242
FXUS65 KBOI 260620
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
1220 AM MDT SAT SEP 26 2026
UPDATE
UPDATED AVIATION DISCUSSION.
KEY MESSAGES
- STRONG COLD FRONT MOVING EASTWARD ACROSS IDAHO ZONES THIS
AFTERNOON BRINGING GUSTY NORTHWEST WINDS, AREAS OF BLOWING
DUST, AND FALLING TEMPERATURES.
- SATURDAY WILL BE 10 TO 20 DEGREES COOLER THAN TODAY, BUT
LESS WINDY.
- WEAK UPPER LEVEL LOW PRESSURE SUPPORTS A SLIGHT CHANCE OF
SHOWERS AND AFTERNOON THUNDERSTORMS NEAR THE NEVADA BORDER
AND IN CENTRAL IDAHO ON SUNDAY.
- SEASONABLE TEMPERATURES AND DRY MONDAY THROUGH THURSDAY.
SLIGHT CHANCE OF RAIN AND SNOW SHOWERS IN THE CENTRAL IDAHO
MOUNTAINS ON FRIDAY, BUT CONTINUED DRY ELSEWHERE.
SHORT TERM /THROUGH MONDAY NIGHT/
ISSUED 200 PM MDT FRI SEP 25 2026
A STRONG COLD FRONT WAS MOVING EASTWARD ACROSS WESTERN IDAHO
THIS AFTERNOON MARKED BY A WIND SHIFT FROM SOUTHEAST TO GUSTY
NORTHWEST AND RAPIDLY FALLING TEMPERATURES. STRONGEST GUSTS,
UP TO 45 MPH, WITH AREAS OF BLOWING DUST, WILL OCCUR IN THE
SNAKE BASIN BETWEEN BOISE AND TWIN FALLS UNTIL AROUND 6 PM MDT.
SHOWERS BEHIND THE FRONT WILL BE LIMITED TO NORTHERNMOST
MOUNTAIN AREAS WITH ONLY MINIMAL RAINFALL EXPECTED. THE REST
OF OUR CWA WILL BE MOSTLY CLOUDY BUT DRY AS THE FRONTAL ZONE
PASSES. SKIES WILL CLEAR FROM WEST TO EAST TONIGHT AND WINDS
WILL DIE DOWN LEADING TO SIGNIFICANTLY COOLER TEMPS OVERNIGHT.
CLOUDS WILL INCREASE AGAIN TOWARD MORNING IN EASTERN OREGON AS
THE NEXT UPPER TROUGH COMES IN FROM THE PACIFIC. CLOUDS WILL
SPREAD ACROSS OUR IDAHO ZONES SATURDAY AND CONTINUE OR INCREASE
FURTHER IN ALL AREAS SATURDAY AFTERNOON AND SATURDAY NIGHT,
AND CONTINUE THROUGH SUNDAY, FINALLY CLEARING IN EASTERN OREGON
SUNDAY NIGHT AND WESTERN IDAHO MONDAY. MODELS HAVE A 15-30
PERCENT CHANCE OF SHOWERS AND THUNDERSTORMS SUNDAY AFTERNOON IN
THE CENTRAL IDAHO MOUNTAINS AND NEAR THE ID/NV BORDER. SATURDAY
WILL BE ABOUT TEN DEGREES COOLER THAN NORMAL, THEN 2-4 DEGREES
WARMER SUNDAY, AND ANOTHER 2-4 DEGREES WARMER MONDAY.
LONG TERM /TUESDAY THROUGH SATURDAY/
ISSUED 200 PM MDT FRI SEP 25 2026
TUESDAY LOOKS BREEZY, DRY, AND SLIGHTLY COOLER AS THE NEXT BROAD
UPPER TROUGH FROM THE NORTH PACIFIC COMES INLAND AND PUTS OUR
AREA UNDER STRONG ZONAL FLOW. MODELS CONTINUE IN WIDE DISAGREEMENT
AFTER THAT WITH GFS STEADILY DEEPENING THE TROUGH FOR CONTINUED
COOLING WHILE ECM WEAKENS THE TROUGH FOR GRADUAL WARMING. OUR
FORECAST, BASED ON NBM, FAVORS THE WARMER ECM THROUGH THURSDAY,
THEN THE COOLER GFS FRIDAY. THE DEEPER AND COLDER GFS WILL
ALLOW A SLIGHT CHANCE OF RAIN SHOWERS AND EVEN SNOW SHOWERS IN
THE CENTRAL IDAHO MOUNTAINS ON FRIDAY.
AVIATION /06Z SATURDAY THROUGH SUNDAY/
ISSUED 1206 AM MDT SAT SEP 26 2026
GENERALLY VFR. PATCHY OF MOUNTAIN VALLEY FOG/LOW STRATUS
DEVELOPING OVERNIGHT. MVFR-LIFR CONDITIONS AND MTN OBSCURATION
IN FOG/LOW STRATUS. SURFACE WINDS: VARIABLE UP TO 10 KT, THEN
GENERALLY NE-NW 5-15 KT THIS AFTERNOON. WINDS ALOFT AT 10KFT
MSL: W 15-30 KT.
KBOI...VFR UNDER HIGH CLOUDS. SURFACE WINDS: W-NW UP TO 10 KT.
SUNDAY OUTLOOK...VFR WITH HIGH/MID LEVEL CEILINGS. ISOLATED
SHOWERS, MAINLY SE OREGON AND OVER CENTRAL ID MOUNTAINS IN THE
MORNING THROUGH EVENING. A 10% CHANCE OF LIGHTNING STRIKES WITH
THE AFTERNOON SHOWERS. SURFACE WINDS: VARIABLE 5-10 KT,
BECOMING SW-NW 5-15 KT WITH GUSTS TO 15-25 KT IN THE AFTERNOON.
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.....SH
SHORT TERM...LC
LONG TERM....LC
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