Area Forecast Discussion
Issued by NWS Boise, ID

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000
FXUS65 KBOI 180355
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
855 PM MST WED DEC 17 2014

.DISCUSSION...THE MID LAYER TROUGH BROUGHT 0.02 INCHES OF PRECIP
TO BURNS AND A TRACE TO BAKER CITY AS OF 8 PM MST. CLOUD TOPS HAVE
WARMED THE LAST COUPLE HOURS AND RADAR ECHOES HAVE DIMINISHED. 00Z
GFS AND NAM BRING SOME LIGHT QPF ACROSS HARNEY/BAKER COUNTIES AND
EVEN LIGHTER AMTS TO CENTRAL IDAHO THROUGH 5 AM ASSOCIATED WITH A
SHEAR VORTICITY ALOFT. BEHIND THAT ANOTHER UPPER RIDGE IS
AMPLIFYING WHICH WILL PUSH THE SHEAR VORTICITY LOBE AND LIGHT QPF
ACROSS CENTRAL IDAHO THURSDAY. LOW QPF AND MIDLING POPS IN THE
FORECAST FAVORING OREGON THIS EVENING AND CENTRAL IDAHO THURSDAY
ARE ON TRACK WITH THIS. AREAS ABOVE 5K-6K FT WILL SEE TWO ROUNDS
OF SNOW...ONE LIGHT ONE FRIDAY AND A HEAVIER ONE SATURDAY NIGHT.
LOCALLY HEAVY SNOW IS EXPECTED SATURDAY NIGHT THROUGH EARLY
SUNDAY IN THE HIGHER MOUNTAINS.

&&

.AVIATION...SCATTERED SNOW SHOWERS WITH AREAS OF MVFR CEILINGS AND
LOCAL IFR CONDITIONS OVER HARNEY/BAKER COUNTIES AND CENTRAL IDAHO
WILL DECREASE OVER OREGON EARLY THURSDAY AND OVER IDAHO THURSDAY
EVENING. MOSTLY VFR THURSDAY NIGHT WITH PATCHY VALLEY FOG. SURFACE
WINDS...EAST TO SOUTH UP TO 10 KTS. WINDS ALOFT...SOUTHWEST 15
KTS UP THROUGH 10K FT MSL.

&&

.PREV DISCUSSION...
SHORT TERM...TONIGHT THROUGH FRIDAY...A WEAK SHORT WAVE TROUGH
WILL MOVE THROUGH OVERNIGHT...SPREADING LIGHT SHOWERS MAINLY INTO
HARNEY COUNTY THIS EVENING...AND THE HIGHER TERRAIN OF THE NORTH
AFTER MIDNIGHT. A WEAK RIDGE AXIS WILL THEN QUICKLY FOLLOW THU AND
THU NIGHT. ON FRIDAY...THE REGION WILL SEE INCREASING MOISTURE AS
SW FLOW ALOFT IS REESTABLISHED IN ADVANCE OF A STRONG MOIST JET
MOVING IN FROM THE PACIFIC. ONE ROUND OF PRECIPITATION WILL MOVE
THROUGH DURING THE DAY FRIDAY...WITH THE BULK IN ERN OREGON IN THE
MORNING AND IN SW IDAHO IN THE AFTERNOON. HOWEVER...SHOWERS ARE
POSSIBLE IN ALL AREAS MOST OF THE DAY. SEVERAL INCHES OF SNOW ARE
LIKELY ABOVE 3500 TO 4000 FEET. TEMPS WILL CONTINUE TO BE ABOVE
NORMAL...WITH LIGHT WINDS AND MOSTLY CLOUDY SKIES LASTING THROUGH
THE SHORT TERM. FRIDAY MORNING RAIN MAY MIX WITH SNOW IN THE
TREASURE VALLEY...BUT TEMPS ARE EXPECTED TO BE JUST ABOVE FREEZING
SO TRAVEL PROBLEMS SHOULD BE MINIMAL.

LONG TERM...FRIDAY NIGHT THROUGH MONDAY...MODELS CONTINUE IN
GOOD AGREEMENT THROUGH MONDAY. MILD ZONAL FLOW WILL BRING A WEAK
DISTURBANCE ACROSS OUR CWA FRIDAY NIGHT WITH MAINLY LIGHT
PRECIPITATION AND SNOW LEVELS AROUND 4000 FEET. SATURDAY THROUGH
SUNDAY THE UPPER LEVEL FLOW WILL BECOME MORE NORTHWESTERLY COMING
AROUND AN UPPER LEVEL RIDGE BUILDING OFF THE CALIFORNIA COAST.
THIS WILL PATTERN WILL TRANSPORT SLIGHTLY WARMER AIR INTO OUR
AREA...ALONG WITH ABUNDANT MOISTURE FOR MODERATE AMOUNTS OF
PRECIPITATION AT ALL ELEVATIONS...MOSTLY FALLING SATURDAY NIGHT
AND SUNDAY MORNING. SNOW LEVELS SATURDAY NIGHT WILL RANGE FROM
4000 FEET IN THE NORTH TO 5000 FEET ALONG THE NEVADA BORDER. ON
SUNDAY SNOW LEVELS WILL RISE CONSIDERABLY...RANGING FROM 5500 FEET
IN THE CENTRAL IDAHO MOUNTAINS TO 8000 FEET IN SOUTHEAST OREGON.
SNOW ACCUMULATIONS OF 6 TO 12 INCHES ARE POSSIBLE IN THE CENTRAL
IDAHO MOUNTAINS ABOVE 5500 FEET BY SUNDAY NIGHT. A CHANCE OF SNOW
WILL CONTINUE OVER THE MOUNTAINS THROUGH MONDAY...WITH A CHANCE OF
RAIN SHOWERS BELOW 6000 FEET. TEMPERATURES WILL REMAIN ABOVE
NORMAL BY 5 TO 15 DEGREES...WITH MONDAY THE WARMEST DAY.

MONDAY NIGHT THROUGH WEDNESDAY...THE REGION WILL BE UNDER THE
INFLUENCE OF A NORTHWEST FLOW WHICH WILL CARRY ENOUGH MOISTURE TO
BRING A CHANCE OF PRECIPITATION TO THE WEST CENTRAL AND BOISE
MOUNTAINS. BY WEDNESDAY AFTERNOON...A SHORTWAVE WILL MOVE INTO THE
REGION FROM THE WEST BRINGING PRECIPITATION TO MOST OF SOUTHEAST
OREGON AND SOUTHWEST IDAHO. TEMPERATURES WILL REMAIN 5-10 DEGREES
ABOVE NORMAL AND WILL COOL SLIGHTLY WITH THE SHORTWAVE. SNOW LEVELS
WILL DROP AS WELL...COMING DOWN TO ABOUT 3000 TO 3500 FEET IN THE
BLUE/WEST CENTRAL/BOISE MOUNTAINS BY WEDNESDAY NIGHT...ALLOWING
PRECIPITATION TO COME IN THE FORM OF SNOW.

&&

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

&&

$$

WEATHER.GOV/BOISE

DISCUSSION...VM
AVIATION.....VM
PREV SHORT TERM...SP
PREV LONG TERM....JT/AB



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