[top]
000
FXUS65 KPIH 151051
AFDPIH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
351 AM MST THU JAN 15 2009
.SHORT TERM...TODAY THROUGH SATURDAY NIGHT. NO PRECIPITATION
EXPECTED WITH UPPER LEVEL RIDGE ACTING AS A BLOCK. MAIN FORECAST
PROBLEM IS EXTENT OF STRATUS AND FOG EVERY NIGHT AND
MORNING...AND WHEN IT MAY BREAK IN ANY GIVEN AREA. THE CLOUD
COVER...OR LACK OF IT WITH A BREAKOUT...WILL BE SOLE DETERMINER OF
HOW WARM ANY GIVEN LOCATION WILL GET. BASED FOG EXTENT AND BREAKS
ON APPROXIMATION OF NAM-12 BOUNDARY LAYER MOISTURE GOING BELOW 90
PERCENT. WIND TO CONTINUE LIGHT. MESSICK
.LONG TERM...SUNDAY THROUGH THURSDAY. HIGH PRESSURE WILL
CONTINUE TO PRODUCE TRANQUIL WEATHER UNTIL MIDDLE OF NEXT WEEK. AT
THAT TIME...A SPLIT FLOW SYSTEM IS EXPECTED TO MOVE INTO THE
REGION AND PRODUCE A CHANCE FOR PRECIPITATION.
&&
.AVIATION...IFR FOG AND/OR STRATUS WILL PERSIST ACROSS THE SNAKE
PLAIN THROUGH MIDDAY AT LEAST. WINDS WILL REMAIN LIGHT DUE TO AN
AREA OF HIGH PRESSURE THAT REMAINS IN CONTROL OVER THE REGION.
&&
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
FREEZING FOG ADVISORY UNTIL 11 AM MST THIS MORNING FOR
IDZ019>021.
&&
$$
[top]
000
FXUS65 KBOI 150934
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
234 AM MST THU JAN 15 2009
.SHORT TERM...TODAY THROUGH FRIDAY...DENSE FOG HIGHLIGHTS REMAINS
THE PRIMARY CONCERN THROUGH FRIDAY. AREAS OF DENSE FOG REPORTED
THROUGH OUT MUCH OF THE TREASURE VALLEY...WESTERN MAGIC
VALLEY...BAKER VALLEY AND LONG VALLEY THIS MORNING...HOWEVER LIGHT
SURFACE WINDS HAVE SHIFTED FOG UP AND DOWN THE TREASURE VALLEY.
SURFACE ANALYSIS SHOWS HIGH PRESSURE OVER WEST CENTRAL MOUNTAINS
WHICH OVER THE LAST 12 HOURS IS SLOWLY BUILDING SE INTO EASTERN
IDAHO. THUS...WEAK NE-SW PRESSURE GRADIENT HAS SETUP OVER THE
VALLEY FOR LIGHT SOUTH-SOUTHEAST WINDS IN THE VALLEY. LIGHT
DOWNSLOPE WINDS AT BOISE HAS PUSHED FOG INTO THE LOWER
TREASURE...THOUGH LOW STRATUS PERSISTS. GUIDANCE HAS STRUGGLE TO
CAPTURE WINDS IN THE VALLEY THIS MORNING PARTLY BECAUSE SURFACE
PROGS HAVE SURFACE HIGH MUCH FURTHER EAST NEAR SALMON. ONLY THE
NAM12 BUILDS THE SURFACE HIGH INTO THE SW IDAHO BY THIS AFTERNOON.
WITH LOW CONFIDENCE IN SURFACE FEATURES FOR TODAY...HAVE DECIDED
TO CONTINUE DENSE FOG ADVISORY...THOUGH IF SURFACE HIGH DOES NOT
MOVE EAST...FOG HIGHLIGHTS COULD BE CANCELLED EARLY. STRATUS
SHOULD PERSIST THROUGHOUT TODAY AS DEEP INVERSION CONTINUES. COULD
SEE SOME BREAKS IN THE STRATUS IN THE WESTERN MAGIC...BUT
OTHERWISE EXPECT THE LOWER AND MUCH OF THE UPPER TREASURE TO
REMAIN IN STRATUS. TEMPERATURES WILL BE VERY SIMILAR TO YESTERDAY.
MORE DENSE FOG HEADLINES WILL BE NEEDED TONIGHT BUT WILL LET DAY
SHIFT TAKE A CLOSER LOOK AT WHERE. EXTENDED DENSE FOG ADV FOR
BAKER COUNTY AS MANY LOWER VALLEYS IN THE COUNTY ARE SHELTERED AND
SHOULD SEE VERY LITTLE WIND TODAY.
.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY...MODELS CONTINUE THE
TREND OF KEEPING THE BLOCKING RIDGE AND STRONG INVERSION OVER THE
REGION THROUGH AT LEAST MONDAY. THIS WILL TEND TO KEEP THE FOG AND
STRATUS OVER THE REGION. ALL THE EXTENDED MODELS CONTINUE TO HINT
AT THE RIDGE BREAKING DOWN BY TUESDAY AND BRING IN AN UPPER LOW
INTO THE REGION WEDNESDAY AND THURSDAY. GFS AND ECMWF DO DISAGREE ON
FROM WHAT DIRECTION THIS LOW APPROACHES WHETHER FROM OVER THE
RIDGE OR UNDERCUTTING IT FROM THE SOUTH. OTHERWISE WITH THE RIDGE
OVER THE REGION DID MAKE A FEW TWEAKS TO THE MAX TEMPS MAINLY OVER
THE MOUNTAIN AREAS WHERE WE WERE TOO COLD BASED ON PAST FEW
DAYTIME HIGHS.
&&
.AVIATION...SATELLITE TRENDS AND SFC OBS SHOWING STRATUS AND FOG
CONTINUES FROM KBKE THROUGH KTWF/KJER. WINDS HAVE PICKED UP ACROSS
PORTIONS OF THE MAGIC AND TREASURE VALLEY WHICH HAS HELPED TO IMPROVE
VISIBILITIES OVER THE AREA AS SFC HIGHS BUILDS TO OUR EAST. WINDS AT
KTWF HAVE GONE FROM SW / DOWNSLOPE / TO A EAST TO NORTHEAST
DIRECTION. THIS IS MAKING THE TAF AT KTWF INTERESTING DEPENDING ON
THE WIND DIRECTION. WINDS HAVE ALSO IMPROVED VIS HERE AT KBOI WHICH
SHOULD CONTINUE THROUGH THE FORECAST PERIOD. MODELS DO INDICATE THAT
KBKE SHOULD REMAIN LIFR TODAY WITH LIGHT WINDS EXPECTED. FORECAST
SOUNDINGS OVER THE WEST CENTRAL MOUNTAINS INDICATING THAT THE
MOISTURE PROFILE EXPECTED TO REMAIN VERY SHALLOW...SO KMYL SHOULD
SEE VRF CONDITIONS BY LATE MORNING.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...DENSE FOG ADVISORY UNTIL 11 AM MST THIS MORNING FOR IDZ011-
IDZ012-IDZ014-IDZ016.
OR...DENSE FOG ADVISORY UNTIL 11 AM MST THIS MORNING FOR ORZ064.
DENSE FOG ADVISORY UNTIL 10 AM PST FRIDAY FOR ORZ062.
&&
$$
WEATHER.GOV/BOISE
SHORT TERM...JDS
LONG TERM....CR
AVIATION.....CR
000
FXUS65 KBOI 150430
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
930 PM MST WED JAN 14 2009
.DISCUSSION...DENSE FOG IS WIDESPREAD IN THE VALLEYS. WILL
CONTINUE DENSE FOG ADVISORY AS CURRENTLY ISSUED. NO CHANGES
EXPECTED OVERNIGHT...AND NO UPDATE WARRANTED AT THIS TIME.
&&
.AVIATION...UPPER LEVEL RIDGE AND ASSOCIATED SURFACE INVERSION HOLD
STRONG OVER THE FORECAST AREA TONIGHT. BELOW 5100 FT - DENSE FOG
REMAINS ENTRENCHED IN VALLEYS AND WILL PERSIST THROUGH THURSDAY
MORNING. EXPECT LIFR CONDITIONS AT ALL TAF SITES THROUGH 18Z.
KBOI/KTWF/KJER AND THE LONG VALLEY WILL EXPERIENCE PERIODS OF MVFR
CONDITIONS THURSDAY AFTERNOON...BUT ARE EXPECTED TO RETURN TO
LIFR/IFR CONDITIONS AFTER SUNSET. ABOVE 5100 FT - PREDOMINANTLY VFR
CONDITIONS UNDER SCATTERED HIGH CLOUDS. LIGHT SURFACE WINDS. LIGHT
NORTHERLY WINDS ALOFT.
&&
.PREV DISCUSSION...
SHORT TERM...ANOTHER DENSE FOG ADVISORY TONIGHT AND THURSDAY MORNING
IN THE ZONES LISTED BELOW. VISIBLE SATELLITE IMAGERY SHOWS A
CONTINUOUS AREA OF FOG ACROSS THE TREASURE VALLEY...NORTHERN PART OF
THE MAGIC VALLEY AND NORTHERN PART OF THE UPPER SNAKE RIVER PLAIN
ALL THE WAY TO YELLOWSTONE. SOUTHERN PARTS OF THE SNAKE RIVER BASIN
SEEM TO BE RELATIVELY FOG-FREE. OVERALL...PERSISTENCE FORECAST
THROUGH FRIDAY AS STRONG UPPER RIDGE CONTINUES TO DOMINATE OUR WX
WITH THE USUAL INVERSION CONDITIONS IN THE VALLEYS AND CLEAR MILD WX
ABOVE. BUT AS THE UPPER RIDGE SLOWLY EDGES INLAND THE SURFACE HIGH
WILL STRENGTHEN IN SERN IDAHO AND FLOW IN THE SNAKE RIVER BASIN WILL
GRADUALLY BECOME MORE EASTERLY...IN TURN PUSHING MOST OF THE FOG
INTO THE LOWER TREASURE VALLEY AND CLEARING OUT THE UPPER TREASURE
VALLEY. IN ADDITION TO VALLEY FOG TONIGHT AND THURSDAY WE WILL ALSO
INCLUDE A SLIGHT CHANCE OF FREEZING DRIZZLE OR VERY LIGHT SNOW AS
ACTUALLY OCCURRED LAST NIGHT. LITTLE CHANGE IN TEMPS THROUGH
FRIDAY. LIGHT WINDS.
LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...PERSISTENT BLOCKING
RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE WEST THROUGH AT LEAST
TUESDAY. HAVE MADE VERY LITTLE CHANGE TO PREVIOUS FORECAST.
TEMPERATURES AND EXACT LOCATION OF FOG AND LOW STRATUS CONTINUE TO
BE THE BIGGEST FORECAST CONCERN IN THE EXTENDED PERIOD. HAVE
CONTINUED THE TREND OF COOLER TEMPERATURES IN THE VALLEYS AND WARMER
TEMPERATURES ABOVE 4500 FT. THINK THAT FOG AND LOW STRATUS WILL
PERSIST IN ALL VALLEYS THROUGH TUESDAY. WHILE THE GFS AND ECMWF
DISAGREE ON HOW THE RIDGE WILL BREAK DOWN...THEY DO BOTH AGREE THAT
THERE WILL BE A PATTERN CHANGE WEDNESDAY ONWARD. THIS WILL INCREASE
WINDS AND HELP TO IMPROVE VISIBILITY AND AIR QUALITY BY THE END OF
THE EXTENDED PERIOD.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...DENSE FOG ADVISORY UNTIL 11 AM MST THURSDAY FOR IDZ011-IDZ012-
IDZ014-IDZ016.
OR...DENSE FOG ADVISORY UNTIL 11 AM MST /10 AM PST/ THURSDAY FOR
ORZ062-ORZ064.
&&
$$
WEATHER.GOV/BOISE
DISCUSSION...SP
AVIATION.....MT
PREV SHORT TERM...LC
PREV LONG TERM....DF
000
FXUS65 KBOI 142151
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
248 PM MST WED JAN 14 2009
.SHORT TERM...ANOTHER DENSE FOG ADVISORY TONIGHT AND THURSDAY MORNING
IN THE ZONES LISTED BELOW. VISIBLE SATELLITE IMAGERY SHOWS A
CONTINUOUS AREA OF FOG ACROSS THE TREASURE VALLEY...NORTHERN PART OF
THE MAGIC VALLEY AND NORTHERN PART OF THE UPPER SNAKE RIVER PLAIN
ALL THE WAY TO YELLOWSTONE. SOUTHERN PARTS OF THE SNAKE RIVER BASIN
SEEM TO BE RELATIVELY FOG-FREE. OVERALL...PERSISTENCE FORECAST
THROUGH FRIDAY AS STRONG UPPER RIDGE CONTINUES TO DOMINATE OUR WX
WITH THE USUAL INVERSION CONDITIONS IN THE VALLEYS AND CLEAR MILD WX
ABOVE. BUT AS THE UPPER RIDGE SLOWLY EDGES INLAND THE SURFACE HIGH
WILL STRENGTHEN IN SERN IDAHO AND FLOW IN THE SNAKE RIVER BASIN WILL
GRADUALLY BECOME MORE EASTERLY...IN TURN PUSHING MOST OF THE FOG
INTO THE LOWER TREASURE VALLEY AND CLEARING OUT THE UPPER TREASURE
VALLEY. IN ADDITION TO VALLEY FOG TONIGHT AND THURSDAY WE WILL ALSO
INCLUDE A SLIGHT CHANCE OF FREEZING DRIZZLE OR VERY LIGHT SNOW AS
ACTUALLY OCCURRED LAST NIGHT. LITTLE CHANGE IN TEMPS THROUGH
FRIDAY. LIGHT WINDS.
.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...PERSISTENT BLOCKING
RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE WEST THROUGH AT LEAST
TUESDAY. HAVE MADE VERY LITTLE CHANGE TO PREVIOUS FORECAST.
TEMPERATURES AND EXACT LOCATION OF FOG AND LOW STRATUS CONTINUE TO
BE THE BIGGEST FORECAST CONCERN IN THE EXTENDED PERIOD. HAVE
CONTINUED THE TREND OF COOLER TEMPERATURES IN THE VALLEYS AND WARMER
TEMPERATURES ABOVE 4500 FT. THINK THAT FOG AND LOW STRATUS WILL
PERSIST IN ALL VALLEYS THROUGH TUESDAY. WHILE THE GFS AND ECMWF
DISAGREE ON HOW THE RIDGE WILL BREAK DOWN...THEY DO BOTH AGREE THAT
THERE WILL BE A PATTERN CHANGE WEDNESDAY ONWARD. THIS WILL INCREASE
WINDS AND HELP TO IMPROVE VISIBILITY AND AIR QUALITY BY THE END OF
THE EXTENDED PERIOD.
&&
.AVIATION...VLIFR-IFR FOG AND LOW STRATUS IS PERSISTING THROUGH THE
SNAKE RIVER PLAIN THROUGH THE TREASURE VALLEY INTO THE VALLEYS OF
BAKER COUNTY. THERE IS IFR-MVFR FOG THROUGH THE LONG VALLEY OF
IDAHO. THE EXCEPTION TO THIS IS KMYL AND KTWF BOTH OF WHICH ARE ON
THE EDGE OF THE FOG. ALL OF THE ABOVE MENTIONED AREAS WILL BE
VLIFR-IFR IN FOG AND LOW STRATUS BY 02Z THIS EVENING AND THROUGH THE
NIGHT...INCLUDING KBKE...KBOI...KJER...AND KMYL. KTWF IS EXPECTED TO
DROP OFF BY EARLY THURSDAY MORNING. THE REST OF SE OREGON AND SW
IDAHO...AND AREAS ABOVE 5000 FT...WILL REMAIN VFR OTHER THAN
SHELTERED MOUNTAIN VALLEYS. SURFACE WINDS WILL BE LIGHT WITH
MODERATE NORTHWEST WINDS ALOFT.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...DENSE FOG ADVISORY FROM 6 PM MST THIS EVENING UNTIL 11 AM MST
THURSDAY FOR IDZ011-IDZ012-IDZ014.
OR...DENSE FOG ADVISORY FROM 6 PM MST /5 PM PST/ THIS EVENING UNTIL
11 AM MST/ 10 AM PST/ THURSDAY FOR ORZ062-ORZ064.
&&
$$
WEATHER.GOV/BOISE
SHORT TERM...LC
LONG TERM....DF
AVIATION.....DF
000
FXUS65 KBOI 142148
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
248 PM MST WED JAN 14 2009
.SHORT TERM...ANOTHER DENSE FOG ADVISORY TONIGHT AND THURSDAY MORNING
IN THE ZONES LISTED BELOW. VISIBLE SATELLITE IMAGERY SHOWS A
CONTINUES AREA OF FOG ACROSS THE TREASURE VALLEY...NORTHERN PART OF
THE MAGIC VALLEY AND NORTHERN PART OF THE UPPER SNAKE RIVER PLAIN
ALL THE WAY TO YELLOWSTONE. SOUTHERN PARTS OF THE SNAKE RIVER BASIN
SEEM TO BE RELATIVELY FOG-FREE. OVERALL...PERSISTENCE FORECAST
THROUGH FRIDAY AS STRONG UPPER RIDGE CONTINUES TO DOMINATE OUR WX
WITH THE USUAL INVERSION CONDITIONS IN THE VALLEYS AND CLEAR MILD WX
ABOVE. BUT AS THE UPPER RIDGE SLOWLY EDGES INLAND THE SURFACE HIGH
WILL STRENGTHEN IN SERN IDAHO AND FLOW IN THE SNAKE RIVER BASIN WILL
GRADUALLY BECOME MORE EASTERLY...IN TURN PUSHING MOST OF THE FOG
INTO THE LOWER TREASURE VALLEY AND CLEARING OUT THE UPPER TREASURE
VALLEY. IN ADDITION TO VALLEY FOG TONIGHT AND THURSDAY WE WILL ALSO
INCLUDE A SLIGHT CHANCE OF FREEZING DRIZZLE OR VERY LIGHT SNOW AS
ACTUALLY OCCURRED LAST NIGHT. LITTLE CHANGE IN TEMPS THROUGH
FRIDAY. LIGHT WINDS.
.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...PERSISTENT BLOCKING
RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE WEST THROUGH AT LEAST
TUESDAY. HAVE MADE VERY LITTLE CHANGE TO PREVIOUS FORECAST.
TEMPERATURES AND EXACT LOCATION OF FOG AND LOW STRATUS CONTINUE TO
BE THE BIGGEST FORECAST CONCERN IN THE EXTENDED PERIOD. HAVE
CONTINUED THE TREND OF COOLER TEMPERATURES IN THE VALLEYS AND WARMER
TEMPERATURES ABOVE 4500 FT. THINK THAT FOG AND LOW STRATUS WILL
PERSIST IN ALL VALLEYS THROUGH TUESDAY. WHILE THE GFS AND ECMWF
DISAGREE ON HOW THE RIDGE WILL BREAK DOWN...THEY DO BOTH AGREE THAT
THERE WILL BE A PATTERN CHANGE WEDNESDAY ONWARD. THIS WILL INCREASE
WINDS AND HELP TO IMPROVE VISIBILITY AND AIR QUALITY BY THE END OF
THE EXTENDED PERIOD.
&&
.AVIATION...VLIFR-IFR FOG AND LOW STRATUS IS PERSISTING THROUGH THE
SNAKE RIVER PLAIN THROUGH THE TREASURE VALLEY INTO THE VALLEYS OF
BAKER COUNTY. THERE IS IFR-MVFR FOG THROUGH THE LONG VALLEY OF
IDAHO. THE EXCEPTION TO THIS IS KMYL AND KTWF BOTH OF WHICH ARE ON
THE EDGE OF THE FOG. ALL OF THE ABOVE MENTIONED AREAS WILL BE
VLIFR-IFR IN FOG AND LOW STRATUS BY 02Z THIS EVENING AND THROUGH THE
NIGHT...INCLUDING KBKE...KBOI...KJER...AND KMYL. KTWF IS EXPECTED TO
DROP OFF BY EARLY THURSDAY MORNING. THE REST OF SE OREGON AND SW
IDAHO...AND AREAS ABOVE 5000 FT...WILL REMAIN VFR OTHER THAN
SHELTERED MOUNTAIN VALLEYS. SURFACE WINDS WILL BE LIGHT WITH
MODERATE NORTHWEST WINDS ALOFT.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...DENSE FOG ADVISORY FROM 6 PM MST THIS EVENING UNTIL 11 AM MST
THURSDAY FOR IDZ011-IDZ012-IDZ014.
OR...DENSE FOG ADVISORY FROM 6 PM MST /5 PM PST/ THIS EVENING UNTIL
11 AM MST/ 10 AM PST/ THURSDAY FOR ORZ062-ORZ064.
&&
$$
WEATHER.GOV/BOISE
SHORT TERM...LC
LONG TERM....DF
AVIATION.....DF
000
FXUS65 KPIH 142100
AFDPIH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
200 PM MST WED JAN 14 2009
.SHORT TERM...TONIGHT THROUGH SATURDAY. LATEST SATELLITE IMAGERY
SHOWING AMPLIFIED UPPER RIDGE POSITIONED ALONG THE PAC COAST WITH A
DRY NW FLOW ACROSS SE IDAHO. UNDER THE RIDGE...A BROAD AREA OF
FOG/STRATUS WAS VISIBLE EXTENDING FROM POCATELLO NE THROUGH ISLAND
PARK. LITTLE CHANGE EXPECTED IN THE OVERALL PATTERN AS THE UPPER
RIDGE EDGES SLOWLY EAST DURING THE PERIOD. THUS HAVE CONTINUED SOME
MENTION OF FOG/STRATUS WITHIN THE VALLEYS DURING THE FORECAST PERIOD
WITH DRIER CONDITIONS ANTICIPATED SATURDAY AS THE 700MB FLOW TURNS
NE PRODUCING A DESICCATING DOWNSLOPE FLOW. TEMPERATURES WILL BE
DRAMATICALLY IMPACTED BY PRESENCE OR ABSENCE OF FOG/STRATUS SO
CONFIDENCE IN AN ACCURATE FORECAST IS LOW EXCEPT IN THOSE AREAS
(MAINLY THE MOUNTAINS) WHERE CLEAR SKIES SHOULD RULE...AND THEN COLD
OVERNIGHT LOWS AND GRADUALLY WARMING DAYTIME HIGHS SHOULD BE THE
GENERAL RULE. HUSTON
&&
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY. A STRONG HIGH
PRESSURE CENTER WILL MOVE OVER SOUTHEAST IDAHO SUNDAY. EXPECT EARLY
MORNING FOG ON SUNDAY AND MONDAY MORNING. FOG CHANCES WILL DECREASE
LATE IN THE PERIOD AS A PACIFIC SYSTEM WEAKENS THE HIGH PRESSURE
RIDGE. THE MODELS HAVE BEEN INCONSISTENT ON THE TIMING AND STRENGTH
OF THIS NEXT SYSTEM. THERE WILL BE A STRONG HIGH PRESSURE RIDGE
OVER US AND MODELS TEND TO TRY AND PUSH THESE TYPES OF HIGH
PRESSURES OUT TOO QUICKLY. THUS...EXPECT WARMER THAN NORMAL DAY TIME
TEMPERATURES WITH MOSTLY SUNNY SKIES THROUGH TUESDAY. TW
&&
.AVIATION...WITH HIGH PRESSURE AND AMPLE MOISTURE...STRATUS IN THE
UPPER SNAKE RIVER PLAIN WILL CONTINUE TO BRING IFR CEILINGS TO IDAHO
FALLS. CURRENTLY POCATELLO IS MVFR...BUT EXPECT VFR CONDITIONS IN
THE NEXT HOUR. SUN VALLEY AND BURLEY HAVE VFR CONDITIONS AND SHOULD
REMAIN VFR OVER THE NEXT 24 HOURS. MODELS ARE INDICATING FOG TO
REFORM THIS EVENING FOR IDAHO FALLS AND OVERNIGHT FOR POCATELLO
PRODUCING IFR/LIFR CONDITIONS ONCE AGAIN. TW/MH
&&
.PIH WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
000
FXUS65 KBOI 141609
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
909 AM MST WED JAN 14 2009
.DISCUSSION...FOG HAS BECOME NEARLY CONTINUOUS ACROSS THE ENTIRE
SNAKE RIVER BASIN FROM VALE/OR ALL THE WAY TO YELLOWSTONE. THE
ONLY FOG-FREE AREA WAS A SECTION OF THE MAGIC VALLEY BUT THAT AREA
WAS FILLING IN FROM BOTH THE EAST AND WEST. INTERESTINGLY...TWF WAS
NO COLDER THAN 34F DURING THE NIGHT BUT AFTER 8 AM FOG ROLLED IN AND
THE TEMP DIPPED TO 25F. JEROME FOGGED IN EARLIER AT A TEMP OF 23F.
WE ARE CURRENTLY ADDING THE WESTERN MAGIC VALLEY TO OUR LIST OF
DENSE FOG ADVISORIES. FOG HAS SLIGHTLY LIFTED TO A LOW OVERCAST AT
ONTARIO...AND IN GENERAL THE FOG IS NOT AS DENSE IN THE TREASURE
VALLEY AS IT WAS YESTERDAY MORNING. BUT THE MAIN WEATHER WORD FOR
THE NEXT 3-5 DAYS IS PERSISTENCE...WITH AREAS OF VALLEY FOG AND
STRATUS AND LITTLE DAY TO DAY TEMPERATURE CHANGE. AT THIS TIME WE
INTEND TO CONTINUE CURRENT DENSE FOG ADVISORIES UNTIL THEIR NOON
EXPIRATIONS. AWAY FROM THE FOGGY AREAS THE WEATHER WILL BE SUNNY
BRIGHT AND WARM THE NEXT FEW DAYS...ESPECIALLY WHERE THERE IS NO
SNOW COVER. ROME/OR ...FOR EXAMPLE...REACHED 58F YESTERDAY AND WE
ARE FORECASTING 56F FOR TODAY AND 54F FOR THURSDAY. AS TO WHEN THE
CURRENT PATTERN WILL END...GFS AND ECM POINT TO NEXT TUESDAY. LATEST
PROGS PUSH OUR PERSISTENT UPPER RIDGE INLAND THIS WEEKEND AND ALL
THE WAY TO THE WESTERN PLAINS STATES BY TUESDAY ALLOWING AN UPPER
TROUGH TO MOVE IN FROM THE NORTHERN GULF OF ALASKA...WITH A NEW
UPPER RIDGE FORMING FURTHER OUT IN THE PACIFIC. IF THIS HAPPENS...
AND THE IDEA WAS ALSO PROGGED YESTERDAY...OUR AREA WILL BECOME
COLDER ALOFT WHICH WILL OVERTURN AND VENT THE SURFACE INVERSION.
NO HELP UNTIL THEN.
&&
.AVIATION...VLIFR-IFR FOG AND LOW STRATUS IS PERSISTING THROUGH THE
SNAKE RIVER PLAIN THROUGH THE TREASURE VALLEY STRETCHING INTO THE
VALLEYS OF BAKER COUNTY AS WELL AS THROUGH THE LONG VALLEY OF IDAHO.
THERE WILL BE SOME IMPROVEMENT IN THESE AREAS FROM 18Z-23Z TO
LIFR-MVFR...BUT CONDITIONS ARE EXPECTED TO ONCE AGAIN DROP THIS
AFTERNOON REMAINING LIFR-VLIFR OVERNIGHT. THE REST OF SE OREGON AND
SW IDAHO...AND AREAS ABOVE 5000 FT...WILL REMAIN VFR OTHER THAN
SHELTERED MOUNTAIN VALLEYS. SURFACE WINDS WILL BE LIGHT WITH
MODERATE NW WINDS ALOFT.
&&
.PREV DISCUSSION...
SHORT TERM...GOING WITH A PERSISTENCE FORECAST TODAY AND THURSDAY AS
SYNOPTIC PATTERN HAS BECOME BLOCKED ACROSS CONUS. A LARGE HIGH
AMPLITUDE RIDGE IS LOCKED IN OVER THE WEST AND A DEEP COLD LONG WAVE
TROF OVER THE EAST. THIS PATTERN DOES NOT CHANGE THROUGH THIS WEEK.
LATEST SATELLITE FOG IMAGES SHOW A SOLID STRATUS AND FOG DECK
BEGINNING TO COMPLETELY FILL THE SNAKE RIVER BASIN FROM WEST TO
EAST...A COMMON PHENOMENON DURING THIS PATTERN. CURRENT DENSE FOG
ADVISORY FOR THE TREASURE VALLEY OF SOUTHWEST IDAHO AND EASTERN
OREGON IN EFFECT UNTIL NOON MST. THIS ADVISORY LOOKS ON TRACK AND
WILL CONTINUE WITH MOST OBSERVATION SITES REPORTING DENSE FOG AND
VSBY BELOW ONE QUARTER MILE AT 230 AM MST. TEMPERATURE FORECASTS ARE
SUBJECT TO WIDE RANGES AND VARIATIONS WITH A DEEP INVERSION OVER
THE AREA. THUS...SNAKE RIVER BASIN WILL BE THE COLDEST WHILE THE
HIGHLANDS OF SOUTHEAST OREGON THE MILDEST. A RECORD HIGH WAS REACHED
AT ROME OREGON YESTERDAY AND IT COULD FALL AGAIN TODAY. THERE WILL
BE MORE THAN 20 DEGREES DIFFERENCE IN HIGH TEMPERATURES TODAY FROM
SOUTHEAST OREGON TO THE TREASURE VALLEY...VERY MUCH LIKE YESTERDAY.
LIGHT SURFACE WINDS WILL PERSIST THROUGH THE FORECAST AREA.
LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...NO SIGNIFICANT CHANGE
IN THE EXTENDED PERIOD AS ALL MODELS CONTINUE THE RIDGE OVER THE
WEST COAST BY THE END OF THE WEEK. MODELS ALSO KEEP THE TREND OF
PUSHING IT OVER THE IDAHO PANHANDLE BY SAT/SUNDAY. SO DONT SEE ANY
REASON TO ALTER THE CURRENT FORECAST WITH WIDESPREAD MORNING FOG IN
THE FOG PRONE AREAS WITH SLIGHTLY IMPROVING CONDITIONS IN THE DAY.
OUTSIDE OF THE FOG...TEMPERATURES ARE EXPECTED TO BE VERY NICE AND
IN SOME PLACES VERY WARM FOR THIS TIME OF YEAR. AREEE WITH DAYSHIFT
FORECASTER THAT WE COULD SEE THE RIDGE BREAK DOWN BY TUESDAY BUT THE
SYSTEM THE MODELS ARE PROGGING TO COME IN LOOKS WEAK AND COULD SPLIT
AS IT HITS THE COAST. SO LOW CONFIDENCE IN THIS FEATURE AT THIS TIME.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...DENSE FOG ADVISORY UNTIL NOON MST TODAY FOR IDZ011-IDZ012-
IDZ014-IDZ016.
OR...DENSE FOG ADVISORY UNTIL NOON MST /11 AM PST/ TODAY FOR
ORZ062-ORZ063-ORZ064.
&&
$$
WEATHER.GOV/BOISE
DISCUSSION...LC
AVIATION.....DF
PREV SHORT TERM...GS
PREV LONG TERM....CR
000
FXUS65 KPIH 141239
AFDPIH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
539 AM MST WED JAN 14 2009
.UPDATE...FOG HAS SPREAD AND THICKENED. WILL BE ISSUING DENSE FOG
ADVISORY FOR SNAKE RIVER PLAIN ZONES. MESSICK
&&
.PREV DISCUSSION... /ISSUED 245 AM MST WED JAN 14 2009/
SHORT TERM...TODAY THROUGH FRI NIGHT. LAST CHANCE FOR SOME
PRECIPITATION IN THE EXTREME NORTHEAST CORNER OF THE FORECAST AREA.
UPPER LEVEL RIDGE COMING FROM PACIFIC WILL BEGIN DOMINATION OF
EASTERN IDAHO WEATHER THAT LOOKS TO LAST AT LEAST THROUGH THE
WEEKEND. SUBSIDENCE WILL ADD TO THE RADIATIONAL COOLING AND CREATE
SOME STRONG INVERSIONS. THUS FOG AND STRATUS WILL CONTINUE TO WREAK
HAVOC WITH LATE NIGHT AND EARLY MORNING HOURS...SOMETIMES LINGERING
INTO THE AFTERNOON. BOUNDARY LAYER MOISTURE PROGS INDICATE THAT
TONIGHT AND THU NIGHT SHOULD BE WORSE THAN FRI NIGHT FOR A GENERAL
TREND. ONLY THE CENTRAL IDAHO MOUNTAINS SEEM TO STAY OUT OF THE
ST/FG. UNDER THE STRATUS AND FOG...WEAK TEMPERATURE SWINGS FROM LOW
TO HIGH. LOW TEMPERATURES APPEAR TO FINALLY DROP INTO THE TEENS THU
NIGHT AS CIRRUS STOPS CROSSING THROUGH OVERNIGHT. WINDS FINALLY HAVE
DROPPED OFF AND SHOULD REMAIN INSIGNIFICANT FOR THE ENTIRE NEAR TERM
PERIOD...EXCEPT THAT LIGHT WIND AIDS FOG DEVELOPMENT. MESSICK
LONG TERM...SUNDAY THROUGH WEDNESDAY. UPPER LEVEL RIDGE WILL
TRANSITION INTO A REX BLOCK PATTERN OVER THE REGION THROUGH THE
EXTENDED. DRY CONDITIONS ARE EXPECTED TO PREVAIL IN THE EXTENDED.
TEMPERATURES WILL CONTINUE TO BE SLIGHTLY ABOVE NORMAL THROUGH THIS
TIME.
AVIATION...HIGH PRESSURE EXPECTED TO PRODUCE LIGHT WINDS TODAY. LOW
STRATUS AND FOG IS EXPECTED TO BE A PROBLEM THIS MORNING FOR THE
UPPER SNAKE VALLEY DOWN TO NEAR POCATELLO. THIS FOG/STRATUS SHOULD
LIFT FOR THE AFTERNOON BUT IS EXPECTED TO REDEVELOP TONIGHT.
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
FREEZING FOG ADVISORY UNTIL NOON MST TODAY FOR IDZ020-021.
&&
$$
000
FXUS65 KBOI 140953
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
250 AM MST WED JAN 14 2009
.SHORT TERM...GOING WITH A PERSISTENCE FORECAST TODAY AND THURSDAY
AS SYNOPTIC PATTERN HAS BECOME BLOCKED ACROSS CONUS. A LARGE HIGH
AMPLITUDE RIDGE IS LOCKED IN OVER THE WEST AND A DEEP COLD LONG WAVE
TROF OVER THE EAST. THIS PATTERN DOES NOT CHANGE THROUGH THIS WEEK.
LATEST SATELLITE FOG IMAGES SHOW A SOLID STRATUS AND FOG DECK
BEGINNING TO COMPLETELY FILL THE SNAKE RIVER BASIN FROM WEST TO
EAST...A COMMON PHENOMENA DURING THIS PATTERN. CURRENT DENSE FOG
ADVISORY FOR THE TREASURE VALLEY OF SOUTHWEST IDAHO AND EASTERN
OREGON IN EFFECT UNTIL 12 NOON. THIS ADVISORY LOOKS ON TRACK AND
WILL CONTINUE WITH MOST OBSERVATION SITES REPORTING DENSE FOG AND
VSBY BELOW ONE QUARTER MILE AT 0230 AM MST. TEMPERATURE FORECASTS
ARE SUBJECT TO WIDE RANGES AND VARIATIONS WITH A DEEP INVERSION OVER
THE AREA. THUS...SNAKE RIVER BASIN WILL BE THE COLDEST WHILE THE
HIGHLANDS OF SOUTHEAST OREGON THE MILDEST. A RECORD HIGH REACHED AT
ROME OREGON YESTERDAY AND IT COULD FALL AGAIN TODAY. THERE WILL BE
MORE THAN 20 DEGREES DIFFERENCE IN HIGH TEMPERATURES TODAY FROM
SOUTHEAST OREGON TO THE TREASURE VALLEY...VERY MUCH LIKE YESTERDAY.
LIGHT SURFACE WINDS WILL PERSIST THROUGH THE FORECAST
AREA.
.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...NO SIGNIFICANT CHANGE
IN THE EXTENDED PERIOD AS ALL MODELS CONTINUE THE RIDGE OVER THE
WEST COAST BY THE END OF THE WEEK. MODELS ALSO KEEP THE TREND OF
PUSHING IT OVER THE IDAHO PANHANDLE BY SAT/SUNDAY. SO DONT SEE ANY
REASON TO ALTER THE CURRENT FORECAST WITH WIDESPREAD MORNING FOG IN
THE FOG PRONE AREAS WITH SLIGHTLY IMPROVING CONDITIONS IN THE DAY.
OUTSIDE OF THE FOG...TEMPERATURES ARE EXPECTED TO BE VERY NICE AND
IN SOME PLACES VERY WARM FOR THIS TIME OF YEAR. AREEE WITH DAYSHIFT
FORECASTER THAT WE COULD SEE THE RIDGE BREAK DOWN BY TUESDAY BUT THE
SYSTEM THE MODELS ARE PROGGING TO COME IN LOOKS WEAK AND COULD SPLIT
AS IT HITS THE COAST. SO LOW CONFIDENCE IN THIS FEATURE AT THIS
TIME.
&&
.AVIATION...NO CHANGE TO CURRENT FORECAST WITH LOCATIONS IN THE
UPPER AND LOWER TREASURE AND MAGIC VALLEY SEEING DENSE FOG ALONG
WITH THE LOWER MOUNTAIN VALLEYS. SLIGHT IMPROVEMENT IS EXPECTED
AROUND 20Z IN THE UPPER TREASURE VALLEY...OTHERWISE DENSE FOG IS
EXPECTED THROUGH THE FORECAST PERIOD. ABOVE THE INVERSION VFR
CONDITIONS WILL CONTINUE. ABOVE THE VALLEY INVERSIONS...FREEZING
LEVELS ARE PROGGED TO BE BETWEEN 9 AND 10,000 FEET THROUGH THIS
EVENING. LIGHT WINDS STILL EXPECTED.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...DENSE FOG ADVISORY UNTIL 12 PM MST WEDNESDAY FOR IDZ011-IDZ012-
IDZ014.
OR...DENSE FOG ADVISORY UNTIL 12 PM MST /11 AM PST/ WEDNESDAY FOR
ORZ062-ORZ063-ORZ064.
&&
$$
WEATHER.GOV/BOISE
SHORT TERM...GS
LONG TERM....CR
AVIATION.....CR
000
FXUS65 KPIH 140944
AFDPIH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
245 AM MST WED JAN 14 2009
.SHORT TERM...TODAY THROUGH FRI NIGHT. LAST CHANCE FOR SOME
PRECIPITATION IN THE EXTREME NORTHEAST CORNER OF THE FORECAST AREA.
UPPER LEVEL RIDGE COMING FROM PACIFIC WILL BEGIN DOMINATION OF
EASTERN IDAHO WEATHER THAT LOOKS TO LAST AT LEAST THROUGH THE
WEEKEND. SUBSIDENCE WILL ADD TO THE RADIATIONAL COOLING AND CREATE
SOME STRONG INVERSIONS. THUS FOG AND STRATUS WILL CONTINUE TO WREAK
HAVOC WITH LATE NIGHT AND EARLY MORNING HOURS...SOMETIMES LINGERING
INTO THE AFTERNOON. BOUNDARY LAYER MOISTURE PROGS INDICATE THAT
TONIGHT AND THU NIGHT SHOULD BE WORSE THAN FRI NIGHT FOR A GENERAL
TREND. ONLY THE CENTRAL IDAHO MOUNTAINS SEEM TO STAY OUT OF THE
ST/FG. UNDER THE STRATUS AND FOG...WEAK TEMPERATURE SWINGS FROM LOW
TO HIGH. LOW TEMPERATURES APPEAR TO FINALLY DROP INTO THE TEENS THU
NIGHT AS CIRRUS STOPS CROSSING THROUGH OVERNIGHT. WINDS FINALLY HAVE
DROPPED OFF AND SHOULD REMAIN INSIGNIFICANT FOR THE ENTIRE NEAR TERM
PERIOD...EXCEPT THAT LIGHT WIND AIDS FOG DEVELOPMENT. MESSICK
&&
.LONG TERM...SUNDAY THROUGH WEDNESDAY. UPPER LEVEL RIDGE WILL
TRANSITION INTO A REX BLOCK PATTERN OVER THE REGION THROUGH THE
EXTENDED. DRY CONDITIONS ARE EXPECTED TO PREVAIL IN THE EXTENDED.
TEMPERATURES WILL CONTINUE TO BE SLIGHTLY ABOVE NORMAL THROUGH THIS
TIME.
&&
AVIATION...HIGH PRESSURE EXPECTED TO PRODUCE LIGHT WINDS TODAY. LOW
STRATUS AND FOG IS EXPECTED TO BE A PROBLEM THIS MORNING FOR THE
UPPER SNAKE VALLEY DOWN TO NEAR POCATELLO. THIS FOG/STRATUS SHOULD
LIFT FOR THE AFTERNOON BUT IS EXPECTED TO REDEVELOP TONIGHT.
&&
.PIH WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
000
FXUS65 KBOI 140309
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
809 PM MST TUE JAN 13 2009
.DISCUSSION...DID AN EARLY UPDATE TO ADD OREGON ZONE 62 AND
63...BAKER AND MALHEUR COUNTIES...AND IDAHO ZONE 11...THE WEST
CENTRAL MOUNTAINS...TO THE DENSE FOG ADVISORY. WILL NOT MAKE ANY
OTHER CHANGES AT THIS TIME...BUT WILL REVISIT LOW TEMPS AND AREAL
COVERAGE OF FOG LATER THIS EVENING TO SEE IF FURTHER UPDATES ARE
NEEDED. AT THIS TIME...ALL OTHER ASPECTS OF PREVIOUS FORECAST ARE
ON TRACK.
&&
.AVIATION...AREAS OF VLIFR WILL CONTINUE THROUGH WEDNESDAY MORNING
AS DENSE FOG PERSISTS THROUGHOUT VALLEYS OF SE OREGON AND SW IDAHO.
AT 03Z...KBOI/KBKE/KEUL/KMYL ALL REPORTING LIFR/VLIFR VISIBILITIES -
WITH KMUO VISIBILITY SLOWLY DETERIORATING AS FOG SPREADS EASTWARD.
THESE SITES EXPECTED TO REMAIN LIFR THROUGH WEDNESDAY MORNING. KBOI
COULD SEE BREAKS TO MVFR WEDNESDAY AFTERNOON...BUT LITTLE TO NO
IMPROVEMENT IS ANTICIPATED THROUGHOUT THE LOWER TREASURE VALLEY.
LIGHT SURFACE WINDS. LIGHT NORTHWESTERLY WINDS ALOFT.
&&
.PREV DISCUSSION...
SHORT TERM...DENSE FOG IN THE VALLEYS HAS NOW BECOME THE MAIN
FORECAST CONCERN. FOG SPREAD UP THE TREASURE VALLEY TO BOISE
LATE THIS MORNING. VISIBILITY IMPROVED IN THE LOWER TREASURE VALLEY
THIS AFTERNOON BUT A PATCH OF DENSE FOG CONTINUED FROM WEST BOISE
THROUGH MERIDIAN AND EAGLE. WE NOTICE THAT DEW POINTS INCREASED
DURING THE DAY WHICH WILL BE FAVORABLE FOR MORE DENSE FOG TONIGHT
AND WEDNESDAY MORNING IN THE TREASURE VALLEY FROM BOISE WEST.
WE ALSO EXPECT AREAS OF DENSE FOG IN THE LONG VALLEY THROUGH MCCALL
AND NEAR BAKER IN OREGON. NEW DENSE FOG ADVISORIES WILL BE ISSUED
WITH THIS FORECAST PACKAGE FOR TONIGHT AND WEDNESDAY MORNING. IN
FACT...A REPEAT IS LIKELY FOR WEDNESDAY NIGHT AND THURSDAY MORNING.
MEANWHILE...WE SEE THAT ROME OREGON HAS WARMED TO 56F WHILE THE
TREASURE VALLEY REMAINS IN THE 30S. THIS DRAMATICALLY ILLUSTRATES
THE STRENGTH OF THE INVERSION IN THE TREASURE VALLEY. ON THE LARGER
SCALE...OUR CWA CONTINUES TO BE DOMINATED BY STRONG HIGH PRESSURE
ALOFT CENTERED ALONG THE COAST ...WHICH WILL INCH ITS WAY INLAND
THROUGH THURSDAY. LITTLE DAY TO DAY CHANGE IN THE WEATHER IN OUR
ZONES IS EXPECTED THROUGH THURSDAY.
LONG TERM...THURSDAY NIGHT THROUGH TUESDAY...LITTLE CHANGE TO THE
FORECAST IN THE EXTENDED AS HIGH PRESSURE AND ACCOMPANYING INVERSION
WILL KEEP FOG AND COOLER TEMPS IN THE LOWER VALLEYS WITH MOSTLY
CLEAR SKIES AND DRY AND MILD CONDITIONS IN THE MOUNTAINS. DAY-TO-DAY
DETAILS OF FOG AND OR STRATUS AND COOLER TEMPS STILL HARD TO PIN
DOWN IN THIS PERIOD AS GRADUAL ENTRAINMENT OF DRY AIR ALOFT AND
DIURNAL SURFACE WINDS WILL PLAY INTO THE EVOLUTION OF THE
FOG/STRATUS LAYER. HAVE CONTINUED TREND OF KEEPING FOG/STRATUS
ENTRENCHED IN THE LOWER TREASURE VALLEY THROUGH MONDAY WITH UPPER
TREASURE AND WESTERN MAGIC BREAKING OUT DURING THE AFTERNOONS.
OPERATIONAL MODELS HINTING AT BREAKING DOWN THE RIDGE BY THE MIDDLE
OF NEXT WEEK...THOUGH A WIDE SPREAD AMONG ENSEMBLE SOLUTIONS MAKES
THAT A LOW CONFIDENCE FORECAST.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...DENSE FOG ADVISORY UNTIL 12 PM MST WEDNESDAY FOR IDZ011-IDZ012-
IDZ014.
OR...DENSE FOG ADVISORY UNTIL 12 PM MST /11 AM PST/ WEDNESDAY FOR
ORZ062-ORZ063-ORZ064.
&&
$$
WEATHER.GOV/BOISE
DISCUSSION...SP
AVIATION.....MT
PREV PREV SHORT TERM...GS
PREV PREV LONG TERM....CR
000
FXUS65 KBOI 132212
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
312 PM MST TUE JAN 13 2009
.SHORT TERM...DENSE FOG IN THE VALLEYS HAS NOW BECOME THE MAIN
FORECAST CONCERN. FOG SPREAD UP THE TREASURE VALLEY TO BOISE
LATE THIS MORNING. VISIBILITY IMPROVED IN THE LOWER TREASURE VALLEY
THIS AFTERNOON BUT A PATCH OF DENSE FOG CONTINUED FROM WEST BOISE
THROUGH MERIDAN AND EAGLE. WE NOTICE THAT DEW POINTS INCREASED
DURING THE DAY WHICH WILL BE FAVORABLE FOR MORE DENSE FOG TONIGHT
AND WEDNESDAY MORNING IN THE TREASURE VALLEY FROM BOISE WEST.
WE ALSO EXPECT AREAS OF DENSE FOG IN THE LONG VALLEY THROUGH MCCALL
AND NEAR BAKER IN OREGON. NEW DENSE FOG ADVISORIES WILL BE ISSUED
WITH THIS FORECAST PACKAGE FOR TONIGHT AND WEDNESDAY MORNING. IN
FACT...A REPEAT IS LIKELY FOR WEDNESDAY NIGHT AND THURSDAY MORNING.
MEANWHILE...WE SEE THAT ROME OREGON HAS WARMED TO 56F WHILE THE
TREASURE VALLEY REMAINS IN THE 30S. THIS DRAMATICALLY ILLUSTRATES
THE STRENGTH OF THE INVERSION IN THE TREASURE VALLEY. ON THE LARGER
SCALE...OUR CWA CONTINUES TO BE DOMINATED BY STRONG HIGH PRESSURE
ALOFT CENTERED ALONG THE COAST ...WHICH WILL INCH ITS WAY INLAND
THROUGH THURSDAY. LITTLE DAY TO DAY CHANGE IN THE WEATHER IN OUR
ZONES IS EXPECTED THROUGH THURSDAY.
.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY...LITTLE CHANGE TO THE
FORECAST IN THE EXTENDED AS HIGH PRESSURE AND ACCOMPANYING INVERSION
WILL KEEP FOG AND COOLER TEMPS IN THE LOWER VALLEYS WITH MOSTLY
CLEAR SKIES AND DRY AND MILD CONDITIONS IN THE MOUNTAINS. DAY-TO-DAY
DETAILS OF FOG AND OR STRATUS AND COOLER TEMPS STILL HARD TO PIN
DOWN IN THIS PERIOD AS GRADUAL ENTRAINMENT OF DRY AIR ALOFT AND
DIURNAL SURFACE WINDS WILL PLAY INTO THE EVOLUTION OF THE
FOG/STRATUS LAYER. HAVE CONTINUED TREND OF KEEPING FOG/STRATUS
ENTRENCHED IN THE LOWER TREASURE VALLEY THROUGH MONDAY WITH UPPER
TREASURE AND WESTERN MAGIC BREAKING OUT DURING THE AFTERNOONS.
OPERATIONAL MODELS HINTING AT BREAKING DOWN THE RIDGE BY THE MIDDLE
OF NEXT WEEK...THOUGH A WIDE SPREAD AMONG ENSEMBLE SOLUTIONS MAKES
THAT A LOW CONFIDENCE FORECAST.
&&
.AVIATION...KBOI RIGHT ON BOUNDARY OF FOG TODAY...MAKING FOR
DIFFICULT FORECAST. BELOW MINIMUM CONDITIONS WILL PERSIST AT THE
TERMINAL THROUGH WEDNESDAY MORNING. DON/T HAVE A CONFIDENT FORECAST
ON WHEN TERMINAL WILL CLIMB BACK ABOVE MINS FOR A PROLONGED
PERIOD...THOUGH BEST GUESS WOULD BE TOMORROW AFTERNOON BETWEEN 20Z
AND 00Z.
FOR THE REST OF SW IDAHO AND SE OREGON MTN VALLEYS THAT HAVE
IMPROVED TO VFR WILL SEE RETURN OF IFR CONDITIONS IN FOG THIS
EVENING AROUND SUNSET. EXPECT THIS PATTERN TO CONTINUE THROUGH THE
WEEK.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...DENSE FOG ADVISORY FROM 6 PM MST TONIGHT TO NOON MST WEDNESDAY
FOR IDZ012-IDZ014.
OR...DENSE FOG ADVISORY FROM 6 PM MST TONIGHT TO NOON MST WEDNESDAY
FOR ORZ064.
&&
$$
WEATHER.GOV/BOISE
DISCUSSION...LC
AVIATION.....DG
PREV SHORT TERM...GS
PREV LONG TERM....CR
000
FXUS65 KPIH 132113
AFDPIH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
200 PM MST TUE JAN 13 2009
.SHORT TERM...TONIGHT THROUGH FRIDAY. LATEST SATELLITE IMAGERY
SHOWING UPPER RIDGE ANCHORED OFF THE NRN CALIFORNIA COAST THIS
AFTERNOON WHILE A SHORT-WAVE FEATURE WAS SHEARING RAPIDLY SE THROUGH
SRN SASKATCHEWAN. LITTLE IMPACT EXPECTED FROM THE PASSING WAVE AS IT
WORKS FURTHER EAST WITH TIME. PAC MOISTURE ARCHING OVER RIDGE
THINNING OUT ACROSS THE ERN PAC AND AS RIDGE CONTINUES TO AMPLIFY
EXPECT MID TO UPPER CLOUD COVER TO DECREASE TONIGHT/WEDNESDAY. THUS
OVERRIDING THEME FOR THIS FORECAST CYCLE IS AREA OF STRATUS
CURRENTLY INHABITING SNAKE RIVER PLAIN. TYPICAL SCENARIO IS THAT
THIS AREA OF LOW CLOUDS WILL REMAIN ENTRENCHED ACROSS THE PLAIN
UNTIL A DESICCATING 850-700MB NE FLOW SETS UP ALONG THE DIVIDE. THIS
IS NOT EXPECTED TO OCCUR UNTIL SATURDAY PER THE GFS AND IT IS
SHORT-LIVED AT THAT. SURFACE HIGH BUILDS INTO ISLAND PARK REGION
WEDNESDAY AND THIS MAY PROVIDE ENOUGH OF A GRADIENT TO MODIFY THE
LOWER LEVEL AIRMASS. THUS HAVE SPLIT THE DIFFERENCE AND MAINTAINED
SOME STRATUS WITHIN THE PLAIN THROUGH THURSDAY AND THEN HAVE BEGUN
TO CHIP AWAY AT THE CLOUD COVER THURSDAY NIGHT/FRIDAY. CLOUD COVER
WILL HAVE A SIGNIFICANT IMPACT ON OVERNIGHT LOWS AND DAYTIME HIGHS.
GENERALLY TRYING TO WARM THE MOUNTAINS GRADUALLY WHILE MAINTAINING
COOLISH TEMPS ACROSS THE PLAIN UNTIL CLOUDS BEGIN TO BREAK. HUSTON
&&
.LONG TERM...SATURDAY THROUGH TUESDAY. A STRONG HIGH PRESSURE SYSTEM
WILL MOVE INTO SOUTHEAST IDAHO. STRONG SUBSIDENCE AND LOW-LEVEL
MOISTURE WILL CREATE MORNING FOG IN THE LOWER VALLEYS SATURDAY AND
SUNDAY. FOG WILL DISSIPATE BY MID-MORNING LEADING TO MOSTLY SUNNY
SKIES. EXPECT WARMER THAN NORMAL TEMPERATURES THROUGHOUT THE
PERIOD. BY TUESDAY PARTLY TO MOSTLY CLOUDY CONDITIONS AND A SLIGHT
CHANCE OF SNOW WILL MOVE INTO THE CENTRAL MOUNTAINS AND THE EASTERN
HIGHLANDS. THIS WILL PRECEDE THE NEXT WINTER SYSTEM. TW
&&
AVIATION...STRATUS TRAPPED WITHIN THE SNAKE PLAIN HAS PRODUCED
IFR/LIFR CEILINGS AT KRXE/KIDA TRENDING DRIER FROM KPIH TO KBYI.
EXPECT THESE CONDITIONS TO CONTINUE OVER THE NEXT 48 HRS.
MODELS ARE INDICATING A WIND SHIFT WITH A HIGH PRESSURE CENTER
STARTING TO MOVE INTO THE AREA. GUSTY CONDITIONS WILL PERSIST FOR
BURLEY AND POCATELLO UNTIL LATE THIS EVENING. TW/MH
&&
.PIH WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
000
FXUS65 KBOI 131720
AFDBOI
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BOISE ID
1020 AM MST TUE JAN 14 2009
.DISCUSSION...DENSE FOG HAS ADVANCED EAST ACROSS BOISE THIS MORNING.
WE HAVE EXTENDED THE DENSE FOG ADVISORY TO NOON MST IN THE UPPER
TREASURE VALLEY AND TO 3 PM MST IN THE LOWER TREASURE VALLEY. IN
ADDITION...WE HAVE LOWERED TODAY/S MAX TEMPERATURE FORECAST IN THE
FOGGY AREAS. FORECAST UPDATES AVAILABLE BY 1030 AM MST.
&&
.PREV DISCUSSION...
DENSE FOG IN THE TREASURE VALLEY SPREAD AS FAR EAST AS BOISE EARLY
THIS MORNING AND OUR DENSE FOG ADVISORY WAS EXPANDED TO INCLUDE THAT
PART OF THE UPPER TREASURE VALLEY...UNTIL 10 AM MST. FURTHER EAST
SKIES WILL BE MOSTLY SUNNY TODAY. LATEST FORECAST MODEL SOUNDINGS
DISAGREE AS TO WHETHER FOG WILL RE-FORM WEDNESDAY IN THE UPPER
TREASURE VALLEY...NAM SAYS IT DEFINITELY WILL...GFS SAYS DEFINITELY
NOT. FOR NOW WE SAY THAT IT WILL RE-FORM BUT WE WILL EXAMINE THIS
IN MORE DETAIL FOR AFTERNOON PACKAGE. MEANWHILE...ON THE LARGER
SCALE...OUR CWA WILL REMAIN UNDER THE INFLUENCE OF STRONG UPPER
RIDGE ALONG THE COAST THROUGH THE WEEK... WITH LITTLE DAY TO DAY
CHANGE ASIDE FROM FOG ISSUES. BUT GFS IS SHOWING SIGNS OF A PATTERN
CHANGE NEXT WEEK FROM UPPER RIDGING TO TROUGHING...WHICH COULD
RESULT IN STORMIER WEATHER. NO FORECAST CHANGES FOR NOW.
&&
.AVIATION...VLIFR CONDITIONS IN FOG HAVE SET UP OVER THE LOWER
TREASURE VALLEY TO JUST WEST OF KBOI AT SUNRISE THIS MORNING. THIS
INCLUDES KEUL AND KONO. FOR KEUL/KONO THERE IS A SLIGHT CHANCE THIS
AFTERNOON THAT THESE SITES COULD IMPROVE TO MVFR CONDITIONS BETWEEN
19Z AND 23Z. AT THIS POINT THINKING IFR-VLIFR CONDITIONS ARE LIKELY
/60 PERCENT CHANCE/ TO DEVELOP THIS EVENING AT KBOI BETWEEN 00Z AND
03Z. WILL REEVALUATE FOR 18Z TAF AND MAKE FORECAST AMENDMENTS AS
CONFIDENCE IN FORECAST INCREASES.
FOR THE REST OF SW IDAHO AND SE OREGON IFR CONDITIONS IN MTN VALLEY
FOG WILL IMPROVE TO MVFR-VFR THIS AFTERNOON WITH FOG REDEVELOPING
AFTER SUNSET THIS EVENING. EXPECT THIS PATTERN TO CONTINUE THROUGH
THE WEEK.
&&
.PREV DISCUSSION...
SHORT TERM...SYNOPTIC PATTERN ACROSS CONUS CONTINUES TO BE HIGH
AMPLITUDE WITH INTENSE UPPER RIDGE ALONG THE WEST COAST AND DEEP
TROF OVER THE EAST. THIS PATTERN TO CONTINUE FOR THE FORESEEABLE
FUTURE. FOR TODAY ACROSS OUR AREA...THERE IS ENOUGH NORTHWEST FLOW
ALOFT OVER IDAHO TO PREVENT CONDITIONS FROM DETERIORATING OVER A
WIDESPREAD AREA. THERE IS HOWEVER...MORE FOG AND LOWER VISIBILITY
BEING REPORTED OVER VARIOUS OBSERVATION SITES THAN THERE HAS BEEN IN
RECENT NIGHTS. BELIEVE THIS IS DUE TO SKIES CLEARING AND RADIATIONAL
FOG DEVELOPING OVER THE SNOWPACK OF THE MOUNTAIN VALLEYS TO THE
NORTH OF THE SNAKE RIVER VALLEY. WE ARE FORECASTING ONE MORE DAY OF
MILD TEMPERATURES DURING THIS STRETCH BEFORE TEMPERATURES FALL AND
WIDESPREAD INVERSION CONDITIONS SET UP. THIS WORSENING CONDITION
SHOULD HAPPEN WEDNESDAY WITH THE WEST COAST RIDGE AXIS NUDGING
EASTWARD ALONG THE CASCADES AND THE NORTHWEST FLOW ALOFT WEAKENING.
THIS POSITIONING OF FEATURES WILL CAUSE COLD AIR TO GET TRAPPED IN
THE LOWER VALLEYS AS WARMER AIR MOVES OVER THE TOP. ALL INDICATIONS
ARE THAT THIS WILL BE THE BEGINNING OF A PROLONGED INVERSION EPISODE
WITH POOR QUALITY IN TIME. HAVE TRENDED TEMPERATURES DOWN
SIGNIFICANTLY STARTING WEDNESDAY AS THIS CONDITION EVOLVES AND
DEEPENS. MUCH LIGHTER WINDS EXPECTED TODAY IN THE MAGIC VALLEY AS
SURFACE LOW PRESSURE OVER THE ROCKIES PULLS EAST AND OVERALL
GRADIENT ACROSS THE SNAKE VALLEY SLACKENS.
LONG TERM...THURSDAY NIGHT THROUGH TUESDAY...MODELS CONTINUE TO BE
IN GOOD AGREEMENT WITH WEST COAST RIDGE REMAINING OVER THE REGION
THROUGH TUESDAY. MAIN CONCERN FOR THE EXTENDED PERIOD REMAINS THE
EXTENT OF FOG ACROSS THE REGION WITH INVERTED CONDITIONS. THINK AT
LEAST THE LOWER TREASURE VALLEY AND LOWER VALLEYS IN BAKER COUNTY
WILL SEE THE BEST CHANCES OF THICKER FOG ALONG WITH THE LONG VALLEY.
PATCHY FOG IS A POSSIBILITY AS YOU MAKE YOUR WAY EASTWARD IN THE
UPPER TREASURE AND MAGIC VALLEY WITH THE EXCEPTION OF THE SNAKE
RIVER AREA. 700 MB TEMPS DRASTICALLY WARM BY FRIDAY MORNING GOING
FROM AROUND 0C FORECAST TODAY TO A +4C BY FRIDAY MORNING. SHOULD SEE
SOME AWESOME CONDITIONS IN THE MOUNTAINS WITH COOLER TEMPS HERE IN
THE LOWER VALLEYS.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...NONE.
&&
$$
WEATHER.GOV/BOISE
DISCUSSION...LC
AVIATION.....DG
PREV SHORT TERM...GS
PREV LONG TERM....CR
000
FXUS65 KBOI 131604
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
904 AM MST TUE JAN 14 2009
.DISCUSSION...DENSE FOG IN THE TREASURE VALLEY SPREAD AS FAR EAST
AS BOISE EARLY THIS MORNING AND OUR DENSE FOG ADVISORY WAS EXPANDED
TO INCLUDE THAT PART OF THE UPPER TREASURE VALLEY...UNTIL 10 AM
MST. FURTHER EAST SKIES WILL BE MOSTLY SUNNY TODAY. LATEST
FORECAST MODEL SOUNDINGS DISAGREE AS TO WHETHER FOG WILL RE-FORM
WEDNESDAY IN THE UPPER TREASURE VALLEY...NAM SAYS IT DEFINITELY
WILL...GFS SAYS DEFINITELY NOT. FOR NOW WE SAY THAT IT WILL RE-FORM
BUT WE WILL EXAMINE THIS IN MORE DETAIL FOR AFTERNOON PACKAGE.
MEANWHILE...ON THE LARGER SCALE...OUR CWA WILL REMAIN UNDER THE
INFLUENCE OF STRONG UPPER RIDGE ALONG THE COAST THROUGH THE WEEK...
WITH LITTLE DAY TO DAY CHANGE ASIDE FROM FOG ISSUES. BUT GFS IS
SHOWING SIGNS OF A PATTERN CHANGE NEXT WEEK FROM UPPER RIDGING TO
TROUGHING...WHICH COULD RESULT IN STORMIER WEATHER. NO FORECAST
CHANGES FOR NOW.
&&
.AVIATION...VLIFR CONDITIONS IN FOG HAVE SET UP OVER THE LOWER
TREASURE VALLEY TO JUST WEST OF KBOI AT SUNRISE THIS MORNING. THIS
INCLUDES KEUL AND KONO. FOR KEUL/KONO THERE IS A SLIGHT CHANCE THIS
AFTERNOON THAT THESE SITES COULD IMPROVE TO MVFR CONDITIONS BETWEEN
19Z AND 23Z. AT THIS POINT THINKING IFR-VLIFR CONDITIONS ARE LIKELY
/60 PERCENT CHANCE/ TO DEVELOP THIS EVENING AT KBOI BETWEEN 00Z AND
03Z. WILL REEVALUATE FOR 18Z TAF AND MAKE FORECAST AMENDMENTS AS
CONFIDENCE IN FORECAST INCREASES.
FOR THE REST OF SW IDAHO AND SE OREGON IFR CONDITIONS IN MTN VALLEY
FOG WILL IMPROVE TO MVFR-VFR THIS AFTERNOON WITH FOG REDEVELOPING
AFTER SUNSET THIS EVENING. EXPECT THIS PATTERN TO CONTINUE THROUGH
THE WEEK.
&&
.PREV DISCUSSION...
SHORT TERM...SYNOPTIC PATTERN ACROSS CONUS CONTINUES TO BE HIGH
AMPLITUDE WITH INTENSE UPPER RIDGE ALONG THE WEST COAST AND DEEP
TROF OVER THE EAST. THIS PATTERN TO CONTINUE FOR THE FORESEEABLE
FUTURE. FOR TODAY ACROSS OUR AREA...THERE IS ENOUGH NORTHWEST FLOW
ALOFT OVER IDAHO TO PREVENT CONDITIONS FROM DETERIORATING OVER A
WIDESPREAD AREA. THERE IS HOWEVER...MORE FOG AND LOWER VISIBILITY
BEING REPORTED OVER VARIOUS OBSERVATION SITES THAN THERE HAS BEEN IN
RECENT NIGHTS. BELIEVE THIS IS DUE TO SKIES CLEARING AND RADIATIONAL
FOG DEVELOPING OVER THE SNOWPACK OF THE MOUNTAIN VALLEYS TO THE
NORTH OF THE SNAKE RIVER VALLEY. WE ARE FORECASTING ONE MORE DAY OF
MILD TEMPERATURES DURING THIS STRETCH BEFORE TEMPERATURES FALL AND
WIDESPREAD INVERSION CONDITIONS SET UP. THIS WORSENING CONDITION
SHOULD HAPPEN WEDNESDAY WITH THE WEST COAST RIDGE AXIS NUDGING
EASTWARD ALONG THE CASCADES AND THE NORTHWEST FLOW ALOFT WEAKENING.
THIS POSITIONING OF FEATURES WILL CAUSE COLD AIR TO GET TRAPPED IN
THE LOWER VALLEYS AS WARMER AIR MOVES OVER THE TOP. ALL INDICATIONS
ARE THAT THIS WILL BE THE BEGINNING OF A PROLONGED INVERSION EPISODE
WITH POOR QUALITY IN TIME. HAVE TRENDED TEMPERATURES DOWN
SIGNIFICANTLY STARTING WEDNESDAY AS THIS CONDITION EVOLVES AND
DEEPENS. MUCH LIGHTER WINDS EXPECTED TODAY IN THE MAGIC VALLEY AS
SURFACE LOW PRESSURE OVER THE ROCKIES PULLS EAST AND OVERALL
GRADIENT ACROSS THE SNAKE VALLEY SLACKENS.
LONG TERM...THURSDAY NIGHT THROUGH TUESDAY...MODELS CONTINUE TO BE
IN GOOD AGREEMENT WITH WEST COAST RIDGE REMAINING OVER THE REGION
THROUGH TUESDAY. MAIN CONCERN FOR THE EXTENDED PERIOD REMAINS THE
EXTENT OF FOG ACROSS THE REGION WITH INVERTED CONDITIONS. THINK AT
LEAST THE LOWER TREASURE VALLEY AND LOWER VALLEYS IN BAKER COUNTY
WILL SEE THE BEST CHANCES OF THICKER FOG ALONG WITH THE LONG VALLEY.
PATCHY FOG IS A POSSIBILITY AS YOU MAKE YOUR WAY EASTWARD IN THE
UPPER TREASURE AND MAGIC VALLEY WITH THE EXCEPTION OF THE SNAKE
RIVER AREA. 700 MB TEMPS DRASTICALLY WARM BY FRIDAY MORNING GOING
FROM AROUND 0C FORECAST TODAY TO A +4C BY FRIDAY MORNING. SHOULD SEE
SOME AWESOME CONDITIONS IN THE MOUNTAINS WITH COOLER TEMPS HERE IN
THE LOWER VALLEYS.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...NONE.
&&
$$
WEATHER.GOV/BOISE
DISCUSSION...LC
AVIATION.....DG
PREV SHORT TERM...GS
PREV LONG TERM....CR
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