000
FXUS65 KGJT 200950
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
250 AM MST TUE JAN 20 2009
.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT...
THE PERSISTENT PATTERN WILL CONTINUE FOR A COUPLE MORE DAYS BEFORE
THE RIDGE BEGINS TO BREAKDOWN WED NIGHT AS PACIFIC MOISTURE AND
ENERGY APPROACH FROM THE WEST-SOUTHWEST.
THE MAIN AREA OF CONCERN FOR TODAY IS THE FOG OVER THE UINTA BASIN.
PRESENTLY A DENSE FOG ADVISORY RUNS UNTIL LATE MORNING...AND I WILL
MAKE NO CHANGES TO THIS HEADLINE. IN A REPEAT FROM SUNDAY NIGHT...
VISIBILITY AT KVEL HAS IMPROVED SOMEWHAT. BUT THE SATELLITE FOG
PRODUCT SHOWS THE FOG BANK SOUTH AND SOUTHWEST OF THE AIRPORT
COVERING A GOOD SIZED PORTION OF THE UINTA BASIN. ALSO EXPECT PATCHY
FOG IN OTHER CENTRAL AND NORTHERN VALLEYS AS WELL THIS MORNING. ONE
DIFFERENCE FOR TODAY ALONG THESE LINES IS THAT I WILL REMOVE THE HAZE
FROM THE CENTRAL VALLEYS IN THE AFTERNOON. INVERSIONS WERE NOT QUITE
AS STRONG ON MONDAY AS THEY HAVE BEEN RECENTLY SINCE TEMPERATURES
INCREASED INTO THE 40S AT GRAND JUNCTION...RIFLE AND MONTROSE. AND
WITH TEMPERATURES SIMILAR TO A COUPLE DEGREES WARMER TODAY THE HAZE
WILL BE TOO THIN TO MENTION.
EXPECT FOG TO THICKEN IN THE UINTA BASIN THIS EVENING...WITH PATCHY
FOG DEVELOPING AGAIN IN OTHER NORTH AND CENTRAL VALLEYS OVERNIGHT.
THE QUESTION REMAINS AS TO HOW THICK AND EXTENSIVE IT WILL BE IN THE
UINTA BASIN. OTHER VALLEY AREAS HAVE SEEN A SLOW WARMING...BUT
OBSERVATIONS AT VERNAL HAVE SHOWN A SLOW COOLING TREND INDICATING
THAT THE INVERSION IS JUST GETTING STRONGER. WILL LET THE DAY SHIFT
DETERMINE IF ANOTHER DENSE FOG ADVISORY IS NEEDED...BUT IF SO
TONIGHT SHOULD BE THE LAST NIGHT.
THE RIDGE BEGINS TO SLOWLY FLATTEN AND SHIFT EAST ON WEDNESDAY FOR
ONE REMAINING DAY WITH LITTLE CHANGE EXCEPT FOR A FEW MORE CLOUDS
MOVING IN FROM THE WEST. TEMPS WILL CONTINUE THEIR SLOW INCREASE.
MOISTURE AND CLOUDS CONTINUE TO INCREASE FROM THE SOUTHWEST WED NIGHT
AS A SHORTWAVE TROUGH MOVES ONSHORE OVER CALIFORNIA. THE ADDITIONAL
CLOUDS AND WARMER TEMPS SHOULD FINALLY PUT AN END THE VALLEY FOG.
A SLIGHT CHANCE OF SHOWERS WILL MOVE IN FROM THE SOUTHWEST LATE
WED NIGHT OVER THE FAR SOUTH.
.LONG TERM...THURSDAY THROUGH MONDAY...
STILL SOME SIGNIFICANT DETAIL DIFFERENCES BETWEEN MODELS AND SUSPECT
FINAL TIMING/INTENSITY TO CHANGE WITH SUBSEQUENT MDL RUNS. OTHERWISE
AN UPPER TROF ALONG THE WEST COAST OF CALIFORNIA WILL PROVIDE A
MOISTENING SOUTHWEST FLOW WEDNESDAY NIGHT ALLOWING A FEW SHOWERS TO
DEVELOP OVER THE SOUTHERN PART OF THE CWA. CHANCES INCREASE THURSDAY
...ESPECIALLY OVER THE SOUTHERN MOUNTAINS AS THE SYSTEM MOVES INTO
CENTRAL AZ. AS THE PACIFIC STORM CONTINUES TO MOVE EASTWARD THURSDAY
NIGHT FLOW BECOMES MORE ZONAL. EXPECT SHOWERS TO CONTINUE AS
INSTABILITY AND OROGRAPHICS INCREASE FAVORING MOUNTAIN LOCATIONS.
THEN THE FLOW WILL VEER TO THE NORTHWEST FRIDAY AS A SHALLOW RIDGE
BUILDS OVER THE WEST COAST. MOISTURE WILL STILL EXIST OVER THE
NORTHERN MOUNTAINS WHERE SHOWER ACTIVITY IS EXPECTED TO CONTINUE
THROUGH SATURDAY.
MEANWHILE A MUCH MORE ENERGETIC SHORT WAVE WITH POLAR JET SUPPORT
AND -32C COLD CORE PROGGED TO DROP INTO THE PACIFIC NORTHWEST LATE
SATURDAY...AND INTO THE GRT BASIN SUNDAY. PRECIP EXPECTED TO BECOME
FAIRLY WIDESPREAD OVER OUR REGION BY SUNDAY AFTERNOON AS BAROCLINIC
ZONE APPROACHES OUR CWA FROM THE NORTH. HOWEVER FRONTAL PASSAGE IS
NOT EXPECTED UNTIL SOMETIME MONDAY. THIS SYSTEM HAS THE POTENTIAL TO
BRING A RETURN OF SIGNIFICANT WINTER WEATHER. CONFIDENCE IN THE
DETAILS STILL REMAINS LOW...BUT AS MENTIONED YESTERDAY CONFIDENCE
IS HIGH THAT WE ARE HEADED INTO A PROGRESSIVE PATTERN WITH A RETURN
TO WINTER WEATHER. AS A RESULT HAVE STARTED TO TREND POPS UPWARD A
LITTLE TOWARD THE BEGINNING OF NEXT WEEK.
EXPECT VALLEY INVERSIONS TO BECOME WEAKER AS GRADIENT WINDS
START TO INCREASE OVER THE REGION. CLOUD COVER ESPECIALLY AT NIGHT
ALSO BECOMES MORE PERSIST INHIBITING RADIATIONAL COOLING THUS
INVERSION FORMATION.
&&
.AVIATION...
STRONG HIGH PRESSURE WILL REMAIN OVER EASTERN UTAH AND WESTERN
COLORADO TODAY AND TONIGHT. AS A RESULT...VFR CONDITIONS WILL
LARGELY PREVAIL ACROSS THE REGION. HOWEVER...FOG AND LOW CLOUDS
WILL PERSIST IN THE EASTERN UINTA BASIN THROUGH ABOUT 19Z BRINGING
PERIODS OF IFR AND LIFR CONDITIONS TO KVEL THIS MORNING. KCAG AND
KGUC MAY ALSO EXPERIENCE FOG FOR BRIEF PERIODS THROUGH ABOUT 16-
17Z. FOG IS EXPECTED TO REFORM SHORTLY AFTER SUNSET WITH ONSET AFTER
07Z IN THE KCAG AND KGUC AREAS AS WELL AS A FEW OTHER FAVORED
LOCATIONS IN THE REGION.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
.CO...NONE.
.UT...DENSE FOG ADVISORY THROUGH 11 AM THIS MORNING FOR THE EASTERN
UINTA BASIN...ZONE 24.
$$
SHORT TERM.....EH
LONG TERM......NL/MC
AVIATION.......TGJT
000
FXUS65 KGJT 192220
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
320 PM MST MON JAN 19 2009
.SHORT TERM...TONIGHT THROUGH WEDNESDAY...
LITTLE CHANGE IN THE SHORT TERM PERIODS. A DOMINATE UPPER RIDGE
OVER THE AREA WILL BEGIN TO LOSE AMPLITUDE OVER THE NEXT COUPLE OF
DAYS BUT CONTINUE TO BE THE MAIN FEATURE. SUNNY AND CLEAR CONDITIONS
WILL PREVAIL WITH INCREASING HIGH CLOUDS FROM THE SOUTHWEST ON
WEDNESDAY. EXPECT FOG AND PATCHY LOW CLOUDS TO DEVELOP IN SOME OF THE
VALLEYS AGAIN TONIGHT AND LINGER THROUGH TUESDAY MORNING. DENSE FOG
PERSISTED IN THE EASTERN UINTAH BASIN LAST NIGHT AND THIS MORNING.
SIMILAR CONDITIONS EXPECTED THERE TONIGHT SO WILL HOIST ANOTHER
ADVISORY FOR THAT AREA.
AFTERNOON TEMPERATURES HAVE WARMED SEVERAL DEGREES ABOVE YESTERDAY IN
SOME OF THE CENTRAL AND SOUTHERN VALLEYS. KEPT DAYTIME HIGHS ON A
SLIGHT UPWARD TREND THE NEXT COUPLE OF DAYS BUT STILL BELOW GUIDANCE.
THE DRY AIRMASS WILL ALLOW FOR CHILLY NIGHTTIME TEMPERATURES WITH
STRONG RADIATIONAL COOLING TAKING PLACE.
.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...
STILL SOME SIGNIFICANT DETAIL DIFFERENCES BETWEEN MODELS AND SUSPECT
FINAL TIMING/INTENSITY TO CHANGE WITH SUBSEQUENT MDL RUNS. OTHERWISE
AN UPPER TROF ALONG THE WEST COAST OF CALIFORNIA WILL PROVIDE A
MOISTENING SOUTHWEST FLOW WEDNESDAY NIGHT ALLOWING A FEW SHOWERS TO
DEVELOP OVER THE SOUTHERN PART OF THE CWA. CHANCES INCREASE
THURSDAY...ESPECIALLY OVER THE SOUTHERN MOUNTAINS AS THE SYSTEM MOVES
INTO CENTRAL AZ. AS THE PACIFIC STORM CONTINUES TO MOVE EASTWARD
THURSDAY NIGHT FLOW BECOMES MORE ZONAL. EXPECT SHOWERS TO CONTINUE AS
INSTABILITY AND OROGRAPHICS INCREASE FAVORING MOUNTAIN LOCATIONS.
THEN THE FLOW WILL VEER TO THE NORTHWEST FRIDAY AS A SHALLOW RIDGE
BUILDS OVER THE WEST COAST. MOISTURE WILL STILL EXIST OVER THE
NORTHERN MOUNTAINS WHERE SHOWER ACTIVITY IS EXPECTED TO CONTINUE
THROUGH SATURDAY.
MEANWHILE A MUCH MORE ENERGETIC SHORT WAVE WITH POLAR JET SUPPORT
AND -32C COLD CORE PROGGED TO DROP INTO THE PACIFIC NORTHWEST LATE
SATURDAY...AND INTO THE GRT BASIN SUNDAY. PRECIP EXPECTED TO BECOME
FAIRLY WIDESPREAD OVER OUR REGION BY SUNDAY AFTERNOON AS BAROCLINIC
ZONE APPROACHES OUR CWA FROM THE NORTH. HOWEVER FRONTAL PASSAGE IS
NOT EXPECTED UNTIL SOMETIME MONDAY. THIS SYSTEM HAS THE POTENTIAL TO
BRING A RETURN OF SIGNIFICANT WINTER WEATHER. CONFIDENCE IN THE
DETAILS STILL REMAINS LOW...BUT AS MENTIONED YESTERDAY CONFIDENCE
IS HIGH THAT WE ARE HEADED INTO A PROGRESSIVE PATTERN WITH A RETURN
TO WINTER WEATHER. AS A RESULT HAVE STARTED TO TREND POPS UPWARD A
LITTLE TOWARD THE BEGINNING OF NEXT WEEK.
EXPECT VALLEY INVERSIONS TO BECOME WEAKER AS GRADIENT WINDS
START TO INCREASE OVER THE REGION. CLOUD COVER ESPECIALLY AT NIGHT
ALSO BECOMES MORE PERSIST INHIBITING RADIATIONAL COOLING THUS
INVERSION FORMATION.
&&
.AVIATION...
STRONG HIGH PRESSURE WILL CONTINUE THE STABLE CONDITIONS ACROSS
EASTERN UTAH AND WESTERN COLORADO. AS A RESULT...VFR WILL LARGELY
PREVAIL ACROSS THE REGION AGAIN TONIGHT AND TUESDAY. HOWEVER...
LOCALIZED FOG AND LOW CLOUDS WILL DEVELOP AGAIN IN VALLEYS RESULTING
IN LOCALIZED MVFR/IFR CONDITIONS. EXPECT FOG TO DEVELOP FAIRLY
RAPIDLY IN THE KVEL AREA AFTER SUNSET AND AFTER 06Z TONIGHT
ELSEWHERE. THE FOG AND LOW CLOUDS ARE EXPECTED TO DISSIPATE BY
16Z-17Z TUESDAY...EXCEPT IN THE KVEL AREA WHERE CONDITIONS WILL
LINGER UNTIL ABOUT 19Z.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
.CO...NONE.
.UT...DENSE FOG ADVISORY FROM 6 PM THIS EVENING THROUGH 11 AM
TUESDAY FOR THE EASTERN UINTA BASIN.
$$
SHORT TERM.....TAL
LONG TERM......MC/NL
AVIATION.......TAL
000
FXUS65 KGJT 191002
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
302 AM MST MON JAN 19 2009
.SHORT TERM...TODAY THROUGH TUESDAY NIGHT...
THE BLOCKING HIGH PRESSURE RIDGE CENTERED OVER NORTHERN ID/NORTHWEST
MT TODAY WILL GRADUALLY BECOME LESS AMPLIFIED AND SHIFT TO THE
SOUTHEAST...WITH ITS AXIS CENTERED OVER THE FORECAST AREA BY TUE
EVENING. THEREFORE THE STABLE CONDITIONS WILL PERSIST...WITH THE
VALLEYS REMAINING STRONGLY INVERTED AND STAGNANT. OF CONCERN IS
THE CONTINUING CHANCE OF FOG AND HAZE. DENSE FOG HAS BEEN REPORTED IN
THE UINTA BASIN WITH VISIBILITY DOWN TO ZERO IN PLACES. AND WHILE
OBSERVATIONS INDICATE THAT VISIBILITY AT KVEL HAS INCREASED...
SATELLITE IMAGES SHOW THAT THE ASOS IS ON THE NORTHEAST EDGE OF
THE FOG DECK. SO WILL CONTINUE THE DENSE FOG ADVISORY THROUGH 9AM MST
THIS MORNING FOR THE UINTA BASIN. PATCHY NIGHTTIME AND MORNING FOG...
AND DAYTIME HAZE WILL ALSO PERSIST IN MANY OTHER VALLEY AREAS TODAY
THROUGH TUESDAY NIGHT SINCE THERE WILL BE NO CHANGE TO THESE STAGNANT
CONDITIONS. THE COLD TRAPPED AIR IN THE VALLEYS...ESPECIALLY THOSE
THAT ARE SNOW COVERED...HAVE KEPT TEMPS WELL BELOW GUIDANCE NUMBERS.
SO HAVE LOWERED TEMPS IN THOSE LOCATIONS.
.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
MODELS FINALLY COMING TO A REASONABLE CONSENSUS REGARDING THE PATTERN
CHANGE PROGGED FOR THE LATTER PART OF THE WEEK. EARLIER RUNS OF THE
GFS AND EC INDICATED A BREAKDOWN OF THE UPPER LEVEL RIDGE WITH A
PACIFIC SHORTWAVE TROF MOVING ACROSS THE SOUTHWEST. HOWEVER...GFS
WAS MUCH MORE ENERGETIC WITH THIS STORM WITH A TRAJECTORY MUCH
FARTHER NORTH THAN THE EUROPEAN MODEL. LATEST GFS VERY SIMILAR TO
THE MORE CONSISTENT ECMWF RESULTING IN FAR GREATER CONFIDENCE IN THE
FORECAST FOR THE LATTER PART OF THE WEEK.
MODELS INDICATED A LOW PRESSURE SYSTEM WILL MOVE INTO SOUTHERN CA
WEDNESDAY NIGHT BRINGING A SLIGHT CHANCE FOR SHOWERS TO THE
SOUTHWEST PORTION OF THE CWFA LATE IN THE NIGHT. CHANCES INCREASE
THURSDAY...ESPECIALLY OVER THE SOUTHERN MOUNTAINS AS THE SYSTEM
MOVES INTO CENTRAL AZ. AS THE PACIFIC STORM CONTINUES TO MOVE
RAPIDLY EASTWARD THURSDAY NIGHT FLOW BECOMES MORE ZONAL. EXPECT
SHOWERS TO CONTINUE AS INSTABILITY AND OROGRAPHICS INCREASE
FAVORING MOUNTAIN LOCATIONS. FLOW WILL VEER TO THE NORTHWEST FRIDAY
AS A SHALLOW RIDGE BUILDS OVER THE WEST COAST. AS MOISTURE IS
SHUNTED NORTH THE NORTHERN MOUNTAINS WILL BECOME THE FAVORED REGION
FOR SHOWER ACTIVITY.
EXPECT VALLEY INVERSIONS TO PERSIST THROUGH THE LATTER PART OF THE
WEEK AS A MUCH STRONGER SYSTEM NEEDED TO SCOUR COLD...STAGNANT AIR.
HOWEVER...CLOUD COVER WILL LIMIT RADIATIONAL COOLING AT NIGHT SO
EXPECT SOME MODERATION OF AFTERNOON HIGHS BEYOND WEDNESDAY.
GFS ALSO SHOWS A RATHER SHARP BAROCLINIC BOUNDARY TO OUR NORTH AS
POLAR JET DIGS INTO THE NRN ROCKIES SATURDAY. RIGHT NOW SURFACE FRONT
PROGGED TO JUST SLIP ACROSS THE NRN CWA BOUNDARY SATURDAY...ENHANCING
THE PRECIP POTENTIAL IN THAT AREA. CONFIDENCE HIGH THAT AN UNSETTLED
PROGRESSIVE PATTERN WILL DEVELOP AND LAST THROUGH/BEYOND THIS PERIOD
...BUT DETAILS REMAIN MUDDLED AT BEST. WILL CONTINUE WITH TREND OF
SCATTERED MOUNTAIN POPS UNTIL DETAILS BECOME MORE CLEAR.
&&
.AVIATION...
VFR CONDITIONS WILL LARGELY PREVAIL ACROSS THE REGION TODAY AND
TONIGHT. HOWEVER...AREAS OF VALLEY FOG WILL BRING LOCAL MVFR/IFR VIS
AFTER 06Z TONIGHT AND LASTING THROUGH 17Z. ONE NOTABLE EXCEPTION WILL
BE THE LOWER PARTS OF THE UINTA BASIN WHERE WIDESPREAD IFR CIGS AND
VSBY WILL PERSIST THROUGH MIDDAY. FOG AND THE STRATUS DECK WILL
EXPAND AGAIN TONIGHT BRINGING A GOOD CHANCE OF IFR/LIFR CIGS AND
VSBY TO KVEL.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
.CO...NONE.
.UT...DENSE FOG ADVISORY THROUGH 9 AM THIS MORNING FOR THE EASTERN
UINTA BASIN...ZONE 24.
$$
SHORT TERM.....EH
LONG TERM......NL/MC
AVIATION.......NL
000
FXUS65 KGJT 190241
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
740 PM MST SUN JAN 18 2009
.EARLY EVENING UPDATE...
WIDESPREAD DENSE FOG HAS ALREADY DEVELOPED IN THE EASTERN UINTAH
BASIN. UHP TROOPERS REPORTING AREAS FROM VERNAL TO DUCHESNE COUNTY
LINE WITH VISIBILITIES DOWN TO ZERO. UPDATED THE NPW AT 1828 MST TO
IMMEDIATELY BEGIN THE DENSE FOG ADVISORY IN THE EASTERN UINTAH
BASIN INSTEAD OF WAITING FOR THE ORIGINAL START TIME OF 2300 MST
TONIGHT.
EXPECT LITTLE CHANGE IN THE WEATHER PATTERN THROUGH THE NEXT FEW
DAYS...AND LITTLE CHANGE IN THE INVERSION/FOG/HAZE SITUATION IN THE
EASTERN UINTAH BASIN. LOWEST RH AT KVEL TODAY WAS 72%...AND
CURRENTLY AT 92%. THEREFORE...SIGNIFICANTLY RAISED RH AND TD
GRID VALUES FOR THE EASTERN UINTAH BASIN THROUGH THE SHORT-TERM
PERIOD. AS THIS PATTERN WILL LIKELY PERSIST THROUGH WEDNESDAY...
LONG-TERM DESK TONIGHT WILL NEED TO CONSIDER RAISING THE RH AND TD
VALUES FOR THE EASTERN UINTAH BASIN ON WEDNESDAY. ANOTHER
CONSIDERATION FOR SHORT-TERM AND LONG-TERM DESKS TONIGHT WILL BE
THE MAX TEMPERATURE FORECASTS FOR THE EASTERN UINTAH BASIN. KVEL MAX
TODAY WAS 25F. CURRENT GRIDS...AND MODEL GUIDANCE...HAVE KVEL MAX
TEMPS GETTING UP INTO THE LOWER 30S THE NEXT 3 DAYS. MODELS ARE
NOTORIOUS FOR BEING TOO WARM FOR MAX TEMPS IN VALLEYS WITH STRONG
WINTERTIME INVERSIONS.
.SHORT TERM...TONIGHT THROUGH TUESDAY...
BLOCKING RIDGE CONTINUES ITS GRIP ACROSS THE WRN CONUS THROUGH
TUESDAY. THE HIGH CORE MOVES FROM THE NRN ROCKIES TODAY TO THE UTAH
AND COLORADO BORDER BY TUESDAY. STRONG INVERSIONS PERSIST OVER SNOW
COVERED VALLEYS...MOST NOTABLY OVER THE UINTA AND YAMPA RIVER
BASINS. A STRATUS/FOG LAYER HAS FORMED OVER PARTS OF THE UINTA
BASIN...PRIMARY SOUTH AND WEST OF VERNAL. A WEATHER SPOTTER AT
PELICAN LAKE ESTIMATED VISIBILITY HAS BEEN 100 YARDS OR SO FOR THE
ENTIRE MORNING. THE HIGH CLOUDS SPREADING FROM THE NORTHEAST HAS
HAD LITTLE IMPACT ON THE STRATUS LAYER TODAY. THE WEAK UPPER LEVEL
VORTICITY LOBE MOVES SOUTH OF OUR FORECAST AREA TONIGHT AND THE HIGH
CLOUDS WILL DECREASE. THE TREND FOR THE PAST COUPLE OF DAYS HAS
BEEN AN EXPANSION OF MORNING FOG ACROSS SNOW COVERED VALLEY. THIS
TREND MAY CONTINUE INTO MONDAY AS THE RIDGE AXIS MOVES TOWARD UTAH
AND COLORADO. WITH THIS IDEA AND COORDINATION FROM WFO SLC...WE WILL
ISSUE A DENSE FOG ADVISORY FOR THE ERN UINTA BASIN.
FOR THE REMAINDER OF THE FORECAST AREA...NEAR PERSISTENCE IS THE
BEST FORECAST. MID LEVEL TEMPERATURES REACH THEIR PEAK TUESDAY
AFTERNOON PER 700 MB MODEL DATA. WARM WINTERTIME TEMPS IN THE
MOUNTAINS CONTINUE FOR THE NEXT TWO DAYS. SRN AND SOME CENTRAL
VALLEYS WILL BE A LITTLE COOLER THAN MOUNTAIN AREAS...BUT STILL
ABOVE SEASONAL NORMS.
.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
DURING THIS PERIOD THE RIDGE GETS FLATTENED AND PUSHED EASTWARD.
FAIRLY BENIGN WX PATTERN WILL CONTINUE UNTIL RIDGE AXIS SHIFTS
EAST OF OUR CWA BY WEDNESDAY AFTERNOON. THEN THE WINDS ALOFT BACK TO
THE SOUTHWEST. EVOLVING PATTERN SOMEWHAT COMPLEX BUT GFS AND EC SHOW
MODERATELY STRONG CLOSED SHORT WAVE STARTING TO PUSH INTO SRN
CALIFORNIA THURSDAY MORNING. GFS FASTER WITH THIS FEATURE AND SEVERAL
HUNDRED MILES NORTH OF THE EC POSITION BY THURSDAY AFTERNOON. FINAL
TRAJECTORY WILL DETERMINE INTENSITY AND HOW WIDESPREAD PCPN WILL
BE...WITH THE GFS OBVIOUSLY THE WETTER SOLUTION. HPC MAP PRODUCTS AT
THIS TIME AGREE WITH THE GFS...AND THATS FOLLOWED. GFS ALSO SHOWS A
RATHER SHARP BAROCLINIC BOUNDARY TO OUR NORTH AS POLAR JET DIGS INTO
THE NRN ROCKIES SATURDAY. RIGHT NOW SURFACE FRONT PROGGED TO JUST
SLIP ACROSS THE NRN CWA BOUNDARY SATURDAY...ENHANCING THE PRECIP
POTENTIAL IN THAT AREA. CONFIDENCE HIGH THAT AN UNSETTLED PROGRESSIVE
PATTERN WILL DEVELOP AND LAST THROUGH/BEYOND THIS PERIOD...BUT
DETAILS REMAIN MUDDLED AT BEST. WILL CONTINUE WITH TREND OF
SCATTERED MOUNTAIN POPS UNTIL DETAILS BECOME CLEARER.
&&
.AVIATION...
VFR CONDITIONS WILL LARGELY PREVAIL ACROSS THE REGION THIS
AFTERNOON THROUGH MONDAY. HOWEVER...PATCHY VALLEY FOG WILL CREATE
LOCAL MVFR/IFR VIS AFTER 06Z TONIGHT AND LASTING THROUGH 17Z.
ONE NOTABLE EXCEPTION WILL BE THE LOWER PARTS OF THE UINTA BASIN
WHERE IFR CIGS AND VIS EXIST AND WILL PERSIST THROUGH MIDDAY MONDAY.
THE STRATUS AND FOG DECK WILL EXPAND TONIGHT AND THERE IS A GOOD
CHANCE THAT KVEL WILL BE AFFECTED BY IFR CONDITIONS.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
.CO...NONE.
.UT...DENSE FOG ADVISORY FOR THE EASTERN UINTAH BASIN (ZONE 24)
THROUGH 9 AM MONDAY.
$$
UPDATE.........JRP
SHORT TERM.....PF
LONG TERM......MC
AVIATION.......PF
000
FXUS65 KGJT 182145
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
245 PM MST SUN JAN 18 2009
.SHORT TERM...TONIGHT THROUGH TUESDAY...
BLOCKING RIDGE CONTINUES ITS GRIP ACROSS THE WRN CONUS THROUGH
TUESDAY. THE HIGH CORE MOVES FROM THE NRN ROCKIES TODAY TO THE UTAH
AND COLORADO BORDER BY TUESDAY. STRONG INVERSIONS PERSIST OVER SNOW
COVERED VALLEYS...MOST NOTABLY OVER THE UINTA AND YAMPA RIVER
BASINS. A STRATUS/FOG LAYER HAS FORMED OVER PARTS OF THE UINTA
BASIN...PRIMARY SOUTH AND WEST OF VERNAL. A WEATHER SPOTTER AT
PELICAN LAKE ESTIMATED VISIBILITY HAS BEEN 100 YARDS OR SO FOR THE
ENTIRE MORNING. THE HIGH CLOUDS SPREADING FROM THE NORTHEAST HAS
HAD LITTLE IMPACT ON THE STRATUS LAYER TODAY. THE WEAK UPPER LEVEL
VORTICITY LOBE MOVES SOUTH OF OUR FORECAST AREA TONIGHT AND THE HIGH
CLOUDS WILL DECREASE. THE TREND FOR THE PAST COUPLE OF DAYS HAS
BEEN AN EXPANSION OF MORNING FOG ACROSS SNOW COVERED VALLEY. THIS
TREND MAY CONTINUE INTO MONDAY AS THE RIDGE AXIS MOVES TOWARD UTAH
AND COLORADO. WITH THIS IDEA AND COORDINATION FROM WFO SLC...WE WILL
ISSUE A DENSE FOG ADVISORY FOR THE ERN UINTA BASIN.
FOR THE REMAINDER OF THE FORECAST AREA...NEAR PERSISTENCE IS THE
BEST FORECAST. MID LEVEL TEMPERATURES REACH THEIR PEAK TUESDAY
AFTERNOON PER 700 MB MODEL DATA. WARM WINTERTIME TEMPS IN THE
MOUNTAINS CONTINUE FOR THE NEXT TWO DAYS. SRN AND SOME CENTRAL
VALLEYS WILL BE A LITTLE COOLER THAN MOUNTAIN AREAS...BUT STILL
ABOVE SEASONAL NORMS.
.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
DURING THIS PERIOD THE RIDGE GETS FLATTENED AND PUSHED EASTWARD.
FAIRLY BENIGN WX PATTERN WILL CONTINUE UNTIL RIDGE AXIS SHIFTS
EAST OF OUR CWA BY WEDNESDAY AFTERNOON. THEN THE WINDS ALOFT BACK TO
THE SOUTHWEST. EVOLVING PATTERN SOMEWHAT COMPLEX BUT GFS AND EC SHOW
MODERATELY STRONG CLOSED SHORT WAVE STARTING TO PUSH INTO SRN
CALIFORNIA THURSDAY MORNING. GFS FASTER WITH THIS FEATURE AND SEVERAL
HUNDRED MILES NORTH OF THE EC POSITION BY THURSDAY AFTERNOON. FINAL
TRAJECTORY WILL DETERMINE INTENSITY AND HOW WIDESPREAD PCPN WILL
BE...WITH THE GFS OBVIOUSLY THE WETTER SOLUTION. HPC MAP PRODUCTS AT
THIS TIME AGREE WITH THE GFS...AND THATS FOLLOWED. GFS ALSO SHOWS A
RATHER SHARP BAROCLINIC BOUNDARY TO OUR NORTH AS POLAR JET DIGS INTO
THE NRN ROCKIES SATURDAY. RIGHT NOW SURFACE FRONT PROGGED TO JUST
SLIP ACROSS THE NRN CWA BOUNDARY SATURDAY...ENHANCING THE PRECIP
POTENTIAL IN THAT AREA. CONFIDENCE HIGH THAT AN UNSETTLED PROGRESSIVE
PATTERN WILL DEVELOP AND LAST THROUGH/BEYOND THIS PERIOD...BUT
DETAILS REMAIN MUDDLED AT BEST. WILL CONTINUE WITH TREND OF
SCATTERED MOUNTAIN POPS UNTIL DETAILS BECOME CLEARER.
&&
.AVIATION...
VFR CONDITIONS WILL LARGELY PREVAIL ACROSS THE REGION THIS
AFTERNOON THROUGH MONDAY. HOWEVER...PATCHY VALLEY FOG WILL CREATE
LOCAL MVFR/IFR VIS AFTER 06Z TONIGHT AND LASTING THROUGH 17Z.
ONE NOTABLE EXCEPTION WILL BE THE LOWER PARTS OF THE UINTA BASIN
WHERE IFR CIGS AND VIS EXIST AND WILL PERSIST THROUGH MIDDAY MONDAY.
THE STRATUS AND FOG DECK WILL EXPAND TONIGHT AND THERE IS A GOOD
CHANCE THAT KVEL WILL BE AFFECTED BY IFR CONDITIONS.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
.CO...NONE.
.UT...DENSE FOG ADVISORY FOR THE EASTERN UINTA BASIN (ZONE 24) FROM
11 PM TONIGHT TO 9 AM MONDAY.
$$
SHORT TERM.....PF
LONG TERM......MC
AVIATION.......PF
000
FXUS65 KGJT 181536
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
836 AM MST SUN JAN 18 2009
.UPDATE...STRONGER TEMPERATURE INVERSIONS HAVE RETURNED TO THE
NORTHERN VALLEYS...FROM THE UINTA BASIN TO THE YAMPA RIVER BASIN.
LOWERED AFTERNOON TEMPERATURES FOR THIS AREA THIS AFTERNOON TO
REFLECT YESTERDAYS OBSERVATIONS. FREEZING FOG HAS HAVING EXPANDED
THIS MORNING COMPARED TO SATURDAY MORNING...INDICATING THAT
THE INVERSIONS HAVE BECOME STRONGER.
.SHORT TERM...TODAY THROUGH MONDAY NIGHT...
BENIGN PATTERN PERSISTS THROUGH THE SHORT TERM PERIOD AS THE WEST
COAST RIDGE SLOWLY SHIFTS OVER THE NORTHERN ROCKIES BY MONDAY/MONDAY
NIGHT. VALLEY INVERSIONS WILL CONTINUE WITH NOT MUCH CHANGE IN THE
COOL TEMPERATURES AND STAGNANT...HAZY CONDITIONS. THEREFORE HAVE GONE
BELOW GUIDANCE FOR TEMPS IN THE VALLEYS. THE WARMEST READINGS WILL BE
ON THE SLOPES AND RIDGES ABOVE THE INVERSIONS WHERE A GRADUAL WARMING
TREND WILL CONTINUE.
.LONG TERM...TUESDAY THROUGH SATURDAY...
MEDIUM RANGE MODELS IN GOOD AGREEMENT WITH HIGH AMPLITUDE RIDGE OVER
THE REGION THROUGH TUESDAY NIGHT. PROFOUND DIFFERENCES BEGIN TO
APPEAR WEDNESDAY AS MODELS STRUGGLED TO COME UP WITH A COHERENT
SOLUTION FOR DEMISE OF THE WESTERN STATES RIDGE. SLOWER AND MORE
SOUTHERN EC SOLUTION WOULD HOLD OFF MOISTURE UNTIL THURSDAY WHILE
SHALLOWER...HENCE MORE PROGRESSIVE GFS WOULD BRING A PACIFIC
SHORTWAVE ACROSS THE CENTER OF THE CWFA BEGINNING WEDNESDAY NIGHT.
HPC FAVORED THE EC SOLUTION AND EC SHOWED GOOD RUN-TO-RUN CONSISTENCY
SO WILL CONTINUE TO BASE FORECAST ON THE STEADIER ECMWF THIS MORNING.
CONSEQUENTLY...KEPT MOISTURE OUT OF THE FORECAST UNTIL LATE
WEDNESDAY NIGHT WHEN SLIGHT CHANCES BEGIN TO WORK IN ACROSS THE
SOUTH. FOR THURSDAY...REDUCED POPS ACROSS THE NORTH AND BOOSTED
THEM A BIT ACROSS THE SOUTH WITH MORE SOUTHERN TRACK FAVORED.
ANOTHER PAC WAVE THEN EXPECTED FOR NEXT WEEKEND. WILL KEEP WITH A
RATHER GENERIC FORECAST OF A CHANCE OF PRECIP THU-SAT MAINLY FOR THE
MTNS UNTIL CONFIDENCE INCREASES ENOUGH TO START ADDING DETAIL.
&&
.AVIATION...
VFR CONDITIONS WILL LARGELY PREVAIL ACROSS THE REGION TODAY AND
TONIGHT. HOWEVER...PATCHY VALLEY FOG WILL CREATE AREAS OF IFR/MVFR
CONDITIONS THROUGH 16Z THIS MORNING AND AGAIN AFTER 06Z TONIGHT...
MAINLY FOR AIRPORTS ALONG AND NORTH OF INTERSTATE 70.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
.CO...NONE.
.UT...NONE.
$$
UPDATE.........PF
SHORT TERM.....EH
LONG TERM......NL/JAD
AVIATION.......TGJT
000
FXUS65 KGJT 181023
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
323 AM MST SUN JAN 18 2009
.SHORT TERM...TODAY THROUGH MONDAY NIGHT...
BENIGN PATTERN PERSISTS THROUGH THE SHORT TERM PERIOD AS THE WEST
COAST RIDGE SLOWLY SHIFTS OVER THE NORTHERN ROCKIES BY MONDAY/MONDAY
NIGHT. VALLEY INVERSIONS WILL CONTINUE WITH NOT MUCH CHANGE IN THE
COOL TEMPERATURES AND STAGNANT...HAZY CONDITIONS. THEREFORE HAVE GONE
BELOW GUIDANCE FOR TEMPS IN THE VALLEYS. THE WARMEST READINGS WILL BE
ON THE SLOPES AND RIDGES ABOVE THE INVERSIONS WHERE A GRADUAL WARMING
TREND WILL CONTINUE.
.LONG TERM...TUESDAY THROUGH SATURDAY...
MEDIUM RANGE MODELS IN GOOD AGREEMENT WITH HIGH AMPLITUDE RIDGE OVER
THE REGION THROUGH TUESDAY NIGHT. PROFOUND DIFFERENCES BEGIN TO
APPEAR WEDNESDAY AS MODELS STRUGGLED TO COME UP WITH A COHERENT
SOLUTION FOR DEMISE OF THE WESTERN STATES RIDGE. SLOWER AND MORE
SOUTHERN EC SOLUTION WOULD HOLD OFF MOISTURE UNTIL THURSDAY WHILE
SHALLOWER...HENCE MORE PROGRESSIVE GFS WOULD BRING A PACIFIC
SHORTWAVE ACROSS THE CENTER OF THE CWFA BEGINNING WEDNESDAY NIGHT.
HPC FAVORED THE EC SOLUTION AND EC SHOWED GOOD RUN-TO-RUN CONSISTENCY
SO WILL CONTINUE TO BASE FORECAST ON THE STEADIER ECMWF THIS MORNING.
CONSEQUENTLY...KEPT MOISTURE OUT OF THE FORECAST UNTIL LATE
WEDNESDAY NIGHT WHEN SLIGHT CHANCES BEGIN TO WORK IN ACROSS THE
SOUTH. FOR THURSDAY...REDUCED POPS ACROSS THE NORTH AND BOOSTED
THEM A BIT ACROSS THE SOUTH WITH MORE SOUTHERN TRACK FAVORED.
ANOTHER PAC WAVE THEN EXPECTED FOR NEXT WEEKEND. WILL KEEP WITH A
RATHER GENERIC FORECAST OF A CHANCE OF PRECIP THU-SAT MAINLY FOR THE
MTNS UNTIL CONFIDENCE INCREASES ENOUGH TO START ADDING DETAIL.
&&
.AVIATION...
VFR CONDITIONS WILL LARGELY PREVAIL ACROSS THE REGION TODAY AND
TONIGHT. HOWEVER...PATCHY VALLEY FOG WILL CREATE AREAS OF IFR/MVFR
CONDITIONS THROUGH 16Z THIS MORNING AND AGAIN AFTER 06Z TONIGHT...
MAINLY FOR AIRPORTS ALONG AND NORTH OF INTERSTATE 70.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
.CO...NONE.
.UT...NONE.
$$
SHORT TERM.....EH
LONG TERM......NL/JAD
AVIATION.......TGJT
000
FXUS65 KGJT 172101
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
200 PM MST SAT JAN 17 2009
.SHORT TERM...TODAY THROUGH MONDAY...
BLOCKING PATTERN OVER THE WRN CONUS CONTINUES BUT THE HIGH CENTER
DOES REPOSITION ITSELF OVER THE NRN ROCKIES BY MONDAY AFTERNOON.
ONLY SUBTLE DAY TO DAY CHANGES EXPECTED FOR SUNDAY AND MONDAY. A
WEAK UPPER LEVEL DISTURBANCE HAS BROUGHT SOME THIN CIRRUS TODAY BUT
WILL DISSIPATE THIS EVENING. VALLEY INVERSIONS WILL STRENGTHEN ON
MONDAY AS THE RIDGE AXIS WILL BE ALONG THE UTAH AND COLORADO BORDER.
PATCHY FOG AND/OR HAZE COULD BECOME MORE PREVALENT ACROSS THE UINTA
BASIN AND THE GRAND VALLEY. THE SLOW WARMING TREND IN THE MOUNTAIN
AREAS ABOVE VALLEY INVERSIONS PEAKS ON MONDAY...BUT NEAR PERSISTENCE
TEMPERATURES CAN BE EXPECTED FOR VALLEY AREAS.
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
HIGH AMPLITUDE BLOCKING PATTERN PERSISTS WITH THE UPPER RIDGE SLIDING
ACROSS OUR FORECAST AREA ABOUT TUESDAY. LOOK FOR A CONTINUATION OF
DRY AND STABLE CONDITIONS MONDAY AND TUESDAY.
GFS AND ECWMF MODELS INDICATE A BREAKDOWN OF THE BLOCKING RIDGE AFTER
MIDWEEK AS PACIFIC WAVES WORK FARTHER INLAND AND THE LARGE EASTERN
U.S. TROUGH SHIFTS OFFSHORE. HOWEVER...MODELS SOLUTIONS REMAIN AT
ODDS IN THE DETAILS. INITIAL PAC WAVE SHOULD SPLIT AS IT ENCOUNTERS
THE RIDGE WED NIGHT AND THU. ECMWF SEEMS TO BE THE MORE CONSISTENT
WITH IT EMPHASIS ON ENERGY MOVING ACROSS THE SOUTHWEST STATES AND
IS PREFERRED AT THIS TIME...THOUGH IF IT DROPS ANY FARTHER SOUTH
PRECIP CHANCES WILL BE EVEN LESS. THE GFS ALTERNATES IT FOCUS
BETWEEN THE NORTHERN AND SOUTHERN STREAMS. ANOTHER PAC WAVE THEN
EXPECTED FOR NEXT WEEKEND. WILL KEEP WITH A RATHER GENERIC FORECAST
OF A CHANCE OF PRECIP THU-SAT MAINLY FOR THE MTNS UNTIL CONFIDENCE
INCREASES ENOUGH TO START ADDING DETAIL.
&&
.AVIATION...
WIDESPREAD VFR CONTINUES...HOWEVER LOCAL MVFR VIS WILL PERSIST AT
KVEL. BETWEEN 10Z AND 16Z...LOCAL MVFR VIS MAY OCCUR AT KEGE AND
SPOTS ALONG THE COLORADO RIVER.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
.CO...NONE.
.UT...NONE.
$$
SHORT TERM.....PF
LONG TERM......JAD
AVIATION.......PF
| 
