968
FXUS65 KBOI 030041
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
641 PM MDT WED SEP 2 2026
UPDATE
UPDATED AVIATION DISCUSSION.
KEY MESSAGES
- INTERMITTENT SHOWERS AND EMBEDDED THUNDERSTORMS ACROSS MUCH
OF SOUTHEAST OREGON AND WEST-CENTRAL IDAHO WEDNESDAY NIGHT
THROUGH FRIDAY WITH SIGNIFICANT RAINFALL TOTALS POSSIBLE.
- MUCH COOLER THIS WEEK, WITH HIGHS 10-20 DEGREES BELOW NORMAL
BY THURSDAY WITH PERIODS OF GUSTY WINDS.
- COOLER THAN NORMAL WEATHER ANTICIPATED LATE THIS WEEKEND INTO
EARLY NEXT WEEK.
SHORT TERM /THROUGH FRIDAY NIGHT/
ISSUED 225 PM MDT WED SEP 2 2026
THE LARGE UPPER LOW IS CONTINUING TO STEER INTO THE NORTHWEST
REGION, CONTINUING A STRONG SOUTHWEST FLOW ALOFT AND SENDING A
PLUME OF PACIFIC MOISTURE INTO OUR AREA. A BAND OF STRATIFORM
RAIN SHOWERS IS MOVING TOWARDS OUR AREA FROM OFF THE NORTHWEST
COAST THIS AFTERNOON, AND EXPECTED TO BRING WIDESPREAD
PRECIPITATION OVER THE AREA THIS EVENING THROUGH MOST OF
THURSDAY. LATEST SATELLITE IMAGERY INDICATES SOME ONGOING
CLEARING AND CUMULUS BUILDUPS AHEAD OF THE PRECIP FRONT,
FAVORING SOME EMBEDDED ISOLATED THUNDERSTORMS OVER EASTERN OR
AND THE CENTRAL ID MOUNTAINS THIS EVENING THROUGH LATE TONIGHT.
THESE THUNDERSTORMS WILL BE CAPABLE OF LOCALIZED HEAVY RAIN.
PERIODS OF RAIN WILL CONTINUE IN VARIED COVERAGE THURSDAY INTO
FRIDAY AS THE PARENT LOW REMAINS POSITIONED OVER THE PACIFIC
NORTHWEST COAST. ALL AREAS SHOULD SEE AT LEAST A TENTH TO A
HALF INCH FROM TODAY THROUGH FRIDAY EXCEPT FOR THE WESTERN
MAGIC VALLEY AND CAMAS PRAIRIE, WHERE LESSER AMOUNTS WILL FALL.
MOUNTAINS SHOULD SEE BENEFICIAL RAINFALL WITH 1.0 TO 1.5 INCH
THROUGH FRIDAY EVENING. EMBEDDED THUNDERSTORMS, CAPABLE OF
PRODUCING LOCALLY HEAVIER AMOUNTS, REMAIN POSSIBLE IN THE
AFTERNOON/EVENING THURSDAY AND FRIDAY AND COULD CAUSE SOME
LOCALIZED FLASH FLOODING ISSUES FOR THE RECENT BURN SCARS NOTED
IN THE FLASH FLOOD WATCH. LOWERING HEIGHTS AND COOL ONSHORE
FLOW WILL KEEP TEMPERATURES WELL BELOW NORMAL THROUGH FRIDAY.
SOUTHEAST OREGON AND THE WEST CENTRAL MOUNTAINS OF IDAHO WILL
SEE RECORD TO NEAR RECORD LOW MAX TEMPERATURES THURSDAY AND
FRIDAY.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
ISSUED 225 PM MDT WED SEP 2 2026
LONG-RANGE GUIDANCE CONTINUES TO FAVOR THE LARGE UPPER LOW
HANGING OVER THE NORTHWEST COAST REGION ON SATURDAY. THIS
PATTERN WILL KEEP OUR AREA UNDER A SOUTHWEST FLOW THAT WILL WARM
TEMPERATURES BACK UP TO NEAR-NORMAL. DRIER CONDITIONS ARE
EXPECTED SATURDAY EXCEPT FOR WEAK SHOWERS OVER HIGH TERRAIN
AREAS OF CENTRAL ID AND EASTERN OR. THE UPPER LEVEL LOW WILL
BEGIN STEERING EAST OVER OUR AREA ON SUNDAY, WHILE CAPTURING
ABUNDANT PACIFIC MOISTURE FROM THE LOWER SOUTHWEST. THIS PATTERN
SHIFT WILL BRING HEIGHTENED CHANCES FOR HEAVY RAINFALL OVER
SOUTH-CENTRAL ID LATE SUNDAY AND THROUGH MOST OF MONDAY. SNOW
LEVELS MAY LOWER ENOUGH TO BRING LIGHT SNOW OR MIXED
PRECIPITATION TO THE HIGHEST PEAKS.
THE PATTERN WILL CONTINUE COOLER THAN NORMAL TEMPERATURES
THROUGH EARLY NEXT WEEK. BY TUESDAY AND WEDNESDAY, ENSEMBLE
CLUSTERS FAVOR A TRANSITION TO DRIER CONDITIONS AND A SUBTLE
WARMING TREND AS AN UPPER LEVEL RIDGE ATTEMPTS TO BUILD INLAND
FROM THE PACIFIC COAST. TEMPERATURES THROUGHOUT THE LONG TERM
PERIOD WILL REMAIN GENERALLY NEAR OR SLIGHTLY BELOW SEASONAL
AVERAGES.
AVIATION /00Z THURSDAY THROUGH FRIDAY/
ISSUED 630 PM MDT WED SEP 2 2026
RAIN BECOMING WIDESPREAD THIS EVENING THROUGH MORNING,
TRANSITIONING TO SCATTERED SHOWERS LATE MORNING BEFORE RETURNING
TO WIDESPREAD THU AFTERNOON. MVFR/IFR CONDITIONS AND MOUNTAIN
OBSCURATION IN HEAVIER PRECIP. A 15% CHANCE OF EMBEDDED
THUNDERSTORMS IN E OREGON AND W-CENTRAL ID THROUGH THURSDAY.
SNOW LEVELS LOWERING TO 7500 FT MSL IN E OREGON THURSDAY PM.
SURFACE WINDS: SW-W 10-20 KT. GUSTS TO 25-35 KT GUSTS THROUGH
LATE TONIGHT. THEN, SE-SW 5-15 KT WITH GUSTS AROUND 20 KT
THURSDAY MORNING. WINDS ALOFT AT 10KFT MSL: S-SW 15-30 KT.
KBOI...GENERALLY VFR. LIGHT RAIN IN VICINITY THIS EVENING,
ARRIVING AT TERMINAL BETWEEN THU/04Z-06Z WITH A 10% CHANCE OF
MVFR CEILINGS. TRANSITIONING TO PERIODIC SHOWERS AFTER
APPROXIMATELY THU/14Z. THEN, CONTINUOUS RAIN RETURNING LATE
THURSDAY AFTERNOON WITH A 20% CHANCE OF MVFR BY THE EVENING.
SURFACE WINDS: SW-W 5-15 KT, SHIFTING TO NW-NE 5-15 KT WITH
ONSET OF RAIN. THEN, E-SE 5-15 KT AFTER THU/11Z.
BOI WATCHES/WARNINGS/ADVISORIES
ID...FLASH FLOOD WATCH FROM THURSDAY AFTERNOON THROUGH FRIDAY
EVENING FOR IDZ011.
FLASH FLOOD WATCH FROM MIDNIGHT MDT TONIGHT THROUGH FRIDAY
EVENING FOR IDZ013.
OR...FLASH FLOOD WATCH FROM THURSDAY AFTERNOON THROUGH FRIDAY
EVENING FOR ORZ061>063.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
AVIATION.....SH
SHORT TERM...JY
LONG TERM....JY
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