Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 251657
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
957 AM MST THU DEC 25 2014

.DISCUSSION...YESTERDAYS SYSTEM HAS MOVED WELL TO THE
EAST...LEAVING ONLY A LITTLE BIT OF WRAP-AROUND SNOWFALL IN THE
MAGIC VALLEY AND SOUTHERN TWIN FALLS COUNTY. OF MUCH MORE
IMPORTANCE IS THE STRONG WINDS BEHIND THE SYSTEM...WITH SUSTAINED
WINDS ABOVE 30 MPH...AND GUSTS ABOVE 45 MPH...COMMON EAST OF
BOISE. HAVE CANCELLED THE WINTER WEATHER WARNINGS AND
ADVISORIES...BUT WILL CONTINUE THE WIND ADVISORY THROUGH THE
AFTERNOON. WINDS SHOULD DIE DOWN QUICKLY THIS EVENING AS THE UPPER
FLOW SHIFTS TO MORE FROM THE NORTHEAST...AND QUICK DECOUPLING OF
SURFACE WINDS TAKES PLACE WHEN CLEAR SKIES ALLOW INVERSIONS TO
QUICKLY FORM. WILL MAKE SOME SLIGHT UPDATES TO GRIDS TO WARM
TEMPERATURES SLIGHTLY IN THE LOWER TREASURE VALLEY TODAY WHERE
DOWNSLOPE WINDS AND CLEAR SKIES WILL ALLOW TEMPS TO GET A FEW
DEGREES WARMER.
&&

.AVIATION...LIGHT SNOW SHOWERS ACROSS THE MAGIC VALLEY SOUTH TO THE
NEVADA BORDER UNTIL 18Z WITH LOCAL MVFR AND ISOLATED IFR CONDITIONS
IN BLOWING AND DRIFTING SNOW.  OTHERWISE VFR CONDITIONS OVER
SOUTHEAST OREGON AND SOUTHWEST IDAHO WITH MID LEVEL CEILINGS.  WEST
TO NORTHWEST SURFACE WINDS 10-20 KNOTS WITH GUSTS OF 20-25
KNOTS...EXCEPT IN THE MAGIC VALLEY SOUTH TO THE NEVADA BORDER WITH
WESTERLY WINDS OF 25-35 KNOTS WITH GUSTS 34-45 KNOTS THROUGH 00Z.
WINDS ALOFT WILL BE NORTHERLY AROUND 35 KNOTS UP THROUGH 10K FEET
MSL.
&&

.PREV DISCUSSION...
SHORT TERM...TODAY THROUGH FRIDAY...MAJOR SYSTEM THAT BROUGHT
SNOW AND WIND TO THE AREA CHRISTMAS EVE IS STILL BRINGING IT TO
THE SOUTHWEST HIGHLANDS...WESTERN MAGIC VALLEY...AND SRN TWIN
FALLS COUNTY THIS MORNING...AND WINDS ARE STILL STRONG IN THE
UPPER TREASURE VALLEY. THEREFORE... THE WINTER STORM WARNING AND
ADVISORY ARE GOING TO BE ALLOWED TO REMAIN IN EFFECT THROUGH
12Z...AND A WIND ADVISORY HAS BEEN ISSUED FOR THESE 4 ZONES
THROUGH 00Z THIS EVENING. OTHERWISE...SNOW ON THE GROUND IN MOST
LOCATIONS WILL HELP KEEP TEMPS FROM RISING MUCH TODAY. WE WENT
BELOW MODEL GUIDANCE TEMPS THROUGH TOMORROW. WINDS WILL FINALLY
DECREASE SIGNIFICANTLY TONIGHT. FRIDAY WILL BE COLD BUT MUCH LESS
WINDY AND SNOW WILL BE CONFINED TO THE MTNS. INVERSION CONDITIONS
WILL BEGIN TO SET UP IN THE VALLEYS.

LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...A COOLER AND DRY
NORTHERLY FLOW WILL CONTINUE FRIDAY NIGHT THROUGH MID DAY
SATURDAY...AS A RIDGE OFF OF THE COAST CONTINUES TO AMPLIFY NORTH OF
BRITISH COLUMBIA. ANOTHER TROUGH AND ASSOCIATED COLD FRONT WILL MOVE
FROM NORTH TO SOUTH SATURDAY NIGHT THROUGH SUNDAY. THIS SYSTEM STILL
LOOKS TO BE COLD ENOUGH TO PRECIP AS SNOW AT ALL VALLEY FLOORS.
LINGERING MOISTURE AND THE SLOW MOVEMENT OF THIS TROUGH MAY
REINFORCE SNOW SHOWERS ON MONDAY. HOWEVER...A SURFACE HIGH WITH ITS
ORIGIN IN NORTHERN CANADA WILL MOVE SOUTH AND BE LOCATED IN
WESTERN MONTANA BY EARLY TUESDAY MORNING KEEPING CONDITIONS DRY
AND COLD. MODELS HAVE BEEN CONSISTENTLY SHOWING THIS FEATURE...AND
HAVE BEEN TRENDING DEEPER. THE CURRENT GFS RUN HAS A 1056 MB
CENTER. WITH THE LIKELY SCENARIO OF SNOW COVER FROM SUNDAY...A
STRONG INVERSION WILL LIKELY SET UP. TEMPERATURES ARE EXPECTED TO
PLUNGE WELL BELOW NORMAL FOR MONDAY NIGHT THROUGH AT LEAST
WEDNESDAY NIGHT...SO THE CURRENT FORECAST IS BELOW MOST GUIDANCE.
THURSDAY LOOKS TO REMAIN DRY AND COLD AS A NORTHERLY FLOW
CONTINUES.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...WIND ADVISORY UNTIL 5 PM MST THIS AFTERNOON IDZ014>016-030.
OR...NONE.

&&

$$

WEATHER.GOV/BOISE

DISCUSSION...TB
AVIATION.....JA
PREV SHORT TERM...SP
PREV LONG TERM....EP


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