775
FXUS65 KBOI 010405
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
905 PM MST SAT JAN 31 2026
DISCUSSION
A HIGH PRESSURE RIDGE REMAINS OVER THE AREA WITH
HIGH CLOUDS STREAMING IN FROM THE WEST-SOUTHWEST FROM A SYSTEM
OFFSHORE. MILD TEMPERATURES CONTINUE WITH PATCHY FOG OVERNIGHT
IN MOUNTAIN VALLEYS AND IN THE LOWER TREASURE VALLEY. SLIGHTLY
WARMER TEMPERATURES EXPECTED ON SUNDAY AFTERNOON. NO UPDATES.
AVIATION
GENERALLY VFR OVERNIGHT AND INTO SUNDAY, WITH THE
POTENTIAL FOR MVFR/IFR CONDITIONS DUE TO VISIBILITY RESTRICTIONS
FOR THE LOWER TREASURE VALLEY OVERNIGHT. SURFACE WINDS:
VARIABLE UP TO 8 KT. WINDS ALOFT AT 10KFT MSL: W 15-25 KT.
KBOI...VFR. 20% CHANCE OF MVFR CONDITIONS DUE TO VISIBILITY
OVERNIGHT. LIGHT SURFACE WINDS.
PREV DISCUSSION
SHORT TERM...TONIGHT THROUGH MONDAY NIGHT...A LONG-WAVE UPPER
RIDGE, QUASI-STATIONARY OVER THE EASTERN PACIFIC AND WESTERN US,
WILL FLATTEN SUNDAY BY A WEAK INCOMING NORTH PACIFIC TROUGH,
THEN REBUILD MONDAY. AN INVERSION WILL CONTINUE IN THE VALLEYS,
UNAFFECTED BY THE PACIFIC UPPER TROUGH. THE RIDGE WILL MAINTAIN
DRY, MILD WEATHER ABOVE THE INVERSION, WHILE THE PACIFIC TROUGH
BRINGS ONLY CLOUDS BUT NO PRECIPITATION. LITTLE DAY-TO-DAY
CHANGE IN TEMPERATURE IN THE VALLEYS, BUT MOUNTAINS WILL BE 2 TO
5 DEGREES COOLER SUNDAY AND MONDAY DUE TO THE TROUGH. LIGHT
WINDS THROUGHOUT.
LONG TERM...TUESDAY THROUGH SATURDAY...A SHORTWAVE TROUGH
PASSING TO OUR NORTH WILL BRING A FEW MORE CLOUDS TO THE AREA
ON MONDAY AND TUESDAY, BUT THE OVERALL DRY WEATHER PATTERN WILL
CONTINUE. THE PERSISTENT UPPER LEVEL RIDGE WILL BUILD BACK EVEN
STRONGER WEDNESDAY THROUGH FRIDAY. THIS PATTERN IS EXPECTED TO
INTENSIFY THE TEMPERATURE INVERSION OVER THE AREA BRINING WARMER
CONDITIONS TO THE MOUNTAINS AND ALLOWING COLD POOLS OF AIR TO
DEVELOP AND BE TRAPPED IN VALLEY LOCATIONS. THE STRONG
TEMPERATURE INVERSION WILL ALSO MAKE THE STAGNANT AIR SITUATION
WORSE TRAPPING POLLUTION IN VALLEYS. FOG AND LOW STATUS CLOUDS
ARE ALSO LIKELY TO FORM IN LOWER VALLEY LOCATIONS WEDNESDAY
THROUGH FRIDAY.
BOI WATCHES/WARNINGS/ADVISORIES
ID...AIR STAGNATION ADVISORY UNTIL 11 AM MST FRIDAY IDZ012-033.
OR...AIR STAGNATION ADVISORY UNTIL 11 AM MST /10 AM PST/ FRIDAY
ORZ064.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
DISCUSSION...KA
AVIATION.....MC
SHORT TERM...LC
LONG TERM....JB
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