260
FXUS65 KBOI 250345
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
945 PM MDT SUN AUG 24 2025
DISCUSSION
EXTENSIVE HIGH CLOUDS CONTINUE TO STREAM NORTHWARD
FROM MONSOON MOISTURE OVER NV AND UT. SOUTH OF THE NV BORDER,
THERE ARE SCATTERED THUNDERSTORMS THIS EVENING SLOWLY DRIFTING
NORTHWARD AND WEAKENING. A SHORTWAVE NEAR LOVELOCK/BATTLE
MOUNTAIN NV WILL SLOWLY DRIFT NORTHWARD OVERNIGHT AND BE THE
FOCUS OF SHOWERS AND THUNDERSTORMS ON MONDAY AFTERNOON, MAINLY
OVER THE IDAHO MOUNTAIN ZONES AND SOUTHWEST IDAHO HIGHLANDS. A
DRY SLOT WILL MOVE ACROSS EASTERN OR, LIMITING DEVELOPMENT
THERE. FORECAST HAS BEEN UPDATED TO LOWER POPS ON MONDAY.
AVIATION
AREAS OF MVFR TO LIFR VISIBILITY FROM SMOKE IN W-CENTRAL
IDAHO (NEAR KMYL), CREATING MTN OBSCURATION. VIRGA AND SCATTERED
LIGHT RAIN OVERNIGHT. THEN, SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS BY MONDAY PM. ERRATIC GUSTY WINDS NEAR STORM ACTIVITY.
SURFACE WINDS: VARIABLE 5-15 KT. WINDS ALOFT AT 10KFT MSL: EASTERLY
10-20 KT.
KBOI...VFR. LIGHT SMOKE LAYERS DEGRADING VISIBILITY. A 30% CHANCE OF
SHOWERS/THUNDERSTORMS HITTING TERMINAL MONDAY AFTERNOON AND EVENING.
ERRATIC GUSTY WINDS FROM DISTANT STORMS WILL BE POSSIBLE. SURFACE
WINDS: NW 5-10 KT THIS EVENING, THEN VARIABLE AROUND 6 KT OVERNIGHT.
PREV DISCUSSION
SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT...THE FOUR CORNERS
HIGH HAS GRADUALLY DIMINISHED IN STRENGTH OVER THE REGION, WITH
SLIGHTLY COOLER TEMPERATURES TODAY UNDER WIDESPREAD CLOUD COVER.
ISOLATED SHOWERS AND THUNDERSTORMS WILL CONTINUE TONIGHT, WITH
LITTLE RAIN TONIGHT AHEAD OF MORE MOISTURE TOMORROW. OUTFLOW
WIND GUSTS UP TO 45 MPH ARE POSSIBLE IN STRONGER
SHOWERS/THUNDERSTORMS, PRIMARILY IN THE SOUTHERN HIGHLANDS AND
OWYHEE MOUNTAINS. COVERAGE WILL EXPAND TOMORROW WITH RAIN AND
THUNDERSTORMS EVERYWHERE EXCEPT FOR THE BAKER/LOWER TREASURE
VALLEY. RAINFALL ACCUMULATIONS WILL BE HIGHER TOMORROW, WITH
MOST SHOWERS PRODUCING AT LEAST A FEW HUNDREDTHS OF RAIN.
HEAVIER ACCUMULATIONS UP TO 0.25-0.50" INCHES OF RAIN ARE
POSSIBLE ON TUESDAY IN STRONGER SHOWERS/THUNDERSTORMS.
MONSOON MOISTURE WILL CONTINUE TO BRING CLOUDY CONDITIONS AND
INCREASED PRECIPITATION CHANCES ON TUESDAY. A SLIGHT COOLING
TREND WILL ACCOMPANY THESE SHOWERS/THUNDERSTORMS AS WELL.
PRECIPITABLE WATER VALUES WILL BE JUST OVER AN INCH BY TUESDAY
ACROSS THE REGION, NEAR THE 95TH PERCENTILE OF CLIMATOLOGICAL
VALUES. STORMS ALSO LOOK TO BE FAIRLY SLOW MOVING, WHICH
INCREASES THE THREAT OF FLASH FLOODING IN STEEP AND ROCKY
DRAINAGES AND BURN SCARS. A HYDROLOGIC OUTLOOK HAS BEEN ISSUED
TO COVER SOME OF THESE CONCERNS IN MORE DEPTH.
VALLEYS IN THE WEST CENTRAL MOUNTAINS WILL LIKELY SEE REDUCED
VISIBILITY FROM NEAR SURFACE SMOKE AND HAZE AGAIN TOMORROW
MORNING THANKS TO SMOKE FROM AREA WILDFIRES. THIS WILL LIKELY
EASE AS THE WEEK PROGRESSES THANKS TO INCOMING PRECIPITATION.
LONG TERM...WEDNESDAY THROUGH SUNDAY...THE THREAT FOR HEAVY RAIN
AND FLASH FLOODING OVER BURN SCARS WILL PERSIST WEDNESDAY INTO
THURSDAY AS MONSOONAL MOISTURE REACHES ITS PEAK. PRECIPITABLE WATER
VALUES ARE FORECAST TO CLIMB INTO THE 97TH TO 99TH PERCENTILE FOR
MID-AUGUST, SUPPORTING EFFICIENT RAINFALL RATES. ADDITIONAL LIFT
FROM THE REMNANTS OF AN UPPER-LEVEL LOW TRACKING THROUGH THE REGION
WILL PROVIDE BETTER DYNAMIC SUPPORT DURING THIS PERIOD, ENHANCING
THE POTENTIAL FOR EMBEDDED CONVECTION. GIVEN THE COMBINATION OF HIGH
MOISTURE AND INSTABILITY, FLASH FLOOD-PRONE AREAS, PARTICULARLY
RECENT BURN SCARS, WILL REQUIRE CLOSE MONITORING FOR RAPID RUNOFF
AND DEBRIS FLOWS.
BY FRIDAY, THE UPPER LOW EXITS AND THE PATTERN TRANSITIONS BACK TO
SOUTHWESTERLY FLOW ALOFT. THIS WILL SHUT OFF THE DEEPER MONSOONAL
FEED, ALLOWING DRIER AIR TO SPREAD BACK INTO THE REGION.
TEMPERATURES WILL ALSO TREND UPWARD, CLIMBING BACK ABOVE NORMAL
THROUGH THE WEEKEND.
BOI WATCHES/WARNINGS/ADVISORIES
ID...NONE.
OR...NONE.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
DISCUSSION...KA
AVIATION.....SH
SHORT TERM...SA
LONG TERM....JDS
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