063
FXUS65 KBOI 021707
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
1007 AM MST TUE DEC 2 2025
DISCUSSION
A COLD FRONT HAS MOVED THROUGH THE AREA WITH COOLER
AIR ALOFT AND UNSTABLE AIR MOVING OVERHEAD TODAY. THIS WILL
PROVIDE ENOUGH LIFT FOR RAIN AND SNOW SHOWERS TUESDAY DURING THE
DAY, WITH SNOW LEVELS AROUND 2500-4000'. MINIMAL PRECIPITATION
EXPECTED WITH THIS SYSTEM, WITH SNOW ACCUMULATIONS AROUND 1-2"
IN THE MOUNTAINS. LITTLE TO NO ACCUMULATION EXPECTED BELOW
3000'. THE SYSTEM WILL BRING AREAS OF LOW CLOUDS AND FOG TO THE
AREA ON WEDNESDAY AS UPPER LEVEL RIDGING BUILDS IN BEHIND THE
COLD FRONT. TEMPERATURES REMAIN NEAR NORMAL. NO UPDATES.
AVIATION
SCATTERED SHOWERS WILL MOVE N TO S TODAY, DECREASING
THIS EVENING. SNOW LEVELS 2500-4000 FT MSL THIS MORNING, INCREASING
TO 3500-5000 FT MSL THIS AFTERNOON. MVFR TO LIFR IN SNOW, WITH MVFR
TO VFR IN RAIN. AREAS OF MTN OBSCURATION. PATCHY FOG AND LOW STRATUS
DEVELOPING LATE TONIGHT. SURFACE WINDS: LIGHT AND VARIABLE, BECOMING
W-NW 5-15 KT THIS AFTERNOON. GUSTS 20-30 KT KMUO TO KJER/KTWF AND IN
SE OREGON. WINDS ALOFT AT 10KFT MSL: NW 20-35 KT, BECOMING N-NE 15-
30 KT AFTER WED/00Z.
KBOI...MAINLY VFR. MVFR/IFR CONDITIONS POSSIBLE FROM ISOLATED
MORNING SNOW SHOWERS AND AFTERNOON RAIN/GRAUPEL SHOWERS. NO SNOW
ACCUMULATION EXPECTED. A 50% CHANCE OF IFR/LIFR LOW STRATUS/FOG
DEVELOPING AT THE TERMINAL LATE TONIGHT/WED MORNING. SURFACE WINDS:
LIGHT AND VARIABLE, BECOMING NW 5-12 KT THIS AFTERNOON WITH
GUSTS TO 20 KT POSSIBLE.
PREV DISCUSSION
SHORT TERM...TODAY THROUGH THURSDAY NIGHT...SEEING SCATTERED
SHOWERS DEVELOP AHEAD OF A SHORTWAVE TROUGH DROPPING THROUGH
CENTRAL WA EARLY THIS MORNING. SHOWER DEVELOPMENT WILL TRACK
WITH THE LOW AS IT CONTINUES TO THE S-SE TODAY. THE FOCUS OF
DEVELOPMENT WILL BE ACROSS THE MTNS AND HIGHER TERRAIN SOUTH OF
THE SNAKE PLAIN AND FAR SE OREGON WHERE A GENERAL 40-60% CHANCE
OF SHOWERS EXISTS. MOST LOWER ELEVATIONS SEE A SLIGHT CHANCE OF
SHOWERS (UP TO 20%) THROUGH THIS AFTERNOON WITH THE PASSAGE OF
THE LOW. THE UPPER LOW WILL ENHANCE NORTHWEST FLOW ALOFT WHICH
WILL RESULT IN BREEZY NORTHWEST WINDS THIS AFTERNOON. GUSTS UP
TO 25 MPH CAN BE EXPECTED WITH THE TYPICALLY WINDIER AREAS
ALONG THE I84 CORRIDOR SEEING GUSTS UP TO 35 MPH THROUGH EARLY
EVENING. SNOW LEVELS ARE NEAR VALLEY FLOORS THIS MORNING, BUT
WILL RISE TO AROUND 4000 FEET BY AFTERNOON. MOUNTAIN VALLEYS
WILL SEE LESS THAN AN INCH WITH 1 TO 3 INCHES POSSIBLE AT
ELEVATIONS ABOVE 6500 FEET. A SHORTWAVE RIDGE FOLDS IN BEHIND
THE EXITING LOW BRINGING DRY AND STABLE CONDITIONS WEDNESDAY AND
THURSDAY. FOG AND LOW STRATUS IS POSSIBLE EACH MORNING WITH
MODEL CONSENSUS TAGGING MTN VALLEYS AND THE CENTRAL SNAKE PLAIN
TONIGHT, POSSIBLY EXPANDING INTO THE LOWER SNAKE ON THURSDAY. A
CHANCE OF RAIN AND SNOW RETURNS TO THE REGION THURSDAY NIGHT AS
DEEP MOISTURE RIDES OVER THE PACIFIC RIDGE ON STRENGTHENING
NORTHWEST FLOW ALOFT.
LONG TERM...FRIDAY THROUGH TUESDAY...AN ACTIVE PATTERN IS
EXPECTED OVER THE LONG TERM AS A STRONG WESTERLY JET OVER THE
NORTH PACIFIC TAKES AIM AT THE PACIFIC NORTHWEST. A MILD AND
VERY MOIST SYSTEM WILL MOVE ACROSS THE AREA FRIDAY INTO EARLY
SATURDAY, BRINGING WIDESPREAD PRECIPITATION. SNOW LEVELS WILL
RISE FROM AROUND 4000-6000 FEET FRIDAY MORNING (STARTING AS
SNOW IN MOUNTAIN VALLEYS) TO AROUND 5500-7000 FEET FRIDAY NIGHT,
AND POSSIBLY AS HIGH AS 8000 FEET AS THE WARM FRONT PASSES
THROUGH LATE IN THE DAY. PRECIPITATION CHANCES WILL INCREASE
THROUGH THE DAY FRIDAY, REACHING A PEAK FRIDAY NIGHT AND
SATURDAY AT AROUND 50-70% IN THE LOWER ELEVATIONS AND 70- 90% IN
THE MOUNTAINS.
PACIFIC MOISTURE WILL CONTINUE TO STREAM INTO THE AREA OVER THE
WEEKEND, WITH ADDITIONAL WEAKER IMPULSES BRINGING MORE RAIN AND
MOUNTAIN SNOW. HOWEVER, PRECIPITATION CHANCES WILL NOT BE QUITE AS
HIGH AS FRIDAY NIGHT/SATURDAY. SNOW LEVELS WILL FLUCTUATE SLIGHTLY
WITH PASSING SYSTEMS, BUT SHOULD AVERAGE AROUND 5000-7000 FEET.
SIGNIFICANT PRECIPITATION TOTALS ARE POSSIBLE THROUGH SUNDAY, WITH
0.10-0.50" LIKELY IN THE LOWER ELEVATIONS AND 0.50-1.50" IN THE
MOUNTAINS, EXCEPT HIGHER AMOUNTS POSSIBLE ON THE PEAKS. ABOVE 6000-
7000 FEET, THIS WILL TRANSLATE TO HEAVY SNOW TOTALS.
A LOW AMPLITUDE UPPER LEVEL RIDGE IS EXPECTED TO REBUILD ACROSS THE
AREA ON MONDAY, BRINGING MOSTLY DRY CONDITIONS. BY TUESDAY, ANOTHER
SYSTEM MAY BRING ADDITIONAL RAIN AND SNOW IF THE RIDGE SHIFTS
SLIGHTLY SOUTH AND ALLOWS THE STORM TRACK TO MOVE BACK OVERHEAD.
HOWEVER, CONFIDENCE IN THIS REMAINS LOW AS SOME MODELS/ENSEMBLES
DEPICT THE RIDGE REMAINING IN PLACE. THIS UNCERTAINTY RESULTS IN A
10-30% CHANCE OF RAIN IN THE LOWER ELEVATIONS, AND A 30-60% CHANCE
OF RAIN/SNOW ACROSS THE MOUNTAINS. TEMPERATURES FRIDAY THROUGH
TUESDAY SHOULD AVERAGE AROUND 10 DEGREES ABOVE NORMAL, AND PASSING
SYSTEMS WILL BRING BREEZY CONDITIONS.
BOI WATCHES/WARNINGS/ADVISORIES
ID...NONE.
OR...NONE.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
DISCUSSION...KA
AVIATION.....CH
SHORT TERM...DG
LONG TERM....ST
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