120
FXUS65 KBOI 151522
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
922 AM MDT MON SEP 15 2025
DISCUSSION
MOSTLY SUNNY TODAY (EXCEPT IN VALLEY COUNTY, ID),
AND BREEZY FROM THE NORTHWEST AS UPPER LOW IN WESTERN MT MOVES
EAST, THEN WARMING AND DRYING THROUGH FRIDAY AS THE NEXT UPPER
RIDGE COMES IN FROM THE WEST. FRIDAY LOOKS LIKE THE WARMEST
DAY, THEN SLIGHT COOLING ALONG WITH A 15-25 PERCENT CHANCE OF
SHOWERS SATURDAY AND SUNDAY, AND LARGE FORECAST UNCERTAINTY
AFTER THAT. NEAR-SURFACE HRRR SMOKE WILL BE MINIMAL THROUGH
TUESDAY. CURRENT FORECAST IS IN GOOD SHAPE. NO UPDATES.
AVIATION
VFR. ISOLATED RAIN SHOWERS AND LOCAL MOUNTAIN
OBSCURATION IN THE WEST CENTRAL IDAHO MOUNTAINS THROUGH THIS
AFTERNOON. PATCHY VALLEY FOG AND LOW STRATUS IN NORTHERN
MOUNTAINS AROUND SUNRISE TUESDAY. SURFACE WINDS: GENERALLY
W-N 10-20 KT. WINDS ALOFT AT 10KFT MSL: NW 10-15 KT.
KBOI...VFR. FEW AFTERNOON CUMULUS, OTHERWISE CLEAR. SURFACE
WINDS: NW AROUND 10 KT.
PREV DISCUSSION
SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT...A FEW SHOWERS ARE
EXPECTED TO LINGER THIS MORNING ACROSS THE WEST-CENTRAL IDAHO
MOUNTAINS AS THE UPPER-LEVEL TROUGH CONTINUES ITS SLOW EASTWARD
PROGRESSION OVER THE NORTHERN ROCKIES. THIS WILL MAINTAIN A
THREAT FOR SHOWERS AND THUNDERSTORMS (20% CHANCE) THROUGH THE
AFTERNOON. THE PRIMARY IMPACT WILL BE COOLER, NORTHWESTERLY FLOW
ACROSS THE AREA, WHICH WILL KEEP TEMPERATURES ABOUT 7 DEGREES
BELOW NORMAL. WE ARE ALSO EXPECTING BREEZY WESTERLY SURFACE
WINDS ACROSS THE SNAKE RIVER PLAIN. AN UPPER-LEVEL RIDGE WILL
BUILD INTO THE REGION ON TUESDAY, ALLOWING TEMPERATURES TO
MODERATE BACK TO NEAR NORMAL. THE RIDGE WILL REMAIN IN PLACE
THROUGH WEDNESDAY, WITH TEMPERATURES WARMING TO NEAR 5 DEGREES
ABOVE NORMAL.
LONG TERM...THURSDAY THROUGH MONDAY...AN UPPER-LEVEL RIDGE
WILL CONTINUE TO BUILD ACROSS THE REGION ON THURSDAY, BRINGING
CLEAR SKIES AND SLIGHTLY ABOVE-NORMAL TEMPERATURES, WITH HIGHS
EXPECTED TO BE ABOUT 5 DEGREES ABOVE NORMAL. ON FRIDAY, THE
RIDGE AXIS WILL GRADUALLY SHIFT EASTWARD, ALLOWING FOR THE
RETURN OF A SOUTH-TO-SOUTHWESTERLY FLOW ALOFT. THIS PATTERN
CHANGE IS DRIVEN BY AN UPPER-LEVEL TROUGH OFF THE COAST OF
CALIFORNIA. AS THE RIDGE CONTINUES TO WEAKEN, THE CHANCE OF
PRECIPITATION WILL SLOWLY INCREASE ON FRIDAY AFTERNOON AND THEN
RISE FURTHER THROUGH SATURDAY AND SUNDAY. THERE REMAINS LARGE
VARIATION IN LONG-RANGE MODEL SOLUTIONS FOR HOW THIS PATTERN
EVOLVES. THEREFORE, CONFIDENCE IS LOW IN ANY SPECIFIC DETAILS
BEYOND THIS PERIOD.
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
DISCUSSION...LC
AVIATION.....LC
SHORT TERM...JDS
LONG TERM....JDS
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