472
FXUS65 KBOI 201624
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
924 AM MST TUE JAN 20 2026
DISCUSSION
PERSISTENCE THE NEXT SEVERAL DAYS, SLIGHTLY
MODIFIED FRIDAY BY A UPPER LEVEL SHORT WAVE TROUGH AND
SURFACE COLD FRONT, THAT SHOULD WEAKEN BUT NOT FULLY SCOUR
THE INVERSION ON THE IDAHO SIDE. FORECAST HIGHS FOR TODAY
HAVE BEEN UPDATED TO BETTER MATCH OBSERVED HIGHS YESTERDAY.
NO OTHER CHANGES.
AVIATION
MVFR-LIFR BELOW 5K-6K FEET MSL IN THE SNAKE PLAIN
AND SURROUNDING BASINS DUE TO PERSISTENT LOW STRATUS AND FOG.
SURFACE WINDS: VARIABLE LESS THAN 8 KT, THEN W-NW 5-10 KT IN
SNAKE PLAIN THIS AFTERNOON. WINDS ALOFT AT 10KFT MSL: NW-N
15-30 KT.
KBOI...MVFR-IFR LOW STRATUS/FOG TO PERSIST THROUGH EARLY
AFTERNOON TODAY. SURFACE WINDS: NW AROUND 5 KT.
AIR STAGNATION
STRONG TEMPERATURE INVERSION, ALONG WITH
LIGHT BOUNDARY LAYER WINDS, WILL CONTINUE TO SUPPORT STAGNANT
VALLEY CONDITIONS ACROSS SOUTHEAST OREGON AND SOUTHWEST IDAHO.
MIXING HEIGHTS ARE EXPECTED TO REMAIN BELOW 2000 FT AGL THROUGH
AT LEAST THURSDAY, AND AN AIR STAGNATION ADVISORY REMAINS IN
EFFECT UNTIL THEN, ALTHOUGH IT MAY NEED TO BE EXTENDED UNTIL
FRIDAY MORNING. COOLING ALOFT FRIDAY SHOULD WEAKEN BUT NOT
FULLY SCOUR THE INVERSION.
PREV DISCUSSION
SHORT TERM...TODAY THROUGH THURSDAY NIGHT...LOW CLOUDS AND FOG
REMAIN IN THE VALLEYS GENERALLY BELOW 5000 FEET THIS MORNING AND
WILL CONTINUE OVER THE NEXT SEVERAL DAYS. THE CLOUDS MAY
PRODUCE FLURRIES AT TIMES. TEMPERATURES WILL REMAIN WELL BELOW
GUIDANCE AND HAVE USED PERSISTENCE IN THE FORECAST AS THE NBM
AND REST OF THE HIGH RESOLUTION GUIDANCE CANNOT RESOLVE THE
VALLEY COLD POOLS.
LONG TERM...FRIDAY THROUGH TUESDAY...DRY CONDITIONS CONTINUE
AND PERSISTENCE WAS USED AS THE ENSEMBLE AND NBM GUIDANCE WAS
USELESS. COOLER AIR ALOFT WILL BEGIN TO MOVE INTO THE AREA ON
FRIDAY WHICH MAY HELP TO MIX OUT THE LOW CLOUDS AND FOG, AND
ACTUALLY WARM UP TEMPERATURES IN THE VALLEYS, ALTHOUGH FORECAST
CONFIDENCE IS LOW. A RIDGE BUILDS INTO THE AREA AGAIN BY
TUESDAY, WITH WARMER AIR ALOFT AND A TEMPERATURE INVERSION
STRENGTHENING AGAIN. WITH PERSISTENCE USED, TEMPERATURES IN THE
VALLEYS REMAIN BELOW NORMAL WITH ABOVE NORMAL TEMPERATURES OVER
THE MOUNTAINS.
BOI WATCHES/WARNINGS/ADVISORIES
ID...AIR STAGNATION ADVISORY UNTIL 11 AM MST THURSDAY
IDZ011>014-016-028-033.
OR...AIR STAGNATION ADVISORY UNTIL 11 AM MST /10 AM PST/ THURSDAY
ORZ061>064.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
DISCUSSION...LC
AVIATION.....JY
AIR STAGNATION...SH/LC
SHORT TERM...KA
LONG TERM....KA
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