930
FXUS65 KBOI 270340
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
840 PM MST FRI DEC 26 2025
DISCUSSION
SNOW IS ACCUMULATING IN THE WEST CENTRAL AND BOISE
MOUNTAINS, WITH JUST OVER FOUR INCHES OF SNOW SHOWN ON THE
MCCALL TOWN SNOW STAKE AS OF 8PM MST. A STRONG COLD FRONT WITH
VERY COLD AIR ALOFT WILL MOVE IN TOMORROW, BRINGING BANDS OF
MODERATE TO HEAVY SNOW ACROSS THE MOUNTAINS AND SOUTH CENTRAL
IDAHO. A LOW CHANCE OF SNOW (20% CHANCE) EXISTS OVER THE SNAKE
RIVER VALLEY IN THE EARLY MORNING AS WELL. THIS WILL LIKELY BE
BRIEF WITH MINIMAL ACCUMULATION IF IT OCCURS AT ALL. HI-RES
MODELS CONTINUE TO SHIFT THE COLDEST AIR AND MOISTURE TO THE
NORTHEAST, WHICH WOULD ELIMINATE ANY CHANCE FOR SNOW IN THE
BOISE METRO AREA.
BREEZY WINDS WILL ACCOMPANY THE FRONTAL PASSAGE, WITH MUCH
COLDER TEMPERATURES OVER THE REGION ANTICIPATED. COLDER
TEMPERATURES COMBINED WITH THE WIND WILL BRING LOW WIND CHILLS,
ESPECIALLY ACROSS HIGHER ELEVATIONS. UPDATED THE FORECAST TO
ACCOUNT FOR THE LOWER POTENTIAL FOR SNOW TOMORROW IN THE
VALLEYS.
AVIATION
NUMEROUS SHOWERS, MAINLY OVER HIGHER TERRAIN TONIGHT,
BECOMING SCATTERED SAT MORNING. IFR/LIFR IN SNOW. MOUNTAINS
OBSCURED. SNOW LEVELS: 3K-4K FEET MSL TONIGHT, DOWN TO VALLEY FLOORS
SAT AM. SURFACE WINDS: SE-SW 5-15 KT, VEERING TO NW-W 5-15 KT BEHIND
COLD FRONT EARLY SAT AM. THEN, INCREASING TO NW-W 10-20 KT WITH 20-
35 KT GUSTS LATE SAT AM. WINDS ALOFT AT 10KFT MSL: W 35-50 KT, THEN
NW 20-35 KT BY SAT/15Z.
KBOI...VFR. SHOWERS IN VICINITY OVER BOISE FOOTHILLS, CREATING
OBSCURATION. POTENTIAL FOR BRIEF SNOW SHOWER AND DEGRADED VISIBILITY
AT KBOI SATURDAY MID MORNING THROUGH EARLY AFTERNOON. HOWEVER,
FORECAST CONFIDENCE IS VERY LOW AS SHOWER ACTIVITY WILL BE FAVORING
HIGHER TERRAIN. SURFACE WINDS: SE-SW 5-10 KT. SHIFTING TO W-NW 8-18
KT WITH GUSTS AROUND 25 KT AFTER SAT/08Z, DECREASING SAT EVE.
SUNDAY OUTLOOK...SHOWERS ENDING SATURDAY EVENING. VFR, COLD, DRY
SUNDAY. SURFACE WINDS LIGHT AND VARIABLE, EXCEPT W-NW 10-15 KT WITH
GUSTS AROUND 25 KT SUN AM IN SOUTH-CENTRAL IDAHO (KTWF-KJER).
AIR STAGNATION
STAGNANT CONDITIONS DEVELOP SUNDAY AS A RIDGE
OF HIGH PRESSURE BEGINS TO BUILD OVER THE AREA. POOR MIXING
HEIGHTS WITH LIGHT WINDS EXPECTED MONDAY THROUGH THURSDAY. A
TEMPERATURE INVERSION WILL STRENGTHEN MONDAY THROUGH WEDNESDAY
OF NEXT WEEK AS THE RIDGE MOVES OVERHEAD WITH WARMER
TEMPERATURES ALOFT.
PREV DISCUSSION
SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT...A BRIEF LULL
CONTINUES IN PRECIPITATION THIS AFTERNOON FROM BOISE, ID TO
ROME OR WITH MOSTLY CLEAR SKIES THROUGH LATE THIS AFTERNOON.
CLOUDS ARE INCREASING IN CENTRAL AND EASTERN OR AHEAD OF THE
NEXT COLD FRONT WITH SNOW DEVELOPING AT BURNS OR AS OF 220PM
MST. THE NEXT COLD FRONT MOVES THROUGH LATE THIS EVENING INTO
SATURDAY MORNING WITH SCATTERED SNOW SHOWERS AND SNOW LEVELS
FALLING TO THE VALLEY FLOORS. PRECIPITATION AMOUNTS WILL BE
LIGHT WITH THIS SYSTEM, WITH MINIMAL SNOW ACCUMULATIONS BELOW
5000 FEET. ABOVE 5000 FEET, SNOW ACCUMULATIONS OF 4 TO 7 INCHES
POSSIBLE WITH LOCALLY HIGHER AMOUNTS ON THE PEAKS WHERE A WINTER
WEATHER ADVISORY REMAINS IN EFFECT. 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 INTO THE AFTERNOON, BUT THE
BEST DYNAMICS FOR HEAVY SNOW SHOWERS WILL GENERALLY BE OVER THE
CENTRAL ID PANHANDLE MOUNTAINS AND NORTHEAST INTO WESTERN MT
WHERE THE COLDEST AIR ALOFT IS. HIGH TEMPERATURES SATURDAY WILL
BE AROUND 10 DEGREES COOLER THAN TODAY. BREEZY WEST-NORTHWEST
WINDS FOLLOW THE FRONT WITH GUSTS OF 25-40 MPH DURING THE
AFTERNOON SATURDAY. SUNDAY WILL BE MOSTLY SUNNY AND DRY WITH
STAGNANT CONDITIONS DEVELOPING AS UPPER LEVEL WINDS WEAKEN.
LONG TERM...MONDAY THROUGH FRIDAY...DRY CONDITIONS THROUGHOUT
THE COMING WEEK. RIDGING WILL BUILD IN ABOVE A LOW OVER THE
PACIFIC, THIS BLOCKING PATTERN (REX BLOCK) WILL ALLOW PROLONGED
HIGH PRESSURE OVER THE REGION. THIS SET-UP WILL RESULT IN
STRONG VALLEY INVERSIONS WITH UPPER-LEVEL SUBSIDENCE AND THE LOW
SUN ANGLE OF THIS TIME OF YEAR. WITH PLENTY OF SURFACE MOISTURE
TO WORK WITH, AND A FAVORABLE PATTERN, FOG AND LOW STRATUS WILL
BE A CONCERN EACH DAY AS WELL AS DECREASING AIR QUALITY BELOW
THE INVERSION. DAY TIME HIGHS MAY BE A LITTLE OVER DONE, WITH
THE POTENTIAL OF A COLD POOL AND REDUCED SURFACE HEATING UNDER
POTENTIAL FOG/LOW STRATUS. CONVERSELY, MORNING LOW TEMPS MAY BE
A BIT UNDER DONE UNDER THE SAME CONDITIONS, WITH CLOUD COVER
REDUCING DIURNAL COOLING.
THE FIRST SIGNS OF A PATTERN CHANGE COME LATE NEXT WEEK. CLUSTER
ANALYSIS IS SHOWING INCREASING AGREEMENT AMONG GRAND ENSEMBLE
MEMBERS; WITH THE FAVORED SOLUTION BEING A TROUGH DIGGING DOWN
FROM THE GULF OF ALASKA LATE THURSDAY INTO EARLY FRIDAY.
INCREASED MIXING WITH THE TROUGH WILL WORK TO LIFT THE INVERSION
IN THE LATE WEEK AS WELL. PRECIPITATION CHANCES WILL INCREASE
THURSDAY AFTERNOON THROUGH FRIDAY AREA-WIDE AS THE TROUGH MOVES
ASHORE.
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...SA
AVIATION.....SH
AIR STAGNATION...KA
SHORT TERM...KA
LONG TERM....NF
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