860
FXUS65 KBOI 261712
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
1012 AM MST FRI DEC 26 2025
DISCUSSION
THE FIRST OF TWO COLD FRONTS HAS MOVED THROUGH THE
AREA, WITH GUSTS UP TO 50 MPH ALONG THE FRONT AND ISOLATED
THUNDERSTORMS THIS MORNING! THE FORECAST HAS BEEN UPDATED TO
ACCOUNT FOR THE LULL IN PRECIPITATION FROM NOW THROUGH AROUND
5PM MST. THE NEXT COLD FRONT MOVES THROUGH LATE THIS EVENING
INTO SATURDAY MORNING WITH SNOW LEVELS FALLING TO THE VALLEY
FLOORS. PRECIPITATION AMOUNTS WILL BE LIGHT WITH THE FRONT, WITH
MINIMAL SNOW ACCUMULATIONS BELOW 5000 FEET. ABOVE 5000 FEET,
SNOW ACCUMULATIONS OF 4 TO 8 INCHES POSSIBLE WITH LOCALLY
HIGHER AMOUNTS ON THE PEAKS. SNOW AMOUNTS WILL BE HIGHLY
VARIABLE DUE TO THE SHOWERY NATURE OF THE PRECIPITATION. HEAVIER
BANDS OF SNOW POSSIBLE OVER THE WEST CENTRAL ID MOUNTAINS EARLY
SATURDAY MORNING, BUT THE BEST DYNAMICS FOR HEAVY SNOW SHOWERS
WILL GENERALLY BE OVER THE CENTRAL ID PANHANDLE MOUNTAINS AND
NORTHEAST INTO WESTERN MT.
AVIATION
SCATTERED SHOWERS IN SW-IDAHO THIS MORNING. BRIEF LULL
IN PRECIP MID-DAY BEFORE INCREASING IN COVERAGE THIS AFTERNOON ALONG
AND BEHIND OF A COLD FRONT. VFR-MVFR IN RAIN SHOWERS, MVFR/LIFR IN
SNOW SHOWERS, MTNS OBSCURED IN PRECIP. SNOW LEVELS: 3.5-4.5 KFT MSL,
LOWERING TO VALLEY FLOORS EARLY SATURDAY MORNING. SURFACE WINDS: SW-
SE 15-25 KT WITH GUSTS TO 25-45 KT. BECOMING W-NW 10-20 KT WITH
GUSTS TO 20-30 KT TONIGHT BEHIND A COLD FRONT. WINDS ALOFT AT 10 KFT
MSL: W-SW 40-50 KT.
KBOI...VFR AND DRY TODAY BUT SHOWERS RETURNING OVER THE FOOTHILLS
THIS AFTERNOON. A 30% CHANCE OF SNOW FLURRIES AFTER SAT/12Z, NO
ACCUMULATION EXPECTED. SURFACE WINDS: SE-SW 7-12 KT, BECOMING W-NW
10-15 KT WITH GUSTS UP TO 25 KT TONIGHT WITH A FRONTAL PASSAGE.
WEEKEND OUTLOOK...SNOW LEVELS LOWERING TO VALLEY FLOORS SATURDAY.
SCATTERED TO NUMEROUS SNOW SHOWERS SATURDAY, WITH MVFR-LIFR
CONDITIONS IN PRECIP. MTNS OBSCURED. SHOWERS ENDING SATURDAY
EVENING. VFR, COLD, DRY SUNDAY. SURFACE WINDS: W TO NW 15-25 KT
SATURDAY WITH 25-35 KT GUSTS. LIGHT WINDS SUNDAY.
PREV DISCUSSION
SHORT TERM...TODAY THROUGH SUNDAY NIGHT...AN UPPER LEVEL
TROUGH ALONG THE WEST COAST THIS MORNING WILL PUSH INLAND TODAY,
MOVING ACROSS THE NORTHERN ROCKIES TONIGHT. THIS WILL BRING
PERIODS OF MODERATE SNOWFALL TO THE CENTRAL IDAHO MOUNTAINS.
ISOLATED SHOWERS CONTINUE ACROSS THE REGION AND WILL EXPAND IN
COVERAGE, PARTICULARLY ACROSS SOUTHEAST OREGON AND THE CENTRAL
IDAHO MOUNTAINS, AFTER SUNRISE AS AN EMBEDDED UPPER LEVEL
SHORTWAVE TRAVERSES THE PACIFIC NORTHWEST. SNOW LEVELS AROUND
5000 FEET THIS MORNING SHOULD BE LOW ENOUGH FOR WET ACCUMULATING
SNOW IN THE MOUNTAINS AS TEMPERATURES HOVER NEAR FREEZING
THROUGH EARLY AFTERNOON. THIS WILL LARGELY LIMIT ACCUMULATIONS
BELOW 5500 FEET THIS MORNING, WITH THE HIGHER MOUNTAIN VALLEYS
SEEING UP TO 4 INCHES OF SNOW.
THE NEXT PUSH OF PRECIPITATION ARRIVES LATER THIS EVENING AHEAD
OF A COLD FRONTAL PASSAGE EXPECTED SATURDAY MORNING. THIS WILL
SUPPORT MORE ACCUMULATING SNOW IN THE MOUNTAINS, PARTICULARLY IN
THE WEST CENTRAL AND BOISE MOUNTAINS WHERE A WINTER WEATHER
ADVISORY REMAINS IN EFFECT. EXPECT AN ADDITIONAL 2 TO 5 INCHES
OF SNOW IN THE MOUNTAIN VALLEYS. LOWER VALLEYS CAN EXPECT RAIN
SHOWERS MIXING WITH OR CHANGING TO WET SNOW EARLY SATURDAY
MORNING, THOUGH LITTLE TO NO ACCUMULATION IS EXPECTED ON VALLEY
FLOORS. IN THE MOUNTAINS, SNOW ACCUMULATING ON ROAD SURFACES
WILL CREATE DIFFICULT TRAVEL CONDITIONS. GUSTY WINDS WILL
ACCOMPANY THE FRONTAL PASSAGE, PARTICULARLY OVER EXPOSED
TERRAIN, THROUGH SATURDAY. HOWEVER, BLOWING OR DRIFTING SNOW
APPEARS UNLIKELY AS THE COLDER AIR WILL NOT REACH THE AREA
UNTIL WELL AFTER THE SNOW HAS ENDED.
SATURDAY WILL SEE LINGERING LIGHT SNOW SHOWERS OVER THE
MOUNTAINS UNDER NORTHWEST FLOW ALOFT, WHILE VALLEY PRECIPITATION
CHANCES DECREASE SIGNIFICANTLY. BREEZY CONDITIONS WILL CONTINUE
THROUGH SATURDAY EVENING ACROSS THE AREA WITH GUSTS UP TO 40 MPH,
THOUGH SPEEDS SHOULD REMAIN WELL BELOW ADVISORY CRITERIA. BY
SATURDAY NIGHT AND SUNDAY, AN UPPER LEVEL RIDGE WILL BEGIN TO
BUILD OVER THE INTERMOUNTAIN WEST. THIS WILL STABILIZE THE
ATMOSPHERE, LEADING TO DRY CONDITIONS BUT INCREASING THE
POTENTIAL FOR VALLEY FOG AND LOW STRATUS AS INVERSIONS
STRENGTHEN. TEMPERATURES WILL TREND COOLER, RETURNING TO NEAR
SEASONAL NORMALS BY SUNDAY.
LONG TERM...MONDAY THROUGH FRIDAY...STRONG HIGH PRESSURE WILL
DOMINATE THE WEATHER PATTERN THROUGH MUCH OF THE LONG TERM
PERIOD. THIS SETUP WILL FOSTER THE DEVELOPMENT OF STRONG VALLEY
INVERSIONS, LIKELY RESULTING IN AREAS OF PERSISTENT FOG AND LOW
STRATUS IN THE SHELTERED VALLEYS OF SOUTHWEST IDAHO AND
SOUTHEAST OREGON. UNDER THIS REGIME, VALLEY TEMPERATURES WILL
REMAIN SUPPRESSED WITH LIMITED MIXING, WHILE HIGHER ELEVATIONS
EXPERIENCE MILDER, SUNNY CONDITIONS. THIS PATTERN RAISES
CONCERNS FOR AIR STAGNATION AND DETERIORATING AIR QUALITY IN
VALLEY LOCATIONS THROUGH AT LEAST WEDNESDAY. VALLEY TEMPERATURES
WILL BE DIFFICULT TO FORECAST, WITH LITTLE DIURNAL VARIATION
EXPECTED SHOULD STRATUS OR FOG DEVELOP.
MODELS SHOW DIVERGENCE REGARDING THE BREAKDOWN OF THE RIDGE LATE
IN THE WEEK. SOME GUIDANCE SUGGESTS A TROUGH MAY BRUSH THE
REGION BY THURSDAY OR FRIDAY, POTENTIALLY WEAKENING THE
INVERSION AND INTRODUCING A CHANCE OF PRECIPITATION. HOWEVER,
OTHER CLUSTERS MAINTAIN THE RIDGE, KEEPING THE AREA DRY AND
STABLE. GIVEN THE UNCERTAINTY, THE FORECAST REFLECTS A GRADUAL
TREND TOWARD CLIMATOLOGICAL NORMALS WITH SLIGHT CHANCES FOR
PRECIPITATION RETURNING TOWARDS THE END OF THE PERIOD.
BOI WATCHES/WARNINGS/ADVISORIES
ID...WINTER WEATHER ADVISORY UNTIL 5 AM MST SATURDAY IDZ011-013.
OR...NONE.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
DISCUSSION...KA
AVIATION.....NF
SHORT TERM...JDS
LONG TERM....JDS
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