191
FXUS65 KBOI 042054
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
254 PM MDT FRI SEP 4 2026
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/
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/
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 POSTION 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 /18Z FRIDAY THROUGH SATURDAY/
ISSUED 1158 AM MDT FRI SEP 4 2026
MOSTLY VFR. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS THIS
AFTERNOON AND TONIGHT. AREAS OF MVFR/IFR AND MOUNTAIN
OBSCURATION IN HEAVIEST PCPN. AREAS OF MVFR/IFR IN VALLEY FOG
AFTER 05/06Z. SNOW LEVEL 7.5K-9.0K FEET MSL IN E OREGON, AND
8.5-10K FEET IN W-CENTRAL ID. SURFACE WINDS: SW-NW 5-15 KT.
GUSTS TO 25 KT THIS AFTERNOON. WINDS ALOFT AT 10KFT MSL:
SW 15-25 KT.
KBOI...VFR WITH SCATTERED SHOWERS THIS AFTERNOON. A 20-30%
CHANCE OF THUNDERSTORMS FROM 21Z-24Z. VFR TONIGHT WITH A 30-40%
CHANCE OF SHOWERS. SURFACE WINDS: NW 5-15 KT. GUSTS TO 20 KT
THIS AFTERNOON. WINDS VARIABLE LESS THAN 5 KTS AFTER 05/06Z
WITH AREAS OF FOG IN THE VICINITY.
WEEKEND OUTLOOK...MOSTLY VFR. SCATTERED SHOWERS SATURDAY MORNING.
ACTIVITY DECREASING FROM SW TO NE LATE MORNING. THEN, SHOWERS
INCREASING AGAIN SUNDAY, WITH HIGHEST CHANCES (50-70%) OVER EAST
OREGON AND W-CENTRAL IDAHO. LOCALIZED MVFR/IFR AND MOUNTAIN
OBSCURATION IN HEAVIEST PCPN. AREAS OF VALLEY/LOW STRATUS
SATURDAY/ SUNDAY MORNINGS. SW-NW SURFACE WINDS 5-10 KT WITH PM
GUSTS TO 20 KT.
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
SHORT TERM...KA
LONG TERM....TL
AVIATION.....TL
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