693
FXUS65 KBOI 031531
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
931 AM MDT FRI OCT 3 2025
DISCUSSION
MAIN RAIN BAND SHOULD BE EAST OF OUR CWA BY NOON
MDT. LATEST HI-RES MODELS HAVE LESS QPF THAN BEFORE IN THE
CENTRAL IDAHO MOUNTAINS, AND WE FEEL SAFE CANCELING THE FLASH
FLOOD WATCH EFFECTIVE 10 AM MDT. MEANWHILE, AN UPPER LOW IN
CALIF IS MOVING EASTWARD AND WILL CONTINUE SHOWERS ACROSS OUR
SOUTHERN-MOST ZONES, AND A WEAK SECONDARY COLD FRONT FROM THE
NORTHWEST WILL MAINTAIN THE SHOWERS AND A 20 PERCENT CHANCE OF
THUNDERSTORMS IN SOUTHEAST OR THROUGH ABOUT 8 PM PDT. THEN
CLEARING AND COOLER. RESIDUAL MOISTURE AT LOW LEVELS WILL LEAD
TO PATCHY VALLEY FOG THE NEXT SEVERAL MORNINGS. COOL TEMPS WILL
OCCUR SATURDAY THROUGH TUESDAY FOLLOWED BY A WARMING AND DRYING
TREND WEDNESDAY THROUGH NEXT SATURDAY. HOWEVER, MONDAY MORNING
LOOKS ALMOST COLD ENOUGH FOR FROST IN THE LOWER TREASURE VALLEY.
AVIATION
SHOWERS BECOMING LESS WIDESPREAD AND SHIFTING EAST
THROUGHOUT THE DAY. MVFR CEILNGS THIS MORNING IMPROVING TO VFR
BY 18Z. MOUNTAINS OBSCURED IN PRECIP AND LOW CEILNGS. SLIGHT
CHANCE OF THUNDERSTORMS IN HIGHER TERRAIN OF SE-OREGON/SW-IDAHO
AFTER 18Z. 10-15% CHANCE OF THUNDERSTORMS IN THE WESTERN MAGIC
VALLEY BETWEEN SAT/00Z AND SAT/03Z. SURFACE WINDS: VARIABLE UP
TO 10 KT THIS MORNING, BECOMING N-NW 5-15 KT THIS AFTERNOON.
KBOI...MVFR/IFR CEILNGS THIS MORNING, FOOTHILLS OBSCURED.
CONDITIONS IMPROVING TO VFR BY MID-DAY WITH WIDESPREAD SHOWERS
ENDING. HOWEVER, ISOLATED/SCATTERED SHOWERS WILL CONTINUE
THROUGH THE AFTERNOON. SURFACE WINDS: NW 8-12 KT, WITH GUSTS
UP TO 20 KT BEGINNING IN THE EARLY EVENING.
WEEKEND OUTLOOK...PATCHY AM FOG FOR SHELTERED MOUNTAIN VALLEYS
AND BASINS. SHOWERS CONTINUING IN CENTRAL IDAHO MOUNTAINS AND
AROUND KTWF/KJER SATURDAY. THEN, ISOLATED SHOWERS OVER CENTRAL
IDAHO MOUNTAINS SUNDAY. MVFR/IFR IN HEAVIER RAIN SHOWERS,
IFR/LIFR IN SNOW. SNOW LEVELS 6500-7500 FT MSL. MOUNTAINS
OBSCURED IN PRECIP. SURFACE WINDS: N-NW 10-20 KT GUSTING TO
20-30 KT SATURDAY, WITH LOCALIZED GUSTS TO 40 KT IN THE SNAKE
PLAIN. THEN, NW-NE 5-10 KT SUNDAY.
PREV DISCUSSION
SHORT TERM...TODAY THROUGH SUNDAY NIGHT...HAVE SEEN STEADY
PRECIPITATION WITH EMBEDDED THUNDERSTORMS OVERNIGHT FOCUSED
ALONG THE LEADING EDGE OF AN UPPER TROUGH. THROUGH 3AM MDT THE
HEAVIER PRECIPITATION RAN A LINE FROM THE OWYHEE MOUNTAINS TO
MCCALL, INTERSECTING THE SNAKE PLAIN IN THE VICINITY OF
CALDWELL/BOISE. THE UPPER TROUGH WILL SHIFT EASTWARD TODAY
WITH A CLOSED LOW OVER CENTRAL CA BECOMING THE DOMINANT FEATURE
FOR PRECIPITATION DEVELOPMENT BY THIS AFTERNOON. THIS WILL
RESULT IN THE GRADUAL WEAKENING THE BAND OF MODERATE TO HEAVY
RAIN THROUGH LATE MORNING. THAT SAID, LEAVING THE FLASH FLOOD
WATCH AS IS FOR NOW AS THE CHANCE OF HEAVIER SHOWERS AND
THUNDERSTORMS REMAINS FOR THIS AFTERNOON ACROSS THE W-CENTRAL
ID MOUNTAINS. THE HRRR COULD BE HEAVY-HANDED BUT IS SHOWING
LOCALIZED 0.50" AMOUNTS WITH AN AREA OF SHOWERS/STORMS. ANOTHER
AREA OF POTENTIALLY HEAVIER PRECIPITATION WILL BE SOUTHERN
HARNEY AND MALHEUR COUNTIES WHICH WILL BE POSITIONED ALONG
THE NORTHERN PERIPHERY OF THE UPPER LOW. SHOWERS AND POSSIBLE
THUNDERSTORMS WILL REGENERATE IN THIS AREA THROUGH THE DAY
RESULTING IN BROAD RAINFALL AMOUNTS BETWEEN 0.15" AND 0.30"
WITH THE POTENTIAL FOR UP TO 0.75" THROUGH THIS EVENING.
FOR THE WEEKEND, THE REGION REMAINS ON THE BACK SIDE OF A
BROADER TROUGH. THIS WILL FEED A 20-40% CHANCE OF SHOWERS
ACROSS THE MOUNTAINS OF BAKER COUNTY AND SW IDAHO WHILE LOW
ELEVATIONS ARE DRY. SNOW LEVELS WILL DROP TO BETWEEN 6-7.5KFT
MSL BY SUNDAY SO HIGHER MOUNTAINS WOULD SEE SNOW SHOWERS, BUT
LITTLE IF ANY ACCUMULATION. NORTHWEST WINDS WILL BECOME GUSTY
FRIDAY NIGHT INTO SATURDAY REACHING 15-30 MPH ACROSS OPEN
TERRAIN, WITH SITES ALONG THE SNAKE RIVER (SOUTH AND EAST OF
BOISE) SEEING GUSTS 40-45 MPH. TEMPERATURES WILL HOLD STEADY,
AVERAGING 5-10 DEGREES BELOW NORMAL.
LONG TERM...MONDAY THROUGH FRIDAY...THE BEGINNING OF THE LONG
TERM WILL PROVIDE SOME RELIEF FROM PRECIPITATION AS FLOW ALOFT
WILL BE FROM THE NORTH. THIS IS THE CASE THANKS TO A BROAD,
POSITIVELY TILTED SHORTWAVE TROUGH SPANNING OVER THE GREAT BASIN
AREA (SOUTH OF THE CWA) THAT WILL SLOWLY MOVE EAST THROUGH
THURSDAY. WITH THIS IN PLACE, AND A BLOCKING PATTERN OVER THE
SOUTHERN U.S. AND GULF STATES, UPPER-LEVEL FLOW WILL BE NEBULOUS
AND VOLATILE. LONG RANGE MODELS VARY BETWEEN WESTERLY FLOW,
SOUTHWESTERLY FLOW, OR VARYING FLOW AROUND A WEAK UPPER-LEVEL
LOW PRESSURE CENTERED NEAR THE ID/NV BORDER. REGARDLESS, A
GRADUAL WARMING TREND FROM TEMPERATURES BELOW NORMAL MONDAY TO
SLIGHTLY ABOVE NORMAL FRIDAY. BEGINNING WEDNESDAY INTO THURSDAY,
A GULF OF ALASKA LOW WILL BEGIN TO SLOWLY MOVE ONSHORE. THIS
WILL BRING SOUTHERLY/SOUTHWESTERLY FLOW AND MOISTURE TRANSPORT
BACK INTO THE REGION, WITH PRECIPITATION CHANCES RETURNING ONCE
AGAIN.
BOI WATCHES/WARNINGS/ADVISORIES
ID...FLASH FLOOD WATCH UNTIL 3 PM MDT THIS AFTERNOON IDZ011-013.
OR...NONE.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
DISCUSSION...LC
AVIATION.....NF
SHORT TERM...DG
LONG TERM....CH
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