611
FXUS65 KBOI 150020
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
620 PM MDT MON SEP 14 2026
UPDATE
UPDATED AVIATION DISCUSSION.
KEY MESSAGES
- SLIGHT WARMING AND DRYING TREND TUESDAY AND WEDNESDAY, WITH
LIGHT WINDS.
- COLD TEMPERATURES TONIGHT WILL BRING PATCHY FROST TO THE
MOUNTAIN VALLEYS.
- ANOTHER LOW PRESSURE SYSTEM WILL BRING PRECIPITATION ACROSS
THE AREA THURSDAY AND FRIDAY.
SHORT TERM /THROUGH WEDNESDAY NIGHT/
ISSUED 205 PM MDT MON SEP 14 2026
BREEZY AND COOL CONDITIONS WILL GRADUALLY DIMINISH THIS EVENING
AS THE UPPER LOW MOVES FURTHER NORTHEAST AWAY FROM THE AREA.
WARM AND DRY CONDITIONS EXPECTED TONIGHT UNDER GENERALLY CLEAR
SKIES. EXCELLENT RADIATIONAL COOLING WILL ALLOW MINIMUM
TEMPERATURES TO DROP TO AROUND 5 DEGREES BELOW SEASONAL
AVERAGES. PATCHY FROST IS POSSIBLE IN THE SHELTERED MOUNTAIN
VALLEYS BY EARLY TUESDAY MORNING.
A WEAK RIDGE ALOFT WILL BUILD OVER THE REGION TUESDAY INTO
WEDNESDAY, LEADING TO A SLIGHT WARMING AND DRYING TREND WITH
LIGHTER WINDS. THIS IS IN RESPONSE TO A DEVELOPING CUT-OFF LOW
PRESSURE SYSTEM FORMING OVER WESTERN OREGON. AFTERNOON HIGH
TEMPERATURES WILL REBOUND CLOSER TO NORMAL VALUES FOR MID
SEPTEMBER. BY LATE WEDNESDAY, THE LOW PRESSURE SYSTEM BEGINS TO
SLOWLY MOVE INLAND. SOUTHWEST FLOW AHEAD OF THIS SYSTEM WILL
BRING INCREASING CLOUD COVER AND AN INFLUX OF MID LEVEL MOISTURE
TO EASTERN OREGON AND SOUTHWESTERN IDAHO, WITH LOW CHANCES FOR
PRECIPITATION ENTERING WESTERN AREAS LATE WEDNESDAY NIGHT.
LONG TERM /THURSDAY THROUGH MONDAY/
ISSUED 205 PM MDT MON SEP 14 2026
THE END OF THE WORK WEEK WILL REMAIN UNSETTLED, WITH AN UPPER-
LEVEL LOW PRESSURE SYSTEM MOVING OVERHEAD. PRECIPITATION CHANCES
WILL BE HIGHEST IN THE WEST-CENTRAL IDAHO MOUNTAINS (50-70%
CHANCE), WITH MENTIONABLE CHANCES ELSEWHERE (15-40% CHANCE),
LOWEST IN THE VALLEYS. AFTER THIS SYSTEM MOVES OUT, AN UPPER-
LEVEL RIDGE WILL BUILD INTO THE NW U.S., BRINGING A CLEARING AND
WARMING TREND BACK TO THE AREA. MODELS ARE SPLIT ON THE FORECAST
STARTING NEXT WEEK, BUT A RETURN TO ANOTHER UNSETTLED PATTERN
LOOKS TO RETURN.
AVIATION /00Z TUESDAY THROUGH WEDNESDAY/
ISSUED 620 PM MDT MON SEP 14 2026
VFR. SURFACE WINDS: SW-NW 6-12 KT THIS EVENING, THEN VARIABLE UP
TO 10 KT OVERNIGHT. WINDS ALOFT AT 10KFT MSL: W-NW 5-15 KT.
KBOI...VFR. SURFACE WINDS: BECOMING LIGHT AND VARIABLE THIS
EVENING. THEN SE 4-10 KT OVERNIGHT AND TUE/AM.
BOI WATCHES/WARNINGS/ADVISORIES
ID...NONE.
OR...NONE.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
AVIATION.....NF
SHORT TERM...JDS
LONG TERM....CH
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