Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 220346
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
846 PM MST SUN DEC 21 2014

.DISCUSSION...RAIN CONTINUES OVER MUCH OF THE LOWER ELEVATIONS
WITH SNOW RETURNING TO THE HIGHER ELEVATIONS DURING THE DAY. WE
EXPECT THE COVERAGE OF PRECIPITATION TO DECREASE OVERNIGHT. WEISER
RIVER CONTINUES TO SLOWLY HEAD BACK DOWN AFTER ALMOST GOING INTO
MINOR FLOOD THIS AFTERNOON. NO OTHER RIVERS APPEAR TO BE CLOSE TO
FLOOD STAGE. WE WILL WARM UP NOTABLY WED BEFORE BEGINNING A TREND
TO MUCH MORE SEASONABLE CONDITIONS FOR CHRISTMAS DAY AND BEYOND.
NO CHANGES AT THIS TIME.

&&

.AVIATION...SHOWERS DIMINISHING OVERNIGHT BECOMING ISOLATED BY
NOON ON MONDAY. ISOLATED IFR/MVFR CONDITIONS WITH RAIN...OTHERWISE
VFR. LIGHT SURFACE WINDS EXCEPT IN THE WESTERN MAGIC VALLEY WHERE
SOUTHWESTERLY WINDS 15-20 KTS WITH GUSTS TO 30 KTS. NORTHWESTERLY
WINDS 20-30KT MONDAY AFTERNOON IN MAGIC VALLEY. WINDS ALOFT AROUND
10K FT MSL...NW 50-75KT DIMINISHING TO NW 35-50KT BY 12Z MONDAY.

&&

.PREV DISCUSSION...
SHORT TERM...STEADY PCPN CONTINUES TO COME IN FROM THE NW THIS
AFTERNOON AND SHOULD LAST WELL INTO THE NIGHT BEFORE DECREASING.
THE WARM FRONT DID NOT GO AS FAR NORTH AS EXPECTED AND TEMPS
STAYED RELATIVELY COOL. RAIN HAS CHANGED BACK TO SNOW AT MOUNTAIN
SITES ABOVE 6000 FEET MSL AND THE SNOW LEVEL SHOULD CONTINUE TO
SLOWLY LOWER THROUGH THE NIGHT AS PCPN CONTINUES. ALSO...WINDS
HAVE DECREASED BELOW ADVISORY LEVELS IN SOUTHERN ZONES SO THE WIND
ADVISORY HAS BEEN CANCELLED. THE WEISER RIVER ALMOST REACHED FLOOD
STAGE AT WEISER BUT APPEARS TO HAVE CRESTED THIS AFTERNOON. OTHER
RIVERS WERE WELL WITHIN THEIR BANKS. OTHERWISE...THE PREVIOUS
FORECASTS STILL LOOK GOOD EXPECTING PCPN TO DECREASE TO SCATTERED
RAIN AND SNOW SHOWERS MONDAY AND GENERALLY END LATE MONDAY.
TUESDAY WILL BE A LITTLE COOLER THAN MONDAY IN THE VALLEYS BUT
STILL SLIGHTLY WARMER THAN NORMAL. MOUNTAINS SITES WILL START
WARMING AGAIN TUESDAY AS NEXT PACIFIC UPPER RIDGE COMES INLAND.

LONG TERM...TUESDAY NIGHT THROUGH FRIDAY...A MORE WINTRY UPPER
LEVEL PATTERN ON THE WAY. AN UPPER LEVEL RIDGE OVER THE THE WEST
COAST TUESDAY WILL BE SUPPRESSED BY COLD UPPER LEVEL TROUGH IN THE
GULF OF ALASKA WEDNESDAY. AS THE RIDGE MOVES EAST A STRONG COLD
FRONT AND ASSOCIATED TROUGH WILL MOVE SOUTHEASTWARD FROM THE GULF OF
ALASKA INTO THE PACIFIC NORTHWEST. SNOW LEVELS WILL FALL TO VALLEY
FLOORS BY THURSDAY MORNING...ALTHOUGH IT IS STILL UNCLEAR WHETHER
SNOW WILL FALL BEHIND THE FRONT. STILL A GOOD CHANCE TO SEE
SNOWFLAKES FLY IN THE LOW VALLEYS FOR CHRISTMAS DAY...TRAVEL THROUGH
MOUNTAIN PASSES COULD BE TRICKY FOR WEDNESDAY NIGHT INTO THURSDAY.
GFS STILL DOES NOT HAVE A GOOD HANDLE ON THIS SYSTEM BECAUSE OF THE
INCONSISTENCY...THUS ELECTED TO USE THE ECMWF GUIDANCE. IN WAKE OF
THE COLD FRONT...EXPECT TEMPERATURES AROUND NORMAL AND PRECIPITATION
TO CONTINUE IN THE HIGHER TERRAIN MAINLY OVER THE BLUES...WALLOWAS
..AND CENTRAL IDAHO MOUNTAINS THROUGH FRIDAY. TEMPERATURE FORECAST
CONFIDENCE BEYOND THURSDAY IS LOW AS ANY NEW SNOW COVER WILL MAKE
TEMPERATURES COLDER.

FRIDAY NIGHT THROUGH SUNDAY...A COLD NORTHWESTERLY FLOW WILL AFFECT
THE REGION THROUGH SATURDAY...BECOMING WESTERLY BY SATURDAY NIGHT.
THERE IS A CHANCE OF PRECIPITATION IN THE WEST CENTRAL AND BOISE
MOUNTAINS BEGINNING SATURDAY NIGHT THROUGH SUNDAY. THE TURN IN WIND
DIRECTION SATURDAY NIGHT INDICATES AN APPROACHING SHORT WAVE
TROUGH WHICH WILL BRING A CHANCE OF PRECIPITATION TO MOST OF THE
REGION BY SUNDAY NIGHT. SNOW LEVELS WILL BE LOW...MOST PRECIPITATION
WILL COME IN THE FORM OF SNOW...AND TEMPERATURES WILL BE NEAR NORMAL
THROUGH THE PERIOD.

&&

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

&&

$$

WEATHER.GOV/BOISE

DISCUSSION...SP
AVIATION.....JS
PREV SHORT TERM...LC
PREV LONG TERM....KA/AB


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