702
FXUS65 KBOI 252340
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
540 PM MDT TUE AUG 25 2026
UPDATE
UPDATED AVIATION DISCUSSION.
KEY MESSAGES
- ISOLATED AFTERNOON THUNDERSTORMS TODAY AND WEDNESDAY, MAINLY
FORMING OVER THE IDAHO MOUNTAINS, AND SOUTHERN TWIN FALLS
COUNTY ON THURSDAY AFTERNOON.
- A SLIGHT WARMING TREND TUESDAY AND WEDNESDAY, THEN GRADUALLY
COOLING THE REST OF THE WEEK WITH BREEZY CONDITIONS.
- SCATTERED SHOWERS AND THUNDERSTORMS OVER SOUTHWEST IDAHO ON
FRIDAY AND SATURDAY. SOME OF THE STORMS MAY BE SEVERE.
SHORT TERM /THROUGH THURSDAY NIGHT/
ISSUED 205 PM MDT TUE AUG 25 2026
A SEASONABLY STRONG ANTICYCLONE OVER ARIZONA AND NEW MEXICO IS
DOMINATING THE SYNOPTIC PATTERN OVER THE WESTERN CONUS, LEAVING
THE INTERIOR NORTHWEST IN BROAD AND STRENGTHENING SOUTHWEST FLOW
ALOFT. THIS ALSO MEANS WARM TEMPERATURES WILL CONTINUE WITH
LITTLE DAY-TO-DAY CHANGE THROUGH THURSDAY. THE PRIMARY CONCERNS
WILL REVOLVE AROUND THE POTENTIAL FOR THUNDERSTORMS EACH
AFTERNOON, AND THEN INCREASING WINDS WITH LOW HUMIDITY BY
THURSDAY. THUNDERSTORMS ARE MOST LIKELY NEAR THE NEVADA BORDER
INTO THE WESTERN MAGIC VALLEY BOTH THIS AFTERNOON AND WEDNESDAY
AFTERNOON, WITH STRONG GUSTY WINDS THE PRIMARY THREAT. ISOLATED
THUNDERSTORMS ARE STILL POSSIBLE OVER THE CENTRAL IDAHO
MOUNTAINS AS WELL. DRIER AIR WILL LIMIT ANY THUNDERSTORM
POTENTIAL OVER EASTERN OREGON, INCLUDING MALHEUR/HARNEY AND THE
OREGON OUTBACK, WITH ONLY LOW PROBABILITIES EXISTING OVER BAKER
COUNTY. BY THURSDAY, THE INCREASE IN SOUTHWEST FLOW ALOFT
ASSOCIATED WITH A STRENGTHENING TROUGH EJECTING EASTWARD ACROSS
OREGON WILL BRING GUSTY WINDS TO SOUTHEAST OREGON AND FAR
SOUTHWEST IDAHO. THIS WILL COMBINE WITH THE ANTECEDENT LOW
RH/DRY CONDITIONS AND WARM TEMPERATURES TO CREATE AN ELEVATED
WIND-DRIVEN FIRE WEATHER THREAT ACROSS THESE AREAS.
LONG TERM /FRIDAY THROUGH TUESDAY/
ISSUED 205 PM MDT TUE AUG 25 2026
DROP TEMPERATURES DOWN TO NEAR NORMAL. AHEAD OF THIS COLD FRONT,
TROPICAL STORM ISELLE WILL WEAKEN, WITH ITS REMNANT MOISTURE
TRANSPORTED OVER OUR AREA IN SOUTHWESTERLY FLOW ALOFT. AS THE LONG
RANGE ENSEMBLE GUIDANCE SEES IT, PWAT VALUES ACROSS SOUTHWEST
IDAHO WILL INCREASE TO AROUND THE 95TH PERCENTILE OF CLIMATOLOGY
(HIGHEST NEAR THE MAGIC VALLEY AND EASTWARD). THE TIMING OF THE
COLD FRONT AND MOISTURE ADVECTION RIGHT NOW LOOKS FAVORABLE FOR
THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS COME FRIDAY
AFTERNOON, MAINLY IN SW IDAHO AND THE SOUTHEASTERN PORTIONS OF
THE GREAT SANDY DESERT. WITH HIGH PWATS, HEAVY RAIN WILL BE A
HAZARD WITH STORMS THAT DEVELOP AND THE FLASH FLOOD RISK WILL
NEED TO BE MONITORED.
THE COLD FRONT AND ASSOCIATED UPPER TROUGH WILL BE QUICK TO PUSH THE
MOISTURE OFF TO THE EAST COME SATURDAY. THE WEEKEND WILL FEATURE
GENERALLY DRY CONDITIONS WITH TEMPERATURES AT OR BELOW NORMAL. COME
MONDAY/TUESDAY, ANOTHER TROUGH DIGGING DOWN THE COAST OF BRITISH
COLUMBIA AND GRAZING OUR AREA WILL BRING A SLIGHT CHANCE OF
PRECIPITATION ACROSS HIGHER TERRAIN OF SOUTHWEST IDAHO. THIS FALL-
LIKE TRANSITION PATTERN LOOKS TO CONTINUE BEYOND THE LONG-TERM
PERIOD, WITH THE EXTENDED OUTLOOKS LEANING TOWARDS ABOVE NORMAL
PRECIPITATION AND BELOW NORMAL TEMPERATURES.
AVIATION /00Z WEDNESDAY THROUGH THURSDAY/
ISSUED 527 PM MDT TUE AUG 25 2026
VFR. ISOLATED SHOWERS AND THUNDERSTORMS THROUGH EVENING MAINLY
AROUND KTWF/KJER AND CENTRAL ID MTNS. THUNDERSTORMS CAPABLE OF
OUTFLOWS TO 30-40 KT AND BLOWING DUST. STORMS RETURNING NEAR
KTWF/KJER AND CENTRAL ID MTNS WED AFTERNOON. HIGH DENSITY
ALTITUDE IN THE AFTERNOONS DUE TO HEAT. SURFACE WINDS:
SE-SW 5-15 KT, GUSTS AROUND 20-25 KT BEFORE SUNSET. THEN,
VARIABLE 5-12 KT OVERNIGHT. WINDS ALOFT AT 10KFT MSL: SW 10-25
KT.
KBOI...VFR. ISOLATED SHOWERS/THUNDERSTORMS MOVING NE THROUGH
UPPER TREASURE VALLEY, MAINLY KEEPING SOUTH AND EAST OF KBOI
VICINITY. STORMS CAPABLE OF OUTFLOWS TO 20-30 KT THAT COULD
REACH AIRPORT. SURFACE WINDS: VARIABLE 5-10 KT, EXCEPT DURING
OUTFLOW GUSTS. SE 5-15 KT AFTER WED/02Z.
BOI WATCHES/WARNINGS/ADVISORIES
ID...FIRE WEATHER WATCH FROM THURSDAY AFTERNOON THROUGH THURSDAY
EVENING FOR IDZ423.
OR...FIRE WEATHER WATCH FROM THURSDAY MORNING THROUGH THURSDAY
EVENING FOR ORZ670>672.
AIR QUALITY ALERT UNTIL NOON PDT WEDNESDAY FOR ORZ062.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
AVIATION.....SH
SHORT TERM...JR
LONG TERM....NF
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