776
FXUS65 KBOI 042346
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
546 PM MDT FRI SEP 4 2026
UPDATE
UPDATED AVIATION DISCUSSION.
KEY MESSAGES
- SHOWERS AND THUNDERSTORMS WITH LOCAL HEAVY RAIN TODAY.
- AREAS OF VALLEY FOG LATE TONIGHT AND EARLY SATURDAY MORNING.
- TEMPERATURES 10 TO 20 DEGREES BELOW NORMAL TODAY, THEN AROUND 10
DEGREES BELOW NORMAL SATURDAY AND SUNDAY.
- COOL MONDAY, THEN WARMING NEXT WEEK, WITH AN INCREASING
CHANCE OF THUNDERSTORMS WEDNESDAY AFTERNOON THROUGH FRIDAY.
SHORT TERM /THROUGH SUNDAY NIGHT/
ISSUED 254 PM MDT FRI SEP 4 2026
AN UPPER LEVEL TROUGH WILL REMAIN ALONG THE OREGON COAST OVER
THE NEXT DAY WITH A FRONT STALLED OUT OVER SOUTHWEST IDAHO.
SHOWERS ALONG THE FRONT THIS AFTERNOON HAVE KEPT TEMPERATURES
WELL BELOW FORECAST FROM ROME OR TO BOISE ID TO THE CENTRAL ID
MOUNTAINS. PARTIAL CLEARING IN EASTERN OR HAS ALLOWED CONDITIONS
TO DESTABILIZE WITH ISOLATED THUNDERSTORMS DEVELOPING IN EASTERN
OR LATE THIS AFTERNOON, AND NEAR THE OWYHEE MOUNTAINS. ISOLATED
SHOWERS WILL CONTINUE OVERNIGHT ACROSS THE BOISE MOUNTAINS
BEFORE TAPERING OFF ON SATURDAY AFTERNOON AS DRIER AIR MOVES IN
FROM THE SOUTHWEST. SHOWERS AND THUNDERSTORMS WILL GENERALLY BE
CONFINED NORTH AND WEST OF BAKER COUNTY IN OR AND NORTHEAST OF
VALLEY COUNTY IN ID. THE TROUGH WILL BEGIN TO MOVE INLAND ON
SUNDAY AND ACROSS SOUTHERN ID LATE SUNDAY NIGHT, WITH SHOWERS
AND THUNDERSTORMS AREAWIDE.
LONG TERM /MONDAY THROUGH FRIDAY/
ISSUED 254 PM MDT FRI SEP 4 2026
HIGH PRESSURE ALOFT WILL START TO BUILD OVER THE AREA
MONDAY/MONDAY NIGHT AS AN UPPER LOW EXITS THE REGION ACROSS
MONTANA INTO SOUTHERN CANADA. THE HIGHER PRESSURE WILL BRING
WARMER AIR BACK INTO OUR CWA THE REST OF THE WEEK, WITH
TEMPERATURES APPROACHING NORMAL WEDNESDAY AND BEYOND. DRIER AIR
WILL SPREAD OVER THE AREA TUESDAY BUT MOISTURE WILL BE ON THE
INCREASE AGAIN LATER IN THE WEEK AS THE NEXT UPPER LOW IS
FORECAST TO MOVE INTO POSITION NEAR THE PACIFIC NORTHWEST COAST
WHILE SOUTHWESTERLY FLOW ALOFT TAPS INTO MOISTURE FROM THE NEXT
WESTWARD-MOVING HURRICANE IN THE PACIFIC SUBTROPICS. WE
THEREFORE HAVE A 20 PERCENT CHANCE OF SHOWERS AND THUNDERSTORMS
IN THE FORECAST AS EARLY AS WEDNESDAY AFTERNOON NEAR THE NEVADA
BORDER, INCREASING TO 20-40 PERCENT ACROSS THE FORECAST AREA
THURSDAY AND FRIDAY.
AVIATION /00Z SATURDAY THROUGH SUNDAY/
ISSUED 535 PM MDT FRI SEP 4 2026
MAINLY VFR. SCATTERED SHOWERS CONTINUE OVERNIGHT. AREAS OF
MVFR/IFR AND MOUNTAIN OBSCURATION IN HEAVIEST PRECIPITATION.
AREAS OF MVFR/IFR IN VALLEY FOG AFTER 05/06Z THROUGH EARLY SAT
MORNING. SNOW LEVEL 8K-10K FEET MSL. ISOLATED SHOWERS AND
THUNDERSTORMS AFTER 05/20Z IN EASTERN OREGON, AND DRY
ELSEWHERE. SURFACE WINDS: SW-NW 5-15 KT, BECOMING VARIABLE
OVERNIGHT. SSW 5-10 KT ON SAT. WINDS ALOFT AT 10KFT MSL:
SW 15-25 KT.
KBOI...VFR. INTERMITTENT SHOWERS THROUGH EARLY SAT MORNING.
AREAS OF FOG DEVELOPING EARLY SAT MORNING, BUT LOW CONFIDENCE
(30% CHANCE) OF AFFECTING THE TERMINAL. WINDS GENERALLY LIGHT
AND VARIABLE.
WEEKEND OUTLOOK...SCATTERED SHOWERS EARLY SAT MORNING BEFORE
DRYING BY LATE MORNING. ISOLATED SHOWERS AND THUNDERSTORMS
DEVELOPING IN EASTERN OREGON SAT AFTERNOON AND EVENING.
SCATTERED SHOWERS AND THUNDERSTORM DEVELOPING AREA-WIDE SUNDAY
AFTERNOON, WITH POTENTIAL FOR BRIEF HEAVY RAIN AND GUSTY OUTFLOW
WINDS. AREAS OF VALLEY LOW STRATUS/FOG EACH MORNING. SW- NW
SURFACE WINDS 5-15 KT WITH PM GUSTS TO 20KT.
BOI WATCHES/WARNINGS/ADVISORIES
ID...FLASH FLOOD WATCH UNTIL 7 PM MDT THIS EVENING FOR IDZ011-013.
OR...FLASH FLOOD WATCH UNTIL 7 PM MDT /6 PM PDT/ THIS EVENING FOR
ORZ061>063.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
AVIATION.....JR
SHORT TERM...KA
LONG TERM....TL
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