Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 272210
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
310 PM MST THU NOV 27 2014

.SHORT TERM...TONIGHT THROUGH SATURDAY...MILD AND MOIST SOUTHWEST
FLOW ASSOCIATED WITH AN UPPER RIDGE OVER THE PAC NW WILL GIVE WAY
TO AN APPROACHING ARCTIC FRONT ON SATURDAY. SE OREGON AND SW IDAHO
WILL REMAIN IN THE WARM SECTOR INTO SATURDAY WITH TEMPERATURES
10-15 DEGREES ABOVE NORMAL MOST LOCATIONS /THOUGH MAGIC VALLEY
WILL SEE TEMPS REACH 60 AGAIN ON FRIDAY/. MOISTURE IN THE
SOUTHWEST FLOW WILL CONCENTRATE OVER EAST-CENTRAL OREGON AND MTNS
OF SW IDAHO TONIGHT...SHIFTING SOUTH THROUGH THE DAY FRIDAY. SNOW
LEVELS WILL REMAIN ABOVE 6K FEET THROUGH TONIGHT...GRADUALLY
DROPPING FRIDAY AND FRIDAY NIGHT IN RESPONSE TO COOLING ALOFT.
PRECIPITATION AMOUNTS WILL RAMP UP STARTING FRIDAY NIGHT AS
DYNAMICS FROM UPPER TROUGH INTERACT WITH MOISTURE STREAMING IN
FROM THE PACIFIC. THROUGH FRIDAY THE SNAKE RIVER VALLEY WILL
REMAIN MOSTLY DRY /ONLY SLIGHT CHANCE OF SHOWERS/ WITH INCREASING
CHANCES FRIDAY NIGHT AND SATURDAY. SOME TIMING DIFFERENCES IN
ARRIVAL OF THE ARCTIC FRONT...BUT BY SATURDAY AFTERNOON ALL
SOLUTIONS SHOW THE FRONT PUSHING THROUGH SE OREGON AND SW IDAHO.
AT THIS TIME HIGHLIGHTS ARE UNNECESSARY AS FORECAST 10+ INCH SNOW
TOTALS WILL BE ABOVE 6K FEET MSL.

.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...MODELS AGREE ON
ARCTIC AIR RE-INVADING THE NORTHERN INTERMOUNTAIN REGION SATURDAY
NIGHT BENEATH AN UPPER LEVEL TROUGH IN NORTHERLY FLOW ALOFT.
WIDESPREAD PRECIPITATION IS EXPECTED SATURDAY NIGHT AS THE ARCTIC
AIR PUSHES SOUTH BENEATH THE MOIST PACIFIC AIR. PRECIPITATION SHOULD
BEGIN AS RAIN IN THE VALLEYS SATURDAY EVENING CHANGING TO SNOW AT
ALL ELEVATIONS OVERNIGHT. ON SUNDAY MUCH DRIER COLD AIR MOVING DOWN
FROM B.C. WILL KEEP MOST OF THE PRECIPITATION ALONG THE NEVADA
BORDER. TEMPERATURES SUNDAY AND MONDAY WILL BE 10 TO 15 DEGREES
BELOW NORMAL. THERE IS UNCERTAINTY REGARDING TIMING OF THE RETURNING
PACIFIC MOISTURE. BOTH THE GFS AND ECMWF HAVE BEEN TRENDING LESS
PROGRESSIVE...ESPECIALLY THE ECMWF...WHICH IS PREFERRED. BASED ON
THIS SLOWER TIMING...THE BEST CHANCE OF PRECIPITATION NOW APPEARS TO
BE TUESDAY NIGHT THROUGH WEDNESDAY NIGHT. TEMPERATURES WILL SLOWLY
MODERATE TO AROUND 5 DEGREES BELOW NORMAL ON TUESDAY AND NEAR NORMAL
WEDNESDAY THROUGH THURSDAY.

&&

.AVIATION...VFR CONDITIONS WILL CONTINUE THROUGH FRIDAY ACROSS
SOUTHEAST OREGON AND THE SNAKE RIVER VALLEY SOUTH TO THE NEVADA
BORDER. OVER THE WEST CENTRAL IDAHO AND BOISE MOUNTAINS AND BAKER
COUNTY EXPECT DETERIORATING CONDITIONS TONIGHT WITH AREAS OF
MVFR/IFR CEILINGS AND MOUNTAIN OBSCURATION IN SNOW ABOVE 5K FT MSL
CONTINUING THROUGH FRIDAY. SCATTERED RAIN SHOWERS WILL SPREAD SOUTH
TO A KREO-KMUO-FAIRFIELD LINE FRIDAY AFTERNOON. SURFACE WINDS...EAST
TO SOUTH 5-15 KTS. WINDS ALOFT...WEST UP TO 25 KTS AT 10K FT MSL.

WEEKEND OUTLOOK...FRIDAY NIGHT THROUGH SATURDAY MORNING MVFR/IFR
SNOW WILL CONTINUE ACROSS BAKER COUNTY OREGON AND THE CENTRAL IDAHO
MOUNTAINS. OTHERWISE EXPECT VFR CONDITIONS FOR MOST OF SOUTHEAST
OREGON AND SOUTHWEST IDAHO. SATURDAY AFTERNOON VALLEY RAIN AND
MOUNTAIN SNOW WILL SPREAD SOUTH TO THE NEVADA LINE AND CONTINUE
ACROSS THE ENTIRE AREA THROUGH SATURDAY NIGHT...WITH SNOW LEVELS
LOWERING TO THE VALLEY FLOORS. SUNDAY DRIER AIR MOVING DOWN FROM THE
NORTH WILL BRING IMPROVING CONDITIONS...WITH MAINLY VFR.

&&

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

&&

$$

WEATHER.GOV/BOISE

SHORT TERM...DG
LONG TERM....JT
AVIATION.....JT


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