Area Forecast Discussion
Issued by NWS Boise, ID

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000
FXUS65 KBOI 281659
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
959 AM MST SUN DEC 28 2014

.DISCUSSION...COLD FRONT OVER SE IAHO AS OF 9 AM BROUGHT WINDS OF
15 TO 25 MPH TO TWIN FALLS AND POINTS SOUTH TO THE NV BORDER
ACROSS SW IDAHO ALTHOUGH HIGHEST MOUNTAINS /SOLDIER MTN/ HAD
HIGHER GUSTS 35-40 MPH. SNOW REPORTS SINCE YESTERDAY WERE 4-7
INCHES ACROSS THE MOUNTAINS /MCCALL-GARDENA-ROBIE CK-LOWMAN/ AND
MOSTLY AROUND 2 INCHES ACROSS THE TREASURE VALLEY. REPORTS FROM SW TWIN
FALLS WHERE GUSTY WINDS OCCURRED HAD AN INCH AND FROM WEST ADA
THROUGH CANYON COUNTY 1.5 TO 2 INCH REPORTS WERE COMMON.
CONVECTIVE SHOWERS TODAY COULD BE STRONG DUE TO ELEVATED
INSTABILITY OVER THE MOUNTAINS /200 J/KG CAPE/ WITH SMALL ICE
PELLETS AND WINDS TO 25 MPH.

&&

.AVIATION...MOUNTAINS OBSCURED.  WIDELY SCATTERED SNOW SHOWERS WILL
CONTINUE OVER THE AREA TODAY WITH LOCAL MVFR/IFR CONDITIONS THROUGH
THE AFTERNOON...ESPECIALLY OVER THE WEST CENTRAL AND BOISE
MOUNTAINS.  WIDESPREAD MVFR CONDITIONS IN THE VALLEYS OF SOUTHWEST
IDAHO DUE TO LOW STRATUS AND FOG.  REST OF THE REGION WILL SEE LOCAL
VFR CONDITIONS AND MID LEVEL CEILINGS.  SURFACE WINDS TODAY WILL BE
WESTERLY 10-20 KNOTS WITH GUSTS IN THE MAGIC VALLEY NEAR 30 KNOTS.
WINDS ALOFT WILL BE NORTHWESTERLY 30-40 KNOTS UP THROUGH 10K FEET
MSL.

&&

.PREV DISCUSSION...
SHORT TERM...TODAY THROUGH MONDAY...ACCUMULATING SNOW WILL TAPER
OFF THIS MORNING AND COME TO AND END IN MOST AREAS BEFORE NOON.
HOWEVER...ISOLATED SNOW SHOWERS ARE EXPECTED TO LINGER ACROSS THE
AREA THIS AFTERNOON THROUGH MONDAY AS A COLD UPPER LEVEL TROUGH
OVER THE AREA EVOLVES INTO A CLOSED UPPER LEVEL LOW OVER NEVADA.
TEMPERATURES WILL REMAIN 5 TO 10 DEGREES BELOW NORMAL THROUGH
MONDAY AND WILL GET EVEN COLDER LATER IN THE WEEK.

LONG TERM...MONDAY NIGHT THROUGH SUNDAY...SCATTERED SNOW SHOWERS
WILL CONTINUE THROUGH TUESDAY MORNING AS A TROUGH SLOWLY DIGS
SOUTHWESTWARD INTO SOUTHERN CALIFORNIA AND CUTS OFF BY THURSDAY. AS
THIS TROUGH DIGS WESTWARD IT WILL DRAW IN COLDER AIR OF POLAR
ORIGINS FROM THE NORTHEAST. WHILE THE COLDEST AIR STAYS EAST OF THE
CONTINENTAL DIVIDE...TEMPERATURES WILL STILL BE IN THE SINGLE DIGITS
IN THE TREASURE VALLEY WEDNESDAY MORNING...MOUNTAIN VALLEYS COULD BE
APPROACHING -10 TO -20F. THE COLD NORTHEASTERLY FLOW SHUTS OFF BY
WEDNESDAY AFTERNOON LEAVING THE COLD AIR TRAPPED IN THE VALLEYS WITH
TEMPERATURES SLOWLY WARMING ON THE MOUNTAIN TOPS. THE MODELS ERODE
THE COLD AIR IN THE VALLEYS TOO QUICKLY WITH TOO MUCH WARMING...
THUS HAVE BLENDED A PERSISTENCE OF A THE PREVIOUS DAY WITH NEW
GUIDANCE TO KEEP THE COLD AIR IN THE VALLEYS LONGER. THE NEXT SYSTEM
ARRIVES FROM THE NORTH LATE SATURDAY INTO SUNDAY BUT CONFIDENCE IS
LOW AS THE LATEST MODELS ARE TRENDING THE SYSTEM FARTHER NORTH AND
MOVING THE RIDGE FARTHER INLAND ALONG THE WEST COAST.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...WINTER WEATHER ADVISORY UNTIL 11 AM MST THIS MORNING
     IDZ011>016-029-030-033.
OR...WINTER WEATHER ADVISORY UNTIL 10 AM PST THIS MORNING ORZ062.

&&

$$

WEATHER.GOV/BOISE

DISCUSSION...VM
AVIATION.....JA
PREV SHORT TERM...JB
PREV LONG TERM....KA



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