSY FEW DAYS...WEATHER WISE...IN STORE FOR NORTHEAST
MONTANA. AN UPPER TROUGH DIGGING INTO THE GREAT BASIN WILL EJECT
WARMER MORE MOIST AIR OVER A POLAR AIRMASS IN PLACE OVER EASTERN
MONTANA. THIS OVERRUNNING WILL DRIVE A MIX OF RAIN AND SNOW ACROSS
THE SOUTHERN ZONES...MAINLY SOUTH OF HIGHWAY 200. HAVE UPGRADED
THE EXISTING WATCH FOR THE SOUTHERN ZONES TO A WINTER STORM
WARNING. NORTHERLY WINDS OF 15 TO 25 MPH WILL ACCOMPANY THE
STORM...HOWEVER GIVEN THE HEAVY WET NATURE TO THE SNOWFALL DO NOT
EXPECT MUCH IN THE WAY OF BLOWING AND DRIFTING. THESE WINDS MAY
ALSO REQUIRE A LAKE WIND ADVISORY FOR FORT PECK LAKE FRIDAY
AFTERNOON. BY FRIDAY EVENING THE LIFT GENERATED BY THE OVERRUNNING
WILL TAPER OFF...SUBSEQUENTLY TAPERING OFF THE RAIN AND SNOW. THIS
LULL WILL LAST INTO SATURDAY MORNING...BEFORE A SECOND MORE
POTENT/WET SYSTEM MOVES IN FROM THE SOUTH. COORDINATED A WATCH
WITH THE EXTENDED FORECASTER THAT STARTS SATURDAY AFTERNOON FOR
AREAS SOUTH OF THE MISSOURI RIVER. SIGNIFICANT SNOW ACCUMULATION
CAN BE EXPECTED ACROSS THE WHOLE OF NORTHEAST MONTANA WITH THIS
SECOND STORM SYSTEM. GILCHRIST
.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...
ONLY MINOR ADJUSTMENTS INTRODUCED TO THE GOING PACKAGE AS
CONFIDENCE REMAINS HIGH IN A MAJOR STORM SYSTEM THIS WEEKEND.
LATEST GFS ENSEMBLES MAINTAIN A TIGHT CLUSTER OF UPPER LOW TRACKS
THROUGH 00Z MONDAY WITH THE DETERMINISTIC RUN EXHIBITING ONLY
SMALL DEVIATIONS FROM PREVIOUS RUNS. ON THE OTHER HAND...THE 12Z
ECMWF HAS TRENDED SLOWER WITH THE LOW/S PROGRESSION BUT AT LEAST
STICKS TO A SIMILAR TRACK. GIVEN PRONOUNCED UPPER LEVEL DIVERGENCE
SATURDAY NIGHT INTO SUNDAY HELPING TO SUSTAIN A WARM TROWAL
SIGNATURE ALONG THE 295-305K ISENTROPIC SURFACE...PERIODS OF HEAVY
SNOW ARE CERTAINLY POSSIBLE AS THE 700MB LOW TRACKS NEAR THE I-94
CORRIDOR. DID RAMP UP SNOW AMOUNTS GIVEN THIS FORCING AND ALSO
ISSUED TWO WINTER STORM WATCHES TO BETTER ADDRESS THE ONSET OF
ACCUMULATING SNOW. MCZ
PREVIOUS LONG TERM DISCUSSION...
A WINTER-LIKE CYCLONIC STORM SYSTEM WILL BE WELL UNDERWAY AND
MOVING THROUGH EASTERN MONTANA WHEN THE EXTENDED PERIOD OPENS ITS
DOOR SATURDAY NIGHT. MODELS AND ENSEMBLES HAVE BECOME COMFORTABLE
WITH THIS WEEKEND STORM. THE USUAL EXPLODED ENSEMBLE SPAGHETTI
PLOTS HAVE ALL LINED UP CRISPLY AROUND THIS LOW THROUGH SUNDAY.
THE 00Z GFS HAS COME TO CLOSELY RESEMBLE THE 12Z ECMWF IN TIMING
AND LOCATION. DETAILS BEGIN TO FUZZ A LITTLE SUNDAY NIGHT AND
MONDAY AS THE MAIN ENERGY OF THE STORM LIFTS INTO CANADA AND THE
FRONT MOVES EAST. MODELS BEGIN TO DIFFER ON HOW LONG THE WRAP-
AROUND COMMA HEAD LINGERS OVER THE FORECAST AREA ON MONDAY. SINCE
THE SYSTEM HAS BEEN RATHER PROGRESSIVE IT WOULD MAKE SENSE THAT BY
MONDAY AFTERNOON THE STORM WILL HAVE EXITED EAST...REPLACED BY A
TEMPORARILY AMPLIFIED UPPER RIDGE FROM THE WEST. THE RIDGE WILL
BECOME FLATTENED TUESDAY BY A QUICK-MOVING SHORTWAVE TREKKING
ACROSS NORTHERN ALBERTA/SASKATCHEWAN. THE REMAINDER OF THE PERIOD
SHOULD CONTINUE MOSTLY DRY AND SEASONAL WITH NEAR ZONAL UPPER
FLOW.
THE MAIN QUESTION CONCERNING SATURDAY NIGHT AND SUNDAY WILL BE
THE AMOUNT OF SNOW THAT COULD FALL. THE LARGE UPPER CLOSED LOW
WILL BE CENTERED OVER SOUTHEASTERN IDAHO AND WESTERN WYOMING. THIS
WILL BE THE PERFECT SPOT TO DIRECT A VERY STRONG UPPER JET INTO
EASTERN MONTANA AND THE WESTERN DAKOTAS. IN ADDITION AN INVERTED
SURFACE TROUGH WILL BE SLIDING NORTH INTO THE SAME AREA. THE
RESULT WILL BE VERY STRONG OMEGA LIFT AND SUPPORT ALONG WITH VERY
IMPRESSIVE NEGATIVE Q-VECTOR DIVERGENCE NUMBERS. THE RESULTING QPF
FOCUS IN THE AFOREMENTIONED AREAS SATURDAY NIGHT IS A HALF INCH TO
INCH OF WATER...WITH ANOTHER HALF INCH ON SUNDAY. THE AMOUNT OF
SNOWFALL COULD DEPEND ON THE TEMPERATURES AND HOW THE
PRECIPITATION BEGINS ON SATURDAY DURING THE DAY. 850MB
TEMPERATURES SATURDAY WILL BEGIN AROUND -4C AND DROP TO -6C BY
SUNDAY MORNING...WHILE GUIDANCE SUGGESTS SURFACE TMIN IN THE MID
20S THEN RISING INTO THE MID 30S SUNDAY. WITH THE PROGRESSIVE
NATURE OF THIS STORM THE RESULTING TEMPERATURES COULD DEVIATE
QUITE A BIT FROM GUIDANCE. EXPECT THE MAJORITY OF PRECIPITATION
TO FALL AS SNOW BUT THE COLD BOUNDARY ONLY EXTENDS A SHORT WAY
BEYOND THE EASTERN BORDER SO THERE REMAINS UNCERTAINTY IN
PRECIPITATION TYPE. SCT
&&
.AVIATION...
VFR THIS EVENING WITH NORTHEAST WINDS REMAINING AROUND 10 KTS AT
ALL TERMINALS. MID LEVEL CLOUDS WILL CONTINUE TO INCREASE IN
COVERAGE TONIGHT AHEAD OF AN INTENSIFYING STORM SYSTEM IN WYOMING.
THIS STORM WILL NUDGE NORTH LATER TONIGHT MAINLY AFFECTING KGDV
WITH POSSIBLE MVFR CONDITIONS AND A MIX OF RAIN AND SNOW LATER
TONIGHT. MVFR CONDITIONS WITH A RAIN/SNOW MIX WILL SLOWLY SPREAD
NORTH ACROSS ALL TERMINALS FRIDAY. RAS/SCT
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR CENTRAL AND SOUTHEAST PHILLIPS-CENTRAL AND
SOUTHERN VALLEY-DANIELS-SHERIDAN-WESTERN ROOSEVELT-NORTHERN
PHILLIPS-SOUTHWEST PHILLIPS-NORTHERN VALLEY-EASTERN ROOSEVELT.
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM MDT FRIDAY
FOR PETROLEUM-GARFIELD-DAWSON-PRAIRIE-WIBAUX.
WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY
AFTERNOON FOR PETROLEUM-GARFIELD-MCCONE-RICHLAND-DAWSON-PRAIRIE-
WIBAUX.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KTFX 100255
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
850 PM MDT THU OCT 9 2008
.DISCUSSION...
UPDATE FORTHCOMING. HAVE MADE RELATIVELY MINOR ADJUSTMENTS TO THE
POP GRIDS TONIGHT MAINLY TO BETTER ALIGN WITH NEIGHBORING OFFICES.
FIRST SIGNIFICANT WINTER STORM OF THE SEASON CONTINUES TO DEVELOP
OVER THE AREA. DEEP UPPER TROF SLOWLY MOVES OVER THE AREA FRIDAY.
OVERRUNNING PRECIPITATION...MAINLY SNOW...STILL LOOKING GOOD THROUGH
THE WEEKEND. EMANUEL
&&
.AVIATION...
UPDATED 0025Z.
AN UPPER LEVEL TROUGH WILL CONTINUE TO DEEPEN OVER THE PACIFIC
NORTHWEST AND INTO THE GREAT BASIN THROUGH 00Z SATURDAY. THE
EASTERLY FLOW ALOFT WILL BECOME INCREASINGLY MOIST DURING THE
PERIOD. HOWEVER...NORTH CENTRAL MONTANA (KCTB AND KHVR TERMINALS)
WILL REMAIN ON THE NORTHERN EDGE OF THE MOISTURE...WHERE VFR
CONDITIONS WITH AREAS OF MID LEVEL CLOUDINESS AND A FEW SHOWERS WILL
PERSIST. FARTHER SOUTH...ACROSS CENTRAL (KGTF AND KLWT) AND
SOUTHWEST (KHLN AND KBZN) MONTANA...WIDESPREAD CLOUDINESS AND
PRECIPITATION WILL KEEP CONDITIONS IN THE LOW VFR/HIGH MVFR RANGE
WITH MOUNTAIN OBSCURATION. HOWEVER...CONDITIONS OVERNIGHT MAY LOWER
TO IFR LEVELS AT TIMES DUE TO CLOUDS AND SNOW. SURFACE WINDS WILL
GENERALLY REMAIN NORTHEASTERLY AND BREEZY. COULSTON
&&
.PREV DISCUSSION...ISSUED 242 PM MDT THU OCT 9 2008
TONIGHT THROUGH SUNDAY...FORECAST AREA IS BENEATH THE INFLUENCE
OF A DEVELOPING UPPER LEVEL TROUGH. FORECAST CONTINUES TO LOOK
FAVORABLE FOR THE DEVELOPMENT OF A SIGNIFICANT EARLY SEASON WINTER
STORM. SHOWERS ARE ALREADY DEVELOPING ACROSS SOUTHERN PORTIONS OF
CENTRAL MONTANA. AS LOW LEVEL UPSLOPE FLOW STRENGTHENS AND A BROAD
AREA OF UPWARD VERTICAL MOTION MOVES ACROSS THE REGION AM EXPECTING
WIDESPREAD SNOW TO DEVELOP ACROSS THE SOUTHERN HALF OF MY CWA
TONIGHT. THE UPPER TROUGH WILL CONTINUE TO STRENGTHEN...BECOMING A
CUTOFF LOW OVER THE GREAT BASIN BY FRIDAY MORNING. THIS FEATURE IS
EXPECTED TO REMAIN IN THIS GENERAL AREA WITH A GRADUAL DRIFT TO
THE NORTHEAST THROUGH SATURDAY AFTERNOON. ABUNDANT MOISTURE WILL
BE PUMPED INTO CENTRAL AND SOUTHWEST MONTANA WITH LIGHT SNOW
CONTINUING ACROSS THE SOUTHERN HALF OF MY CWA THROUGH THE WEEKEND.
HAVE DECIDED TO ISSUE A WINTER STORM WARNING FOR THE ENTIRE
SOUTHERN HALF OF MY FORECAST AREA BEGINNING TONIGHT AND CONTINUING
CLEAR THROUGH SUNDAY AFTERNOON. ALTHOUGH SNOW AMOUNTS ARE NOT
EXPECTED TO BE ESPECIALLY HEAVY IN ANY 12 OR 24 HOUR PERIOD...AND
THERE WILL INITIALLY BE SOME MELTING DUE TO WARM GROUND
TEMPERATURES...BY THE END OF THE WEEKEND AM EXPECTING 3 TO 6
INCHES SNOWFALL OVER THE PLAINS...WITH 15 TO 30 INCHES OVER THE
MOUNTAINS. I AM ALSO EXPECTING THAT THERE COULD BE SOME DAMAGE TO
TREES SINCE THERE ARE STILL LEAVES HAVE NOT FALLEN IN SOME
LOCATIONS...AND ROADWAYS COULD BECOME QUITE SLICK AS MELTING SNOW
FREEZES ONCE TEMPERATURES FALL. MPJ
FOR MONDAY THROUGH TUESDAY...EXPECT A NICE WARMING TREND OVER THE
REGION...AS A WEAK UPPER LEVEL RIDGE TRIES TO REBUILD OVER THE
REGION. TEMPERATURES WILL WARM UP NICELY IN THE CUT BANK AREA...AS A
BROWN GROUND AND BREEZY WEST WIND DEVELOPS. HOWEVER...IN AREAS THAT
RECEIVE A SNOW COVER OVER SOUTHWEST AND CENTRAL MONTANA...IT WILL
TAKE A FEW DAYS FOR THE SNOW TO MELT AND TEMPERATURES WILL BE SLOWER
TO WARM UP. ANY PRECIP WILL BE CONFINED MAINLY TO THE WESTERN
MOUNTAINS ON TUESDAY. BRUSDA
WEDNESDAY AND THURSDAY...LATEST MODELS INDICATE A HIGH PRESSURE
BUILDING OVER THE PACIFIC NORTHWEST DURING THIS PERIOD. WEAK
DISTURBANCES WILL FLOW THROUGH BUT MOISTURE APPEARS LIMITED AT THIS
POINT SO KEPT SLIGHT CHANCE POPS ALONG THE DIVIDE. TEMPERATURES ARE
EXPECTED TO BE NEAR SEASONAL AVERAGES. JNS
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 26 37 23 34 / 60 30 50 40
CTB 24 37 21 34 / 20 30 30 30
HLN 30 39 25 34 / 60 60 50 50
BZN 29 38 26 36 / 90 100 80 70
WEY 22 33 19 30 / 60 80 70 80
DLN 25 33 20 30 / 80 70 60 50
HVR 24 44 25 39 / 20 20 30 30
LWT 26 36 22 30 / 90 70 80 80
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM MDT SUNDAY
FOR MTZ008-012-014-015-050>055.
&&
$$
SHORT TERM...EMANUEL/MPJ
LONG TERM...BRUSDA/JNS
AVIATION...COULSTON
WEATHER.GOV/GREATFALLS
000
FXUS65 KMSO 100152
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
752 PM MDT THU OCT 9 2008
.UPDATE...INCREASED THE POTENTIAL FOR PRECIPITATION THIS EVENING
IN THE VALLEYS OF WESTERN MONTANA. ALSO INCREASED WINDS THROUGH
TONIGHT IN THE HIGHER ELEVATIONS.
&&
.DISCUSSION...A BROAD AREA OF LIGHT RAIN AND SNOW SHOWERS
CONTINUES OVER WESTERN MONTANA AND CENTRAL IDAHO THIS EVENING.
SNOW LEVELS HAVE DIPPED BETWEEN 4500 AND 5000 FEET ALONG AND JUST
WEST OF THE CONTINENTAL DIVIDE. MANY MOUNTAIN PASSES HAVE SEEN AT
LEAST SOME MINOR SNOW ACCUMULATIONS. SOME RAIN AND SNOW HAVE BEEN
REPORTED IN THE VALLEYS ACROSS WESTERN MONTANA THIS EVENING SO
DECIDED TO INCREASE THE POTENTIAL FOR MEASURABLE
PRECIPITATION...THOUGH ANY SNOW ACCUMULATIONS WILL STILL BE MINOR.
&&
.AVIATION...A COLD AND WINTRY WEATHER SYSTEM WILL IMPACT THE
NORTHERN ROCKIES BEGINNING THIS EVENING AND CONTINUING THROUGH THE
WEEKEND BEFORE EXITING THE AREA. EASTERLY WINDS WILL INCREASE AND
BECOME GUSTY THIS EVENING AS THE SURFACE PRESSURE GRADIENT
TIGHTENS. WINDS ARE EXPECTED TO REMAIN STRONG THROUGH FRIDAY NIGHT.
SNOW AND BLOWING SNOW WILL IMPACT THE NORTHERN ROCKIES WITH THIS
SYSTEM WITH HEAVIER SNOWFALL EXPECTED NEAR TERMINALS KSMN AND
KBTM. IFR CEILINGS ARE NOT OUT OF THE QUESTION NEAR THESE
TERMINALS AND THEIR VICINITIES UNDER HEAVIER BANDS OF
PRECIPITATION. VISIBILITIES WILL BE REDUCED AT TIMES WITH MOUNTAIN
AND PASS OBSCURATIONS LIKELY.
&&
.PREV DISCUSSION... /ISSUED 250 PM MDT THU OCT 9 2008/
..FIRST MAJOR WINTER STORM OF THE FALL SEASON TO AFFECT SOUTHWEST
MONTANA AND LEMHI COUNTY IDAHO...
DISCUSSION...A HIGHLY DYNAMIC WINTER WEATHER SYSTEM WILL BEGIN TO
AFFECT THE NORTHERN ROCKIES STARTING TONIGHT AND WILL CONTINUE
THROUGH THE DURATION OF THE WEEKEND. LOCATIONS IN HIGHER
ELEVATIONS ABOVE 5500 FEET WILL BE THE FIRST TO SEE SNOW SHOWERS
DEVELOPING THIS EVENING WITH LIGHT ACCUMULATIONS POSSIBLE. AREAS
TO BE MOSTLY IMPACTED BY THESE ACCUMULATIONS WILL BE ALONG THE
CONTINENTAL DIVIDE...LEMHI COUNTY AND LOST TRAIL PASS. NORTHWEST MT
VALLEYS WILL NOT BE IMPACTED BY SNOW WITH THIS EVENT...BUT WILL
EXPERIENCE GUSTY NORTHEAST WINDS.
SNOW OVER SOUTHWEST MT AND LEMHI COUNTY WILL CONTINUE STEADILY
THROUGH THE DAY FRIDAY AND INTO SATURDAY WITH SNOW LEVELS LOWERING
TO THE VALLEY FLOORS AND MAY EXPERIENCE LIGHT SNOW ACCUMULATIONS. A
TIGHTENING NORTHEAST TO SOUTHEAST PRESSURE GRADIENT WILL ALLOW
GUSTY NORTHEAST WINDS TO DEVELOP FRIDAY THROUGH SATURDAY...WITH
AREAS OF BLOWING SNOW. IT SHOULD BE NOTED THAT WITH THESE TYPE OF
GUSTY WINDS...OVERNIGHT TEMPERATURES WILL FEEL QUITE BRISK AS THE
WINDS HELP TO LOWER TEMPERATURES INTO THE TEENS. DUE TO THE EARLY
ONSET OF SNOW FOR THIS SEASON...DECIDUOUS TREES RUN THE RISK OF
BROKEN BRANCHES DUE TO ACCUMULATING SNOW. WINTER WEATHER
ADVISORIES HAVE BEEN UPGRADED TO WINTER STORM WARNINGS TO ACCOUNT
FOR THE LONG DURATION OF ACCUMULATING SNOW AND THE POSSIBILITY OF
DAMAGE TO TREES.
THE DEEP LOW PRESSURE SYSTEM WILL DIG AS FAR SOUTH AS UTAH BY
SATURDAY AFTERNOON WITH MOISTURE WRAPPING AROUND IT...CONTINUING
SNOWS OVER SOUTHWEST MT AND LEMHI COUNTY INTO EARLY SUNDAY. BY SUNDAY
AFTERNOON...THE LOW TRACKS INTO EASTERN MT WITH SNOW TAPERING
OFF. ANOTHER VERY COLD NIGHT IS EXPECTED SUNDAY NIGHT...AS CLOUDS
BEGIN TO CLEAR OUT OF THE AREA.
MONDAY THROUGH THURSDAY...A BRIEF DRY PERIOD WILL TAKE HOLD ON MONDAY
AS THE OVERALL WEATHER PATTERN TRANSITIONS FROM THE STRONG UPPER
LEVEL LOW FROM THE PAST WEEKEND TO MORE OF A WESTERLY FLOW FOR THE
REMAINDER OF THE WEEK. THIS TYPE OF FLOW PATTERN TYPICALLY
INDICATES A SHOWERY PRECIPITATION REGIME THAT SHOULD BE CONFINED
MAINLY TO HIGHER TERRAIN.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WARNING FROM 3 AM FRIDAY TO 6 PM MDT SATURDAY FOR
BUTTE/BLACKFOOT REGION.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 12 PM MDT
FRIDAY FOR BITTERROOT/SAPPHIRE MOUNTAINS.
ID...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM MDT SATURDAY
FOR EASTERN LEMHI COUNTY.
&&
$$
UPDATE...LOEFFELBEIN
PREVIOUS DISCUSSION...ALLEGRETTO/FELSCH
AVIATION...LOEFFELBEIN
000
FXUS65 KTFX 100027
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
625 PM MDT THU OCT 9 2008
...UPDATE TO AVIATION...
.DISCUSSION...
TONIGHT THROUGH SUNDAY...FORECAST AREA IS BENEATH THE INFLUENCE
OF A DEVELOPING UPPER LEVEL TROUGH. FORECAST CONTINUES TO LOOK
FAVORABLE FOR THE DEVELOPMENT OF A SIGNIFICANT EARLY SEASON WINTER
STORM. SHOWERS ARE ALREADY DEVELOPING ACROSS SOUTHERN PORTIONS OF
CENTRAL MONTANA. AS LOW LEVEL UPSLOPE FLOW STRENGTHENS AND A BROAD
AREA OF UPWARD VERTICAL MOTION MOVES ACROSS THE REGION AM EXPECTING
WIDESPREAD SNOW TO DEVELOP ACROSS THE SOUTHERN HALF OF MY CWA
TONIGHT. THE UPPER TROUGH WILL CONTINUE TO STRENGTHEN...BECOMING A
CUTOFF LOW OVER THE GREAT BASIN BY FRIDAY MORNING. THIS FEATURE IS
EXPECTED TO REMAIN IN THIS GENERAL AREA WITH A GRADUAL DRIFT TO
THE NORTHEAST THROUGH SATURDAY AFTERNOON. ABUNDANT MOISTURE WILL
BE PUMPED INTO CENTRAL AND SOUTHWEST MONTANA WITH LIGHT SNOW
CONTINUING ACROSS THE SOUTHERN HALF OF MY CWA THROUGH THE WEEKEND.
HAVE DECIDED TO ISSUE A WINTER STORM WARNING FOR THE ENTIRE
SOUTHERN HALF OF MY FORECAST AREA BEGINNING TONIGHT AND CONTINUING
CLEAR THROUGH SUNDAY AFTERNOON. ALTHOUGH SNOW AMOUNTS ARE NOT
EXPECTED TO BE ESPECIALLY HEAVY IN ANY 12 OR 24 HOUR PERIOD...AND
THERE WILL INITIALLY BE SOME MELTING DUE TO WARM GROUND
TEMPERATURES...BY THE END OF THE WEEKEND AM EXPECTING 3 TO 6
INCHES SNOWFALL OVER THE PLAINS...WITH 15 TO 30 INCHES OVER THE
MOUNTAINS. I AM ALSO EXPECTING THAT THERE COULD BE SOME DAMAGE TO
TREES SINCE THERE ARE STILL LEAVES HAVE NOT FALLEN IN SOME
LOCATIONS...AND ROADWAYS COULD BECOME QUITE SLICK AS MELTING SNOW
FREEZES ONCE TEMPERATURES FALL. MPJ
FOR MONDAY THROUGH TUESDAY...EXPECT A NICE WARMING TREND OVER THE
REGION...AS A WEAK UPPER LEVEL RIDGE TRIES TO REBUILD OVER THE
REGION. TEMPERATURES WILL WARM UP NICELY IN THE CUT BANK AREA...AS A
BROWN GROUND AND BREEZY WEST WIND DEVELOPS. HOWEVER...IN AREAS THAT
RECEIVE A SNOW COVER OVER SOUTHWEST AND CENTRAL MONTANA...IT WILL
TAKE A FEW DAYS FOR THE SNOW TO MELT AND TEMPERATURES WILL BE SLOWER
TO WARM UP. ANY PRECIP WILL BE CONFINED MAINLY TO THE WESTERN
MOUNTAINS ON TUESDAY. BRUSDA
WEDNESDAY AND THURSDAY...LATEST MODELS INDICATE A HIGH PRESSURE
BUILDING OVER THE PACIFIC NORTHWEST DURING THIS PERIOD. WEAK
DISTURBANCES WILL FLOW THROUGH BUT MOISTURE APPEARS LIMITED AT THIS
POINT SO KEPT SLIGHT CHANCE POPS ALONG THE DIVIDE. TEMPERATURES ARE
EXPECTED TO BE NEAR SEASONAL AVERAGES. JNS
&&
.AVIATION...
UPDATED 0025Z.
AN UPPER LEVEL TROUGH WILL CONTINUE TO DEEPEN OVER THE PACIFIC
NORTHWEST AND INTO THE GREAT BASIN THROUGH 00Z SATURDAY. THE
EASTERLY FLOW ALOFT WILL BECOME INCREASINGLY MOIST DURING THE
PERIOD. HOWEVER...NORTH CENTRAL MONTANA (KCTB AND KHVR TERMINALS)
WILL REMAIN ON THE NORTHERN EDGE OF THE MOISTURE...WHERE VFR
CONDITIONS WITH AREAS OF MID LEVEL CLOUDINESS AND A FEW SHOWERS WILL
PERSIST. FARTHER SOUTH...ACROSS CENTRAL (KGTF AND KLWT) AND
SOUTHWEST (KHLN AND KBZN) MONTANA...WIDESPREAD CLOUDINESS AND
PRECIPITATION WILL KEEP CONDITIONS IN THE LOW VFR/HIGH MVFR RANGE
WITH MOUNTAIN OBSCURATION. HOWEVER...CONDITIONS OVERNIGHT MAY LOWER
TO IFR LEVELS AT TIMES DUE TO CLOUDS AND SNOW. SURFACE WINDS WILL
GENERALLY REMAIN NORTHEASTERLY AND BREEZY. COULSTON
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 26 37 23 34 / 60 30 50 40
CTB 24 37 21 34 / 20 30 30 30
HLN 30 39 25 34 / 60 60 50 50
BZN 29 38 26 36 / 90 100 80 70
WEY 22 33 19 30 / 60 80 70 80
DLN 25 33 20 30 / 80 70 60 50
HVR 24 44 25 39 / 20 20 30 30
LWT 26 36 22 30 / 90 70 80 80
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM MDT SUNDAY
FOR MTZ008-012-014-015-050>055.
&&
$$
SHORT TERM...MPJ
LONG TERM...BRUSDA/JNS
AVIATION...COULSTON
WEATHER.GOV/GREATFALLS
000
FXUS65 KBYZ 092127
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
327 PM MDT THU OCT 9 2008
...MAJOR EARLY SEASON WINTER STORM WILL IMPACT THE AREA THROUGH THE
WEEKEND...
.SHORT TERM...VALID FOR FRI AND SAT...
CONFIDENCE CONTINUED TO INCREASE FOR MAJOR EARLY WINTER STORM TO
AFFECT THE REGION BEGINNING TONIGHT. WATER VAPOR IMAGERY SHOWED
UPPER TROUGH DIGGING INTO THE PACIFIC NW THIS AFTERNOON. THE
ECMWF/GFS/WRF WERE HANDLING THE SYSTEM WELL AND WERE SIMILAR WITH
THE EVOLUTION AND TRACK OF THE SYSTEM INTO SAT. MODELS HAVE ALSO
BEEN SHOWING GOOD RUN-TO-RUN CONTINUITY. HOWEVER...THE MODELS
DIVERGED A BIT WITH THEIR SOLUTIONS AFTER SAT.
BAROCLINIC LEAF EVIDENT ON SATELLITE AND RADAR IMAGERY THIS
AFTERNOON REFLECTED THE FRONTOGENESIS OCCURRING ALOFT WITH THE
DEVELOPING SYSTEM. SOME OF THE MOISTURE HAD MOVED N INTO THE
FORECAST AREA AND PRODUCED A FEW RAIN AND SNOW SHOWERS THIS
AFTERNOON. THE UPPER TROUGH WAS FORECAST TO CUT OFF INTO AN UPPER
LOW AS IT DIGS S INTO ID/N NV TONIGHT...AND A BAROCLINIC ZONE WILL
SET UP TO THE SE OF THE AREA. 700 MB WARM ADVECTION WILL HELP TO
QUICKLY SATURATE THE LOWERS LEVELS ACROSS THE AREA THIS EVENING AS
TEMPERATURES AT 850 MB FALL TO BETWEEN 0 AND -2 DEGS C. 700 MB FLOW
WILL BECOME E OVERNIGHT. THE SYSTEM WAS TAPPING PACIFIC MOISTURE
THIS AFTERNOON AND WILL HAVE PLENTY OF MOISTURE FOR PRECIPITATION
TONIGHT. ABOVE FACTORS SUPPORTED CATEGORICAL POPS ACROSS THE AREA.
WILL HAVE A RAIN/SNOW MIX EARLY THIS EVENING CHANGING TO ALL SNOW BY
LATE EVENING. FAVORABLE DENDRITIC GROWTH ZONE WILL BE HIGH IN THE
ATMOSPHERE TONIGHT SO SNOWFALL ACCUMULATIONS WILL BE BETWEEN 1 AND 4
INCHES WITH HIGHEST AMOUNTS IN THE FOOTHILLS AND MOUNTAINS.
THE UPPER LOW WILL ELONGATE OVER NV ON FRI AND SEND PIECES OF
VORTICITY NE THROUGH THE AREA. 850 MB TEMPERATURES WILL GENERALLY BE
BELOW ZERO THROUGH THE DAY. EAST TO NE FLOW WILL CONTINUE AT LOWER
TO MID LEVELS FAVORABLE FOR UPSLOPE AS 700 MB LOW REMAINS OVER ID.
THE MID LEVELS WILL COOL DOWN OVER THE WESTERN AND CENTRAL ZONES
WHICH WILL SUPPORT BETTER DENDRITIC GROWTH. TEMPERATURES SHOULD NOT
CLIMB OUT OF THE 30S ON FRI. CONTINUED CATEGORICAL POPS ACROSS THE
AREA WITH SEVERAL INCHES OF SNOW ACCUMULATION. AMOUNTS WILL AGAIN BE
HIGHER OVER THE FOOTHILLS AND MOUNTAINS.
FOR FRI NIGHT AND SAT...THE UPPER LOW WAS FORECAST TO DEEPEN OVER NV
AND SHIFT OVER TO N UT WHILE SENDING ENERGY NE THROUGH THE AREA.
UPPER DIFLUENCE WILL ALSO MOVE OVER THE REGION. IN ADDITION THE
SYSTEM WILL BEGIN TO TAP MOISTURE FROM THE TROPICAL SYSTEM NEAR THE
BAJA. THE COLDER AIR AT 700 MB WILL INTERSECT THE LIFT OVER THE
SOUTHERN PART OF THE AREA ALLOWING FOR GREATER SNOW ACCUMULATIONS.
OTHERWISE...SEVERAL INCHES OF SNOW WILL BE POSSIBLE. DID NOT MAKE
MANY CHANGES TO POPS.
ON SAT NIGHT...GFS BROUGHT SOME ENERGY OUT OF THE MAIN UPPER LOW
INTO SE MT AS THE MAIN LOW BEGINS WOBBLING NE. DYNAMICS AHEAD OF THE
LOW WILL INCREASE OVER THE AREA CONTINUING THE ACCUMULATING SNOW. IF
THE GFS PANS OUT...THE E COULD SEE SIGNIFICANT SNOW ACCUMULATION.
HAVE TRENDED HIGHER WITH SNOW ACCUMULATIONS OVER THE E DUE TO
INCREASED DYNAMICS AND FRONTAL BOUNDARY WRAPPING W INTO THE AREA.
HAVE GONE WITH A WINTER STORM WARNING FOR ENTIRE AREA BEGINNING AT
03Z TONIGHT TO COVER THE IMPACTS OF THE SYSTEM INCLUDING POSSIBLE
SIGNIFICANT SNOW ACCUMULATION SAT NIGHT...HEAVY WET SNOWFALL CAUSING
POWER OUTAGES AND EFFECTS ON TRAVEL. ARTHUR
.LONG TERM...VALID FOR SUN...MON...TUE...WED...THU...
THE WINTER STORMS IMPACT WILL CONTINUE INTO SUNDAY. GFS/ECMWF
CONSISTENT WITH UPPER LOW PROGRESSING FROM NORTHERN WYOMING INTO
EASTERN MONTANA ON SUNDAY. WRAP AROUND MOISTURE WILL REMAIN
ENTRENCHED ACROSS THE REGION. GIVEN THIS TRACK SOLUTION...THE
HEAVIEST SNOW WOULD LINGER FROM BILLINGS NORTHWESTWARD FOR YET
ANOTHER 3 OR 5 INCHES OF ADDITIONAL SNOWFALL INTO SUNDAY NIGHT. A
FEW SNOW SHOWERS COULD LINGER IN CYCLONIC FLOW AROUND THE SYSTEM
INTO MONDAY BUT NO ADDITIONAL ACCUMULATIONS BEFORE EVERYTHING
CLEARS OUT.
MOSTLY DRY PATTERN DEVELOPS FOR TUESDAY AND BEYOND AS FLOW BECOMES
MORE ZONAL AND DOWNSLOPE. HAVE LOWERED TEMPERATURES EARLY IN THE
WEEK IN ANTICIPATION OF A DEEPER SNOW COVER TO MELT OFF. FRIEDERS
&&
.AVIATION...
CONDITIONS WILL CONTINUE TO DETERIORATE THROUGH THIS FORECAST
PERIOD AS THE STORM SYSTEM CONTINUES TO DEVELOP. A RAIN/SNOW MIX
WILL START EARLY THIS EVENING AND MOST AREAS SHOULD TRANSITION TO
ALL SNOW BY MIDNIGHT WITH RAPIDLY LOWERING CEILINGS. THESE IMPACTS
TO CONTINUE WITH MOSTLY IFR TO LIFR CONDITIONS THROUGH FRIDAY.
FRIEDERS
&&
.PRELIMINARY POINT TEMP/POPS...
FRI SAT SUN MON TUE WED THU
-----------------------------------------------------------
BIL 027/034 026/033 026/034 023/043 028/053 032/053 033/054
++/S ++/S +8/S 31/B 10/B 11/B 11/B
LVM 022/033 019/032 019/036 022/046 027/053 032/053 033/054
++/S ++/S +8/S 31/N 10/B 11/B 21/B
HDN 028/037 026/034 026/038 022/046 027/054 031/054 032/055
++/S ++/S +8/S 31/B 10/B 11/B 11/B
MLS 031/039 026/037 026/038 024/046 029/055 032/055 033/056
++/O 89/S 97/S 31/B 11/B 11/B 21/U
4BQ 030/037 025/035 025/037 023/046 028/055 030/055 031/056
++/S ++/S +6/S 31/B 10/U 11/U 21/B
BHK 027/037 025/035 025/039 022/045 024/053 029/053 031/054
++/S 78/S 85/O 31/B 11/B 11/B 21/B
SHR 028/036 025/034 026/035 022/045 027/053 029/053 031/054
++/S ++/S +8/S 31/B 10/U 11/U 12/W
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WARNING IN EFFECT FROM 9 PM THIS EVENING TO 6 AM
MDT MONDAY FOR ZONES 28>42-56>58-63>68.
WY...WINTER STORM WARNING IN EFFECT FROM 9 PM THIS EVENING TO 6 AM
MDT MONDAY FOR ZONES 98-99.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KGGW 092103
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
303 PM MDT THU OCT 9 2008
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SATURDAY...
A BUSY FEW DAYS...WEATHER WISE...IN STORE FOR NORTHEAST MONTANA. AN
UPPER TROUGH DIGGING INTO THE GREAT BASIN WILL EJECT WARMER MORE
MOIST AIR OVER A POLAR AIRMASS IN PLACE OVER EASTERN MONTANA. THIS
OVERRUNNING WILL DRIVE A MIX OF RAIN AND SNOW ACROSS THE SOUTHERN
ZONES...MAINLY SOUTH OF HIGHWAY 200. HAVE UPGRADED THE EXISTING
WATCH FOR THE SOUTHERN ZONES TO A WINTER STORM WARNING. NORTHERLY
WINDS OF 15 TO 25 MPH WILL ACCOMPANY THE STORM...HOWEVER GIVEN THE
HEAVY WET NATURE TO THE SNOWFALL DO NOT EXPECT MUCH IN THE WAY OF
BLOWING AND DRIFTING. THESE WINDS MAY ALSO REQUIRE A LAKE WIND
ADVISORY FOR FORT PECK LAKE FRIDAY AFTERNOON. BY FRIDAY EVENING
THE LIFT GENERATED BY THE OVERRUNNING WILL TAPER
OFF...SUBSEQUENTLY TAPERING OFF THE RAIN AND SNOW. THIS LULL WILL
LAST INTO SATURDAY MORNING...BEFORE A SECOND MORE POTENT/WET
SYSTEM MOVES IN FROM THE SOUTH. COORDINATED A WATCH WITH THE
EXTENDED FORECASTER THAT STARTS SATURDAY AFTERNOON FOR AREAS SOUTH
OF THE MISSOURI RIVER. SIGNIFICANT SNOW ACCUMULATION CAN BE
EXPECTED ACROSS THE WHOLE OF NORTHEAST MONTANA WITH THIS SECOND
STORM SYSTEM. GILCHRIST
.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...
ONLY MINOR ADJUSTMENTS INTRODUCED TO THE GOING PACKAGE AS
CONFIDENCE REMAINS HIGH IN A MAJOR STORM SYSTEM THIS WEEKEND.
LATEST GFS ENSEMBLES MAINTAIN A TIGHT CLUSTER OF UPPER LOW TRACKS
THROUGH 00Z MONDAY WITH THE DETERMINISTIC RUN EXHIBITING ONLY
SMALL DEVIATIONS FROM PREVIOUS RUNS. ON THE OTHER HAND...THE 12Z
ECMWF HAS TRENDED SLOWER WITH THE LOW/S PROGRESSION BUT AT LEAST
STICKS TO A SIMILAR TRACK. GIVEN PRONOUNCED UPPER LEVEL DIVERGENCE
SATURDAY NIGHT INTO SUNDAY HELPING TO SUSTAIN A WARM TROWAL
SIGNATURE ALONG THE 295-305K ISENTROPIC SURFACE...PERIODS OF HEAVY
SNOW ARE CERTAINLY POSSIBLE AS THE 700MB LOW TRACKS NEAR THE I-94
CORRIDOR. DID RAMP UP SNOW AMOUNTS GIVEN THIS FORCING AND ALSO
ISSUED TWO WINTER STORM WATCHES TO BETTER ADDRESS THE ONSET OF
ACCUMULATING SNOW. MCZ
PREVIOUS LONG TERM DISCUSSION...
A WINTER-LIKE CYCLONIC STORM SYSTEM WILL BE WELL UNDERWAY AND
MOVING THROUGH EASTERN MONTANA WHEN THE EXTENDED PERIOD OPENS ITS
DOOR SATURDAY NIGHT. MODELS AND ENSEMBLES HAVE BECOME COMFORTABLE
WITH THIS WEEKEND STORM. THE USUAL EXPLODED ENSEMBLE SPAGHETTI
PLOTS HAVE ALL LINED UP CRISPLY AROUND THIS LOW THROUGH SUNDAY.
THE 00Z GFS HAS COME TO CLOSELY RESEMBLE THE 12Z ECMWF IN TIMING
AND LOCATION. DETAILS BEGIN TO FUZZ A LITTLE SUNDAY NIGHT AND
MONDAY AS THE MAIN ENERGY OF THE STORM LIFTS INTO CANADA AND THE
FRONT MOVES EAST. MODELS BEGIN TO DIFFER ON HOW LONG THE WRAP-
AROUND COMMA HEAD LINGERS OVER THE FORECAST AREA ON MONDAY. SINCE
THE SYSTEM HAS BEEN RATHER PROGRESSIVE IT WOULD MAKE SENSE THAT BY
MONDAY AFTERNOON THE STORM WILL HAVE EXITED EAST...REPLACED BY A
TEMPORARILY AMPLIFIED UPPER RIDGE FROM THE WEST. THE RIDGE WILL
BECOME FLATTENED TUESDAY BY A QUICK-MOVING SHORTWAVE TREKKING
ACROSS NORTHERN ALBERTA/SASKATCHEWAN. THE REMAINDER OF THE PERIOD
SHOULD CONTINUE MOSTLY DRY AND SEASONAL WITH NEAR ZONAL UPPER
FLOW.
THE MAIN QUESTION CONCERNING SATURDAY NIGHT AND SUNDAY WILL BE
THE AMOUNT OF SNOW THAT COULD FALL. THE LARGE UPPER CLOSED LOW
WILL BE CENTERED OVER SOUTHEASTERN IDAHO AND WESTERN WYOMING. THIS
WILL BE THE PERFECT SPOT TO DIRECT A VERY STRONG UPPER JET INTO
EASTERN MONTANA AND THE WESTERN DAKOTAS. IN ADDITION AN INVERTED
SURFACE TROUGH WILL BE SLIDING NORTH INTO THE SAME AREA. THE
RESULT WILL BE VERY STRONG OMEGA LIFT AND SUPPORT ALONG WITH VERY
IMPRESSIVE NEGATIVE Q-VECTOR DIVERGENCE NUMBERS. THE RESULTING QPF
FOCUS IN THE AFOREMENTIONED AREAS SATURDAY NIGHT IS A HALF INCH TO
INCH OF WATER...WITH ANOTHER HALF INCH ON SUNDAY. THE AMOUNT OF
SNOWFALL COULD DEPEND ON THE TEMPERATURES AND HOW THE
PRECIPITATION BEGINS ON SATURDAY DURING THE DAY. 850MB
TEMPERATURES SATURDAY WILL BEGIN AROUND -4C AND DROP TO -6C BY
SUNDAY MORNING...WHILE GUIDANCE SUGGESTS SURFACE TMIN IN THE MID
20S THEN RISING INTO THE MID 30S SUNDAY. WITH THE PROGRESSIVE
NATURE OF THIS STORM THE RESULTING TEMPERATURES COULD DEVIATE
QUITE A BIT FROM GUIDANCE. EXPECT THE MAJORITY OF PRECIPITATION
TO FALL AS SNOW BUT THE COLD BOUNDARY ONLY EXTENDS A SHORT WAY
BEYOND THE EASTERN BORDER SO THERE REMAINS UNCERTAINTY IN
PRECIPITATION TYPE. SCT
&&
.AVIATION...
VFR THRU THIS EVENING WITH NORTHEAST WINDS REMAINING AROUND 10
KTS AT ALL TERMINALS. MID LEVEL CLOUDS WILL INCREASE IN COVERAGE
THIS EVENING AHEAD OF AN INTENSIFYING STORM SYSTEM IN WYOMING.
THIS STORM WILL NUDGE NORTH TONIGHT MAINLY AFFECTING KGDV WITH
POSSIBLE MVFR CONDITIONS AND A MIX OF RAIN AND SNOW AFTER 09Z.
MVFR CONDITIONS WITH A RAIN/SNOW MIX WILL SPREAD FROM SOUTH TO
NORTH ACROSS ALL TERMINALS BY MID MORNING. RAS
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR CENTRAL AND SOUTHEAST PHILLIPS-CENTRAL AND
SOUTHERN VALLEY-DANIELS-SHERIDAN-WESTERN ROOSEVELT-NORTHERN
PHILLIPS-SOUTHWEST PHILLIPS-NORTHERN VALLEY-EASTERN ROOSEVELT.
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM MDT FRIDAY
FOR PETROLEUM-GARFIELD-DAWSON-PRAIRIE-WIBAUX.
WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY
AFTERNOON FOR PETROLEUM-GARFIELD-MCCONE-RICHLAND-DAWSON-PRAIRIE-
WIBAUX.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KMSO 092050
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
250 PM MDT THU OCT 9 2008
...FIRST MAJOR WINTER STORM OF THE FALL SEASON TO AFFECT SOUTHWEST
MONTANA AND LEMHI COUNTY IDAHO...
.DISCUSSION...A HIGHLY DYNAMIC WINTER WEATHER SYSTEM WILL BEGIN TO
AFFECT THE NORTHERN ROCKIES STARTING TONIGHT AND WILL CONTINUE
THROUGH THE DURATION OF THE WEEKEND. LOCATIONS IN HIGHER
ELEVATIONS ABOVE 5500 FEET WILL BE THE FIRST TO SEE SNOW SHOWERS
DEVELOPING THIS EVENING WITH LIGHT ACCUMULATIONS POSSIBLE. AREAS
TO BE MOSTLY IMPACTED BY THESE ACCUMULATIONS WILL BE ALONG THE
CONTINENTAL DIVIDE...LEMHI COUNTY AND LOST TRAIL PASS. NORTHWEST MT
VALLEYS WILL NOT BE IMPACTED BY SNOW WITH THIS EVENT...BUT WILL
EXPERIENCE GUSTY NORTHEAST WINDS.
SNOW OVER SOUTHWEST MT AND LEMHI COUNTY WILL CONTINUE STEADILY
THROUGH THE DAY FRIDAY AND INTO SATURDAY WITH SNOW LEVELS LOWERING
TO THE VALLEY FLOORS AND MAY EXPERIENCE LIGHT SNOW ACCUMULATIONS. A
TIGHTENING NORTHEAST TO SOUTHEAST PRESSURE GRADIENT WILL ALLOW
GUSTY NORTHEAST WINDS TO DEVELOP FRIDAY THROUGH SATURDAY...WITH
AREAS OF BLOWING SNOW. IT SHOULD BE NOTED THAT WITH THESE TYPE OF
GUSTY WINDS...OVERNIGHT TEMPERATURES WILL FEEL QUITE BRISK AS THE
WINDS HELP TO LOWER TEMPERATURES INTO THE TEENS. DUE TO THE EARLY
ONSET OF SNOW FOR THIS SEASON...DECIDUOUS TREES RUN THE RISK OF
BROKEN BRANCHES DUE TO ACCUMULATING SNOW. WINTER WEATHER
ADVISORIES HAVE BEEN UPGRADED TO WINTER STORM WARNINGS TO ACCOUNT
FOR THE LONG DURATION OF ACCUMULATING SNOW AND THE POSSIBILITY OF
DAMAGE TO TREES.
THE DEEP LOW PRESSURE SYSTEM WILL DIG AS FAR SOUTH AS UTAH BY
SATURDAY AFTERNOON WITH MOISTURE WRAPPING AROUND IT...CONTINUING
SNOWS OVER SOUTHWEST MT AND LEMHI COUNTY INTO EARLY SUNDAY. BY SUNDAY
AFTERNOON...THE LOW TRACKS INTO EASTERN MT WITH SNOW TAPERING
OFF. ANOTHER VERY COLD NIGHT IS EXPECTED SUNDAY NIGHT...AS CLOUDS
BEGIN TO CLEAR OUT OF THE AREA.
MONDAY THROUGH THURSDAY...A BRIEF DRY PERIOD WILL TAKE HOLD ON MONDAY
AS THE OVERALL WEATHER PATTERN TRANSITIONS FROM THE STRONG UPPER
LEVEL LOW FROM THE PAST WEEKEND TO MORE OF A WESTERLY FLOW FOR THE
REMAINDER OF THE WEEK. THIS TYPE OF FLOW PATTERN TYPICALLY
INDICATES A SHOWERY PRECIPITATION REGIME THAT SHOULD BE CONFINED
MAINLY TO HIGHER TERRAIN.
&&
.AVIATION...A COLD AND WINTRY WEATHER SYSTEM WILL IMPACT THE
NORTHERN ROCKIES BEGINNING THIS EVENING AND CONTINUING THROUGH THE
WEEKEND BEFORE EXITING THE AREA. EASTERLY WINDS WILL INCREASE AND
BECOME GUSTY THIS EVENING AS THE SURFACE PRESSURE GRADIENT
TIGHTENS. WINDS ARE EXPECTED TO REMAIN STRONG THROUGH FRIDAY NIGHT.
SNOW AND BLOWING SNOW WILL IMPACT THE NORTHERN ROCKIES WITH THIS
SYSTEM WITH HEAVIER SNOWFALL EXPECTED NEAR TERMINALS KSMN AND
KBTM. IFR CEILINGS ARE NOT OUT OF THE QUESTION NEAR THESE
TERMINALS AND THEIR VICINITIES UNDER HEAVIER BANDS OF
PRECIPITATION. VISIBILITIES WILL BE REDUCED AT TIMES WITH MOUNTAIN
AND PASS OBSCURATIONS LIKELY.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WARNING FROM 3 AM FRIDAY TO 6 PM MDT SATURDAY FOR
BUTTE/BLACKFOOT REGION.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 12 PM MDT
FRIDAY FOR BITTERROOT/SAPPHIRE MOUNTAINS.
ID...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM MDT SATURDAY
FOR EASTERN LEMHI COUNTY.
&&
$$
SHORT TERM...ALLEGRETTO
LONG TERM....FELSCH/DEROSA
AVIATION...DEROSA
000
FXUS65 KTFX 092042
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
242 PM MDT THU OCT 9 2008
.DISCUSSION...
TONIGHT THROUGH SUNDAY...FORECAST AREA IS BENEATH THE INFLUENCE
OF A DEVELOPING UPPER LEVEL TROUGH. FORECAST CONTINUES TO LOOK
FAVORABLE FOR THE DEVELOPMENT OF A SIGNIFICANT EARLY SEASON WINTER
STORM. SHOWERS ARE ALREADY DEVELOPING ACROSS SOUTHERN PORTIONS OF
CENTRAL MONTANA. AS LOW LEVEL UPSLOPE FLOW STRENGTHENS AND A BROAD
AREA OF UPWARD VERTICAL MOTION MOVES ACROSS THE REGION AM EXPECTING
WIDESPREAD SNOW TO DEVELOP ACROSS THE SOUTHERN HALF OF MY CWA
TONIGHT. THE UPPER TROUGH WILL CONTINUE TO STRENGTHEN...BECOMING A
CUTOFF LOW OVER THE GREAT BASIN BY FRIDAY MORNING. THIS FEATURE IS
EXPECTED TO REMAIN IN THIS GENERAL AREA WITH A GRADUAL DRIFT TO
THE NORTHEAST THROUGH SATURDAY AFTERNOON. ABUNDANT MOISTURE WILL
BE PUMPED INTO CENTRAL AND SOUTHWEST MONTANA WITH LIGHT SNOW
CONTINUING ACROSS THE SOUTHERN HALF OF MY CWA THROUGH THE WEEKEND.
HAVE DECIDED TO ISSUE A WINTER STORM WARNING FOR THE ENTIRE
SOUTHERN HALF OF MY FORECAST AREA BEGINNING TONIGHT AND CONTINUING
CLEAR THROUGH SUNDAY AFTERNOON. ALTHOUGH SNOW AMOUNTS ARE NOT
EXPECTED TO BE ESPECIALLY HEAVY IN ANY 12 OR 24 HOUR PERIOD...AND
THERE WILL INITIALLY BE SOME MELTING DUE TO WARM GROUND
TEMPERATURES...BY THE END OF THE WEEKEND AM EXPECTING 3 TO 6
INCHES SNOWFALL OVER THE PLAINS...WITH 15 TO 30 INCHES OVER THE
MOUNTAINS. I AM ALSO EXPECTING THAT THERE COULD BE SOME DAMAGE TO
TREES SINCE THERE ARE STILL LEAVES HAVE NOT FALLEN IN SOME
LOCATIONS...AND ROADWAYS COULD BECOME QUITE SLICK AS MELTING SNOW
FREEZES ONCE TEMPERATURES FALL. MPJ
FOR MONDAY THROUGH TUESDAY...EXPECT A NICE WARMING TREND OVER THE
REGION...AS A WEAK UPPER LEVEL RIDGE TRIES TO REBUILD OVER THE
REGION. TEMPERATURES WILL WARM UP NICELY IN THE CUT BANK AREA...AS A
BROWN GROUND AND BREEZY WEST WIND DEVELOPS. HOWEVER...IN AREAS THAT
RECEIVE A SNOW COVER OVER SOUTHWEST AND CENTRAL MONTANA...IT WILL
TAKE A FEW DAYS FOR THE SNOW TO MELT AND TEMPERATURES WILL BE SLOWER
TO WARM UP. ANY PRECIP WILL BE CONFINED MAINLY TO THE WESTERN
MOUNTAINS ON TUESDAY. BRUSDA
WEDNESDAY AND THURSDAY...LATEST MODELS INDICATE A HIGH PRESSURE
BUILDING OVER THE PACIFIC NORTHWEST DURING THIS PERIOD. WEAK
DISTURBANCES WILL FLOW THROUGH BUT MOISTURE APPEARS LIMITED AT THIS
POINT SO KEPT SLIGHT CHANCE POPS ALONG THE DIVIDE. TEMPERATURES ARE
EXPECTED TO BE NEAR SEASONAL AVERAGES. JNS
&&
.AVIATION...
UPDATED 1815Z.
VFR CONDITIONS WILL CONTINUE ACROSS MOST OF SOUTHWEST...CENTRAL AND
NORTH CENTRAL MONTANA THROUGH 06Z. BROKEN LOW AND MID CLOUDS WILL
MOVE OVER THE AREA OVERNIGHT INTO FRIDAY MORNING WITH GENERALLY
LIGHT WINDS. AN UPPER LEVEL TROUGH WILL DEEPEN OVER THE GREAT BASIN
SETTING UP A MOIST SOUTHWESTERLY FLOW ALOFT OVER THE AREA. THIS WILL
BRING INCREASING LOW AND MID LEVEL CLOUDINESS TO THE TERMINALS
DURING THE AFTERNOON AND EVENING...ESPECIALLY ACROSS SOUTHWEST AND
CENTRAL MONTANA (KBZN KHLN KGTF KLWT TERMINALS). SCATTERED SNOW
SHOWERS WITH AREAS OF MVFR CONDITIONS WILL ALSO DEVELOP ACROSS THIS
AREA AFTER 00Z AND WILL PERSIST UNTIL 18Z FRIDAY. BRITTON
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 26 37 23 34 / 60 30 50 40
CTB 24 37 21 34 / 20 30 30 30
HLN 30 39 25 34 / 60 60 50 50
BZN 29 38 26 36 / 90 100 80 70
WEY 22 33 19 30 / 60 80 70 80
DLN 25 33 20 30 / 80 70 60 50
HVR 24 44 25 39 / 20 20 30 30
LWT 26 36 22 30 / 90 70 80 80
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM MDT SUNDAY
FOR MTZ008-012-014-015-050>055.
&&
$$
SHORT TERM...MPJ
LONG TERM...BRUSDA/JNS
AVIATION...BRITTON
WEATHER.GOV/GREATFALLS
000
FXUS65 KTFX 091816
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1215 AM MDT THU OCT 9 2008
.UPDATE...HAVE MADE MINOR TWEAKS TO THE MORNING FORECAST TO LOWER
POPS IN SOUTHWEST MONTANA WHERE SKIES ARE GENERALLY CLEAR AT THIS
TIME. IN THE NORTH...CLOUDS ARE ALREADY DEVELOPING ACROSS THE
REGION SO HAVE INCREASED SKY CONDITION TO MOSTLY CLOUDY FOR TODAY.
OVERALL THE GOING FORECAST IS IN GOOD SHAPE WITH A SIGNIFICANT
FALL STORM MOVING INTO THE REGION TONIGHT. MORNING MODEL RUNS COMING
IN AT THIS TIME SUGGEST THAT SNOW MAY EXTEND FARTHER NORTH THAN
PREVIOUSLY FORECAST. SINCE ADDITIONAL MODELS STILL NEED TO COME IN
WILL HOLD OFF UNTIL THE AFTERNOON PACKAGE TO MAKE ADDITIONAL
CHANGES...BUT WOULD ANTICIPATE THAT THE CURRENT WINTER STORM WATCH
WILL BE REPLACED BY WARNINGS/ADVISORIES AND COULD BE EXPANDED IN
AREA. MPJ
&&
.AVIATION...
UPDATED 1815Z.
VFR CONDITIONS WILL CONTINUE ACROSS MOST OF SOUTHWEST...CENTRAL AND
NORTH CENTRAL MONTANA THROUGH 06Z. BROKEN LOW AND MID CLOUDS WILL
MOVE OVER THE AREA OVERNIGHT INTO FRIDAY MORNING WITH GENERALLY
LIGHT WINDS. AN UPPER LEVEL TROUGH WILL DEEPEN OVER THE GREAT BASIN
SETTING UP A MOIST SOUTHWESTERLY FLOW ALOFT OVER THE AREA. THIS WILL
BRING INCREASING LOW AND MID LEVEL CLOUDINESS TO THE TERMINALS
DURING THE AFTERNOON AND EVENININ...ESPECIALLY ACROSS SOUTHWEST AND
CENTRAL MONTANA (KBZN KHLN KGTF KLWT TERMINALS). SCATTERED SNOW
SHOWERS WITH AREAS OF MVFR CONDITIONS WILL ALSO DEVELOP ACROSS THIS
AREA AFTER 00Z AND WILL PERSIST UNTIL 18Z FRIDAY. BRITTON
&&
.PREV DISCUSSION...
/ISSUED 407 AM MDT THU OCT 9 2008/
MAIN FORECAST CONCERN IS HEAVY SNOW POTENTIAL ACROSS CENTRAL AND
SOUTHWEST MONTANA.
TODAY...A TROUGH OF LOW PRESSURE CURRENTLY ENTERING THE PACIFIC
NORTHWEST WILL DEEPEN AS IT ENTERS THE NORTHERN ROCKIES LATER TODAY
WHILE HIGH PRESSURE OVER CANADA WILL ALLOW FOR COOLER AIR TO PUSH
SOUTH. QUIET WEATHER IS EXPECTED FOR TODAY WITH MORNING SUNSHINE
THEN INCREASING CLOUDS THROUGHOUT THE AFTERNOON WITH HIGH
TEMPERATURES TOPPING OUT ABOUT TEN DEGREES BELOW AVERAGE.
TONIGHT THROUGH SATURDAY...THE LOW WILL CUT OFF AS IT ENTERS THE
WESTERN ROCKIES LATER TODAY BEFORE GRADUALLY SHIFTING NORTH AND EAST
WITH 500MB WINDS DRAWING MOISTURE INTO THE REGION FROM THE EASTERN
ROCKIES THROUGH SATURDAY. MEANWHILE...NORTHERLY WINDS AT THE
SURFACE WILL PERSIST ACROSS NORTHERN AND CENTRAL MONTANA CAUSING
OVERRUNNING PRECIPITATION TO DEVELOP ALONG THE MOUNTAINS AND NEARBY
VALLEYS ACROSS CENTRAL AND SOUTHWEST MONTANA. UNSEASONABLY COOL
TEMPERATURES IN THE 30S AND EVEN UPPER 20S IN HIGHER ELEVATIONS ARE
EXPECTED FOR FRIDAY AND SATURDAY.SNOW WILL BEGIN AROUND 06Z FRIDAY
AND CONTINUE THROUGH SATURDAY. FOR NOW WILL GO WITH A WINTER STORM
WATCH EFFECTIVE 06Z TONIGHT THROUGH 12Z SUNDAY FOR
CASCADE...FERGUS... JUDITH BASIN...MEAGHER...BROADWATER...MADISON
AND GALLATIN COUNTIES AND A WINTER WEATHER ADVISORY FROM 06Z FRIDAY
THROUGH 00Z SATURDAY FOR BEAVERHEAD AND JEFFERSON COUNTIES. AS WE
GAIN A BETTER HANDLE ON HOW FAR NORTH AND WEST HEAVY PRECIPITATION
WILL FALL...ADDITIONAL COUNTIES MAY BE ADDED TO THE WINTER
HEADLINES. AS FOR STORM TOTAL ACCUMULATIONS...LOCATIONS IN THE
ADVISORY CAN EXPECT BETWEEN 2 TO 5 INCHES THROUGH SATURDAY WITH AT
LEAST 6 TO 10 INCHES IN THE LOWER ELEVATIONS IN THE WATCH AREA AND
10 TO 20 INCHES ACROSS HIGHER ELEVATIONS THROUGH EARLY SUNDAY.
MLS/BRUSDA
SATURDAY NIGHT THROUGH SUNDAY...THE MAIN AREA OF LOW PRESSURE THAT
WILL CAUSE ALL THE SNOW OVER THE REGION ON FRIDAY AND SATURDAY WILL
SLOWLY MOVE INTO THE UPPER MIDWEST BY SUNDAY EVENING. THUS EXPECT
SNOW...HEAVY AT TIMES TO AFFECT SOUTHWEST AND CENTRAL MONTANA
SATURDAY NIGHT INTO SUNDAY MORNING...THEN GRADUALLY TAPPER OFF TO
ISOLATED SNOW SHOWERS BY SUNDAY EVENING. AGAIN THE HEAVIEST SNOW
SHOULD REMAIN JUST SOUTH AND EAST OF GREAT FALLS...MAINLY IN THE
LEWISTOWN...STANFORD...WHITE SULPHUR SPRINGS...AND BOZEMAN AREAS.
LITTLE IF ANY SNOW IS EXPECTED NORTHWEST OF GREAT FALLS.
FOR MONDAY THROUGH TUESDAY...EXPECT A NICE WARMING TREND OVER THE
REGION...AS A WEAK UPPER LEVEL RIDGE TRIES TO REBUILD OVER THE
REGION. TEMPERATURES WILL WARM UP NICELY IN THE CUT BANK AREA...AS A
BROWN GROUND AND BREEZY WEST WIND DEVELOPS. HOWEVER...IN AREAS THAT
RECEIVE A SNOW COVER OVER SOUTHWEST AND CENTRAL MONTANA...IT WILL
TAKE A FEW DAYS FOR THE SNOW TO MELT AND TEMPERATURES WILL BE SLOWER
TO WARM UP. ANY PRECIP WILL BE CONFINED MAINLY TO THE WESTERN
MOUNTAINS ON TUESDAY. BRUSDA
WEDNESDAY AND THURSDAY...LATEST MODELS INDICATE A HIGH PRESSURE
BUILDING OVER THE PACIFIC NORTHWEST DURING THIS PERIOD. WEAK
DISTURBANCES WILL FLOW THROUGH BUT MOISTURE APPEARS LIMITED AT THIS
POINT SO KEPT SLIGHT CHANCE POPS ALONG THE DIVIDE. TEMPERATURES ARE
EXPECTED TO BE NEAR SEASONAL AVERAGES. JNS
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 48 27 38 23 / 10 30 20 40
CTB 44 24 37 21 / 10 20 30 30
HLN 48 30 39 25 / 20 50 50 50
BZN 51 30 40 25 / 30 70 80 70
WEY 46 23 35 19 / 30 40 80 70
DLN 45 25 33 19 / 20 60 60 60
HVR 52 22 41 25 / 10 10 20 30
LWT 47 26 37 22 / 10 50 70 70
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE SATURDAY NIGHT
FOR MTZ012-015-050-051-053>055.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM MDT
SATURDAY FOR MTZ008-052.
&&
$$
UPDATE...MPJ
SHORT TERM...SYNER/BRUSDA
LONG TERM...BRUSDA/SAUCIER
AVIATION...COULSTON
WEATHER.GOV/GREATFALLS
000
FXUS65 KBYZ 091533
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
933 AM MDT THU OCT 9 2008
.SHORT TERM...VALID FOR TDY AND FRI...
UPDATE TO ZFP AND WRKAFP. BAROCLINIC LEAF EVIDENT IN SATELLITE AND
RADAR IMAGERY THIS MORNING OVER N WY TO SE MT...AHEAD OF DEEPENING
UPPER TROUGH OVER THE PACIFIC NW. OBSERVER IN BURGESS JUNCTION COULD
SEE SNOW FALLING IN THE DISTANCE SO PRECIPITATION SEEN ON RADAR
WAS REACHING THE GROUND. 12Z UPPER AIR DATA INDICATED 700 MB LOW
ALREADY FORMING OVER ID...ZERO DEG LINE AT 850 MB ALONG
MT/CANADIAN BORDER...AND -12 DEG C LINE AT 700 MB DIPPING INTO N
MT. 12Z WRF INITIALIZED WELL WITH MOST FEATURES EXCEPT WAS A
LITTLE WARM AT 700 MB. BASED ON RADAR/SATELLITE TRENDS AND NEW
WRF...HAVE RAISED POPS ACROSS THE AREA THROUGH THE AFTERNOON. BEST
CHANCES FOR PRECIPITATION WILL BE OVER NE FACING SLOPES OF THE
BEARTOOTHS/ABSAROKAS AND OVER THE SE AND SOUTH CENTRAL PARTS OF
THE AREA DUE TO UPSLOPE FLOW AND ABUNDANT MOISTURE. NOTED
PRECIPITABLE WATERS JUST S OF FORECAST AREA WERE RUNNING GREATER
THAN 100 PERCENT ABOVE NORMAL. OLD GFS/ECMWF AND NEW WRF HAD 850
TEMPS FALLING TO NEAR ZERO OVER THE SE THIS AFTERNOON DUE TO
EVAPORATIVE COOLING. FEW SNOWFLAKES MAY MIX IN WITH THE RAIN
THERE. BUMPED UP SNOW AMOUNTS OVER SW MOUNTAINS AND NE BIG HORNS
TO 2 INCHES FOR TODAY WITH THE UPDATE. LOWERED TEMPERATURES OVER
THE E DUE TO THE CLOUD COVER AND ADVANCING PRECIPITATION.
TONIGHT/S POPS WERE IN GOOD SHAPE BASED ON NEW WRF. WILL EVALUATE
GFS AND OTHER DATA THROUGH THE DAY TO UPDATE WINTER HIGHLIGHTS AS
NEEDED. ARTHUR
.LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED...
THE LATEST GUIDANCE REMAINS CONSISTENT WITH THE EARLY MAJOR
WINTER STORM...RESULTING IN SIGNIFICANT IMPACTS ACROSS THE AREA
THIS WEEKEND. THE STRONG UPPER LOW IS EXPECTED TO BEGIN MOVING
NORTHWARD SATURDAY AFTER BOTTOMING OUT ACROSS THE GREAT BASIN.
SNOW IS EXPECTED TO BE ONGOING AT THE START OF THE FORECAST
PERIOD...WITH DEEP UPSLOPE FLOW...STRONG OVERRUNNING PATTERN...AND
AND STRONG DIFFLUENCE ALOFT CONTRIBUTING TO THE INTENSIFICATION OF
PRECIPITATION ACROSS THE REGION. SATURDAY THROUGH SUNDAY SHOULD
BRING THE BULK OF SNOW FOR THIS STORM EVENT. WRAP AROUND SNOWS
WILL BEGIN SUBSIDING SUNDAY NIGHT AND CLEAR THE AREA TO THE EAST
MONDAY MORNING. MOUNTAIN AREAS WILL LIKELY SEE SEVERAL FEET OF
SNOW...WHILE A STRONG LIKELIHOOD OF AROUND A FOOT OF SNOW
ACCUMULATION IS POSSIBLE ACROSS THE LOWER ELEVATIONS.
ONCE THE STORM SYSTEM CLEARS OUT...THE AREA IS RETURNED TO A
ZONAL TYPE DOWNSLOPING FLOW PATTERN. IT LOOKS PRETTY DRY BEYOND
MONDAY...WITH WARMING TREND APPROACHING 60S BY THE END OF THE
PERIOD. GILSTAD
&&
.AVIATION...
CONDITIONS WILL BEGIN TO DETERIORATE THROUGH THIS FORECAST PERIOD
AS THE STORM SYSTEM CONTINUES TO DEVELOP. MID LEVEL CLOUDINESS
WILL TRANSITION TO LOWER CEILINGS AND EVENTUALLY PRECIPITATION BY
LATE THIS AFTERNOON AND EARLY EVENING. VFR CONDITIONS WILL
TRANSITION TO IFR BY TONIGHT WITH LOCAL LIFR IN HEAVIER SNOW
SHOWERS. FRIEDERS
&&
.PRELIMINARY POINT TEMP/POPS...
TDY FRI SAT SUN MON TUE WED
-------------------------------------------------------
BIL 046 030/035 026/033 026/034 024/048 030/053 034/053
5/R ++/S ++/S +8/S 31/B 10/B 11/B
LVM 046 024/034 020/033 020/036 023/051 029/053 034/053
4/R ++/S ++/S +8/S 31/N 10/B 11/B
HDN 050 030/037 026/034 025/038 023/051 029/054 033/054
6/O ++/S ++/S +8/S 31/B 10/B 11/B
MLS 048 033/039 028/036 027/038 025/051 031/055 034/055
6/R 98/O 88/S 97/S 31/B 11/B 11/B
4BQ 047 030/039 027/037 027/037 024/051 030/055 032/055
8/O ++/O ++/S +6/S 31/B 10/U 11/U
BHK 046 030/039 026/035 025/039 023/050 026/053 031/053
6/R 97/O 77/S 85/O 31/B 11/B 11/B
SHR 049 028/038 025/034 025/035 023/050 029/053 031/053
6/O ++/S ++/S +8/S 31/B 10/U 11/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WATCH IN EFFECT FROM 9 PM MDT THIS EVENING
THROUGH LATE SUNDAY NIGHT FOR ZONES 28>42-56>58-63>68.
WY...WINTER STORM WATCH IN EFFECT FROM 9 PM MDT THIS EVENING
THROUGH LATE SUNDAY NIGHT FOR ZONES 98-99.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KGGW 091530
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
930 AM MDT THU OCT 9 2008
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH SATURDAY...
UPDATE...DIGGING UPPER TROUGH OVER THE WEST COAST IS BUILDING
HIGH LEVEL CLOUDS INTO THE SOUTHEAST ZONES. THE REMAINDER OF THE
FORECAST AREA IS SEEING CLEAR TO MOSTLY CLEAR SKIES. THUS UPDATED
TO LOWER CLOUD COVER THERE...AND TO INCREASE TEMPS AS ADDED SUN WILL
HELP WARM THINGS. STRONG EARLY SEASON STORM POISED TO IMPACT THE
SOUTHERN ZONES LATE TONIGHT INTO FRIDAY...AND THE WHOLE OF NEMONT
SATURDAY AFTERNOON INTO SUNDAY. CURRENT WATCH LOOKS ON TRACK FOR
NOW. GILCHRIST
PREVIOUS DISCUSSION...THE UPPER TROUGH THAT WILL BECOME THE
WEATHER MAKER FOR THE NEXT SEVERAL DAYS WILL MOVE OFF THE PACIFIC
OCEAN THIS MORNING AND DEEPEN AS IT MOVES INTO THE GREAT BASIN ON
THIS AFTERNOON...SOUTHWEST FLOW ALOFT WILL SPREAD MOISTURE
NORTHWARD TOWARD MONTANA. A CLOSED LOW WILL FORM IN THIS UPPER
TROUGH TONIGHT.
A LOW PRESSURE SYSTEM DEVELOPS ALONG A STATIONARY FRONT NEAR THE
WYOMING/COLORADO BORDER DURING THE DAY TODAY. THE MOISTURE ON THE
SOUTHWEST FLOW ALOFT WILL START OVERRUNNING THE FRONT AND BECOME A
WIDESPREAD AREA OF RAIN INTO SOUTHERN MONTANA THIS EVENING THEN
MIXING WITH OR CHANGING TO SNOW THROUGH THE NIGHT AND INTO FRIDAY.
MODEL GENERALLY BRING THE PRECIPITATION AS FAR NORTH AS
WINNETT...JORDAN AND GLENDIVE TONIGHT AND FRIDAY. WITH NORTHERLY
WINDS FEEDING LOW LEVEL DRY AIR INTO NORTHERN MONTANA...THE
RAIN/SNOW FROM THIS SYSTEM WILL HAVE A HARD TIME GETTING NORTH OF
THE MISSOURI RIVER. MODELS KEEP TEMPERATURES ALOFT NEAR FREEZING
WHICH MAKES DETERMINING WHETHER THE PRECIPITATION WILL BE RAIN OR
SNOW TOUGH. CHANCES ARE...IT WILL BE MAINLY SNOW LATE TONIGHT AND
FRIDAY IN THE HIGHER ELEVATIONS AND A MIX OF RAIN AND SNOW IN THE
VALLEYS. WITH A HALF INCH OR MORE OF PRECIPITATION POSSIBLE SOUTH
OF MONTANA HIGHWAY 200...IF A HIGHER ELEVATION LOCATION GETS
MOSTLY SNOW BETWEEN MIDNIGHT TONIGHT AND FRIDAY AFTERNOON...IT
WOULD ADD UP TO 6 INCHES OR MORE OF SNOW. GIVEN THE POSSIBILITY OF
HEAVY SNOW AND BEING EARLY OCTOBER...WILL ISSUE A WINTER STORM
WATCH BETWEEN MIDNIGHT TONIGHT AND FRIDAY AFTERNOON.
WILL SEE A BREAK IN THE PRECIPITATION FRIDAY NIGHT AND EARLY
SATURDAY BEFORE THE SECOND WAVE OF MOISTURE MOVES NORTH STARTING
SATURDAY AFTERNOON AS THE UPPER LOW STARTS LIFTING NORTH. HEAVY
SNOW IS LIKELY WITH THIS SYSTEM WITH THE BULK OF THE SNOW
OCCURRING SATURDAY NIGHT AND SUNDAY. WITH A WATCH CURRENTLY IN
EFFECT FOR THE FIRST WAVE OF PRECIPITATION WILL HOLD OFF ON
ISSUING ANY WATCHES FOR THE WEEKEND FOR NOW.
.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...
A WINTER-LIKE CYCLONIC STORM SYSTEM WILL BE WELL UNDERWAY AND
MOVING THROUGH EASTERN MONTANA WHEN THE EXTENDED PERIOD OPENS ITS
DOOR SATURDAY NIGHT. MODELS AND ENSEMBLES HAVE BECOME COMFORTABLE
WITH THIS WEEKEND STORM. THE USUAL EXPLODED ENSEMBLE SPAGHETTI
PLOTS HAVE ALL LINED UP CRISPLY AROUND THIS LOW THROUGH SUNDAY.
THE 00Z GFS HAS COME TO CLOSELY RESEMBLE THE 12Z ECMWF IN TIMING
AND LOCATION. DETAILS BEGIN TO FUZZ A LITTLE SUNDAY NIGHT AND
MONDAY AS THE MAIN ENERGY OF THE STORM LIFTS INTO CANADA AND THE
FRONT MOVES EAST. MODELS BEGIN TO DIFFER ON HOW LONG THE WRAP-
AROUND COMMA HEAD LINGERS OVER THE FORECAST AREA ON MONDAY. SINCE
THE SYSTEM HAS BEEN RATHER PROGRESSIVE IT WOULD MAKE SENSE THAT BY
MONDAY AFTERNOON THE STORM WILL HAVE EXITED EAST...REPLACED BY A
TEMPORARILY AMPLIFIED UPPER RIDGE FROM THE WEST. THE RIDGE WILL
BECOME FLATTENED TUESDAY BY A QUICK-MOVING SHORTWAVE TREKKING
ACROSS NORTHERN ALBERTA/SASKATCHEWAN. THE REMAINDER OF THE PERIOD
SHOULD CONTINUE MOSTLY DRY AND SEASONAL WITH NEAR ZONAL UPPER
FLOW.
THE MAIN QUESTION CONCERNING SATURDAY NIGHT AND SUNDAY WILL BE
THE AMOUNT OF SNOW THAT COULD FALL. THE LARGE UPPER CLOSED LOW
WILL BE CENTERED OVER SOUTHEASTERN IDAHO AND WESTERN WYOMING. THIS
WILL BE THE PERFECT SPOT TO DIRECT A VERY STRONG UPPER JET INTO
EASTERN MONTANA AND THE WESTERN DAKOTAS. IN ADDITION AN INVERTED
SURFACE TROUGH WILL BE SLIDING NORTH INTO THE SAME AREA. THE
RESULT WILL BE VERY STRONG OMEGA LIFT AND SUPPORT ALONG WITH VERY
IMPRESSIVE NEGATIVE Q-VECTOR DIVERGENCE NUMBERS. THE RESULTING QPF
FOCUS IN THE AFOREMENTIONED AREAS SATURDAY NIGHT IS A HALF INCH TO
INCH OF WATER...WITH ANOTHER HALF INCH ON SUNDAY. THE AMOUNT OF
SNOWFALL COULD DEPEND ON THE TEMPERATURES AND HOW THE
PRECIPITATION BEGINS ON SATURDAY DURING THE DAY. 850MB
TEMPERATURES SATURDAY WILL BEGIN AROUND -4C AND DROP TO -6C BY
SUNDAY MORNING...WHILE GUIDANCE SUGGESTS SURFACE TMIN IN THE MID
20S THEN RISING INTO THE MID 30S SUNDAY. WITH THE PROGRESSIVE
NATURE OF THIS STORM THE RESULTING TEMPERATURES COULD DEVIATE
QUITE A BIT FROM GUIDANCE. EXPECT THE MAJORITY OF PRECIPITATION
TO FALL AS SNOW BUT THE COLD BOUNDARY ONLY EXTENDS A SHORT WAY
BEYOND THE EASTERN BORDER SO THERE REMAINS UNCERTAINTY IN
PRECIPITATION TYPE. SCT
&&
.AVIATION...
VFR TODAY...WITH NORTHWESTERLY 10KT WIND VEERING TO THE NORTHEAST
THIS AFTERNOON. MID LEVEL CLOUDS INCREASE IN COVERAGE TODAY AHEAD
OF AN INTENSIFYING STORM SYSTEM IN WYOMING. THIS STORM WILL NUDGE
NORTH INTO SOUTHERN ZONES TONIGHT MAINLY AFFECTING KGDV WITH RAIN
AND/OR SNOW. SCT
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM LATE TONIGHT THROUGH FRIDAY AFTERNOON
FOR PETROLEUM-GARFIELD-DAWSON-PRAIRIE-WIBAUX.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KTFX 091507
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
907 AM MDT THU OCT 9 2008
.UPDATE...HAVE MADE MINOR TWEAKS TO THE MORNING FORECAST TO LOWER
POPS IN SOUTHWEST MONTANA WHERE SKIES ARE GENERALLY CLEAR AT THIS
TIME. IN THE NORTH...CLOUDS ARE ALREADY DEVELOPING ACROSS THE
REGION SO HAVE INCREASED SKY CONDITION TO MOSTLY CLOUDY FOR TODAY.
OVERALL THE GOING FORECAST IS IN GOOD SHAPE WITH A SIGNIFICANT
FALL STORM MOVING INTO THE REGION TONIGHT. MORNING MODEL RUNS COMING
IN AT THIS TIME SUGGEST THAT SNOW MAY EXTEND FARTHER NORTH THAN
PREVIOUSLY FORECAST. SINCE ADDITIONAL MODELS STILL NEED TO COME IN
WILL HOLD OFF UNTIL THE AFTERNOON PACKAGE TO MAKE ADDITIONAL
CHANGES...BUT WOULD ANTICIPATE THAT THE CURRENT WINTER STORM WATCH
WILL BE REPLACED BY WARNINGS/ADVISORIES AND COULD BE EXPANDED IN
AREA. MPJ
&&
.AVIATION...
UPDATED 0510Z.
VFR CONDITIONS WILL CONTINUE ACROSS MOST OF SOUTHWEST...CENTRAL AND
NORTH CENTRAL MONTANA THROUGH 06Z FRIDAY. ONLY SCATTERED MID AND
HIGH CLOUDS WILL MOVE OVER THE AREA OVERNIGHT INTO THURSDAY MORNING
WITH GENERALLY LIGHT WINDS. AS CANADIAN SURFACE HIGH PRESSURE BUILDS
SOUTH INTO NORTH CENTRAL AND CENTRAL MONTANA DURING THE
MORNING...WINDS WILL SHIFT MORE NORTHERLY. AN UPPER LEVEL TROUGH
WILL THEN DEEPEN OVER THE PACIFIC NORTHWEST INTO THE GREAT BASIN ON
THURSDAY...SETTING UP AN INCREASINGLY MOIST SOUTHWESTERLY FLOW ALOFT
OVER THE AREA. THIS WILL BRING INCREASING MID LEVEL CLOUDINESS TO
THE TERMINALS DURING THE AFTERNOON...ESPECIALLY ACROSS SOUTHWEST AND
CENTRAL MONTANA (KBZN KHLN KGTF KLWT TERMINALS). ISOLATED TO
SCATTERED SNOW SHOWERS WITH AREAS OF MVFR CONDITIONS WILL ALSO
DEVELOP ACROSS THIS AREA BETWEEN 00Z AND 06Z FRIDAY. COULSTON
&&
.PREV DISCUSSION...
/ISSUED 407 AM MDT THU OCT 9 2008/
MAIN FORECAST CONCERN IS HEAVY SNOW POTENTIAL ACROSS CENTRAL AND
SOUTHWEST MONTANA.
TODAY...A TROUGH OF LOW PRESSURE CURRENTLY ENTERING THE PACIFIC
NORTHWEST WILL DEEPEN AS IT ENTERS THE NORTHERN ROCKIES LATER TODAY
WHILE HIGH PRESSURE OVER CANADA WILL ALLOW FOR COOLER AIR TO PUSH
SOUTH. QUIET WEATHER IS EXPECTED FOR TODAY WITH MORNING SUNSHINE
THEN INCREASING CLOUDS THROUGHOUT THE AFTERNOON WITH HIGH
TEMPERATURES TOPPING OUT ABOUT TEN DEGREES BELOW AVERAGE.
TONIGHT THROUGH SATURDAY...THE LOW WILL CUT OFF AS IT ENTERS THE
WESTERN ROCKIES LATER TODAY BEFORE GRADUALLY SHIFTING NORTH AND EAST
WITH 500MB WINDS DRAWING MOISTURE INTO THE REGION FROM THE EASTERN
ROCKIES THROUGH SATURDAY. MEANWHILE...NORTHERLY WINDS AT THE
SURFACE WILL PERSIST ACROSS NORTHERN AND CENTRAL MONTANA CAUSING
OVERRUNNING PRECIPITATION TO DEVELOP ALONG THE MOUNTAINS AND NEARBY
VALLEYS ACROSS CENTRAL AND SOUTHWEST MONTANA. UNSEASONABLY COOL
TEMPERATURES IN THE 30S AND EVEN UPPER 20S IN HIGHER ELEVATIONS ARE
EXPECTED FOR FRIDAY AND SATURDAY.SNOW WILL BEGIN AROUND 06Z FRIDAY
AND CONTINUE THROUGH SATURDAY. FOR NOW WILL GO WITH A WINTER STORM
WATCH EFFECTIVE 06Z TONIGHT THROUGH 12Z SUNDAY FOR
CASCADE...FERGUS... JUDITH BASIN...MEAGHER...BROADWATER...MADISON
AND GALLATIN COUNTIES AND A WINTER WEATHER ADVISORY FROM 06Z FRIDAY
THROUGH 00Z SATURDAY FOR BEAVERHEAD AND JEFFERSON COUNTIES. AS WE
GAIN A BETTER HANDLE ON HOW FAR NORTH AND WEST HEAVY PRECIPITATION
WILL FALL...ADDITIONAL COUNTIES MAY BE ADDED TO THE WINTER
HEADLINES. AS FOR STORM TOTAL ACCUMULATIONS...LOCATIONS IN THE
ADVISORY CAN EXPECT BETWEEN 2 TO 5 INCHES THROUGH SATURDAY WITH AT
LEAST 6 TO 10 INCHES IN THE LOWER ELEVATIONS IN THE WATCH AREA AND
10 TO 20 INCHES ACROSS HIGHER ELEVATIONS THROUGH EARLY SUNDAY.
MLS/BRUSDA
SATURDAY NIGHT THROUGH SUNDAY...THE MAIN AREA OF LOW PRESSURE THAT
WILL CAUSE ALL THE SNOW OVER THE REGION ON FRIDAY AND SATURDAY WILL
SLOWLY MOVE INTO THE UPPER MIDWEST BY SUNDAY EVENING. THUS EXPECT
SNOW...HEAVY AT TIMES TO AFFECT SOUTHWEST AND CENTRAL MONTANA
SATURDAY NIGHT INTO SUNDAY MORNING...THEN GRADUALLY TAPPER OFF TO
ISOLATED SNOW SHOWERS BY SUNDAY EVENING. AGAIN THE HEAVIEST SNOW
SHOULD REMAIN JUST SOUTH AND EAST OF GREAT FALLS...MAINLY IN THE
LEWISTOWN...STANFORD...WHITE SULPHUR SPRINGS...AND BOZEMAN AREAS.
LITTLE IF ANY SNOW IS EXPECTED NORTHWEST OF GREAT FALLS.
FOR MONDAY THROUGH TUESDAY...EXPECT A NICE WARMING TREND OVER THE
REGION...AS A WEAK UPPER LEVEL RIDGE TRIES TO REBUILD OVER THE
REGION. TEMPERATURES WILL WARM UP NICELY IN THE CUT BANK AREA...AS A
BROWN GROUND AND BREEZY WEST WIND DEVELOPS. HOWEVER...IN AREAS THAT
RECEIVE A SNOW COVER OVER SOUTHWEST AND CENTRAL MONTANA...IT WILL
TAKE A FEW DAYS FOR THE SNOW TO MELT AND TEMPERATURES WILL BE SLOWER
TO WARM UP. ANY PRECIP WILL BE CONFINED MAINLY TO THE WESTERN
MOUNTAINS ON TUESDAY. BRUSDA
WEDNESDAY AND THURSDAY...LATEST MODELS INDICATE A HIGH PRESSURE
BUILDING OVER THE PACIFIC NORTHWEST DURING THIS PERIOD. WEAK
DISTURBANCES WILL FLOW THROUGH BUT MOISTURE APPEARS LIMITED AT THIS
POINT SO KEPT SLIGHT CHANCE POPS ALONG THE DIVIDE. TEMPERATURES ARE
EXPECTED TO BE NEAR SEASONAL AVERAGES. JNS
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 48 27 38 23 / 10 30 20 40
CTB 44 24 37 21 / 10 20 30 30
HLN 48 30 39 25 / 20 50 50 50
BZN 51 30 40 25 / 30 70 80 70
WEY 46 23 35 19 / 30 40 80 70
DLN 45 25 33 19 / 20 60 60 60
HVR 52 22 41 25 / 10 10 20 30
LWT 47 26 37 22 / 10 50 70 70
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE SATURDAY NIGHT
FOR MTZ012-015-050-051-053>055.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM MDT
SATURDAY FOR MTZ008-052.
&&
$$
UPDATE...MPJ
SHORT TERM...SYNER/BRUSDA
LONG TERM...BRUSDA/SAUCIER
AVIATION...COULSTON
WEATHER.GOV/GREATFALLS
000
FXUS65 KTFX 091007
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
407 AM MDT THU OCT 9 2008
.DISCUSSION...
MAIN FORECAST CONCERN IS HEAVY SNOW POTENTIAL ACROSS CENTRAL AND
SOUTHWEST MONTANA.
TODAY...A TROUGH OF LOW PRESSURE CURRENTLY ENTERING THE PACIFIC
NORTHWEST WILL DEEPEN AS IT ENTERS THE NORTHERN ROCKIES LATER TODAY
WHILE HIGH PRESSURE OVER CANADA WILL ALLOW FOR COOLER AIR TO PUSH
SOUTH. QUIET WEATHER IS EXPECTED FOR TODAY WITH MORNING SUNSHINE
THEN INCREASING CLOUDS THROUGHOUT THE AFTERNOON WITH HIGH
TEMPERATURES TOPPING OUT ABOUT TEN DEGREES BELOW AVERAGE.
TONIGHT THROUGH SATURDAY...THE LOW WILL CUT OFF AS IT ENTERS THE
WESTERN ROCKIES LATER TODAY BEFORE GRADUALLY SHIFTING NORTH AND EAST
WITH 500MB WINDS DRAWING MOISTURE INTO THE REGION FROM THE EASTERN
ROCKIES THROUGH SATURDAY. MEANWHILE...NORTHERLY WINDS AT THE
SURFACE WILL PERSIST ACROSS NORTHERN AND CENTRAL MONTANA CAUSING
OVERRUNNING PRECIPITATION TO DEVELOP ALONG THE MOUNTAINS AND NEARBY
VALLEYS ACROSS CENTRAL AND SOUTHWEST MONTANA. UNSEASONABLY COOL
TEMPERATURES IN THE 30S AND EVEN UPPER 20S IN HIGHER ELEVATIONS ARE
EXPECTED FOR FRIDAY AND SATURDAY.SNOW WILL BEGIN AROUND 06Z FRIDAY
AND CONTINUE THROUGH SATURDAY. FOR NOW WILL GO WITH A WINTER STORM
WATCH EFFECTIVE 06Z TONIGHT THROUGH 12Z SUNDAY FOR
CASCADE...FERGUS... JUDITH BASIN...MEAGHER...BROADWATER...MADISON
AND GALLATIN COUNTIES AND A WINTER WEATHER ADVISORY FROM 06Z FRIDAY
THROUGH 00Z SATURDAY FOR BEAVERHEAD AND JEFFERSON COUNTIES. AS WE
GAIN A BETTER HANDLE ON HOW FAR NORTH AND WEST HEAVY PRECIPITATION
WILL FALL...ADDITIONAL COUNTIES MAY BE ADDED TO THE WINTER
HEADLINES. AS FOR STORM TOTAL ACCUMULATIONS...LOCATIONS IN THE
ADVISORY CAN EXPECT BETWEEN 2 TO 5 INCHES THROUGH SATURDAY WITH AT
LEAST 6 TO 10 INCHES IN THE LOWER ELEVATIONS IN THE WATCH AREA AND
10 TO 20 INCHES ACROSS HIGHER ELEVATIONS THROUGH EARLY SUNDAY.
MLS/BRUSDA
SATURDAY NIGHT THROUGH SUNDAY...THE MAIN AREA OF LOW PRESSURE THAT
WILL CAUSE ALL THE SNOW OVER THE REGION ON FRIDAY AND SATURDAY WILL
SLOWLY MOVE INTO THE UPPER MIDWEST BY SUNDAY EVENING. THUS EXPECT
SNOW...HEAVY AT TIMES TO AFFECT SOUTHWEST AND CENTRAL MONTANA
SATURDAY NIGHT INTO SUNDAY MORNING...THEN GRADUALLY TAPPER OFF TO
ISOLATED SNOW SHOWERS BY SUNDAY EVENING. AGAIN THE HEAVIEST SNOW
SHOULD REMAIN JUST SOUTH AND EAST OF GREAT FALLS...MAINLY IN THE
LEWISTOWN...STANFORD...WHITE SULPHUR SPRINGS...AND BOZEMAN AREAS.
LITTLE IF ANY SNOW IS EXPECTED NORTHWEST OF GREAT FALLS.
FOR MONDAY THROUGH TUESDAY...EXPECT A NICE WARMING TREND OVER THE
REGION...AS A WEAK UPPER LEVEL RIDGE TRIES TO REBUILD OVER THE
REGION. TEMPERATURES WILL WARM UP NICELY IN THE CUT BANK AREA...AS A
BROWN GROUND AND BREEZY WEST WIND DEVELOPS. HOWEVER...IN AREAS THAT
RECEIVE A SNOW COVER OVER SOUTHWEST AND CENTRAL MONTANA...IT WILL
TAKE A FEW DAYS FOR THE SNOW TO MELT AND TEMPERATURES WILL BE SLOWER
TO WARM UP. ANY PRECIP WILL BE CONFINED MAINLY TO THE WESTERN
MOUNTAINS ON TUESDAY. BRUSDA
WEDNESDAY AND THURSDAY...LATEST MODELS INDICATE A HIGH PRESSURE
BUILDING OVER THE PACIFIC NORTHWEST DURING THIS PERIOD. WEAK
DISTURBANCES WILL FLOW THROUGH BUT MOISTURE APPEARS LIMITED AT THIS
POINT SO KEPT SLIGHT CHANCE POPS ALONG THE DIVIDE. TEMPERATURES ARE
EXPECTED TO BE NEAR SEASONAL AVERAGES. JNS
&&
.AVIATION...
UPDATED 0510Z.
VFR CONDITIONS WILL CONTINUE ACROSS MOST OF SOUTHWEST...CENTRAL AND
NORTH CENTRAL MONTANA THROUGH 06Z FRIDAY. ONLY SCATTERED MID AND
HIGH CLOUDS WILL MOVE OVER THE AREA OVERNIGHT INTO THURSDAY MORNING
WITH GENERALLY LIGHT WINDS. AS CANADIAN SURFACE HIGH PRESSURE BUILDS
SOUTH INTO NORTH CENTRAL AND CENTRAL MONTANA DURING THE
MORNING...WINDS WILL SHIFT MORE NORTHERLY. AN UPPER LEVEL TROUGH
WILL THEN DEEPEN OVER THE PACIFIC NORTHWEST INTO THE GREAT BASIN ON
THURSDAY...SETTING UP AN INCREASINGLY MOIST SOUTHWESTERLY FLOW ALOFT
OVER THE AREA. THIS WILL BRING INCREASING MID LEVEL CLOUDINESS TO
THE TERMINALS DURING THE AFTERNOON...ESPECIALLY ACROSS SOUTHWEST AND
CENTRAL MONTANA (KBZN KHLN KGTF KLWT TERMINALS). ISOLATED TO
SCATTERED SNOW SHOWERS WITH AREAS OF MVFR CONDITIONS WILL ALSO
DEVELOP ACROSS THIS AREA BETWEEN 00Z AND 06Z FRIDAY. COULSTON
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 48 27 38 23 / 10 30 20 40
CTB 44 24 37 21 / 10 20 30 30
HLN 48 30 39 25 / 20 50 50 50
BZN 51 30 40 25 / 30 70 80 70
WEY 46 23 35 19 / 30 40 80 70
DLN 45 25 33 19 / 20 60 60 60
HVR 52 22 41 25 / 10 10 20 30
LWT 47 26 37 22 / 10 50 70 70
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE SATURDAY NIGHT
FOR MTZ012-015-050-051-053>055.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM MDT
SATURDAY FOR MTZ008-052.
&&
$$
SHORT TERM...SYNER/BRUSDA
LONG TERM...BRUSDA/SAUCIER
AVIATION...COULSTON
WEATHER.GOV/GREATFALLS
000
FXUS65 KMSO 090951
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
351 AM MDT THU OCT 9 2008
.DISCUSSION...AN APPROACHING UPPER LEVEL TROUGH OF LOW PRESSURE
WILL BE INCREASING CLOUDS AND OFFERING LOW CHANCE POPS TO THE
NORTHERN ROCKIES LATER TODAY. THE AIR MASS WILL REMAIN QUITE DRY
AT THE LOWER ELEVATIONS LIMITING ANY CHANCES FOR MEASURABLE
PRECIPITATION IN MOST VALLEYS... WITH BETTER CHANCES IN THE
MOUNTAINS.
TONIGHT AND FRIDAY...THE UPPER TROUGH WILL DEEPEN RESULTING IN THE
DEVELOPMENT OF A CLOSED LOW CIRCULATION TRACKING ACROSS SOUTHERN
IDAHO. THE POSITION OF THE MID-LEVEL CIRCULATION AND ITS TRACK
FAVORS THE ENHANCEMENT OF MOISTURE OVER PORTIONS OF NORTH-CENTRAL
IDAHO AND SOUTHWEST MONTANA. THE ATMOSPHERE WILL BE COLD ENOUGH
FOR SNOW DOWN TO THE VALLEY FLOORS. A WINTER WEATHER ADVISORY WILL
BE ISSUED TO ADDRESS THE ACCUMULATING SNOW POTENTIAL IN PORTIONS
OF LEMHI COUNTY...BUTTE AND GEORGETOWN LAKE AREAS...INCLUDING
HOMESTAKE PASS. A NORTHERLY SURFACE PRESSURE GRADIENT COMBINED
WITH WINDS ALOFT WILL MAINTAIN BREEZY CONDITIONS...BUT NOTHING TOO
STRONG.
FRIDAY NIGHT AND SATURDAY...THE HIGHLY AMPLIFIED UPPER LEVEL FLOW
PATTERN WILL NOT BE TOO PROGRESSIVE WITH THE PRIMARY LOW CIRCULATION
SOMEWHERE OVER THE GREAT BASIN REGION. THIS MAY MAKE PIN-POINTING
THE WHEREABOUTS OF STEADY PRECIPITATION A BIT MORE DIFFICULT.
HOWEVER...THE IDEA THAT THE BETTER CHANCES OF PRECIPITATION MAY BE
CONFINED TO THE SOUTHEASTERN-MOST PORTION OF LEMHI COUNTY IS
FEASIBLE...WHILE PRECIPITATION CHANCES DIMINISH AS YOU EXTEND
NORTHWARD INTO WEST-CENTRAL MONTANA.
SUNDAY THROUGH WEDNESDAY...A RIDGE OF HIGH PRESSURE WILL BE
BUILDING INTO THE AREA BY MONDAY AND WILL BECOME A ZONAL WESTERLY
FLOW BY WEDNESDAY.
&&
.AVIATION...HIGH CLOUDS WILL BE MOVING INTO NORTHERN IDAHO AND
WESTERN MONTANA THIS MORNING...WITH CEILINGS LOWERING AND
INCREASED CHANCE OF SHOWERS OVER THE HIGHER TERRAIN THIS
AFTERNOON. MOUNTAIN TOPS ARE LIKELY TO BECOME PARTLY OBSCURED IN
CLOUDS AND SHOWERS LATER IN THE DAY. A DEVELOPING LOW PRESSURE
SYSTEM WILL INCREASE CLOUDS AND CONTINUE THE TREND OF LOWERING
CEILING TONIGHT. PRECIPITATION (LIKELY SNOW) WILL ALSO BE
INCREASING PRIMARILY ACROSS THE CONTINENTAL DIVIDE AND WEST-
CENTRAL MONTANA...AS WELL AS PORTIONS OF NORTH-CENTRAL IDAHO
INCLUDING LEMHI COUNTY. MOUNTAINS WILL BECOME OBSCURED IN CLOUDS
AND SNOW WITH CONDITIONS IN GENERAL DETERIORATING.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 12 PM MDT
FRIDAY FOR BUTTE/BLACKFOOT REGION.
ID...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 12 PM MDT
FRIDAY FOR EASTERN LEMHI COUNTY.
&&
$$
MSJ
000
FXUS65 KGGW 090948
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
348 AM MDT THU OCT 9 2008
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH SATURDAY...
THE UPPER TROUGH THAT WILL BECOME THE WEATHER MAKER FOR THE NEXT
SEVERAL DAYS WILL MOVE OFF THE PACIFIC OCEAN THIS MORNING AND
DEEPEN AS IT MOVES INTO THE GREAT BASIN ON THIS
AFTERNOON...SOUTHWEST FLOW ALOFT WILL SPREAD MOISTURE NORTHWARD
TOWARD MONTANA. A CLOSED LOW WILL FORM IN THIS UPPER TROUGH TONIGHT.
A LOW PRESSURE SYSTEM DEVELOPS ALONG A STATIONARY FRONT NEAR THE
WYOMING/COLORADO BORDER DURING THE DAY TODAY. THE MOISTURE ON THE
SOUTHWEST FLOW ALOFT WILL START OVERRUNNING THE FRONT AND BECOME A
WIDESPREAD AREA OF RAIN INTO SOUTHERN MONTANA THIS EVENING THEN
MIXING WITH OR CHANGING TO SNOW THROUGH THE NIGHT AND INTO FRIDAY.
MODEL GENERALLY BRING THE PRECIPITATION AS FAR NORTH AS
WINNETT...JORDAN AND GLENDIVE TONIGHT AND FRIDAY. WITH NORTHERLY
WINDS FEEDING LOW LEVEL DRY AIR INTO NORTHERN MONTANA...THE
RAIN/SNOW FROM THIS SYSTEM WILL HAVE A HARD TIME GETTING NORTH OF
THE MISSOURI RIVER. MODELS KEEP TEMPERATURES ALOFT NEAR FREEZING
WHICH MAKES DETERMINING WHETHER THE PRECIPITATION WILL BE RAIN OR
SNOW TOUGH. CHANCES ARE...IT WILL BE MAINLY SNOW LATE TONIGHT AND
FRIDAY IN THE HIGHER ELEVATIONS AND A MIX OF RAIN AND SNOW IN THE
VALLEYS. WITH A HALF INCH OR MORE OF PRECIPITATION POSSIBLE SOUTH
OF MONTANA HIGHWAY 200...IF A HIGHER ELEVATION LOCATION GETS
MOSTLY SNOW BETWEEN MIDNIGHT TONIGHT AND FRIDAY AFTERNOON...IT
WOULD ADD UP TO 6 INCHES OR MORE OF SNOW. GIVEN THE POSSIBILITY OF
HEAVY SNOW AND BEING EARLY OCTOBER...WILL ISSUE A WINTER STORM
WATCH BETWEEN MIDNIGHT TONIGHT AND FRIDAY AFTERNOON.
WILL SEE A BREAK IN THE PRECIPITATION FRIDAY NIGHT AND EARLY
SATURDAY BEFORE THE SECOND WAVE OF MOISTURE MOVES NORTH STARTING
SATURDAY AFTERNOON AS THE UPPER LOW STARTS LIFTING NORTH. HEAVY
SNOW IS LIKELY WITH THIS SYSTEM WITH THE BULK OF THE SNOW
OCCURRING SATURDAY NIGHT AND SUNDAY. WITH A WATCH CURRENTLY IN
EFFECT FOR THE FIRST WAVE OF PRECIPITATION WILL HOLD OFF ON
ISSUING ANY WATCHES FOR THE WEEKEND FOR NOW.
.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...
A WINTER-LIKE CYCLONIC STORM SYSTEM WILL BE WELL UNDERWAY AND
MOVING THROUGH EASTERN MONTANA WHEN THE EXTENDED PERIOD OPENS ITS
DOOR SATURDAY NIGHT. MODELS AND ENSEMBLES HAVE BECOME COMFORTABLE
WITH THIS WEEKEND STORM. THE USUAL EXPLODED ENSEMBLE SPAGHETTI
PLOTS HAVE ALL LINED UP CRISPLY AROUND THIS LOW THROUGH SUNDAY.
THE 00Z GFS HAS COME TO CLOSELY RESEMBLE THE 12Z ECMWF IN TIMING
AND LOCATION. DETAILS BEGIN TO FUZZ A LITTLE SUNDAY NIGHT AND
MONDAY AS THE MAIN ENERGY OF THE STORM LIFTS INTO CANADA AND THE
FRONT MOVES EAST. MODELS BEGIN TO DIFFER ON HOW LONG THE WRAP-
AROUND COMA HEAD LINGERS OVER THE FORECAST AREA ON MONDAY. SINCE
THE SYSTEM HAS BEEN RATHER PROGRESSIVE IT WOULD MAKE SENSE THAT BY
MONDAY AFTERNOON THE STORM WILL HAVE EXITED EAST...REPLACED BY A
TEMPORARILY AMPLIFIED UPPER RIDGE FROM THE WEST. THE RIDGE WILL
BECOME FLATTENED TUESDAY BY A QUICK-MOVING SHORTWAVE TREKKING
ACROSS NORTHERN ALBERTA/SASKATCHEWAN. THE REMAINDER OF THE PERIOD
SHOULD CONTINUE MOSTLY DRY AND SEASONAL WITH NEAR ZONAL UPPER
FLOW.
THE MAIN QUESTION CONCERNING SATURDAY NIGHT AND SUNDAY WILL BE
THE AMOUNT OF SNOW THAT COULD FALL. THE LARGE UPPER CLOSED LOW
WILL BE CENTERED OVER SOUTHEASTERN IDAHO AND WESTERN WYOMING. THIS
WILL BE THE PERFECT SPOT TO DIRECT A VERY STRONG UPPER JET INTO
EASTERN MONTANA AND THE WESTERN DAKOTAS. IN ADDITION AN INVERTED
SURFACE TROUGH WILL BE SLIDING NORTH INTO THE SAME AREA. THE
RESULT WILL VERY STRONG OMEGA LIFT AND SUPPORT ALONG WITH VERY
IMPRESSIVE NEGATIVE Q-VECTOR DIVERGENCE NUMBERS. THE RESULTING QPF
FOCUS IN THE AFOREMENTIONED AREAS SATURDAY NIGHT IS A HALF INCH TO
INCH OF WATER...WITH ANOTHER HALF INCH ON SUNDAY. THE AMOUNT OF
SNOWFALL COULD DEPEND ON THE TEMPERATURES AND HOW THE
PRECIPITATION BEGINS ON SATURDAY DURING THE DAY. 850MB
TEMPERATURES SATURDAY WILL BEGIN AROUND -4C AND DROP TO -6C BY
SUNDAY MORNING...WHILE GUIDANCE SUGGESTS SURFACE TMIN IN THE MID
20S THEN RISING INTO THE MID 30S SUNDAY. WITH THE PROGRESSIVE
NATURE OF THIS STORM THE RESULTING TEMPERATURES COULD DEVIATE
QUITE A BIT FROM GUIDANCE. EXPECT THE MAJORITY OF PRECIPITATION
TO FALL AS SNOW BUT THE COLD BOUNDARY ONLY EXTENDS A SHORT WAY
BEYOND THE EASTERN BORDER SO THERE REMAINS UNCERTAINTY IN
PRECIPITATION TYPE. SCT
&&
.AVIATION...
VFR TODAY...WITH NORTHWESTERLY 10KT WIND VEERING TO THE NORTHEAST
THIS AFTERNOON. MID LEVEL CLOUDS INCREASE IN COVERAGE TODAY AHEAD
OF AN INTENSIFYING STORM SYSTEM IN WYOMING. THIS STORM WILL NUDGE
NORTH INTO SOUTHERN ZONES TONIGHT MAINLY AFFECTING KGDV WITH RAIN
AND/OR SNOW. SCT
&&
.CLIMATE...
MUCH OF NE MT HAS ALREADY HAD FREEZING TEMPERATURES THIS FALL.
FOR MANY LOCATIONS THIS OCCURRED YESTERDAY...OCT 7TH. SPOTTY
FREEZES THOUGH OCCURRED IN THE AREA ON SEVERAL OTHER EARLIER
OCCASIONS...AS EARLY AS AUG 23RD. THE REMAINDER OF THE
AREA...INCLUDING THE GLASGOW AIRPORT...CAN EXPECT THEIR FIRST
FREEZE LATE TONIGHT/THU MORN. THE LAST TIME THERE WAS A LATER
FIRST FREEZE OF THE SEASON WAS IN 1986. SHOULD ANY SNOW ACCUMULATE
IN GLASGOW THIS WEEKEND...IT WOULD BE THE EARLIEST FIRST MEASURABLE
SNOW OF THE SEASON SINCE 1999. SIMONSEN
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM LATE TONIGHT THROUGH FRIDAY AFTERNOON
FOR PETROLEUM-GARFIELD-DAWSON-PRAIRIE-WIBAUX.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KBYZ 090918
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
318 AM MDT THU OCT 9 2008
.SHORT TERM...VALID FOR TDY AND FRI...
MAJOR WINTER STORM WILL IMPACT THE AREA BEGINNING TONIGHT...AND
LASTING THROUGH SUNDAY. DUE TO THE STRENGTH AND DURATION EXPECTED
FROM THIS STORM...IT COULD TURN OUT TO BE A HISTORICAL SNOW
PRODUCER BY THE TIME THINGS WIND DOWN SUNDAY NIGHT...ESPECIALLY
ALONG THE NORTHEAST SLOPES OF THE MOUNTAINS.
BAROCLINIC LEAF NOW TAKING SHAPE FROM ID TO WY AS ENERGY DIGS
ALONG THE PACIFIC COAST...AND HIGH CLOUD IS BEGINNING TO SPREAD
INTO OUR SW AS ISENTROPIC LIFT INCREASES. THIS LIFT WILL BECOME
QUITE STRONG TODAY...AND LOOKS LIKE A GOOD CHANCE OF RAIN BY THIS
AFTERNOON ACROSS OUR SOUTH AND IN UPSLOPE AREAS. WINDS ALREADY
TURNING EASTERLY ACROSS THE AREA.
CURRENT DEW POINTS IN THE TEENS AND LOWER 20S SHOULD ALLOW FOR A
FAIRLY RAPID COOLING AND TRANSITION TO SNOW ONCE THE AIRMASS
SATURATES LATER TODAY AND THIS EVENING. PREDOMINANT PCPN TYPE
SHOULD BE SNOW BY MIDNIGHT FOR THE WEST HALF...BUT WITHOUT A
SURGE OF COLDER AIR FROM THE NORTH THINK A MIX WITH RAIN MAY
PERSIST FOR THE LOWER ELEVATIONS IN THE EAST FOR A WHILE LONGER.
HAVE HOISTED A WINTER STORM WATCH ACROSS THE AREA BEGINNING 03Z
THIS EVENING. STILL SOME ISSUES TO BE WORKED OUT THOUGH...MAINLY
REGARDING SURFACE TEMPS. 700MB TEMPS FALL TO -10C TO -12C IN THE
WEST AFTER 06Z TONIGHT. THIS WILL ALLOW FOR DEEP/MOIST UPSLOPE
FLOW INTO THE DENDRITIC LAYER. SO CONFIDENCE IS HIGH IN AN
ACCUMULATING SNOW WEST TONIGHT...ESPECIALLY THE EASTERN SLOPES
WHERE PCPN SHOULD BECOME HEAVY. TO THE EAST...DENDRITIC LAYER IS
QUITE HIGH...NEAR 550MB AND ABOVE THE STRONGEST LIFT/MOISTURE...AND
SFC TEMPS ARE A BIT MORE IFFY. GFS KEEPS TEMPS ABOVE FREEZING...
BUT THE NAM DYNAMICALLY COOLS THEM ENOUGH TO SUPPORT SNOW. NOT
SURE HOW THIS WILL PAN OUT EXACTLY... BUT IF PCPN BECOMES HEAVY
ENOUGH...WHICH IT MAY GIVEN A PERIOD OF VERY STRONG FRONTOGENESIS
OUT THERE...ACCUMULATING SNOW IS POSSIBLE. M0RE THAN LIKELY THE
SNOW ACCUMULATIONS DURING THE INITIAL STAGES WILL BE ELEVATION
DEPENDENT. TO OUR SOUTH...FLOW DOES NOT REALLY FAVOR THE BIG HORNS
UNTIL FRIDAY...AND LOWER ELEVATIONS MAY ALSO STAY A BIT WARM FOR
MUCH ACCUMULATION AROUND SHERIDAN TONIGHT. IN THE END BASED ON
THESE UNCERTAINTIES TO BE WORKED OUT HAVE DECIDED TO ISSUE THE
WATCH EVERYWHERE BEGINNING 03Z. HOWEVER THINGS PAN OUT TONIGHT...
PCPN WILL TURN TO ALL SNOW FRI/FRI NITE. UPSLOPE AREAS WILL
CONTINUE TO BE HIT...BUT SHOULD SEE A LITTLE BREAK IN OUR EAST
ONCE INITIAL SURGE LIFTS THROUGH TO THE NORTH.
TEMPS CONTINUE TO COOL THROUGH THE LAYER IN THE WEST HALF FRI
NITE...AND WITH DEEPENING DENDRITIC LAYER WOULD EXPECT SNOW RATIOS
TO BECOME GREATER THROUGH THIS PERIOD...SETTING THE STAGE FOR EVEN
STRONGER DYNAMICS TO COME SAT INTO SUN. SEE EXTENDED DISCUSSION
FOR THAT.
AGAIN MUST STRESS SERIOUSNESS IN THIS UPCOMING WINTER STORM.
JKL
.LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED...
THE LATEST GUIDANCE REMAINS CONSISTENT WITH THE EARLY MAJOR
WINTER STORM...RESULTING IN SIGNIFICANT IMPACTS ACROSS THE AREA
THIS WEEKEND. THE STRONG UPPER LOW IS EXPECTED TO BEGIN MOVING
NORTHWARD SATURDAY AFTER BOTTOMING OUT ACROSS THE GREAT BASIN.
SNOW IS EXPECTED TO BE ONGOING AT THE START OF THE FORECAST
PERIOD...WITH DEEP UPSLOPE FLOW...STRONG OVERRUNNING PATTERN...AND
AND STRONG DIFFLUENCE ALOFT CONTRIBUTING TO THE INTENSIFICATION OF
PRECIPITATION ACROSS THE REGION. SATURDAY THROUGH SUNDAY SHOULD
BRING THE BULK OF SNOW FOR THIS STORM EVENT. WRAP AROUND SNOWS
WILL BEGIN SUBSIDING SUNDAY NIGHT AND CLEAR THE AREA TO THE EAST
MONDAY MORNING. MOUNTAIN AREAS WILL LIKELY SEE SEVERAL FEET OF
SNOW...WHILE A STRONG LIKELIHOOD OF AROUND A FOOT OF SNOW
ACCUMULATION IS POSSIBLE ACROSS THE LOWER ELEVATIONS.
ONCE THE STORM SYSTEM CLEARS OUT...THE AREA IS RETURNED TO A
ZONAL TYPE DOWNSLOPING FLOW PATTERN. IT LOOKS PRETTY DRY BEYOND
MONDAY...WITH WARMING TREND APPROACHING 60S BY THE END OF THE
PERIOD. GILSTAD
&&
.AVIATION...
VFR CONDITIONS WILL CONTINUE THROUGH LATE MORNING UNDER INCREASING
CLOUDINESS. MID LEVEL CLOUD WILL SPREAD ACROSS THE REGION THURSDAY
MORNING AND LOWER THROUGHOUT THE DAY. MVFR CEILINGS WILL BE
POSSIBLE ALONG AND WEST OF A SHERIDAN...BILLINGS...ROUNDUP LINE
BY LATE AFTERNOON...CEILING WILL CONTINUE TO DROP TO IFR
CONDITIONS OVERNIGHT TONIGHT. WIDESPREAD SHOWERS WILL ACCOMPANY
LOWERING CEILINGS. MOUNTAIN VISIBILITY IS LIKELY TO BE FULLY
OBSCURED BY MID AFTERNOON. GILSTAD
&&
.PRELIMINARY POINT TEMP/POPS...
TDY FRI SAT SUN MON TUE WED
-------------------------------------------------------
BIL 046 030/035 026/033 026/034 024/048 030/053 034/053
4/R ++/S ++/S +8/S 31/B 10/B 11/B
LVM 046 024/034 020/033 020/036 023/051 029/053 034/053
4/R ++/S ++/S +8/S 31/N 10/B 11/B
HDN 050 030/037 026/034 025/038 023/051 029/054 033/054
6/R ++/S ++/S +8/S 31/B 10/B 11/B
MLS 053 033/039 028/036 027/038 025/051 031/055 034/055
4/R 98/O 88/S 97/S 31/B 11/B 11/B
4BQ 050 030/039 027/037 027/037 024/051 030/055 032/055
6/O ++/O ++/S +6/S 31/B 10/U 11/U
BHK 051 030/039 026/035 025/039 023/050 026/053 031/053
3/R 97/O 77/S 85/O 31/B 11/B 11/B
SHR 049 028/038 025/034 025/035 023/050 029/053 031/053
6/O ++/S ++/S +8/S 31/B 10/U 11/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WATCH IN EFFECT FROM THIS EVENING THROUGH LATE
SUNDAY NIGHT FOR ZONES 28>42-56>58-63>68.
WY...WINTER STORM WATCH IN EFFECT FROM THIS EVENING THROUGH LATE
SUNDAY NIGHT FOR ZONES 98-99.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KTFX 090510
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1110 PM MDT WED OCT 8 2008
...UPDATE TO AVIATION...
.DISCUSSION...
UPDATE FORTHCOMING. HAVE MADE ADJUSTMENTS TO THE SKY CONDITION GRIDS
TO BETTER REFLECT THE CURRENT CONDITION OF DECREASING CLOUD COVER.
FORECAST OF DEEPENING UPPER TROF OVER THE PACIFIC NORTHWEST PERSISTS
WITH AN INCREASING MOIST SOUTHWEST FLOW ALOFT ON THURSDAY.
PRECIPITATION EVENT FOR FRIDAY AND INTO THE WEEKEND CONTINUES TO
LOOK ON TRACK. MIDNIGHT SHIFT WILL EVALUATE 00Z MODELS TO DETERMINE
IF HIGHLIGHTS WILL BE WARRANTED. EMANUEL
&&
.AVIATION...
UPDATED 0510Z.
VFR CONDITIONS WILL CONTINUE ACROSS MOST OF SOUTHWEST...CENTRAL AND
NORTH CENTRAL MONTANA THROUGH 06Z FRIDAY. ONLY SCATTERED MID AND
HIGH CLOUDS WILL MOVE OVER THE AREA OVERNIGHT INTO THURSDAY MORNING
WITH GENERALLY LIGHT WINDS. AS CANADIAN SURFACE HIGH PRESSURE BUILDS
SOUTH INTO NORTH CENTRAL AND CENTRAL MONTANA DURING THE
MORNING...WINDS WILL SHIFT MORE NORTHERLY. AN UPPER LEVEL TROUGH
WILL THEN DEEPEN OVER THE PACIFIC NORTHWEST INTO THE GREAT BASIN ON
THURSDAY...SETTING UP AN INCREASINGLY MOIST SOUTHWESTERLY FLOW ALOFT
OVER THE AREA. THIS WILL BRING INCREASING MID LEVEL CLOUDINESS TO
THE TERMINALS DURING THE AFTERNOON...ESPECIALLY ACROSS SOUTHWEST AND
CENTRAL MONTANA (KBZN KHLN KGTF KLWT TERMINALS). ISOLATED TO
SCATTERED SNOW SHOWERS WITH AREAS OF MVFR CONDITIONS WILL ALSO
DEVELOP ACROSS THIS AREA BETWEEN 00Z AND 06Z FRIDAY. COULSTON
&&
.PREV DISCUSSION...ISSUED 253 PM MDT WED OCT 8 2008
TONIGHT THROUGH FRIDAY...A STRONG WESTERLY FLOW ALOFT DIMINISHES
OVERNIGHT AS A SIGNIFICANT UPPER LEVEL TROUGH BEGINS TO DEVELOP OVER
THE WESTERN CONUS. BY THURSDAY AFTERNOON THIS TROUGH WILL BE WELL
ESTABLISHED OVER THE PACIFIC NORTHWEST WITH A SURFACE LOW
STRENGTHENING OVER THE CENTRAL ROCKY MOUNTAIN REGION. SURFACE FLOW
ACROSS MONTANA WILL BE NORTHERLY AND BECOMING INCREASINGLY MOIST
AS THE UPPER TROUGH PUMPS MOISTURE INTO THE REGION. THERE WILL BE
AN INCREASING LIKELIHOOD OF SNOW ACROSS SOUTHWEST MONTANA THURSDAY
AFTERNOON WITH SNOW SPREADING INTO SOUTHERN PORTION OF CENTRAL
MONTANA THURSDAY NIGHT. AT THIS TIME...IT APPEARS THAT A WINTER
WEATHER ADVISORY COULD BE REQUIRED THURSDAY NIGHT INTO FRIDAY
ACROSS SOUTHWEST MONTANA AND SOUTHERN PORTIONS OF CENTRAL MONTANA.
LOWER ELEVATION SNOW ACCUMULATIONS COULD TOTAL 2 TO 6 INCHES...
ESPECIALLY THROUGH JUDITH GAP. FOR NOW WILL CONTINUE MENTION OF
ACCUMULATING SNOWS AND MUCH COLDER THAN NORMAL TEMPERATURES IN THE
HAZARDOUS WEATHER OUTLOOK. MPJ
FRIDAY NIGHT THROUGH SUNDAY NIGHT...BOTH THE GFS AND ECMWF ARE IN
BETTER AGREEMENT TONIGHT FOR THE UPCOMING SNOWSTORM THAT POTENTIAL
COULD AFFECT THE REGION FRIDAY NIGHT THROUGH SUNDAY. EXPECT
UNSEASONABLY COLD AIR TO CONTINUE TO RESIDE OVER THE REGION THROUGH
THE WEEKEND...THUS ALL OF THE PRECIPITATION WILL FALL IN THE FORM OF
SNOW AT ALL ELEVATIONS OVER THE WEEKEND. BOTH MODELS CONTINUE TO
PROG ACCUMULATING SNOWFALL OVER SOUTHWEST AND CENTRAL MONTANA. RIGHT
NOW...FORECAST SNOW ACCUMULATIONS OF 2 TO 4 INCHES ARE POSSIBLE AT
LOWER ELEVATIONS FROM FRIDAY NIGHT THROUGH SATURDAY NIGHT...WITH 10
TO 16 INCHES LIKELY IN THE MOUNTAINS...THEN ADDITIONAL SNOW
ACCUMULATIONS ARE POSSIBLE SUNDAY. THE MAIN AREA TO SEE THE SNOW
ACCUMULATION IS OVER MUCH OF SOUTHWEST MONTANA AND IN THE LEWISTOWN
AREA. IN THE GREAT FALLS AND HAVRE AREAS...CURRENT FORECAST MODELS
CONTINUE TO SHOW THE GOOD ACCUMULATING SNOWS STAYING JUST SOUTH AND
EAST OF THESE CITIES...BUT SHOULD THE FORECAST TRACK MOVE
NORTHWESTWARD 30 TO 40 MILES...HEAVIER SNOW COULD FALL IN THESE
LOCATIONS. FOR THE CUT BANK AREA...SNOW ACCUMULATIONS SHOULD BE
MINOR.
FOR MONDAY AND MONDAY NIGHT...EXPECT WARMER AIR TO MOVE INTO THE
REGION...AS A WEAK UPPER LEVEL RIDGE BUILDS IN FROM THE WEST.
TEMPERATURES WILL BE SLOW TO WARM UP IN SOUTHWEST MONTANA...AS A
FRESH SNOW COVER ON SUNDAY SHOULD ALLOW FOR A FAIRLY COLD NIGHT ON
SUNDAY NIGHT. BRUSDA
TUESDAY AND WEDNESDAY...A WESTERLY FLOW ALOFT IS EXPECTED TO BRING
IN PACIFIC MOISTURE TO THE ZONES BY WEDNESDAY. TEMPERATURES WILL BE
SLIGHTLY BELOW SEASONAL AVERAGES ON THE NORTH CENTRAL PLAINS. JNS
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 25 47 26 37 / 0 10 30 20
CTB 23 45 23 37 / 0 10 20 20
HLN 27 49 31 38 / 10 20 50 30
BZN 22 51 29 40 / 0 30 70 50
WEY 22 44 21 35 / 0 30 40 40
DLN 22 45 25 34 / 10 20 60 60
HVR 25 51 25 42 / 0 10 10 20
LWT 23 45 25 34 / 0 10 50 40
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...EMANUEL/MPJ
LONG TERM...BRUSDA/JNS
AVIATION...COULSTON
WEATHER.GOV/GREATFALLS
000
FXUS65 KBYZ 090325
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
925 PM MDT WED OCT 8 2008
.SHORT TERM...VALID FOR THU AND FRI...
...MAJOR EARLY WINTER STORM STILL ON TRACK TO IMPACT THE AREA LATE
THIS WEEK THROUGH THE WEEKEND...
ONE MORE QUIET NIGHT AHEAD. RELATIVELY LIGHT WINDS AND LOW
DEWPOINTS SHOULD LEND ITSELF TO A CHILLY NIGHT ACROSS AREA. ONE
CAVEAT THOUGH...THERE IS SOME MID TO HIGH LEVEL MOISTURE/CLOUD
COVER TO MOVE OVER THE SOUTHERN SECTIONS LATE WHICH MAY PREVENT
TEMPS FROM HITTING POTENTIAL BOTTOM. HAVE JUST TWEAKED OVERNIGHT
LOWS BUT NO MAJOR CHANGE THERE.
HOWEVER...ONE SIGNIFICANT CHANGE FOR THIS UPDATE PACKAGE...RAISED
POPS FOR ZONES MAINLY EAST OF BILLINGS. NEW NAM PROGGS INDICATE
ATMOSPHERIC MOISTURE TO QUICKLY DEEPEN LATTER PART OF THURSDAY
AFTERNOON IN SOUTHEAST AS VERY GOOD ISENTROPIC PATTERN SETS UP.
RAISED POPS FROM SCATTERED TO LIKELY IN THIS AREA. REST OF
FORECAST ON TRACK AS SIGNIFICANT WEATHER SYSTEM STILL LOOKS TO
IMPACT REGION THROUGH WEEKEND. FORTHCOMING HIGHLIGHTS WILL LIKELY
BE ISSUED OVER THE NEXT SHIFT OR TWO. CHECK OUT WEATHER STORY
LINKS 2 AND 3 ON OUR WEBSITE AT WWW.WRH.NOAA.GOV FOR EARLY
POTENTIAL SNOWFALL ESTIMATES. BT
.LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED...
THE LATEST GUIDANCE CONTINUES TO BE CONSISTENT WITH OUR EARLY
SEASON MAJOR WINTER STORM WHICH COULD RESULT IN SOME SIGNIFICANT
IMPACTS ACROSS THE AREA THIS WEEKEND. THE STRONG UPPER LOW
ANTICIPATED TO BE BOTTOMING OUT ACROSS THE GREAT BASIN EARLY
SATURDAY AND BEGIN THE TURN TO THE NORTHWEST. A DEEP UPSLOPE FLOW
AND STRONG OVERUNNING PATTERN AND DIFFLUENT FLOW ALOFT SHOULD HAVE
THE SNOW ONGOING FOR MOST AREAS AT THE START OF THIS FORECAST
PERIOD. EXPECTING THIS LIGHTER TO MODERATE PRECIP EVENT TO ENHANCE
AS WE PROGRESS THROUGH SATURDAY INTO SATURDAY NIGHT AS THE UPPER
LOW TRACKS ACROSS WYOMING SATURDAY AND INTO EASTERN MONTANA
SUNDAY. THIS SHOULD BE THE MAIN EVENT FOR THIS STORM FOR MONTANA
AND NORTHERN WYOMING WITH VERY STRONG DYNAMICS AND A DEEP AND
MOIST UPSLOPE FLOW RESULTING IN HEAVY SNOWFALL RATES. TEMPERATURE
PROFILES ALSO THE BEST DURING THIS TIME FRAME FOR SIGNIFICANT
ACCUMULATIONS. WRAP AROUND SNOWS WILL LINGER INTO SUNDAY BUT SHOULD
BEGIN TO TAPER OFF AS THE STORM BEGINS TO LIFT OFF TO THE
NORTHEAST LATE INTO THE DAY AND INTO EARLY MONDAY. WHEN ALL SAID
AND DONE...WE COULD BE TALKING ABOUT SEVERAL FEET OF SNOW FOR THE
MOUNTAINS...ESPECIALLY THOSE FAVORED NORTH AND NORTHEAST UPSLOPE
AREAS. DEPENDING ON THE EXACT PATH...THERE SHOULD BE A BAND OF
HEAVY LOW ELEVATION SNOW AS WELL THAT COULD REACH UPWARDS OF A
FOOT OF WET SNOW.
BEYOND MONDAY...FLOW BEGINS TO TAKE ON A ZONAL LOOK FOR AN OVERALL
DOWNSLOPING PATTERN. SHOULD BE MOSTLY DRY WITH AN OVERALL WARMING
TREND.
FRIEDERS
&&
.AVIATION...
VFR CONDITIONS ARE EXPECTED ACROSS THE FORECAST AREA TONIGHT INTO
LATE THURSDAY MORNING. MID LEVEL CLOUD COVER WILL DEVELOP THURSDAY
MORNING AND LOWER THROUGH THE DAY WITH OCCASIONAL MVFR CEILINGS
POSSIBLE ALONG AND WEST OF A SHERIDAN...BILLINGS...ROUNDUP LINE
BY LATE AFTERNOON. MOUNTAIN OBSCURATION IS LIKELY THURSDAY
AFTERNOON. SHOWER ACTIVITY WILL INCREASE FROM THE SOUTHWEST
THURSDAY AFTERNOON WITH ISOLATED COVERAGE IN THE EARLY AFTERNOON
BECOMING SCATTERED BY LATE IN THE DAY. CHAMBERS
&&
.PRELIMINARY POINT TEMP/POPS...
THU FRI SAT SUN MON TUE WED
-----------------------------------------------------------
BIL 029/047 030/038 026/033 026/034 024/048 030/053 034/053
04/R 77/O 78/S 86/S 21/B 10/B 11/B
LVM 023/049 023/037 019/033 020/036 023/051 029/053 034/053
04/R 87/O 68/S 77/S 21/N 10/B 11/B
HDN 027/051 030/039 026/034 025/038 023/051 029/054 033/054
06/R 76/O 77/S 86/S 21/B 10/B 11/B
MLS 029/053 033/042 028/036 027/038 025/051 031/055 034/055
05/R 76/O 67/S 76/S 21/B 11/B 11/B
4BQ 029/052 029/042 027/037 027/037 024/051 030/055 032/055
06/O 77/O 78/S 85/S 21/B 10/U 11/U
BHK 025/050 025/042 024/035 025/039 023/050 026/053 031/053
03/R 76/O 67/S 75/O 21/B 11/B 11/B
SHR 028/050 028/040 025/034 025/035 023/050 029/053 031/053
06/O 77/O 78/S 86/S 21/B 10/U 11/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KGGW 090315
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
915 PM MDT WED OCT 8 2008
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT...
AFTER A WINDY DAY...SURFACE PRESSURE GRADIENTS ARE STEADILY
WEAKENING WITH RESULTING LESSENING OF WINDS SPEEDS FOLLOWING DE-
COUPLING WITH HIGHER LEVELS. LAKE WIND ADVISORY EXPIRED WITH
EARLIER UPDATE. STRONG WESTERLY JET OVER OUR AREA...BUT NOW
DECREASING IN STRENGTH...AND WATER VAPOR SATELLITE CHANNEL
INDICATES THE AIRMASS OVER NE MT IS QUITE DRY ALOFT...RESULTING IN
CLEAR SKIES. SOMEWHAT COOL TEMPS WITH HIGHS MOSTLY IN THE 50S
TODAY...BUT WITH DEW POINTS ONLY IN THE 20S. THIS WILL RESULT IN
LOWS BELOW FREEZING TONIGHT NEARLY ALL LOCATIONS IN NE MT. 850 MB
TEMPS COOL TO 0-3C BY 12Z. THE UPDATE IS MAINLY FOR LOWERING OF
CLOUD COVER ONLY. SIMONSEN
PREVIOUS SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH
FRIDAY...JET STREAK MOVING OFF TO THE EAST THIS AFTERNOON WITH
WINDS BEGINNING TO DIMINISH ACROSS CENTRAL MONTANA. WITH HIGH
PRESSURE SPREADING INTO EASTERN MONTANA OVERNIGHT EXPECT WINDS TO
DROP OFF IN THE WEST AROUND SUNSET. THE WINDS MAY STAY STRONGER
ACROSS THE EAST LONGER...AS WILL TAKE SOME TIME FOR THE GRADIENT
TO RELAX. KEEPING LAKE WIND ADVISORY GOING UNTIL 7PM.
WITH THE HIGH PRESSURE...AND RESULTANT LIGHT WINDS AND CLEARING
SKIES...EXPECT GOOD RADIATIONAL COOLING TONIGHT. THIS WILL LIKELY
DROP TEMPERATURES BELOW FREEZING FOR MOST AREAS.
THE UPPER TROUGH THAT WILL BECOME THE WEATHER MAKER FOR THE NEXT
SEVERAL DAYS MOVES INTO THE GREAT BASIN ON THURSDAY...SPREADING
MOISTURE NORTHWARD TOWARD MONTANA. A LOW PRESSURE SYSTEM
DEVELOPS ALONG A STATIONARY FRONT NEAR THE WYOMING/COLORADO BORDER
DURING THE DAY ON THURSDAY. THE MOISTURE ON THE SOUTHWEST FLOW
ALOFT WILL START OVERRUNNING THE FRONT AND BECOME A WIDESPREAD
AREA OF RAIN INTO SOUTHERN MONTANA DURING THE EVENING THEN MIXING
WITH OR CHANGING TO SNOW THROUGH THE NIGHT AND INTO FRIDAY. SOME
MODEL DISAGREEMENT WITH HOW FAR NORTH THE PRECIPITATION WILL
SPREAD BUT WITH NORTHERLY WINDS FEEDING LOW LEVEL DRY AIR INTO
NORTHERN MONTANA WILL LIMIT THE NORTHWARD EXTENT OF THE RAIN/SNOW
FROM THIS SYSTEM. FOR NOW WILL KEEP THE HIGHEST CHANCES OF
PRECIPITATION TO THE SOUTH. MODELS SOUNDINGS SUPPORT PRECIP
CHANGING TO SNOW FAIRLY QUICKLY THURSDAY NIGHT ACROSS ALL BUT THE
FAR SOUTHEAST ZONES. AT THIS POINT EXPECT BEST ACCUMULATIONS TO BE
OVER THE HIGHER TERRAIN AREAS IN THE SOUTH. EBERT
.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
CONFIDENCE REMAINS HIGH IN A SIGNIFICANT STORM SYSTEM TO AFFECT
THE REGION PRIMARILY THIS WEEKEND. LATEST ECMWF...NOGAPS...GFS
AND ITS ENSEMBLES ARE IN GOOD AGREEMENT WITH THE EVENTUAL
DEVELOPMENT AND TRACK OF THE GREAT BASIN LOW. OUTSIDE OF SMALL
COLLABORATION EDITS...INHERITED FORECAST IS ENTIRELY
REPRESENTATIVE OF THIS SYSTEM. MCZ
PREVIOUS LONG TERM DISCUSSION...
MODELS ARE IN AGREEMENT BEGINNING THE EXTENDED PERIOD WITH A HUGE
DEEPENING OF AN UPPER TROUGH OVER THE WEST WITH A CLOSED UPPER LOW
WRAPPED UP OVER THE GREAT BASIN REGION. ASSOCIATED WITH THIS LARGE
TROUGH WILL BE 850MB TEMPERATURES RANGING FROM -6C TO -1C THROUGH
SUNDAY NIGHT. WHILE MAINTAINING THE NEAR WINTER TEMPERATURES THE
LOW IS EXPECTED TO LIFT NORTHEAST UP THROUGH NORTHEAST MONTANA AND
SURROUNDING REGIONS THIS WEEKEND. THEN A WEAK UPPER RIDGE WILL
MOVE IN BEHIND THE DEPARTING LOW AROUND MONDAY/MONDAY NIGHT.
INITIALLY FRIDAY NIGHT WHILE THE LOW IS CENTERED OVER THE GREAT
BASIN IT WILL EJECT PACIFIC MOISTURE NORTHEAST INTO NORTHERN
PLAINS. THE RESULTING WAA DRIVEN PRECIPITATION PROMISES TO INCLUDE
SNOW IN THE MIX. WITH THE ARCTIC BOUNDARY PLACED TO THE EAST OVER
THE DAKOTAS...ACCORDING TO THE GFS...THE BRUNT OF THE PRECIPITATION
COULD BE FOCUSED THERE. ON THE OTHER HAND THE EC WHICH HAS BEEN
THE FAVORED MODEL BY HPC NUDGES THE BOUNDARY CLOSER TO MONTANA.
THE EC FOCUSES SIGNIFICANT QPF OVER THE LOCAL AREA. THE BROAD
EXTENT OF THE MOISTURE WILL INCLUDE NORTHEAST MONTANA IN ANY CASE.
SOMETIME LATE SATURDAY OR SUNDAY THE VORTEX/UPPER JET WILL RUN
OVER THE FORECAST AREA AS THE LOW LIFTS INTO CANADA. QPF AMOUNT
ARE IMPRESSIVE IN BOTH THE EC AND GFS FOR SATURDAY NIGHT AND
SUNDAY MORNING. THE BRUNT OF THE STORM WILL LIFT INTO SASKATCHEWAN
SUNDAY NIGHT BUT SOME WRAP-AROUND MOISTURE WILL CONTINUE TO
PRODUCE DIMINISHING PRECIPITATION INTO MONDAY MORNING.
DETAILS AND TIMING AMONG THE MODELS FOR THE WEEKEND ARE STILL
SETTLING BUT SIGNIFICANT QPF AND THE COLD TEMPERATURES WILL LIKELY
PRODUCE THE FIRST WINTER STORM OF THE SEASON.
INCREASING HEIGHTS MONDAY AND BEYOND WILL TREND TEMPERATURES BACK
TOWARDS NORMAL FOR THE REMAINDER OF THE PERIOD. THERE ARE HINTS OF
A WEAK SHORTWAVE TROUGH RACING ACROSS SOUTHERN
ALBERTA/SASKATCHEWAN MONDAY NIGHT AND TUESDAY BUT MOST ACTION
SHOULD REMAIN TO OUR NORTH. THE MAIN EFFECT WILL BE TO PUT A LID
ON TEMPERATURES RISING ABOVE NORMAL NEXT WEEK. SCT
&&
.AVIATION...
EXPECT VFR CONDITIONS INTO THURSDAY. LIGHT WINDS OVERNIGHT WILL
VEER NORTHEASTERLY BY MORNING AS MID LEVEL CLOUDS INCREASE IN
COVERAGE AHEAD OF AN INTENSIFYING STORM SYSTEM IN WYOMING. MCZ/SCT
&&
.CLIMATE...
MUCH OF NE MT HAS ALREADY HAD FREEZING TEMPERATURES THIS FALL.
FOR MANY LOCATIONS THIS OCCURRED YESTERDAY...OCT 7TH. SPOTTY
FREEZES THOUGH OCCURRED IN THE AREA ON SEVERAL OTHER EARLIER
OCCASIONS...AS EARLY AS AUG 23RD. THE REMAINDER OF THE
AREA...INCLUDING THE GLASGOW AIRPORT...CAN EXPECT THEIR FIRST
FREEZE LATE TONIGHT/THU MORN. THE LAST TIME THERE WAS A LATER
FIRST FREEZE OF THE SEASON WAS IN 1986. SHOULD ANY SNOW ACCUMULATE
IN GLASGOW THIS WEEKEND...IT WOULD BE THE EARLIEST FIRST MEASURABLE
SNOW OF THE SEASON SINCE 1999. SIMONSEN
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KTFX 090259
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
850 PM MDT WED OCT 8 2008
.DISCUSSION...
UPDATE FORTHCOMING. HAVE MADE ADJUSTMENTS TO THE SKY CONDITION GRIDS
TO BETTER REFLECT THE CURRENT CONDITION OF DECREASING CLOUD COVER.
FORECAST OF DEEPENING UPPER TROF OVER THE PACIFIC NORTHWEST PERSISTS
WITH AN INCREASING MOIST SOUTHWEST FLOW ALOFT ON THURSDAY.
PRECIPITATION EVENT FOR FRIDAY AND INTO THE WEEKEND CONTINUES TO
LOOK ON TRACK. MIDNIGHT SHIFT WILL EVALUATE 00Z MODELS TO DETERMINE
IF HIGHLIGHTS WILL BE WARRANTED. EMANUEL
&&
.AVIATION...
UPDATED 0025Z.
VFR CONDITIONS WILL CONTINUE ACROSS MOST OF SOUTHWEST...CENTRAL AND
NORTH CENTRAL MONTANA THROUGH AT LEAST 00Z FRIDAY. THE WESTERLY FLOW
ALOFT WILL DECREASE THROUGH 12Z THURSDAY...WITH ONLY SCATTERED MID
AND HIGH CLOUDS MOVING OVER THE AREA DURING THIS TIME. GUSTY
WESTERLY WINDS WILL ALSO DECREASE THROUGH THE EARLY EVENING HOURS AS
THEY DECOUPLE. A WEAK SURFACE BOUNDARY WILL MOVE SOUTH OVER NORTH
CENTRAL AND CENTRAL MONTANA AFTER 06Z...SHIFTING THE LIGHT WINDS
NORTHERLY. AN UPPER LEVEL TROUGH WILL DEEPEN OVER THE PACIFIC
NORTHWEST INTO THE GREAT BASIN ON THURSDAY...SETTING UP A MORE MOIST
SOUTHWESTERLY FLOW ALOFT OVER THE AREA. THIS WILL BRING INCREASING
MID LEVEL CLOUDINESS TO THE TERMINALS DURING THE
AFTERNOON...ESPECIALLY ACROSS SOUTHWEST AND CENTRAL MONTANA (KBZN
KHLN KGTF KLWT TERMINALS) WHERE A FEW SHOWERS MAY ALSO OCCUR.
COULSTON
&&
.PREV DISCUSSION...ISSUED 253 PM MDT WED OCT 8 2008
TONIGHT THROUGH FRIDAY...A STRONG WESTERLY FLOW ALOFT DIMINISHES
OVERNIGHT AS A SIGNIFICANT UPPER LEVEL TROUGH BEGINS TO DEVELOP OVER
THE WESTERN CONUS. BY THURSDAY AFTERNOON THIS TROUGH WILL BE WELL
ESTABLISHED OVER THE PACIFIC NORTHWEST WITH A SURFACE LOW
STRENGTHENING OVER THE CENTRAL ROCKY MOUNTAIN REGION. SURFACE FLOW
ACROSS MONTANA WILL BE NORTHERLY AND BECOMING INCREASINGLY MOIST
AS THE UPPER TROUGH PUMPS MOISTURE INTO THE REGION. THERE WILL BE
AN INCREASING LIKELIHOOD OF SNOW ACROSS SOUTHWEST MONTANA THURSDAY
AFTERNOON WITH SNOW SPREADING INTO SOUTHERN PORTION OF CENTRAL
MONTANA THURSDAY NIGHT. AT THIS TIME...IT APPEARS THAT A WINTER
WEATHER ADVISORY COULD BE REQUIRED THURSDAY NIGHT INTO FRIDAY
ACROSS SOUTHWEST MONTANA AND SOUTHERN PORTIONS OF CENTRAL MONTANA.
LOWER ELEVATION SNOW ACCUMULATIONS COULD TOTAL 2 TO 6 INCHES...
ESPECIALLY THROUGH JUDITH GAP. FOR NOW WILL CONTINUE MENTION OF
ACCUMULATING SNOWS AND MUCH COLDER THAN NORMAL TEMPERATURES IN THE
HAZARDOUS WEATHER OUTLOOK. MPJ
FRIDAY NIGHT THROUGH SUNDAY NIGHT...BOTH THE GFS AND ECMWF ARE IN
BETTER AGREEMENT TONIGHT FOR THE UPCOMING SNOWSTORM THAT POTENTIAL
COULD AFFECT THE REGION FRIDAY NIGHT THROUGH SUNDAY. EXPECT
UNSEASONABLY COLD AIR TO CONTINUE TO RESIDE OVER THE REGION THROUGH
THE WEEKEND...THUS ALL OF THE PRECIPITATION WILL FALL IN THE FORM OF
SNOW AT ALL ELEVATIONS OVER THE WEEKEND. BOTH MODELS CONTINUE TO
PROG ACCUMULATING SNOWFALL OVER SOUTHWEST AND CENTRAL MONTANA. RIGHT
NOW...FORECAST SNOW ACCUMULATIONS OF 2 TO 4 INCHES ARE POSSIBLE AT
LOWER ELEVATIONS FROM FRIDAY NIGHT THROUGH SATURDAY NIGHT...WITH 10
TO 16 INCHES LIKELY IN THE MOUNTAINS...THEN ADDITIONAL SNOW
ACCUMULATIONS ARE POSSIBLE SUNDAY. THE MAIN AREA TO SEE THE SNOW
ACCUMULATION IS OVER MUCH OF SOUTHWEST MONTANA AND IN THE LEWISTOWN
AREA. IN THE GREAT FALLS AND HAVRE AREAS...CURRENT FORECAST MODELS
CONTINUE TO SHOW THE GOOD ACCUMULATING SNOWS STAYING JUST SOUTH AND
EAST OF THESE CITIES...BUT SHOULD THE FORECAST TRACK MOVE
NORTHWESTWARD 30 TO 40 MILES...HEAVIER SNOW COULD FALL IN THESE
LOCATIONS. FOR THE CUT BANK AREA...SNOW ACCUMULATIONS SHOULD BE
MINOR.
FOR MONDAY AND MONDAY NIGHT...EXPECT WARMER AIR TO MOVE INTO THE
REGION...AS A WEAK UPPER LEVEL RIDGE BUILDS IN FROM THE WEST.
TEMPERATURES WILL BE SLOW TO WARM UP IN SOUTHWEST MONTANA...AS A
FRESH SNOW COVER ON SUNDAY SHOULD ALLOW FOR A FAIRLY COLD NIGHT ON
SUNDAY NIGHT. BRUSDA
TUESDAY AND WEDNESDAY...A WESTERLY FLOW ALOFT IS EXPECTED TO BRING
IN PACIFIC MOISTURE TO THE ZONES BY WEDNESDAY. TEMPERATURES WILL BE
SLIGHTLY BELOW SEASONAL AVERAGES ON THE NORTH CENTRAL PLAINS. JNS
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 25 47 26 37 / 0 10 30 20
CTB 23 45 23 37 / 0 10 20 20
HLN 27 49 31 38 / 10 20 50 30
BZN 22 51 29 40 / 0 30 70 50
WEY 22 44 21 35 / 0 30 40 40
DLN 22 45 25 34 / 10 20 60 60
HVR 25 51 25 42 / 0 10 10 20
LWT 23 45 25 34 / 0 10 50 40
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...EMANUEL/MPJ
LONG TERM...BRUSDA/JNS
AVIATION...COULSTON
WEATHER.GOV/GREATFALLS
000
FXUS65 KMSO 090107
AFDMSO
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MISSOULA MT
707 PM MDT WED OCT 8 2008
.DISCUSSION...TOOK OUT MENTION OF SHOWERS IN THE FORECAST FOR TONIGHT
AS NO ACTIVITY IS CURRENTLY ON RADAR AND LOW LEVELS OF THE ATMOSPHERE
ARE FAIRLY DRY. EXPECTING CLEAR SKIES ACROSS SOUTHWEST MONTANA AND
THE SOUTHERN CLEARWATERS OF CENTRAL IDAHO AND PARTLY CLOUDY
ELSEWHERE IN THE AREA. ADDED A SMALL AMOUNT OF FREEZING FOG TO
THE FORECAST FOR THE DIXIE AND ELK CITY AREAS AND ALONG IDAHO
HIGHWAY 14 MAINLY DUE TO THE LACK OF CLOUDS AND BEING A FOG PRONE
AREA...OTHER FOG PRONE AREAS SUCH AS THE DWORSHAK RESERVOIR IN
IDAHO AND NORTHWEST MONTANA WILL SEE TOO MUCH CLOUD COVER OVERNIGHT FOR
FOG. FINALLY MADE MINOR ADJUSTMENTS TO LOW TEMPERATURES AND SKY
COVERAGE FOR TONIGHT.
&&
.AVIATION...WEAK RIDGE OF HIGH PRESSURE WILL BE OVER WESTERN
MONTANA AND NORTH CENTRAL IDAHO TONIGHT. THIS WILL ALLOW THE
WINDS TO DECREASE AND SKIES WILL CLEAR. CLOUDS WILL BE INCREASING
DURING THE DAY THURSDAY AS A WEATHER SYSTEM APPROACHES FROM THE
PACIFIC. SOME MOUNTAINS AND PASSES COULD BE OBSCURED BY CLOUDS AND
PRECIPITATION THURSDAY.
&&
.PREV DISCUSSION... /ISSUED 248 PM MDT WED OCT 8 2008/
..WINTER LIKE STORM SYSTEM TO BRING SNOW ALONG THE CONTINENTAL
DIVIDE...SOUTHWEST MONTANA AND LEMHI COUNTY LATE THURSDAY NIGHT
INTO THIS COMING WEEKEND...
DISCUSSION...A WEAK RIDGE WILL BUILD TONIGHT OVER THE NORTHERN
ROCKIES AHEAD OF AN APPROACHING TROUGH OF LOW PRESSURE. COMBINED
WITH LIGHT WINDS AND MOSTLY CLEAR SKIES...BELOW FREEZING
TEMPERATURES ARE EXPECTED WHICH WILL CAUSE A WIDESPREAD HARD
FREEZE OVERNIGHT.
THE LOW PRESSURE TROUGH WILL THEN BEGIN DIGGING OVER THE PACIFIC
NORTHWEST DURING THE DAY THURSDAY. THE TROUGH WILL MOVE INTO THE
INTERMOUNTAIN WEST OVERNIGHT THURSDAY INTO FRIDAY MORNING. WITH
THIS...MUCH COOLER TEMPERATURES AND LOWERING SNOW LEVELS WILL
OCCUR...WITH MANY SNOW LEVELS LOWERING TO VALLEY FLOORS BY
FRIDAY MORNING. AS THE SYSTEM APPROACHES...THERE IS A SLIGHT
CHANCE FOR SOME EARLY SNOW SHOWERS POSSIBLE THURSDAY IN HIGHER
ELEVATIONS. STRONG WINDS OUT OF THE EAST WILL DOWNSLOPE NORTHWEST
MONTANA...PARTICULARLY VALLEYS LOCATED IN THIS AREA...KEEPING THE
GREATEST AREA FOR SNOW SHOWERS TO OCCUR IN SOUTHWEST MONTANA AND
LEMHI COUNTY THROUGH FRIDAY MORNING.
BY FRIDAY MORNING...THE DEEP COLD LOW PRESSURE SYSTEM DIGS OVER
SOUTHERN IDAHO AND NEVADA RAMPING UP SNOW OVER SOUTHWEST MT AND
LEMHI COUNTY WITH COLDER AIR FILTERING OVER THE DIVIDE WITH GUSTY
NORTHEAST WINDS DEVELOPING. THE GFS...EC AND UK MODELS KEEP THE SNOW
GOING THROUGH FRIDAY IN THIS AREA WHILE THE NAM KEEPS THE BEST ENERGY
TO THE SOUTH AND DRYING OUT NORTHWEST MT BY AFTERNOON. PREFER THE
CONSISTENCY OF THE OTHER MODELS AND LEANING MORE TO ACCUMULATING SNOWS
OVER SOUTHWEST MT AND LEMHI COUNTY AND MORE CLOUDINESS REGION WIDE. WINTER
WEATHER HIGHLIGHTS ARE VERY LIKELY TO BE ISSUED FOR THIS WINTER
LIKE STORM WITH VERY COLD TEMPERATURES EXPECTED FOR THIS TIME OF
YEAR. FOR THE MOST PART NORTHWEST MT VALLEYS WILL BE DOWN SLOPED
BY THE GUSTY NORTHEAST FLOW AND REMAIN DRY FOR THIS EVENT. BY
FRIDAY EVENING AS THE UPSLOPE NORTHEAST WINDS INCREASE ALONG THE
DIVIDE...SNOW WILL ALSO BEGIN TO ACCUMULATE OVER HIGHER TERRAIN
FARTHER TO THE NORTH. GUSTY NORTH TO NORTHEAST WINDS WILL
CONTINUE. ON SATURDAY...THE UPPER LEVEL CLOSED LOW PRESSURE SYSTEM
MOVES VERY SLOWLY CENTERED OVER SALT LAKE UT AND CONTINUES TO
BRING ACCUMULATING SNOWS TO ALONG THE DIVIDE...SOUTHWEST MT AND
LEMHI COUNTY. ON SUNDAY...THE LOW PRESSURE SYSTEM EJECTS TO THE
NORTHEAST TO EASTERN MT WITH SNOW TAPERING OFF OVER SOUTHWEST MT
AND LEMHI COUNTY DURING THE DAY. MONDAY ON...A FLAT RIDGE OF HIGH
PRESSURE IS EXPECTED TO BUILD FOR A WARMING AND DRYING TREND. BUT BEYOND
THIS TIME FRAME...MODEL SOLUTIONS ARE NOT CONSISTENT AND THEREFORE DID
NOT CHANGE THE ON GOING FORECAST FOR SLIGHT CHANCES OF
PRECIPITATION.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&
$$
UPDATE...FOSTER
PREVIOUS DISCUSSION....FELSCH/ALLEGRETTO
AVIATION...LOEFFELBEIN
000
FXUS65 KTFX 090029
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
625 PM MDT WED OCT 8 2008
...UPDATE TO AVIATION...
.DISCUSSION...
TONIGHT THROUGH FRIDAY...A STRONG WESTERLY FLOW ALOFT DIMINISHES
OVERNIGHT AS A SIGNIFICANT UPPER LEVEL TROUGH BEGINS TO DEVELOP OVER
THE WESTERN CONUS. BY THURSDAY AFTERNOON THIS TROUGH WILL BE WELL
ESTABLISHED OVER THE PACIFIC NORTHWEST WITH A SURFACE LOW
STRENGTHENING OVER THE CENTRAL ROCKY MOUNTAIN REGION. SURFACE FLOW
ACROSS MONTANA WILL BE NORTHERLY AND BECOMING INCREASINGLY MOIST
AS THE UPPER TROUGH PUMPS MOISTURE INTO THE REGION. THERE WILL BE
AN INCREASING LIKELIHOOD OF SNOW ACROSS SOUTHWEST MONTANA THURSDAY
AFTERNOON WITH SNOW SPREADING INTO SOUTHERN PORTION OF CENTRAL
MONTANA THURSDAY NIGHT. AT THIS TIME...IT APPEARS THAT A WINTER
WEATHER ADVISORY COULD BE REQUIRED THURSDAY NIGHT INTO FRIDAY
ACROSS SOUTHWEST MONTANA AND SOUTHERN PORTIONS OF CENTRAL MONTANA.
LOWER ELEVATION SNOW ACCUMULATIONS COULD TOTAL 2 TO 6 INCHES...
ESPECIALLY THROUGH JUDITH GAP. FOR NOW WILL CONTINUE MENTION OF
ACCUMULATING SNOWS AND MUCH COLDER THAN NORMAL TEMPERATURES IN THE
HAZARDOUS WEATHER OUTLOOK. MPJ
FRIDAY NIGHT THROUGH SUNDAY NIGHT...BOTH THE GFS AND ECMWF ARE IN
BETTER AGREEMENT TONIGHT FOR THE UPCOMING SNOWSTORM THAT POTENTIAL
COULD AFFECT THE REGION FRIDAY NIGHT THROUGH SUNDAY. EXPECT
UNSEASONABLY COLD AIR TO CONTINUE TO RESIDE OVER THE REGION THROUGH
THE WEEKEND...THUS ALL OF THE PRECIPITATION WILL FALL IN THE FORM OF
SNOW AT ALL ELEVATIONS OVER THE WEEKEND. BOTH MODELS CONTINUE TO
PROG ACCUMULATING SNOWFALL OVER SOUTHWEST AND CENTRAL MONTANA. RIGHT
NOW...FORECAST SNOW ACCUMULATIONS OF 2 TO 4 INCHES ARE POSSIBLE AT
LOWER ELEVATIONS FROM FRIDAY NIGHT THROUGH SATURDAY NIGHT...WITH 10
TO 16 INCHES LIKELY IN THE MOUNTAINS...THEN ADDITIONAL SNOW
ACCUMULATIONS ARE POSSIBLE SUNDAY. THE MAIN AREA TO SEE THE SNOW
ACCUMULATION IS OVER MUCH OF SOUTHWEST MONTANA AND IN THE LEWISTOWN
AREA. IN THE GREAT FALLS AND HAVRE AREAS...CURRENT FORECAST MODELS
CONTINUE TO SHOW THE GOOD ACCUMULATING SNOWS STAYING JUST SOUTH AND
EAST OF THESE CITIES...BUT SHOULD THE FORECAST TRACK MOVE
NORTHWESTWARD 30 TO 40 MILES...HEAVIER SNOW COULD FALL IN THESE
LOCATIONS. FOR THE CUT BANK AREA...SNOW ACCUMULATIONS SHOULD BE
MINOR.
FOR MONDAY AND MONDAY NIGHT...EXPECT WARMER AIR TO MOVE INTO THE
REGION...AS A WEAK UPPER LEVEL RIDGE BUILDS IN FROM THE WEST.
TEMPERATURES WILL BE SLOW TO WARM UP IN SOUTHWEST MONTANA...AS A
FRESH SNOW COVER ON SUNDAY SHOULD ALLOW FOR A FAIRLY COLD NIGHT ON
SUNDAY NIGHT. BRUSDA
TUESDAY AND WEDNESDAY...A WESTERLY FLOW ALOFT IS EXPECTED TO BRING
IN PACIFIC MOISTURE TO THE ZONES BY WEDNESDAY. TEMPERATURES WILL BE
SLIGHTLY BELOW SEASONAL AVERAGES ON THE NORTH CENTRAL PLAINS. JNS
&&
.AVIATION...
UPDATED 0025Z.
VFR CONDITIONS WILL CONTINUE ACROSS MOST OF SOUTHWEST...CENTRAL AND
NORTH CENTRAL MONTANA THROUGH AT LEAST 00Z FRIDAY. THE WESTERLY FLOW
ALOFT WILL DECREASE THROUGH 12Z THURSDAY...WITH ONLY SCATTERED MID
AND HIGH CLOUDS MOVING OVER THE AREA DURING THIS TIME. GUSTY
WESTERLY WINDS WILL ALSO DECREASE THROUGH THE EARLY EVENING HOURS AS
THEY DECOUPLE. A WEAK SURFACE BOUNDARY WILL MOVE SOUTH OVER NORTH
CENTRAL AND CENTRAL MONTANA AFTER 06Z...SHIFTING THE LIGHT WINDS
NORTHERLY. AN UPPER LEVEL TROUGH WILL DEEPEN OVER THE PACIFIC
NORTHWEST INTO THE GREAT BASIN ON THURSDAY...SETTING UP A MORE MOIST
SOUTHWESTERLY FLOW ALOFT OVER THE AREA. THIS WILL BRING INCREASING
MID LEVEL CLOUDINESS TO THE TERMINALS DURING THE
AFTERNOON...ESPECIALLY ACROSS SOUTHWEST AND CENTRAL MONTANA (KBZN
KHLN KGTF KLWT TERMINALS) WHERE A FEW SHOWERS MAY ALSO OCCUR.
COULSTON
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 25 47 26 37 / 0 10 30 20
CTB 23 45 23 37 / 0 10 20 20
HLN 27 49 31 38 / 10 20 50 30
BZN 22 51 29 40 / 0 30 70 50
WEY 22 44 21 35 / 0 30 40 40
DLN 22 45 25 34 / 10 20 60 60
HVR 25 51 25 42 / 0 10 10 20
LWT 23 45 25 34 / 0 10 50 40
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...MPJ
LONG TERM...BRUSDA/JNS
AVIATION...COULSTON
WEATHER.GOV/GREATFALLS
000
FXUS65 KGGW 082122
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
322 PM MDT WED OCT 8 2008
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH FRIDAY...
JET STREAK MOVING OFF TO THE EAST THIS AFTERNOON WITH WINDS
BEGINNING TO DIMINISH ACROSS CENTRAL MONTANA. WITH HIGH PRESSURE
SPREADING INTO EASTERN MONTANA OVERNIGHT EXPECT WINDS TO DROP OFF
IN THE WEST AROUND SUNSET. THE WINDS MAY STAY STRONGER ACROSS THE
EAST LONGER...AS WILL TAKE SOME TIME FOR THE GRADIENT TO RELAX.
KEEPING LAKE WIND ADVISORY GOING UNTIL 7PM.
WITH THE HIGH PRESSURE...AND RESULTANT LIGHT WINDS AND CLEARING
SKIES...EXPECT GOOD RADIATIONAL COOLING TONIGHT. THIS WILL LIKELY
DROP TEMPERATURES BELOW FREEZING FOR MOST AREAS.
THE UPPER TROUGH THAT WILL BECOME THE WEATHER MAKER FOR THE NEXT
SEVERAL DAYS MOVES INTO THE GREAT BASIN ON THURSDAY...SPEADING
MOISTURE NORTHWARD TOWARD MONTANA. A LOW PRESSURE SYSTEM
DEVELOPS ALONG A STATIONARY FRONT NEAR THE WYOMING/COLORADO BORDER
DURING THE DAY ON THURSDAY. THE MOISTURE ON THE SOUTHWEST FLOW
ALOFT WILL START OVERRUNNING THE FRONT AND BECOME A WIDESPREAD
AREA OF RAIN INTO SOUTHERN MONTANA DURING THE EVENING THEN MIXING
WITH OR CHANGING TO SNOW THROUGH THE NIGHT AND INTO FRIDAY. SOME
MODEL DISAGREEMENT WITH HOW FAR NORTH THE PRECIPITATION WILL
SPREAD BUT WITH NORTHERLY WINDS FEEDING LOW LEVEL DRY AIR INTO
NORTHERN MONTANA WILL LIMIT THE NORTHWARD EXTENT OF THE RAIN/SNOW
FROM THIS SYSTEM. FOR NOW WILL KEEP THE HIGHEST CHANCES OF
PRECIPITATION TO THE SOUTH. MODELS SOUNDINGS SUPPORT PRECIP
CHANGING TO SNOW FAIRLY QUICKLY THURSDAY NIGHT ACROSS ALL BUT THE
FAR SOUTHEAST ZONES. AT THIS POINT EXPECT BEST ACCUMULATIONS TO BE
OVER THE HIGHER TERRAIN AREAS IN THE SOUTH. EBERT
.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
CONFIDENCE REMAINS HIGH IN A SIGNIFICANT STORM SYSTEM TO AFFECT
THE REGION PRIMARILY THIS WEEKEND. LATEST ECMWF...NOGAPS...GFS
AND ITS ENSEMBLES ARE IN GOOD AGREEMENT WITH THE EVENTUAL
DEVELOPMENT AND TRACK OF THE GREAT BASIN LOW. OUTSIDE OF SMALL
COLLABORATION EDITS...INHERITED FORECAST IS ENTIRELY
REPRESENTATIVE OF THIS SYSTEM. MCZ
PREVIOUS LONG TERM DISCUSSION...
MODELS ARE IN AGREEMENT BEGINNING THE EXTENDED PERIOD WITH A HUGE
DEEPENING OF AN UPPER TROUGH OVER THE WEST WITH A CLOSED UPPER LOW
WRAPPED UP OVER THE GREAT BASIN REGION. ASSOCIATED WITH THIS LARGE
TROUGH WILL BE 850MB TEMPERATURES RANGING FROM -6C TO -1C THROUGH
SUNDAY NIGHT. WHILE MAINTAINING THE NEAR WINTER TEMPERATURES THE
LOW IS EXPECTED TO LIFT NORTHEAST UP THROUGH NORTHEAST MONTANA AND
SURROUNDING REGIONS THIS WEEKEND. THEN A WEAK UPPER RIDGE WILL
MOVE IN BEHIND THE DEPARTING LOW AROUND MONDAY/MONDAY NIGHT.
INITIALLY FRIDAY NIGHT WHILE THE LOW IS CENTERED OVER THE GREAT
BASIN IT WILL EJECT PACIFIC MOISTURE NORTHEAST INTO NORTHERN
PLAINS. THE RESULTING WAA DRIVEN PRECIPITATION PROMISES TO INCLUDE
SNOW IN THE MIX. WITH THE ARCTIC BOUNDARY PLACED TO THE EAST OVER
THE DAKOTAS...ACCORDING TO THE GFS...THE BRUNT OF THE PRECIPITATION
COULD BE FOCUSED THERE. ON THE OTHER HAND THE EC WHICH HAS BEEN
THE FAVORED MODEL BY HPC NUDGES THE BOUNDARY CLOSER TO MONTANA.
THE EC FOCUSES SIGNIFICANT QPF OVER THE LOCAL AREA. THE BROAD
EXTENT OF THE MOISTURE WILL INCLUDE NORTHEAST MONTANA IN ANY CASE.
SOMETIME LATE SATURDAY OR SUNDAY THE VORTEX/UPPER JET WILL RUN
OVER THE FORECAST AREA AS THE LOW LIFTS INTO CANADA. QPF AMOUNT
ARE IMPRESSIVE IN BOTH THE EC AND GFS FOR SATURDAY NIGHT AND
SUNDAY MORNING. THE BRUNT OF THE STORM WILL LIFT INTO SASKATCHEWAN
SUNDAY NIGHT BUT SOME WRAP-AROUND MOISTURE WILL CONTINUE TO
PRODUCE DIMINISHING PRECIPITATION INTO MONDAY MORNING.
DETAILS AND TIMING AMONG THE MODELS FOR THE WEEKEND ARE STILL
SETTLING BUT SIGNIFICANT QPF AND THE COLD TEMPERATURES WILL LIKELY
PRODUCE THE FIRST WINTER STORM OF THE SEASON.
INCREASING HEIGHTS MONDAY AND BEYOND WILL TREND TEMPERATURES BACK
TOWARDS NORMAL FOR THE REMAINDER OF THE PERIOD. THERE ARE HINTS OF
A WEAK SHORTWAVE TROUGH RACING ACROSS SOUTHERN
ALBERTA/SASKATCHEWAN MONDAY NIGHT AND TUESDAY BUT MOST ACTION
SHOULD REMAIN TO OUR NORTH. THE MAIN EFFECT WILL BE TO PUT A LID
ON TEMPERATURES RISING ABOVE NORMAL NEXT WEEK. SCT
&&
.AVIATION...
EXPECT VFR CONDITIONS INTO THURSDAY AS SCATTERED CUMULUS AND
STRONG NORTHWEST WINDS THIS AFTERNOON DISSIPATE BY SUNSET. LIGHT
WINDS OVERNIGHT WILL VEER NORTHEASTERLY BY MORNING AS MID LEVEL
CLOUDS INCREASE IN COVERAGE AHEAD OF AN INTENSIFYING STORM SYSTEM
IN WYOMING. MCZ
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY UNTIL 7 PM MDT THIS EVENING FOR FORT PECK
LAKE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KBYZ 082115
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
315 PM MDT WED OCT 8 2008
...MAJOR EARLY WINTER STORM STILL ON TRACK TO IMPACT THE AREA LATE
THIS WEEK THROUGH THE WEEKEND...
.SHORT TERM...VALID FOR THU AND FRI...
SHORTWAVE OFF THE BC COAST THIS AFTERNOON PER WATER VAPOR IMAGERY
WILL BE THE CATALYST FOR A MAJOR CHANGE IN THE WEATHER LATE IN THE
WEEK. LATEST MODELS WERE IN DECENT AGREEMENT IN FORECASTING THE
DEVELOPMENT AND TRACK OF A STORM SYSTEM THAT WILL IMPACT THE REGION
DURING THE SHORT-TERM AND BEYOND. MODELS HAVE ALSO BEEN SHOWING
RUN-TO-RUN CONSISTENCY WITH THE STORM TRACK. MADE A FEW CHANGES TO
THE FORECAST TO REFLECT GROWING CONFIDENCE IN THE SYSTEM.
FOR TONIGHT AND THU...SHORTWAVE WILL DIVE SE FROM GULF OF AK TO
CARVE OUT A TROUGH OVER THE PACIFIC NW. WARM ADVECTION WILL DEVELOP
OVER WY BY 12Z THU WITH SOME ASSOCIATED MOISTURE. THESE FEATURES
COULD GENERATE AN ISOLATED SNOW SHOWER OVER THE NE BIG HORNS LATE
TONIGHT SO HAVE SLIGHT CHANCE POPS IN THIS AREA. LOW TEMPERATURES
WERE IN GOOD SHAPE. ON THU...700 MB LOW DEVELOPS NEAR THE SW PART OF
THE AREA. ISENTROPIC LIFT DEVELOPS E OF THIS LOW AND MOVES N THROUGH
THE AREA ESPECIALLY DURING THE AFTERNOON. GOING POPS LOOKED
REASONABLE. ONLY CHANGES WERE TO SPREAD THE CHANCE POPS FURTHER N
THU AFTERNOON AND TO RAISE POPS OVER KSHR TO LIKELY DUE TO DEEP
MOISTURE AND UPSLOPE FLOW. NUDGED THU TEMPERATURES UP A TAD TOWARD
THE BIAS CORRECTED MOS AS THERE SHOULD BE SOME WARMING IN THE
MORNING AHEAD OF THE PRECIP CHANCES IN THE AFTERNOON.
THE UPPER TROUGH WILL CUT OFF INTO AN UPPER LOW AND DIG S TOWARD NV
THU NIGHT. EASTERLY UPSLOPE FLOW WILL DEVELOP ACROSS THE AREA AND
PLENTY OF MOISTURE WAS FORECAST OVER THE REGION. IN
ADDITION...ECMWF/GFS SHOWED FAIRLY STRONG Q VECTOR CONVERGENCE OVER
THE SW. THE COMBINATION OF THESE FACTORS SUPPORTED LIKELY POPS
ACROSS THE AREA. ONLY POSSIBLE FLY IN THE OINTMENT WAS THAT A PIECE
OF ENERGY WAS FORECAST TO EJECT NE FROM THE LOW AND CREATE SOME LIFT
ALONG FRONTAL BOUNDARY SE OF THE AREA. THE EJECTING ENERGY MAY
CREATE A DRY SLOT BETWEEN THE 700 MB LOW OVER ID AND THE EJECTING
LOW WHICH COULD RESULT IN A BREAK IN THE PRECIPITATION OVER THE
CENTRAL ZONES. WILL NEED TO KEEP AN EYE ON THIS POSSIBILITY AND FINE
TUNE POPS AS NEEDED. 850 MB TEMPERATURES WERE FORECAST TO FALL TO
BETWEEN ZERO AND -2 DEGS C WHICH WILL ALLOW SNOW TO MIX WITH THE
RAIN OVERNIGHT...AND TURN TO ALL SNOW BY 12Z FRI. MIN TEMPERATURES
IN THE 20S OVER WESTERN ZONES COULD ALLOW MELTING SNOW TO FREEZE ON
THE ROADS SO WILL NEED TO MONITOR THIS POSSIBILITY.
850 MB TEMPERATURES WILL HOVER AT OR JUST BELOW ZERO DEGS C ON
FRI AS UPPER LOW SETTLES OVER NV. EASTERLY UPSLOPE FLOW AND PLENTY
OF MOISTURE WILL CONTINUE OVER THE AREA BRINGING THE LIKELIHOOD OF
PRECIPITATION. EXPECT HIGH TEMPERATURES IN THE 30S TO LOWER 40S
AND A RAIN/SNOW MIX OVER THE LOWER ELEVATIONS WITH SNOW IN THE
MOUNTAINS. COULD POSSIBLY SEE 1 TO 2 INCHES OF SNOW OVER LOW
ELEVATIONS...WITH SEVERAL INCHES IN THE FOOTHILLS AND MOUNTAINS.
UPPER LOW WILL PIVOT OVER NV/UT FRI NIGHT AND UPPER DIFLUENCE WILL
OVERTAKE THE FORECAST AREA. MOIST EASTERLY UPSLOPE FLOW WILL
CONTINUE AND 850 MB TEMPS WILL BE BELOW ZERO. SNOW WILL BE LIKELY
ACROSS THE AREA. GFS TIME HEIGHT CROSS SECTIONS INDICATED LIFT IN
THE DENDRITIC GROWTH ZONE SO WILL HAVE POTENTIAL FOR SOME HEAVIER
SNOW. WILL BE HIGHLIGHTING DETAILS OF FORECAST IN THE HWO AND WILL
BRIEF LATER SHIFTS THAT WATCH WILL LIKELY BE NEEDED BEGINNING FRI
NIGHT CLOSER TO THIS PERIOD. ARTHUR
.LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED...
THE LATEST GUIDANCE CONTINUES TO BE CONSISTENT WITH OUR EARLY
SEASON MAJOR WINTER STORM WHICH COULD RESULT IN SOME SIGNIFICANT
IMPACTS ACROSS THE AREA THIS WEEKEND. THE STRONG UPPER LOW
ANTICIPATED TO BE BOTTOMING OUT ACROSS THE GREAT BASIN EARLY
SATURDAY AND BEGIN THE TURN TO THE NORTHWEST. A DEEP UPSLOPE FLOW
AND STRONG OVERUNNING PATTERN AND DIFFLUENT FLOW ALOFT SHOULD HAVE
THE SNOW ONGOING FOR MOST AREAS AT THE START OF THIS FORECAST
PERIOD. EXPECTING THIS LIGHTER TO MODERATE PRECIP EVENT TO ENHANCE
AS WE PROGRESS THROUGH SATURDAY INTO SATURDAY NIGHT AS THE UPPER
LOW TRACKS ACROSS WYOMING SATURDAY AND INTO EASTERN MONTANA
SUNDAY. THIS SHOULD BE THE MAIN EVENT FOR THIS STORM FOR MONTANA
AND NORTHERN WYOMING WITH VERY STRONG DYNAMICS AND A DEEP AND
MOIST UPSLOPE FLOW RESULTING IN HEAVY SNOWFALL RATES. TEMPERATURE
PROFILES ALSO THE BEST DURING THIS TIME FRAME FOR SIGNIFICANT
ACCUMULATIONS. WRAP AROUND SNOWS WILL LINGER INTO SUNDAY BUT SHOULD
BEGIN TO TAPER OFF AS THE STORM BEGINS TO LIFT OFF TO THE
NORTHEAST LATE INTO THE DAY AND INTO EARLY MONDAY. WHEN ALL SAID
AND DONE...WE COULD BE TALKING ABOUT SEVERAL FEET OF SNOW FOR THE
MOUNTAINS...ESPECIALLY THOSE FAVORED NORTH AND NORTHEAST UPSLOPE
AREAS. DEPENDING ON THE EXACT PATH...THERE SHOULD BE A BAND OF
HEAVY LOW ELEVATION SNOW AS WELL THAT COULD REACH UPWARDS OF A
FOOT OF WET SNOW.
BEYOND MONDAY...FLOW BEGINS TO TAKE ON A ZONAL LOOK FOR AN OVERALL
DOWNSLOPING PATTERN. SHOULD BE MOSTLY DRY WITH AN OVERALL WARMING
TREND.
FRIEDERS
&&
.AVIATION...
VFR CONDITIONS WILL CONTINUE INTO THURSDAY MORNING. THE GUSTY
NORTHWEST WINDS WILL DECREASE EARLY THIS EVENING. FRIEDERS
&&
.PRELIMINARY POINT TEMP/POPS...
THU FRI SAT SUN MON TUE WED
-----------------------------------------------------------
BIL 032/047 030/038 026/033 026/034 024/048 030/053 034/053
03/R 77/O 78/S 86/S 21/B 10/B 11/B
LVM 022/049 023/037 019/033 020/036 023/051 029/053 034/053
04/R 87/O 68/S 77/S 21/N 10/B 11/B
HDN 029/051 030/039 026/034 025/038 023/051 029/054 033/054
03/R 76/O 77/S 86/S 21/B 10/B 11/B
MLS 029/053 033/042 028/036 027/038 025/051 031/055 034/055
02/R 76/O 67/S 76/S 21/B 11/B 11/B
4BQ 029/052 029/042 027/037 027/037 024/051 030/055 032/055
04/O 77/O 78/S 85/S 21/B 10/U 11/U
BHK 025/050 025/042 024/035 025/039 023/050 026/053 031/053
02/R 76/O 67/S 75/O 21/B 11/B 11/B
SHR 028/050 028/040 025/034 025/035 023/050 029/053 031/053
16/O 77/O 78/S 86/S 21/B 10/U 11/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KTFX 082053
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
253 PM MDT WED OCT 8 2008
.DISCUSSION...
TONIGHT THROUGH FRIDAY...A STRONG WESTERLY FLOW ALOFT DIMINISHES
OVERNIGHT AS A SIGNIFICANT UPPER LEVEL TROUGH BEGINS TO DEVELOP OVER
THE WESTERN CONUS. BY THURSDAY AFTERNOON THIS TROUGH WILL BE WELL
ESTABLISHED OVER THE PACIFIC NORTHWEST WITH A SURFACE LOW
STRENGTHENING OVER THE CENTRAL ROCKY MOUNTAIN REGION. SURFACE FLOW
ACROSS MONTANA WILL BE NORTHERLY AND BECOMING INCREASINGLY MOIST
AS THE UPPER TROUGH PUMPS MOISTURE INTO THE REGION. THERE WILL BE
AN INCREASING LIKELIHOOD OF SNOW ACROSS SOUTHWEST MONTANA THURSDAY
AFTERNOON WITH SNOW SPREADING INTO SOUTHERN PORTION OF CENTRAL
MONTANA THURSDAY NIGHT. AT THIS TIME...IT APPEARS THAT A WINTER
WEATHER ADVISORY COULD BE REQUIRED THURSDAY NIGHT INTO FRIDAY
ACROSS SOUTHWEST MONTANA AND SOUTHERN PORTIONS OF CENTRAL MONTANA.
LOWER ELEVATION SNOW ACCUMULATIONS COULD TOTAL 2 TO 6 INCHES...
ESPECIALLY THROUGH JUDITH GAP. FOR NOW WILL CONTINUE MENTION OF
ACCUMULATING SNOWS AND MUCH COLDER THAN NORMAL TEMPERATURES IN THE
HAZARDOUS WEATHER OUTLOOK. MPJ
FRIDAY NIGHT THROUGH SUNDAY NIGHT...BOTH THE GFS AND ECMWF ARE IN
BETTER AGREEMENT TONIGHT FOR THE UPCOMING SNOWSTORM THAT POTENTIAL
COULD AFFECT THE REGION FRIDAY NIGHT THROUGH SUNDAY. EXPECT
UNSEASONABLY COLD AIR TO CONTINUE TO RESIDE OVER THE REGION THROUGH
THE WEEKEND...THUS ALL OF THE PRECIPITATION WILL FALL IN THE FORM OF
SNOW AT ALL ELEVATIONS OVER THE WEEKEND. BOTH MODELS CONTINUE TO
PROG ACCUMULATING SNOWFALL OVER SOUTHWEST AND CENTRAL MONTANA. RIGHT
NOW...FORECAST SNOW ACCUMULATIONS OF 2 TO 4 INCHES ARE POSSIBLE AT
LOWER ELEVATIONS FROM FRIDAY NIGHT THROUGH SATURDAY NIGHT...WITH 10
TO 16 INCHES LIKELY IN THE MOUNTAINS...THEN ADDITIONAL SNOW
ACCUMULATIONS ARE POSSIBLE SUNDAY. THE MAIN AREA TO SEE THE SNOW
ACCUMULATION IS OVER MUCH OF SOUTHWEST MONTANA AND IN THE LEWISTOWN
AREA. IN THE GREAT FALLS AND HAVRE AREAS...CURRENT FORECAST MODELS
CONTINUE TO SHOW THE GOOD ACCUMULATING SNOWS STAYING JUST SOUTH AND
EAST OF THESE CITIES...BUT SHOULD THE FORECAST TRACK MOVE
NORTHWESTWARD 30 TO 40 MILES...HEAVIER SNOW COULD FALL IN THESE
LOCATIONS. FOR THE CUT BANK AREA...SNOW ACCUMULATIONS SHOULD BE
MINOR.
FOR MONDAY AND MONDAY NIGHT...EXPECT WARMER AIR TO MOVE INTO THE
REGION...AS A WEAK UPPER LEVEL RIDGE BUILDS IN FROM THE WEST.
TEMPERATURES WILL BE SLOW TO WARM UP IN SOUTHWEST MONTANA...AS A
FRESH SNOW COVER ON SUNDAY SHOULD ALLOW FOR A FAIRLY COLD NIGHT ON
SUNDAY NIGHT. BRUSDA
TUESDAY AND WEDNESDAY...A WESTERLY FLOW ALOFT IS EXPECTED TO BRING
IN PACIFIC MOISTURE TO THE ZONES BY WEDNESDAY. TEMPERATURES WILL BE
SLIGHTLY BELOW SEASONAL AVERAGES ON THE NORTH CENTRAL PLAINS. JNS
&&
.AVIATION...
UPDATED 1725Z.
AERODROMES BENEATH BRISK WESTERLY FLOW ALOFT TODAY WITH MID/HIGH
LEVEL CLOUDINESS OVER SOUTHWEST MONTANA AND NEAR HAVRE. EXPECT
VFR CONDITIONS OVER THE ENTIRE REGION. GUSTY SURFACE WINDS ARE
LIKELY TODAY OVER THE PLAINS OF NORTH CENTRAL MONTANA. A CANADIAN
COLD FRONT WILL MOVE SOUTH THROUGH THE REGION AFTER 07Z
THURSDAY... RESULTING IN A WIND SHIFT TO THE NORTH OVER NORTH
CENTRAL MONTANA BY 12Z THURSDAY. BRITTON
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 25 47 26 37 / 0 10 30 20
CTB 23 45 23 37 / 0 10 20 20
HLN 27 49 31 38 / 10 20 50 30
BZN 22 51 29 40 / 0 30 70 50
WEY 22 44 21 35 / 0 30 40 40
DLN 22 45 25 34 / 10 20 60 60
HVR 25 51 25 42 / 0 10 10 20
LWT 23 45 25 34 / 0 10 50 40
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...MPJ
LONG TERM...BRUSDA/JNS
AVIATION...BRITTON
WEATHER.GOV/GREATFALLS
000
FXUS65 KMSO 082048
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
248 PM MDT WED OCT 8 2008
...WINTER LIKE STORM SYSTEM TO BRING SNOW ALONG THE CONTINENTAL
DIVIDE...SOUTHWEST MONTANA AND LEMHI COUNTY LATE THURSDAY NIGHT
INTO THIS COMING WEEKEND...
.DISCUSSION...A WEAK RIDGE WILL BUILD TONIGHT OVER THE NORTHERN
ROCKIES AHEAD OF AN APPROACHING TROUGH OF LOW PRESSURE. COMBINED
WITH LIGHT WINDS AND MOSTLY CLEAR SKIES...BELOW FREEZING
TEMPERATURES ARE EXPECTED WHICH WILL CAUSE A WIDESPREAD HARD
FREEZE OVERNIGHT.
THE LOW PRESSURE TROUGH WILL THEN BEGIN DIGGING OVER THE PACIFIC
NORTHWEST DURING THE DAY THURSDAY. THE TROUGH WILL MOVE INTO THE
INTERMOUNTAIN WEST OVERNIGHT THURSDAY INTO FRIDAY MORNING. WITH
THIS...MUCH COOLER TEMPERATURES AND LOWERING SNOW LEVELS WILL
OCCUR...WITH MANY SNOW LEVELS LOWERING TO VALLEY FLOORS BY
FRIDAY MORNING. AS THE SYSTEM APPROACHES...THERE IS A SLIGHT
CHANCE FOR SOME EARLY SNOW SHOWERS POSSIBLE THURSDAY IN HIGHER
ELEVATIONS. STRONG WINDS OUT OF THE EAST WILL DOWNSLOPE NORTHWEST
MONTANA...PARTICULARLY VALLEYS LOCATED IN THIS AREA...KEEPING THE
GREATEST AREA FOR SNOW SHOWERS TO OCCUR IN SOUTHWEST MONTANA AND
LEMHI COUNTY THROUGH FRIDAY MORNING.
BY FRIDAY MORNING...THE DEEP COLD LOW PRESSURE SYSTEM DIGS OVER
SOUTHERN IDAHO AND NEVADA RAMPING UP SNOW OVER SOUTHWEST MT AND
LEMHI COUNTY WITH COLDER AIR FILTERING OVER THE DIVIDE WITH GUSTY
NORTHEAST WINDS DEVELOPING. THE GFS...EC AND UK MODELS KEEP THE SNOW
GOING THROUGH FRIDAY IN THIS AREA WHILE THE NAM KEEPS THE BEST ENERGY
TO THE SOUTH AND DRYING OUT NORTHWEST MT BY AFTERNOON. PREFER THE
CONSISTENCY OF THE OTHER MODELS AND LEANING MORE TO ACCUMULATING SNOWS
OVER SOUTHWEST MT AND LEMHI COUNTY AND MORE CLOUDINESS REGION WIDE. WINTER
WEATHER HIGHLIGHTS ARE VERY LIKELY TO BE ISSUED FOR THIS WINTER
LIKE STORM WITH VERY COLD TEMPERATURES EXPECTED FOR THIS TIME OF
YEAR. FOR THE MOST PART NORTHWEST MT VALLEYS WILL BE DOWN SLOPED
BY THE GUSTY NORTHEAST FLOW AND REMAIN DRY FOR THIS EVENT. BY
FRIDAY EVENING AS THE UPSLOPE NORTHEAST WINDS INCREASE ALONG THE
DIVIDE...SNOW WILL ALSO BEGIN TO ACCUMULATE OVER HIGHER TERRAIN
FARTHER TO THE NORTH. GUSTY NORTH TO NORTHEAST WINDS WILL
CONTINUE. ON SATURDAY...THE UPPER LEVEL CLOSED LOW PRESSURE SYSTEM
MOVES VERY SLOWLY CENTERED OVER SALT LAKE UT AND CONTINUES TO
BRING ACCUMULATING SNOWS TO ALONG THE DIVIDE...SOUTHWEST MT AND
LEMHI COUNTY. ON SUNDAY...THE LOW PRESSURE SYSTEM EJECTS TO THE
NORTHEAST TO EASTERN MT WITH SNOW TAPERING OFF OVER SOUTHWEST MT
AND LEMHI COUNTY DURING THE DAY. MONDAY ON...A FLAT RIDGE OF HIGH
PRESSURE IS EXPECTED TO BUILD FOR A WARMING AND DRYING TREND. BUT BEYOND
THIS TIME FRAME...MODEL SOLUTIONS ARE NOT CONSISTENT AND THEREFORE DID
NOT CHANGE THE ON GOING FORECAST FOR SLIGHT CHANCES OF
PRECIPITATION.
&&
.AVIATION...WEAK RIDGE OF HIGH PRESSURE WILL BE OVER WESTERN
MONTANA AND NORTH CENTRAL IDAHO TONIGHT. THIS WILL ALLOW THE
WINDS TO DECREASE AND SKIES WILL CLEAR. CLOUDS WILL BE INCREASING
DURING THE DAY THURSDAY AS A WEATHER SYSTEM APPROACHES FROM THE
PACIFIC. SOME MOUNTAINS AND PASSES COULD BE OBSCURED BY CLOUDS AND
PRECIPITATION DURING THE MORNING...WITH SHOWERS MOVING INTO THE
VALLEYS DURING THE AFTERNOON.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&
$$
SHORT TERM...FELSCH
LONG TERM....ALLEGRETTO
AVIATION...KOLATA
000
FXUS65 KTFX 081728
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1125 AM MDT WED OCT 8 2008
.UPDATE...MY FORECAST AREA WILL BE BENEATH A CONTINUED FAST WEST
TO NORTHWEST FLOW ALOFT TODAY. GOING FORECAST IS PRETTY MUCH ON
TRACK EXCEPT FOR AN AREA OF CLOUDS OVER MY NORTHEAST ZONES WHICH
IS EXPECTED TO LINGER MUCH OF THE DAY. NEW MODELS COMING IN
CONTINUE TO SUGGEST THE REGION IS IN FOR A MAJOR CHANGE IN THE
WEATHER WITH MUCH COLDER TEMPERATURES MOVING IN OVER THE NEXT TWO
DAYS. MPJ
&&
.AVIATION...
UPDATED 1725Z.
AERODROMES BENEATH BRISK WESTERLY FLOW ALOFT TODAY WITH MID/HIGH
LEVEL CLOUDINESS OVER SOUTHWEST MONTANA AND NEAR HAVRE. EXPECT VFR
CONDITIONS OVER THE ENTIRE REGION. GUSTY SURFACE WINDS ARE LIKELY
TODAY OVER THE PLAINS OF NORTH CENTRAL MONTANA. A CANADIAN COLD
FRONT WILL MOVE SOUTH THROUGH THE REGION AFTER 07Z THURSDAY...
RESULTING IN A WIND SHIFT TO THE NORTH OVER NORTH CENTRAL MONTANA BY
12Z THURSDAY. BRITTON
&&
.PREV DISCUSSION...
/ISSUED 600 AM MDT WED OCT 8 2008/
TODAY THROUGH FRIDAY...STRONG...ZONAL FLOW WILL CONTINUE OVER THE
ZONES. THE GRADIENT WILL BEGIN TO WEAKEN AND WINDS WILL DROP OFF
DURING THE AFTERNOON. WEAK DISTURBANCES WILL CONTINUE TO MOVE
THROUGH THE FLOW ALOFT AND A STRONGER DISTURBANCE WILL MOVE THROUGH
ALBERTA THIS EVENING. SURFACE WINDS WILL SWITCH TO THE NORTH BEHIND
THIS DISTURBANCE AND THIS WILL BEGIN A LENGTHY PERIOD OF UPSLOPE
FLOW...NORTH TO NORTHEAST FLOW REMAINS THROUGH FRIDAY. A LOW
PRESSURE TROF WILL MOVE ACROSS THE PACIFIC NORTHWEST THURSDAY
EVENING AND MOISTURE WILL GRADUAL INCREASE ACROSS SOUTHWEST
MONTANA. TEMPERATURES ALOFT WILL HAVE COOLED ENOUGH FOR MOST PRECIP
IN THE MOUNTAINS TO FALL AS SNOW AND SNOW LEVELS WILL CONTINUE TO
DROP DURING THE PERIOD. A SECOND AREA OF PRECIPITATION WILL DEVELOP
FROM THE NORTH ON FRIDAY...A COLD FRONT WILL CROSS THE CANADIAN
BORDER BY MID AFTERNOON...SHOULD BE THROUGH CTB BY EVENING WITH LOW
CLOUDS AND A CHANCE OF RAIN AND SNOW. TEMPERATURES WILL BE NEAR OR
BELOW NORMALS ACROSS MOST OF THE AREA TODAY. THE AIRMASS WILL
CONTINUE TO COOL THROUGH FRIDAY AND TEMPS WILL BE 15 TO 20 DEGREES
BELOW NORMALS BY FRIDAY. ZELZER
FRIDAY NIGHT THROUGH SUNDAY NIGHT...BOTH THE GFS AND ECMWF ARE IN
BETTER AGREEMENT TONIGHT FOR THE UPCOMING SNOWSTORM THAT POTENTIAL
COULD AFFECT THE REGION FRIDAY NIGHT THROUGH SUNDAY. EXPECT
UNSEASONABLY COLD AIR TO CONTINUE TO RESIDE OVER THE REGION THROUGH
THE WEEKEND...THUS ALL OF THE PRECIPITATION WILL FALL IN THE FORM OF
SNOW AT ALL ELEVATIONS OVER THE WEEKEND. BOTH MODELS CONTINUE TO
PROG ACCUMULATING SNOWFALL OVER SOUTHWEST AND CENTRAL MONTANA. RIGHT
NOW...FORECAST SNOW ACCUMULATIONS OF 2 TO 4 INCHES ARE POSSIBLE AT
LOWER ELEVATIONS FROM FRIDAY NIGHT THROUGH SATURDAY NIGHT...WITH 10
TO 16 INCHES LIKELY IN THE MOUNTAINS...THEN ADDITIONAL SNOW
ACCUMULATIONS ARE POSSIBLE SUNDAY. THE MAIN AREA TO SEE THE SNOW
ACCUMULATION IS OVER MUCH OF SOUTHWEST MONTANA AND IN THE LEWISTOWN
AREA. IN THE GREAT FALLS AND HAVRE AREAS...CURRENT FORECAST MODELS
CONTINUE TO SHOW THE GOOD ACCUMULATING SNOWS STAYING JUST SOUTH AND
EAST OF THESE CITIES...BUT SHOULD THE FORECAST TRACK MOVE
NORTHWESTWARD 30 TO 40 MILES...HEAVIER SNOW COULD FALL IN THESE
LOCATIONS. FOR THE CUT BANK AREA...SNOW ACCUMULATIONS SHOULD BE
MINOR.
FOR MONDAY AND MONDAY NIGHT...EXPECT WARMER AIR TO MOVE INTO THE
REGION...AS A WEAK UPPER LEVEL RIDGE BUILDS IN FROM THE WEST.
TEMPERATURES WILL BE SLOW TO WARM UP IN SOUTHWEST MONTANA...AS A
FRESH SNOW COVER ON SUNDAY SHOULD ALLOW FOR A FAIRLY COLD NIGHT ON
SUNDAY NIGHT. BRUSDA
TUESDAY AND WEDNESDAY...A WESTERLY FLOW ALOFT IS EXPECTED TO BRING
IN PACIFIC MOISTURE TO THE ZONES BY WEDNESDAY. TEMPERATURES WILL BE
SLIGHTLY BELOW SEASONAL AVERAGES ON THE NORTH CENTRAL PLAINS. JNS
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 54 24 47 24 / 0 10 10 20
CTB 51 22 45 20 / 0 10 10 20
HLN 54 26 48 29 / 10 10 20 30
BZN 57 21 50 27 / 0 10 20 50
WEY 48 21 47 21 / 10 20 30 40
DLN 51 22 45 24 / 10 10 20 50
HVR 57 25 50 23 / 0 10 10 10
LWT 52 23 46 23 / 0 10 10 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...MPJ
LONG TERM...BRUSDA/JNS
AVIATION...BRUSDA
WEATHER.GOV/GREATFALLS
000
FXUS65 KGGW 081608
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
1008 AM MDT WED OCT 8 2008
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH FRIDAY...
MINOR UPDATE THIS MORNING. AREA OF CLOUDS SLIDING ACROSS NORTH
CENTRAL MONTANA THIS MORNING IN THE SLIGHTLY CYCLONIC FLOW. EXPECT
THESE CLOUDS TO SLIDE FURTHER EAST THROUGH THE DAY AND ADJUSTED
SKY COVER TO ACCOUNT FOR THIS. OTHERWISE CURRENT FORECAST ON
TRACK. DEEP MIXING ALREADY IN PLACE FOR WINDY CONDITIONS. EBERT
PREVIOUS SHORT TERM DISCUSSION...WITH THE SHORT WAVE AND COLD
FRONT HAVING MOVED TO THE EAST... NORTHEAST MONTANA IS LEFT WITH
STRONG ZONAL FLOW ALOFT AND GUSTY WEST WINDS FOR TODAY. TIGHT
SURFACE GRADIENT WILL REMAIN OVER EASTERN MONTANA TODAY WITH LOW
PRESSURE OVER SASKATCHEWAN AND HIGH PRESSURE OVER IDAHO. WHILE
SURFACE GRADIENT WILL GRADUALLY RELAX AS THE LOW MOVES TO THE
EAST...GOOD MIXING WILL KEEP THE GUSTY WEST WINDS GOING UNTIL
AROUND SUNSET THIS EVENING WHEN WINDS WILL DECOUPLE. GOING LAKE
WIND ADVISORY FOR FORT PECK LAKE UNTIL 7 PM LOOKS GOOD. DRY AIR
TODAY WILL ALLOW FOR MOSTLY SUNNY SKIES.
HIGH PRESSURE WILL BUILD IN FROM THE WEST TONIGHT DIMINISHING THE
WINDS. WITH LIGHT WINDS...MOST LOCATIONS WILL SEE THEIR FIRST HARD
FREEZE OF THE FALL TONIGHT AS MOST AREAS DROP TO MID TO UPPER 20S
FOR LOWS.
THE UPPER TROUGH THAT WILL BECOME THE WEATHER MAKER FOR THE NEXT
SEVERAL DAYS MOVES INLAND FROM THE PACIFIC ON THURSDAY MORNING AND
DIGS ACROSS THE PACIFIC NORTHWEST DURING THE DAY ON THURSDAY AND
FORM A CLOSED UPPER LOW OVER NEVADA THURSDAY NIGHT. MEANWHILE...THE
FLOW ALOFT GRADUALLY TURNS SOUTHWEST OVER MONTANA. A LOW PRESSURE
SYSTEM DEVELOPS ALONG A STATIONARY FRONT NEAR THE WYOMING/COLORADO
BORDER DURING THE DAY ON THURSDAY. MOISTURE ON SOUTHWEST FLOW
ALOFT WILL START OVERRUNNING THE FRONT AND BECOME A WIDESPREAD
AREA OF RAIN AND/OR SNOW ACROSS SOUTHERN MONTANA...NORTHERN
WYOMING AND SOUTHERN NORTH DAKOTA THURSDAY NIGHT AND CONTINUE
THROUGH THE DAY ON FRIDAY. THE MODELS ARE IN AGREEMENT WITH MOST
ASPECTS OF THIS SYSTEM THROUGH FRIDAY WITH THE EXCEPTION OF THE
NORTHERN EXTENT OF THE PRECIPITATION WHICH WILL LIKELY BE
SOMEWHERE IN FORECAST AREA. THE GFS AND ECMWF HAVE THE NORTHERN
EXTENT OF THE RAIN/SNOW ALONG US 2 WHILE THE NAM HAS IT SOUTH OF
JORDAN AND NEAR GLENDIVE. NORTHERLY WINDS WILL BE FEEDING LOW
LEVEL DRY AIR INTO NORTHERN MONTANA WHICH WILL HELP LIMIT THE
NORTHWARD EXTENT OF THE RAIN/SNOW FROM THIS SYSTEM. THERE HAS BEEN
SOME RUN TO RUN DIFFERENCES WITH THE NORTHERN BOUNDARY ALSO. WITH
THE SYSTEM MORE THAN 36 HOURS AWAY AT THIS POINT...WILL GO NO
HIGHER THAN CHANCE OF RAIN AND SNOW IN THE SOUTH OF THE MISSOURI
RIVER AFTER MIDNIGHT THURSDAY AND ALL DAY FRIDAY AND SLIGHT
CHANCE NORTH OF THE MISSOURI RIVER. 850 MB TEMPERATURES WILL NEAR
ZERO CELSIUS FOR THIS EVENT WHICH IS BORDERLINE FOR RAIN AND SNOW.
WITH ALL OF THE CHANCES FOR SNOW THROUGH THE WEEKEND...WILL ISSUE
A HAZARDOUS WEATHER OUTLOOK. FORRESTER
.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
MODELS ARE IN AGREEMENT BEGINNING THE EXTENDED PERIOD WITH A HUGE
DEEPENING OF AN UPPER TROUGH OVER THE WEST WITH A CLOSED UPPER LOW
WRAPPED UP OVER THE GREAT BASIN REGION. ASSOCIATED WITH THIS
LARGE TROUGH WILL BE 850MB TEMPERATURES RANGING FROM -6C TO -1C
THROUGH SUNDAY NIGHT. WHILE MAINTAINING THE NEAR WINTER
TEMPERATURES THE LOW IS EXPECTED TO LIFT NORTHEAST UP THROUGH
NORTHEAST MONTANA AND SURROUNDING REGIONS THIS WEEKEND. THEN A
WEAK UPPER RIDGE WILL MOVE IN BEHIND THE DEPARTING LOW AROUND
MONDAY/MONDAY NIGHT.
INITIALLY FRIDAY NIGHT WHILE THE LOW IS CENTERED OVER THE GREAT
BASIN IT WILL EJECT PACIFIC MOISTURE NORTHEAST INTO NORTHERN
PLAINS. THE RESULTING WAA DRIVEN PRECIPITATION PROMISES TO INCLUDE
SNOW IN THE MIX. WITH THE ARCTIC BOUNDARY PLACED TO THE EAST OVER
THE DAKOTAS...ACCORDING TO THE GFS...THE BRUNT OF THE PRECIPITATION
COULD BE FOCUSED THERE. ON THE OTHER HAND THE EC WHICH HAS BEEN
THE FAVORED MODEL BY HPC NUDGES THE BOUNDARY CLOSER TO MONTANA.
THE EC FOCUSES SIGNIFICANT QPF OVER THE LOCAL AREA. THE BROAD
EXTENT OF THE MOISTURE WILL INCLUDE NORTHEAST MONTANA IN ANY CASE.
SOMETIME LATE SATURDAY OR SUNDAY THE VORTEX/UPPER JET WILL RUN
OVER THE FORECAST AREA AS THE LOW LIFTS INTO CANADA. QPF AMOUNT
ARE IMPRESSIVE IN BOTH THE EC AND GFS FOR SATURDAY NIGHT AND
SUNDAY MORNING. THE BRUNT OF THE STORM WILL LIFT INTO SASKATCHEWAN
SUNDAY NIGHT BUT SOME WRAP-AROUND MOISTURE WILL CONTINUE TO
PRODUCE DIMINISHING PRECIPITATION INTO MONDAY MORNING.
DETAILS AND TIMING AMONG THE MODELS FOR THE WEEKEND ARE STILL
SETTLING BUT SIGNIFICANT QPF AND THE COLD TEMPERATURES WILL LIKELY
PRODUCE THE FIRST WINTER STORM OF THE SEASON.
INCREASING HEIGHTS MONDAY AND BEYOND WILL TREND TEMPERATURES BACK
TOWARDS NORMAL FOR THE REMAINDER OF THE PERIOD. THERE ARE HINTS OF
A WEAK SHORTWAVE TROUGH RACING ACROSS SOUTHERN
ALBERTA/SASKATCHEWAN MONDAY NIGHT AND TUESDAY BUT MOST ACTION
SHOULD REMAIN TO OUR NORTH. THE MAIN EFFECT WILL BE TO PUT A LID
ON TEMPERATURES RISING ABOVE NORMAL NEXT WEEK. SCT
&&
.AVIATION...
VFR WITH FEW TO SCATTERED CLOUDS AROUND 9K FT AGL. LOW LEVEL WIND
SHEAR CONDITIONS AT GGW AND OLF THIS MORNING WILL DIMINISH BY LATE
MORNING AS NORTHWEST SURFACE WINDS INCREASE TO 20-25KT WITH GUSTS
TO 40 KT. THIS WIND WILL DIMINISH TO AROUND 10KT BY LATE EVENING.
SCT/MCZ
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY UNTIL 7 PM MDT THIS EVENING FOR FORT PECK
LAKE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KBYZ 081514
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
914 AM MDT WED OCT 8 2008
.SHORT TERM...VALID FOR TDY AND THU...
NO UPDATE THIS MORNING. SATELLITE IMAGERY AND SURFACE OBSERVATIONS
SHOWED A FEW AREAS OF MID TO HIGH CLOUDS OVER THE REGION. CLOUDS
WERE ASSOCIATED WITH 150 KT JET OVER THE AREA AND WEAK SHORTWAVES.
MODELS WERE SIMILAR AND WERE VERIFYING WELL THIS MORNING. PROGGED
SOUNDINGS SHOWED MID/HIGH LEVEL MOISTURE MIXING OUT WITH TIME. THUS
WILL LEAVE SKY COVER GRIDS ALONE. WITH SOME MOISTURE AND LIFT OVER
MOUNTAINS WILL LEAVE THE LOW POPS ALONE BUT ANY ACTIVITY WILL BE
QUITE ISOLATED AS AIRMASS DRIES OUT. WILL HAVE MIXING TO 700 MB
TODAY UNDER A FAST WNW FLOW WHICH WILL SUPPORT TEMPERATURES IN THE
UPPER 50S TO LOWER 60S. IT WILL BE WINDY...WITH THE STRONGEST WINDS
IN THE EAST...AS 20 TO 30 KT WINDS MIX DOWN TO THE SURFACE.
DEWPOINTS WERE IN THE UPPER TEENS AND 20S THIS MORNING AND WILL
BOTTOM OUT MOSTLY IN THE TEENS THIS AFTERNOON. SOME DEWPOINTS MAY
END UP BEING A LITTLE LOWER THAN WHAT WAS IN THE GOING
FORECAST...BUT THE EFFECT ON RESULTANT RELATIVE HUMIDITIES WILL BE
NEGLIGIBLE.
ATTENTION THIS AFTERNOON WILL TURN TOWARD STORM SYSTEM THAT WILL
DEVELOP AS SHORTWAVE IN GULF OF AK THIS MORNING...SEEN ON WATER
VAPOR IMAGERY...DIGS INTO THE PACIFIC NW. GLANCE AT NEW WRF SHOWED
MOISTURE AND WARM ADVECTION DEVELOPING OVER THE REGION DURING THU
WHICH WILL BRING A CHANCE OF PRECIPITATION TO THE AREA. NO CHANGES
NEEDED TO FORECAST AT THIS TIME. ARTHUR
.LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE...
EARLY WINTER STORM CONTINUES TO TAKE SHAPE...WITH IMPROVING
CONFIDENCE DUE TO MODEL AGREEMENT AND CONSISTENCY NOW OVER SEVERAL
RUNS. SEVERAL CHANGES AS CONSISTENCY AND AGREEMENT OF MODELS
IMPROVES.
EVERYTHING SEEMS TO BE COMING TOGETHER FOR THE WINTER STORM SYSTEM
COMING THROUGH THE AREA THURSDAY THROUGH MONDAY MORNING. EXTENDED
PICKS UP SYSTEM ON FRIDAY...WHICH SHOULD SEE A BIT OF A LULL IN
PRECIP AS LOW MAKES TURN TO THE NORTHEAST. DO NOT EXPECT SNOW TO
STOP...BUT RATHER DECREASE IN INTENSITY FOR A SHORT TIME AS
MOVEMENT OF THE SYSTEM REORIENTS ITSELF...SO CONTINUED WITH HIGH
POPS ACROSS THE REGION. THE LOW PRESSURE CENTER SHOULD BEGIN
MOVING NORTHEASTWARD LATE FRIDAY NIGHT OR EARLY SATURDAY
MORNING...WITH MAIN CORE OF THE LOW EXITING THE NORTHEAST CORNER
OF CWA LATE SUNDAY NIGHT OR EARLY MONDAY MORNING...KEEPING US
WITH A CHANCE FOR WRAP AROUND SNOW THROUGH MUCH OF MONDAY. GOOD
MOISTURE AVAILABILITY AND LIFT...COMBINE WITH WELL BELOW NORMAL
TEMPERATURES TO RAISE POTENTIAL FOR EXTENSIVE SNOW ACROSS THE
REGION...IF EVERYTHING PANS OUT. CONTINUED OF INCREASING POPS
THROUGH THIS STORM PERIOD AS CONSISTENCY CONTINUES AND GENERALLY
LOWERING TEMPS...TOWARD MEX NUMBERS...THROUGH THE PERIOD AS EACH
RUN LOOKS COOLER. ON THE DOWNSIDE...IT REALLY WOULDN/T TAKE MUCH
OF A CHANGE IN PATH OF THE LOW TO THROW A WRENCH IN THE WHOLE
PLAN. SINCE TEMPS ARE SO CLOSE TO FREEZING...A SLIGHT WARM UP DUE
TO A POSITION SHIFT OF THE LOW WOULD KNOCK OUT ANY CHANCE FOR SNOW
IN THE PLAINS.
TEMPS REBOUND QUICKLY BEHIND THIS SYSTEM...RETURNING TO THE MID
50S MONDAY AS THE SYSTEM MOVES OUT OF THE AREA...AND RISING TO THE
UPPER 50S BY WEDNESDAY...UNDER SHALLOW RIDGING. THE AREA ALSO
DRIES OUT RAPIDLY BEHIND THE STORM SYSTEM...BUT SOME SHORTWAVE
ENERGY WEDNESDAY NIGHT MAY BRING A SLIGHT CHANCE FOR PRECIP
ACROSS THE AREA...SO POPULATED WITH CLIMO TYPE POPS DUE TO DEPTH
INTO THE EXTENDED. GILSTAD
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL. NORTHWEST WINDS WILL BE GUSTY FROM
LATE MORNING THROUGH THE AFTERNOON WITH AN OCCASIONAL GUST OF 25
TO 30 KTS. THE WINDS WILL DROP OFF QUICKLY IN THE EARLY EVENING.
FRIEDERS
&&
.PRELIMINARY POINT TEMP/POPS...
TDY THU FRI SAT SUN MON TUE
-------------------------------------------------------
BIL 060 032/046 031/038 026/034 026/036 027/052 032/055
0/N 03/R 77/O 77/S 65/J 21/B 10/B
LVM 059 022/047 025/037 019/035 020/038 026/055 031/055
0/N 04/R 87/S 67/S 66/J 21/N 11/B
HDN 062 029/049 030/039 026/036 025/040 026/055 031/056
0/U 03/R 66/O 77/S 65/W 21/B 10/B
MLS 061 029/052 030/042 028/038 027/040 028/055 033/057
0/N 02/R 55/O 56/O 65/W 21/B 11/B
4BQ 059 029/050 029/042 027/039 027/039 027/055 032/057
0/N 04/R 77/O 77/O 74/W 21/B 10/U
BHK 057 025/051 026/042 024/037 025/041 026/054 028/055
0/N 02/R 65/O 56/S 64/W 21/B 11/B
SHR 061 028/048 028/040 025/036 025/037 026/054 031/055
0/B 14/R 77/O 77/S 75/J 21/B 10/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KTFX 081511
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
911 AM MDT WED OCT 8 2008
.UPDATE...MY FORECAST AREA WILL BE BENEATH A CONTINUED FAST WEST
TO NORTHWEST FLOW ALOFT TODAY. GOING FORECAST IS PRETTY MUCH ON
TRACK EXCEPT FOR AN AREA OF CLOUDS OVER MY NORTHEAST ZONES WHICH
IS EXPECTED TO LINGER MUCH OF THE DAY. NEW MODELS COMING IN
CONTINUE TO SUGGEST THE REGION IS IN FOR A MAJOR CHANGE IN THE
WEATHER WITH MUCH COLDER TEMPERATURES MOVING IN OVER THE NEXT TWO
DAYS. MPJ
&&
.AVIATION...
UPDATED 1200Z.
A BRISK WESTERLY FLOW ALOFT WILL RESIDE OVER THE REGION TODAY...AS
MID/HIGH LEVEL CLOUDINESS CONTINUES TO AFFECT THE ROCKY MOUNTAIN
FRONT AND THE HAVRE AREA. ANY PRECIP TODAY WILL CONFINED TO THE
MOUNTAINS OF THE ROCKY MOUNTAIN FRONT...AND MAINLY BEFORE 18Z.
EXPECT VFR CONDITIONS OVER THE ENTIRE REGION...EXCEPT OVER THE
NORTHERN ROCKIES WHERE SOME LOCAL MVFR CONDITIONS AND MOUNTAIN
OBSCURATIONS WILL OCCUR BEFORE 20Z. GUSTY SURFACE WINDS ARE ALSO
LIKELY AGAIN TODAY OVER THE PLAINS OF NORTH CENTRAL MONTANA. A
CANADIAN COLD FRONT WILL MOVE SOUTH THROUGH THE REGION AFTER 07Z
THURSDAY...RESULTING IN A WIND SHIFT TO THE NORTH OVER NORTH CENTRAL
MONTANA BY 12Z THURSDAY. BRUSDA
&&
.PREV DISCUSSION...
/ISSUED 600 AM MDT WED OCT 8 2008/
TODAY THROUGH FRIDAY...STRONG...ZONAL FLOW WILL CONTINUE OVER THE
ZONES. THE GRADIENT WILL BEGIN TO WEAKEN AND WINDS WILL DROP OFF
DURING THE AFTERNOON. WEAK DISTURBANCES WILL CONTINUE TO MOVE
THROUGH THE FLOW ALOFT AND A STRONGER DISTURBANCE WILL MOVE THROUGH
ALBERTA THIS EVENING. SURFACE WINDS WILL SWITCH TO THE NORTH BEHIND
THIS DISTURBANCE AND THIS WILL BEGIN A LENGTHY PERIOD OF UPSLOPE
FLOW...NORTH TO NORTHEAST FLOW REMAINS THROUGH FRIDAY. A LOW
PRESSURE TROF WILL MOVE ACROSS THE PACIFIC NORTHWEST THURSDAY
EVENING AND MOISTURE WILL GRADUAL INCREASE ACROSS SOUTHWEST
MONTANA. TEMPERATURES ALOFT WILL HAVE COOLED ENOUGH FOR MOST PRECIP
IN THE MOUNTAINS TO FALL AS SNOW AND SNOW LEVELS WILL CONTINUE TO
DROP DURING THE PERIOD. A SECOND AREA OF PRECIPITATION WILL DEVELOP
FROM THE NORTH ON FRIDAY...A COLD FRONT WILL CROSS THE CANADIAN
BORDER BY MID AFTERNOON...SHOULD BE THROUGH CTB BY EVENING WITH LOW
CLOUDS AND A CHANCE OF RAIN AND SNOW. TEMPERATURES WILL BE NEAR OR
BELOW NORMALS ACROSS MOST OF THE AREA TODAY. THE AIRMASS WILL
CONTINUE TO COOL THROUGH FRIDAY AND TEMPS WILL BE 15 TO 20 DEGREES
BELOW NORMALS BY FRIDAY. ZELZER
FRIDAY NIGHT THROUGH SUNDAY NIGHT...BOTH THE GFS AND ECMWF ARE IN
BETTER AGREEMENT TONIGHT FOR THE UPCOMING SNOWSTORM THAT POTENTIAL
COULD AFFECT THE REGION FRIDAY NIGHT THROUGH SUNDAY. EXPECT
UNSEASONABLY COLD AIR TO CONTINUE TO RESIDE OVER THE REGION THROUGH
THE WEEKEND...THUS ALL OF THE PRECIPITATION WILL FALL IN THE FORM OF
SNOW AT ALL ELEVATIONS OVER THE WEEKEND. BOTH MODELS CONTINUE TO
PROG ACCUMULATING SNOWFALL OVER SOUTHWEST AND CENTRAL MONTANA. RIGHT
NOW...FORECAST SNOW ACCUMULATIONS OF 2 TO 4 INCHES ARE POSSIBLE AT
LOWER ELEVATIONS FROM FRIDAY NIGHT THROUGH SATURDAY NIGHT...WITH 10
TO 16 INCHES LIKELY IN THE MOUNTAINS...THEN ADDITIONAL SNOW
ACCUMULATIONS ARE POSSIBLE SUNDAY. THE MAIN AREA TO SEE THE SNOW
ACCUMULATION IS OVER MUCH OF SOUTHWEST MONTANA AND IN THE LEWISTOWN
AREA. IN THE GREAT FALLS AND HAVRE AREAS...CURRENT FORECAST MODELS
CONTINUE TO SHOW THE GOOD ACCUMULATING SNOWS STAYING JUST SOUTH AND
EAST OF THESE CITIES...BUT SHOULD THE FORECAST TRACK MOVE
NORTHWESTWARD 30 TO 40 MILES...HEAVIER SNOW COULD FALL IN THESE
LOCATIONS. FOR THE CUT BANK AREA...SNOW ACCUMULATIONS SHOULD BE
MINOR.
FOR MONDAY AND MONDAY NIGHT...EXPECT WARMER AIR TO MOVE INTO THE
REGION...AS A WEAK UPPER LEVEL RIDGE BUILDS IN FROM THE WEST.
TEMPERATURES WILL BE SLOW TO WARM UP IN SOUTHWEST MONTANA...AS A
FRESH SNOW COVER ON SUNDAY SHOULD ALLOW FOR A FAIRLY COLD NIGHT ON
SUNDAY NIGHT. BRUSDA
TUESDAY AND WEDNESDAY...A WESTERLY FLOW ALOFT IS EXPECTED TO BRING
IN PACIFIC MOISTURE TO THE ZONES BY WEDNESDAY. TEMPERATURES WILL BE
SLIGHTLY BELOW SEASONAL AVERAGES ON THE NORTH CENTRAL PLAINS. JNS
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 54 24 47 24 / 0 10 10 20
CTB 51 22 45 20 / 0 10 10 20
HLN 54 26 48 29 / 10 10 20 30
BZN 57 21 50 27 / 0 10 20 50
WEY 48 21 47 21 / 10 20 30 40
DLN 51 22 45 24 / 10 10 20 50
HVR 57 25 50 23 / 0 10 10 10
LWT 52 23 46 23 / 0 10 10 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...MPJ
LONG TERM...BRUSDA/JNS
AVIATION...BRUSDA
WEATHER.GOV/GREATFALLS
000
FXUS65 KMSO 081341
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
741 AM MDT WED OCT 8 2008
.UPDATE...QUICK UPDATE THIS MORNING...TO INCREASE SKY COVER ACROSS
MOST OF THE FORECAST AREA.
&&
.DISCUSSION...LOW CLOUD DECK ACROSS MOST OF WESTERN MONTANA THIS
MORNING AND IT LOOKS LIKE IT WILL REMAIN MOSTLY CLOUDY THROUGH THE
DAY. REST OF THE FORECAST LOOKS TO BE ON TRACK.
&&
.AVIATION...A STRONG UPPER LEVEL JET WILL KEEP GUSTY WINDS OVER
HIGHER TERRAIN TODAY WITH ISOLATED SNOW SHOWERS ALONG THE DIVIDE.
THESE SHOWERS WILL OBSCURE MOUNTAINS THROUGH THE DAY. THE VALLEYS
WILL BECOME BREEZY AGAIN THIS AFTERNOON...BUT NOT AS STRONG AS
TUESDAY. THE JET WILL FINALLY PUSH OFF TO THE EAST THIS EVENING AS
AN UPPER LEVEL TROUGH DIGS OVER THE PACIFIC NORTHWEST OVERNIGHT.
&&
.PREV DISCUSSION... /ISSUED 311 AM MDT WED OCT 8 2008/
..WINTER LIKE STORM SYSTEM TO BRING SNOW ALONG THE CONTINENTAL
DIVIDE...SOUTHWEST MONTANA AND LEMHI COUNTY LATE THURSDAY NIGHT
INTO THIS COMING WEEKEND...
DISCUSSION...PROGRESSIVE WEST FLOW AND STRONG UPPER JET WILL KEEP
MOUNTAIN SHOWERS ACROSS THE NORTH TODAY. WINDS ARE EXPECTED TO MIX
TO THE VALLEYS AGAIN THIS AFTERNOON...BUT WILL NOT BE AS STRONG AS
TUESDAY. THE JET WILL PUSH SOUTH AND EAST THIS EVENING AS A TROUGH
DIGS OVER THE PACIFIC NORTHWEST. THE DIGGING TROUGH WILL PUSH A
WEAK RIDGE OVER THE INTERMOUNTAIN REGION TONIGHT AND ALLOW
TEMPERATURES TO FALL BELOW FREEZING IN MANY VALLEY LOCATIONS. A
WIDESPREAD HARD FREEZE IS EXPECTED TONIGHT AS A RESULT.
THE AFOREMENTIONED TROUGH WILL MOVE INTO THE INTERMOUNTAIN WEST
THURSDAY EVENING AND WILL BE THE DOMINANT FEATURE THROUGH THE
WEEKEND. THIS SYSTEM WILL BRING WINTER TO THE DIVIDE...SOUTHWEST
MONTANA...THE SOUTHEAST CLEARWATERS AND LEMHI COUNTY. MODELS ARE
STILL STRUGGLING WITH EXACT PLACEMENT OF BEST PRECIPITATION WITH
THIS SYSTEM...SO WILL CONTINUE TO HIGHLIGHT THE POTENTIAL WINTER
WEATHER IN THE HAZARDOUS WEATHER OUTLOOK. WINTER HIGHLIGHTS ARE A
STRONG POSSIBILITY EARLY FRIDAY THROUGH THE WEEKEND SO OUTDOOR
ENTHUSIASTS SHOULD STAY ALERT TO LATER FORECASTS. NORTHERN
CLEARWATER MOUNTAINS OF IDAHO AND NORTHWEST MONTANA WILL BE
SHADOWED AS STRONG EAST WINDS WILL DOWNSLOPE THESE LOCATIONS. THE
MISSOULA VALLEY IS STILL ON THE BORDER BETWEEN WINTER WEATHER AND
DOWNSLOPED CONDITIONS DEPENDING WHICH MODEL IS PREFERRED. AT THIS
TIME FORECAST LEANS WITH A BLEND...WITH SLIGHTLY MORE PREFERENCE
GIVEN TO DOWNSLOPED SCENARIO. WILL CONTINUE TO MONITOR LATER RUNS
AND ADJUST FORECAST ACCORDINGLY AS MODELS COME INTO BETTER
AGREEMENT.
THE TROUGH IS EXPECTED TO MOVE NORTHEAST OF THE INTERMOUNTAIN
REGION SUNDAY NIGHT AS A WEAK RIDGE NOSES INTO THE PACIFIC
NORTHWEST. THIS RIDGE WILL BE SHORT LIVED AS ANOTHER PACIFIC TROUGH
WILL KNOCK DOWN THE RIDGE AND BRING MORE WEATHER TO NORTHWEST
MONTANA MONDAY NIGHT AND TUESDAY. THE GOOD NEWS IS TEMPERATURES
MONDAY AND TUESDAY WILL WARM...BUT ARE EXPECTED TO REMAIN JUST
BELOW NORMAL.
AVIATION...A STRONG UPPER LEVEL JET WILL KEEP GUSTY WINDS OVER
HIGHER TERRAIN TODAY WITH ISOLATED SNOW SHOWERS ALONG THE DIVIDE.
THESE SHOWERS WILL OBSCURE MOUNTAINS THROUGH THE DAY. THE VALLEYS
WILL BECOME BREEZY AGAIN THIS AFTERNOON...BUT NOT AS STRONG AS
TUESDAY. THE JET WILL FINALLY PUSH OFF TO THE EAST THIS EVENING AS
AN UPPER LEVEL TROUGH DIGS OVER THE PACIFIC NORTHWEST OVERNIGHT.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&
$$
SHORT TERM...KOLATA
LONG TERM....MEAD
AVIATION...MEAD
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