788
FXUS65 KBOI 060336
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
836 PM MST THU FEB 5 2026
DISCUSSION
TEMPERATURES WERE UNSEASONABLY WARM THIS
AFTERNOON, WITH 50S AND 60S OBSERVED IN THE LOWER ELEVATIONS.
MOSTLY CLEAR SKIES TONIGHT WILL ALLOW LOCALIZED FOG/MIST TO
FORM IN STAGNANT VALLEYS BY EARLY FRIDAY MORNING, SUCH AS THE
LOWER SNAKE PLAIN AND SHELTERED MOUNTAIN VALLEYS. OVERCAST SKIES
ARE ANTICIPATED FRIDAY AS A WEAK LOW PRESSURE DISTURBANCE
UNDERCUTS THE UPPER RIDGE AND SPREADS MID/HIGH LEVEL MOISTURE
ACROSS THE NORTHWEST U.S. NO CHANGES TO CURRENT FORECAST.
AVIATION
VFR. LOCALIZED IFR CONDITIONS RETURN OVERNIGHT WITH
REDEVELOPMENT OF MIST/FOG ACROSS PORTIONS OF LOWER SNAKE PLAIN
(KEUL-KONO) AND IN MTN VALLEYS. SURFACE WINDS: UP TO 10 KT,
EXCEPT E-NE 10-20 KT IN THE CENTRAL SNAKE PLAIN (KJER-KGNG).
WINDS ALOFT AT 10KFT MSL: SOUTHERLY 5-15 KT.
KBOI...VFR AND CLEAR, BECOMING OVERCAST WITH MID/HIGH CLOUDS
AFTER FRI/18Z. LIGHT, DIURNAL SURFACE WINDS.
WEEKEND OUTLOOK...LOCALIZED IFR IN MIST/FOG IN LOWER SNAKE
PLAIN AND MOUNTAIN VALLEYS SATURDAY. OTHERWISE VFR THROUGH
SATURDAY NIGHT. LOWERING CEILINGS AND A CHANCE OF RAIN AND SNOW
INCREASING ON SUNDAY. PERIODS OF MVFR/IFR IN THE E-CENTRAL OR
AND W-CENTRAL ID VALLEYS FROM PRECIP AND LOWER CIGS. IFR/LIFR
DEVELOPING IN THE MTNS, WITH MTNS BECOMING OBSCURED. SNOW LEVELS
6K-7K FEET MSL SUN, LOWERING TO 4K-6K FEET SUN NIGHT. SW-SE
SURFACE WINDS INCREASING SUNDAY.
AIR STAGNATION
WEAK WINDS AND HIGH PRESSURE WILL CONTINUE TO
SUPPORT INVERTED CONDITIONS THROUGH THE WEEKEND. AN UPPER-LEVEL
LOW PRESSURE SYSTEM, AND ITS ASSOCIATED COLD FRONT, WILL MOVE
THROUGH THE AREA BEGINNING SUNDAY. INCREASED WINDS AND COOLING
ALOFT WILL SUPPORT VERTICAL MIXING, ALLOWING VALLEY INVERSIONS
TO ERODE AS EARLY AS SUNDAY AFTERNOON.
PREV DISCUSSION
SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT...INVERTED
CONDITIONS CONTINUE THROUGHOUT THE SHORT-TERM PERIOD. MILD
TEMPERATURES WILL PERSIST THROUGH SATURDAY FOR VALLEY LOCATIONS,
WITH FORECASTED DAYTIME HIGHS THAT ARE ON PAR WITH WHAT WOULD
BE EXPECTED IF IT WERE LATE MARCH. NOT MUCH DAILY VARIATION IN
TEMPERATURES IS EXPECTED, WITH DAYTIME HIGHS IN THE MID TO
UPPER 50S IN LOWER ELEVATIONS (MOUNTAIN TEMPS IN THE 40S).
OVERNIGHT LOWS TONIGHT WILL GENERALLY BE NEAR OR BELOW FREEZING,
WARMING A COUPLE DEGREES EACH NIGHT. COME FRIDAY, AN UPPER
LEVEL SHORTWAVE WILL CLOSE OFF INTO A SHALLOW LOW AND DIVE DOWN
NEAR SOCAL. WHILE OUR AREA WILL REMAIN DRY, THIS FEATURE WILL
BRING INCREASED HIGH CLOUD COVER AND WEAKEN (BUT NOT BREAK) THE
INVERSION. HIGHER ELEVATIONS WILL BE A FEW DEGREES COOLER ON
SATURDAY AS A RESULT OF THE PASSING LOW. RIDGING WILL BRIEFLY
BUILD BACK IN SATURDAY, AHEAD OF THE NEXT SYSTEM IN THE LONG-
TERM PERIOD. FOG/HAZE WILL BE IN PLAY EACH MORNING IN LOWER
BASINS AND MOUNTAIN VALLEYS, AS MOISTURE AND COOLER AIR
CONTINUES TO GET TRAPPED UNDER THE INVERSION.
LONG TERM...SUNDAY THROUGH THURSDAY...THE UPPER RIDGE GIVES WAY ON
SUNDAY AS WESTERLY FLOW PUSHES IN FROM THE PACIFIC. A SHORTWAVE
TROUGH IS PEGGED TO MOVE INTO THE PAC NW SUNDAY NIGHT, LED BY A
SURFACE COLD FRONT. MOUNTAINS WILL SEE RAIN AND SNOW SUNDAY NIGHT
CHANGE TO MOSTLY SNOW ON MONDAY BEHIND THE FRONT. MOUNTAIN VALLEYS
COULD SEE LIGHT ACCUMULATIONS MONDAY MORNING AS SNOW LEVELS DROP
FROM 6-7KFT TO BETWEEN 4-5KFT MSL. HEAVIER SNOWFALL IS EXPECTED
ABOVE 6KFT MSL WHERE THE PROBABILITY OF >4" EXCEEDS 60%. LOWER
ELEVATIONS ACROSS SE OREGON AND THE SNAKE PLAIN IN SW IDAHO WILL SEE
A PERIOD OF LIGHT RAIN ACCOMPANY THE COLD FRONTAL PASSAGE LATE
SUN/MON WITH LIQUID AMOUNTS LIKELY TOTALING LESS THAN 0.10 INCHES.
PRECIPITATION CHANCES DROP OFF AFTER MONDAY AS A SPLIT FLOW WILL
DIRECT STORMS TO OUR NORTH/SOUTH, SHIELDING THE AREA FROM ANY
SIGNIFICANT PRECIPITATION. THERE IS UNCERTAINTY IN THE DETAILS OF
THE STORM TRACKS AND ENSEMBLE GUIDANCE KEEPS A LOW CHANCE OF SHOWERS
(15-30%) MAINLY IN THE MOUNTAINS FOR TUE-THUR. MOUNTAINS WILL SEE
TEMPERATURES COOL 10-15 DEGREES FROM SUNDAY TO MONDAY, WITH UP TO 10
DEGREES OF COOLING IN THE VALLEYS WHERE THE INVERSION WILL FINALLY
BREAK. TEMPERATURES NEXT WEEK WILL RUN SLIGHTLY ABOVE NORMAL.
BOI WATCHES/WARNINGS/ADVISORIES
ID...AIR STAGNATION ADVISORY UNTIL 5 AM MST MONDAY
IDZ012-014-016-033.
OR...AIR STAGNATION ADVISORY UNTIL 5 AM MST /4 AM PST/ MONDAY
ORZ062>064.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
DISCUSSION...SH
AVIATION.....SH
AIR STAGNATION...SH
SHORT TERM...NF
LONG TERM....DG
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