Area Forecast Discussion
Issued by NWS Boise, ID

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000
FXUS65 KBOI 281658
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
958 AM MST FRI NOV 28 2014

.DISCUSSION...SOUTHEAST OREGON AND SOUTHWEST IDAHO REMAIN IN THE
WARM SECTOR TODAY. PRECIPITATION IS MOSTLY CONFINED TO THE WEST-
CENTRAL IDAHO MTNS THIS MORNING...BUT IS STILL EXPECTED TO DEVELOP
SOUTHWARD INTO THE BOISE MTNS THIS AFTERNOON. PRECIP GENERATION IS
MOSTLY OROGRAPHIC SO OUTSIDE OF SOME SPRINKLES...VALLEYS WILL
REMAIN DRY THROUGH THIS AFTERNOON. HAVE MADE SOME UPDATES TO THE
FORECAST FOR PATCHY DENSE FOG OVER THE LOWER TREASURE VALLEY THIS
MORNING AND TO DECREASE POPS OVER SOUTHERN ZONES. SEEING GUSTY
WINDS THIS MORNING IN THE BAKER AND LONG VALLEYS AND WITH LITTLE
CHANGE IN THE SURFACE PRESSURE GRADIENT EXPECT THE WINDS TO REMAIN
GUSTY IN THESE AREAS THROUGH THE DAY. THUS HAVE BUMPED UP WINDS IN
THESE AREAS AND ACROSS SE OREGON WHERE AFTERNOON MIXING WILL RAMP
UP WINDS OUT OF THE SOUTHWEST.

&&

.AVIATION...GENERALLY VFR UNDER BKN-OVC MID CLOUD DECKS. EXCEPT IFR
FOG IN LOWER TREASURE VALLEY NEAR KONO. MOUNTAINS NORTH OF KBNO-KONO-
KBOI-KSUN LINE OBSCURED WITH TERRAIN-INDUCED PRECIPITATION
CONTINUING. SNOW LEVELS AROUND 5000FT IN WEST CENTRAL MOUNTAINS
AND 8000FT ALONG NV BORDER. SURFACE WINDS...VARIABLE 12KT OR LESS
IN TREASURE VALLEY...SOUTHWEST 15-25 WITH GUSTS TO 40KT IN
SOUTHEAST OREGON NEAR KREO. SOUTHERLY WINDS 10-20KT IN BAKER
VALLEY AND NORTH- SOUTH ORIENTED MOUNTAIN VALLEYS. WINDS ALOFT
NEAR 10K FEET MSL...WESTERLY 40-55KT.

&&

.PREV DISCUSSION...
SHORT TERM...TODAY THROUGH SUNDAY...SW FLOW ALOFT AHEAD OF AN
INCOMING COLD SHORT WAVE WILL CONTINUE THE PATTERN OF MID AND
HIGH LEVEL MOISTURE STREAMING ACROSS THE AREA TODAY. RAIN AND SNOW
WILL INCREASE IN MOST AREAS TODAY...ESPECIALLY IN THE NORTH. THE
SNOW LEVEL WILL BE SLOWLY FALLING TODAY...BUT PLACE LIKE MCCALL...
WHERE RAIN HAS BEEN FALLING ALL MORNING...WILL NOT CHANGE OVER TO
SNOW UNTIL LATE TONIGHT. TEMPS WILL REMAIN MILD TODAY...AVERAGING
10 TO 15 DEGREES ABOVE NORMAL. TONIGHT...PRECIP WILL CONTINUE IN
MOST AREAS...ESPECIALLY THE NORTH...AS SNOW LEVELS GRADUALLY FALL
IN ADVANCE OF THE SHORT WAVE. SATURDAY...A SHARP COLD FRONT WILL
MOVE THROUGH FROM NW TO SE. THIS WILL ENTER BAKER COUNTY IN THE
MORNING...REACH THE BOISE AREA IN THE AFTERNOON...AND GET TO THE
WESTERN MAGIC VALLEY BY MIDNIGHT. THIS WILL BE A SIGNIFICANT COLD
FRONT...WITH TEMPERATURES DROPPING SHARPLY BEHIND. PRECIPITATION
WILL INCREASE IN THE SNAKE RIVER VALLEY SATURDAY...WITH MOST OF
THE PRECIP FALLING AS RAIN BEFORE THE FRONT MOVES THROUGH. THERE
MAY BE A BRIEF PERIOD OF SNOW AFTER THE FRONT PASSES...BUT FRONTAL
PASSAGE SHOULD SIGNAL THE END OF THE NOTABLE PRECIP. THROUGHOUT
THESE FIRST TWO DAYS...PRECIP IN THE MOUNTAINS WILL BE HEAVY.
LOCATIONS ABOVE AROUND 7000 FEET COULD SEE OVER A FOOT OF SNOW.
PLACES LIKE MCCALL...AT 5000 FEET...WILL SEE SEVERAL INCHES OF WET
HEAVY SNOW. AT THIS TIME...IT APPEARS THAT ROAD TEMPS WILL PREVENT
THE SNOW FROM CAUSING SIGNIFICANT TRAVEL PROBLEMS IN THE POPULATED
AREAS...SO NO SNOW ADVISORY WILL BE ISSUED. HOWEVER...IF YOU PLAN
ON TRAVELING OVER THE HIGHER PASSES...BE PREPARED FOR HEAVY SNOW
AND SNOW-PACKED ROADS THROUGH THE WEEKEND.

SATURDAY NIGHT THE COLD AIR WILL POUR INTO THE REGION BEHIND THE
DEPARTING COLD FRONT. THERE WILL BE SIGNIFICANT DRYING AND PRECIP
WILL DECREASE. ON SUNDAY...THE PRECIP WILL TAPER OFF TO SHOWERS...
AND THESE WILL BE FOUND MAINLY IN THE SOUTH AND EAST. HIGHS SUNDAY
WILL BE 10 TO 20 DEGREES COLDER THAN SATURDAY. WINDS THAT WILL BE
GUSTY SATURDAY NIGHT BEHIND THE COLD FRONT WILL DIMINISH BY SUNDAY
AFTERNOON.

LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...WARM FRONT
ASSOCIATED WITH A MOIST PACIFIC LOW PRESSURE SYSTEM APPROACHING
THE CALIFORNIA COAST LIFTS NORTH ACROSS THE FORECAST AREA ON
MONDAY. 00Z GFS/06Z NAM HAVE THE FASTEST TIMING OF THE FRONTAL
PASSAGE...REACHING MCCALL/BAKER CITY AROUND 18Z MONDAY. 00Z ECMWF
IS ABOUT 6 HOURS SLOWER. ALL GUIDANCE SUGGESTS THE COLD AIR WILL
MIX OUT OF MOST OF THE TREASURE VALLEY BY THE AFTERNOON WITH
INCREASED SOUTHEASTERLY WINDS. THE WARM FRONTAL PASSAGE WILL
INITIALLY BE DRY AS IT MOVES NORTHWARD THROUGH THE DRY ARCTIC
AIRMASS. MOISTURE WILL INCREASE ALONG THE FRONT AS THE UPPER LOW
REACHES THE CA COAST AND MOISTURE IS ADVECTED NORTHEASTWARD.
THERE IS UNCERTAINTY REGARDING TIMING OF THE RETURNING PACIFIC
MOISTURE SO HAVE LEFT POPS HIGHER ACROSS MUCH OF THE CWA MONDAY.
THE CWA REMAINS IN THE WARM SECTOR OF THE PACIFIC LOW OFF THE CA
COAST THROUGH EARLY WEDNESDAY WHICH WILL BRING PERIODS OF
WIDESPREAD PRECIPITATION. THE LOW WEAKENS AS IT MOVES INLAND LATE
WEDNESDAY LEAVING MOIST WESTERLY FLOW OVER THE INTERMOUNTAIN WEST.
TEMPERATURES...BELOW NORMAL ON MONDAY...WILL WARM QUICKLY AND
REMAIN ABOVE OR NEAR NORMAL TUESDAY THROUGH THURSDAY.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...NONE.

&&

$$

WEATHER.GOV/BOISE

DISCUSSION...DG
AVIATION.....KA
PREV SHORT TERM...SP
PREV LONG TERM....JS


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