610
FXUS65 KBOI 021207
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
607 AM MDT WED SEP 2 2026
UPDATE
UPDATED AVIATION DISCUSSION.
KEY MESSAGES
- ISOLATED TO SCATTERED THUNDERSTORMS THIS MORNING, MAINLY
ACROSS THE MOUNTAINS OF CENTRAL IDAHO.
- WIDESPREAD SHOWERS AND EMBEDDED THUNDERSTORMS ACROSS MUCH OF
SOUTHEAST OREGON AND WEST-CENTRAL IDAHO WEDNESDAY NIGHT
THROUGH THURSDAY WITH SIGNIFICANT RAINFALL TOTALS POSSIBLE.
- MUCH COOLER THIS WEEK, WITH HIGHS 10-20 DEGREES BELOW NORMAL
BY THURSDAY WITH PERIODS OF GUSTY WINDS.
- ADDITIONAL WET AND COOL WEATHER ANTICIPATED LATE THIS WEEKEND
INTO EARLY NEXT WEEK.
SHORT TERM /THROUGH FRIDAY NIGHT/
ISSUED 300 AM MDT WED SEP 2 2026
A NEGATIVELY TILTED UPPER LEVEL TROUGH IS PUSHING THROUGH THE
REGION THIS MORNING, INITIALLY TRIGGERING MAINLY VIRGA SHOWERS
ACROSS SOUTHEAST OREGON DUE TO DRY LOW LEVEL AIR. RH'S ACROSS
SOUTHEAST OREGON REMAIN IN THE TEENS THIS MORNING, THUS LIMITING
RAINFALL. HOWEVER, AS THE SYSTEM TRACKS EASTWARD TOWARD
SOUTHWEST IDAHO BY SUNRISE, IT WILL INTERACT WITH A CORRIDOR OF
DEEPER ATMOSPHERIC MOISTURE. THIS INTERACTION WILL ALLOW SHOWERS
TO BECOME MORE ORGANIZED, INCREASING PRECIPITATION COVERAGE AND
CHANCES FOR RAIN AND THUNDERSTORMS FOR LOWER ELEVATIONS AND
MOUNTAIN ZONES ALIKE.
BY THIS EVENING, A LARGE UPPER LEVEL LOW APPROACHES THE
WASHINGTON COAST, SENDING A BROAD PLUME OF PACIFIC MOISTURE OVER
OUR AREA. THE SETUP RESEMBLES A LATE FALL OR EARLY WINTER
WEATHER PATTERN, CHARACTERIZED BY STRONG SOUTHWESTERLY FLOW
ALOFT. DOWNSLOPE WINDS OFF SURROUNDING TERRAIN WILL LIKELY CAUSE
SOME VALLEY SHADOWING INITIALLY, LIMITING PRECIPITATION TOTALS
FOR THE TREASURE VALLEY AND BAKER VALLEY BEFORE LOWER LEVELS
SATURATE.
PERIODS OF RAIN 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 OF AN INCH FROM
TODAY THROUGH FRIDAY EXCEPT FOR THE WESTERN MAGIC VALLEY AND
CAMAS PRAIRIE. MOUNTAINS SHOULD SEE BENEFICIAL RAINFALL NEAR AN
INCH TOTAL WITH THE VALLEY SEEING AROUND 0.25'. EMBEDDED
THUNDERSTORMS COULD PRODUCE LOCALLY HIGHER AMOUNTS. ALTHOUGH
RAIN LOOKS TO BE STEADY THROUGH FRIDAY ACROSS MUCH OF THE AREA,
THE AMOUNT OF PRECIPITATION COULD CAUSE SOME LOCALIZED FLOODING
ISSUES FOR THE RECENT BURN SCARS. 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 300 AM MDT WED SEP 2 2026
MODEL ENSEMBLES SHOW THE BROAD UPPER LEVEL LOW MAINTAINING ITS
INFLUENCE OVER THE PACIFIC NORTHWEST THROUGH THE WEEKEND BEFORE
GRADUALLY SHIFTING EASTWARD EARLY NEXT WEEK. ON SATURDAY,
PERSISTENT SOUTHWESTERLY FLOW ALOFT WILL MAINTAIN A CHANCE OF
SHOWERS, PRIMARILY FOCUSED OVER THE HIGHER TERRAIN OF CENTRAL
IDAHO AND EASTERN OREGON, WHILE LOWER VALLEYS EXPERIENCE LOWER
PRECIPITATION ODDS. THE UPPER LEVEL LOW PUSHES EAST ACROSS THE
AREA ON SUNDAY AND THIS IS WHEN IT COULD POTENTIALLY LINK UP
WITH MOISTURE FROM HURRICANE MARIE, INCREASING THE THREAT FOR
HEAVIER PRECIPITATION ACROSS SOUTH-CENTRAL IDAHO. OVERALL
CONFIDENCE REMAINS LOW AT THIS TIME, BUT A GROWING NUMBER OF
ENSEMBLES HAVE SHIFTED TOWARDS THIS MOISTURE MOVING ACROSS THE
GREAT BASIN IN THE LATEST RUNS.
AS THE MAIN LOW AXIS FINALLY CROSSES THE NORTHERN ROCKIES
MONDAY, COOLER TEMPERATURES AND ADDITIONAL SHOWER ACTIVITY WILL
SWEEP THROUGH THE REGION. SNOW LEVELS MAY LOWER ENOUGH TO BRING
LIGHT SNOW OR MIXED PRECIPITATION TO THE HIGHEST PEAKS. 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. HIGH
TEMPERATURES THROUGHOUT THE LONG TERM PERIOD WILL REMAIN
GENERALLY NEAR OR SLIGHTLY BELOW SEASONAL AVERAGES.
AVIATION /12Z WEDNESDAY THROUGH THURSDAY/
ISSUED 603 AM MDT WED SEP 2 2026
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WILL CONTINUE ACROSS
TREASURE VALLEY AND W-CENTRAL ID THROUGH THE REMAINDER OF THE
MORNING. THUNDERSTORMS CAPABLE OF BRIEF MVFR/IFR HEAVY RAIN,
HAIL, AND GUSTY OUTFLOWS. THEN, WIDESPREAD RAIN DEVELOPING EARLY
THIS EVENING, WITH MTNS BECOMING OBSCURED. SURFACE WINDS: SW-NW
5-15 KT, GUSTS TO 20-30 KT DURING AM PRECIP. THEN, SW 10-20 KT
WITH 25- 30 KT GUSTS THIS AFTERNOON. WINDS ALOFT AT 10KFT MSL:
S-SW 10- 20 KT.
KBOI...VFR. A 30 PERCENT CHANCE OF LIGHT RAIN SHOWERS DURING MORNING
HOURS, THEN RAIN EXPECTED THIS EVENING THROUGH MUCH OF THURSDAY. SURFACE
WINDS: SE 5-10 KT, BECOMING NW OR VARIABLE AROUND WED/10Z. THEN
SW 5- 15 KT, WITH GUSTS AROUND 20-25 KT THIS AFTERNOON.
BOI WATCHES/WARNINGS/ADVISORIES
ID...OR...NONE.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
AVIATION.....JDS
SHORT TERM...JDS
LONG TERM....JDS
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