564
FXUS65 KMSO 221529
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
929 AM MDT SAT AUG 22 2026
UPDATE
RED FLAG WARNING ISSUED ACROSS THE WEST LOLO AND
KOOTENAI NATIONAL FORESTS 5 PM TODAY THROUGH 6 AM SUNDAY FOR
LIGHTNING AND OUTFLOW WINDS. RED FLAG WARNING ISSUED FOR
DEERLODGE/WEST BEAVERHEAD FROM 1 PM TO 8 PM SUNDAY DUE TO WINDY
AND DRY CONDITIONS.
PREV DISCUSSION
/ISSUED 400 AM MDT SAT AUG 22 2026/
DISCUSSION...
KEY MESSAGES:
- STRONG TO SEVERE THUNDERSTORMS TODAY THROUGH THE AFTERNOON AND
EVENING.
- COLD FRONT SUNDAY BRINGS COOLER TEMPERATURES BUT STRONG
WESTERLY WINDS AND VERY DRY AIR.
- RIDGE REBUILDS INTO NEXT WEEK.
LIGHT RAIN SHOWERS THIS MORNING DEPICTED ON RADAR CONTINUE TO
EXPAND NORTHWARD. THE MAIN CONVECTIVE EVENT DEVELOPS THIS
AFTERNOON AROUND AND AFTER 2PM MDT. STORMS WILL GENERALLY TRACK
FROM SOUTHWEST TO NORTHEAST. A MARGINAL RISK FOR SEVERE
THUNDERSTORMS COVERS THE REGION, WITH DAMAGING WIND GUSTS TOWARD
60 MPH REMAINING THE PRIMARY HAZARD OF CONCERN ALONGSIDE SMALL
HAIL AND FREQUENT LIGHTNING. HIGH PRECIPITABLE WATER VALUES
ENTERING THE REGION UNDER MONSOONAL FLOW WILL SUPPORT BRIEF HEAVY
RAINFALL UNDER STRONGER SHOWERS AND STORMS BRINGING LOCALIZED
THREATS FOR EXCESSIVE RUNOFF AND FLASH FLOODING OVER URBAN AREAS
AND WITHIN STEEP TERRAIN AND BURN SCARS. LINGERING SHOWERS AND
ISOLATED CONVECTION WILL PERSIST THROUGH THE OVERNIGHT AS THE
STRONG TO SEVERE THUNDERSTORM THREAT BEGINS TO DIMINISH.
A COLD FRONT CROSSED THE NORTHERN ROCKIES LATE TONIGHT INTO
SUNDAY, USHERING IN A BRIEF TEMPERATURE RESPITE WITH DAYTIME HIGHS
DROPPING 10 TO 15 DEGREES TO NEAR SEASONAL AVERAGES. DEEP
BOUNDARY-LAYER MIXING BEHIND THE FRONT WILL DRIVE STRONG WESTERLY
WINDS WITHIN THE VERY DRY POST-FRONTAL AIRMASS. ELEVATED TO
CRITICAL FIRE WEATHER CONDITIONS ARE ANTICIPATED ACROSS THE REGION
ON SUNDAY.
HIGH PRESSURE REBUILDS EARLY NEXT WEEK MARKING THE RETURN OF HOT
DAYTIME TEMPERATURES AND GENERALLY DRY CONDITIONS. NEAR-DAILY
AFTERNOON SHOWERS AND THUNDERSTORMS WILL REMAIN POSSIBLE IN
SOUTHWESTERN MONTANA AND LEMHI COUNTY.
ENSEMBLE CLUSTER ANALYSIS SHOWS MODERATELY HIGH CONFIDENCE (70%)
IN A PROGRESSIVE PATTERN RETURNING TO THE REGION BY MID-TO-LATE
NEXT WEEK, THOUGH DETAILS ABOUT TIMING AND STRENGTH OF ANY
INBOUND TROUGHING REMAIN UNCERTAIN AT THIS TIME.
AVIATION...MORNING LIGHT RAIN SHOWERS WILL YIELD TO STRONG
AFTERNOON AND EVENING THUNDERSTORMS TRACKING SOUTHWEST TO
NORTHEAST BETWEEN 22/2000Z AND 23/0400Z. LOCALIZED DIRECT IMPACTS
FROM CONVECTION WILL BRING ERRATIC OUTFLOW WIND GUSTS OF 30 TO 50
KNOTS, SMALL HAIL, BRIEF HEAVY RAINFALL CAUSING LOCALIZED
MVFR/IFR VISIBILITY, ALONG WITH LLWS AND TURBULENCE NEAR STORM
CORES. STRONG WESTERLY WINDS DEVELOP POST-FRONTALLY ON SUNDAY ON
AN OTHERWISE DRY AND LESS-PROBLEMATIC DAY FOR AVIATION.
MSO WATCHES/WARNINGS/ADVISORIES
MT...RED FLAG WARNING FROM 5 PM THIS AFTERNOON TO 6 AM MDT SUNDAY FOR
KOOTENAI...WEST LOLO.
RED FLAG WARNING FROM 1 PM TO 8 PM MDT SUNDAY FOR DEERLODGE/WEST
BEAVERHEAD.
ID...NONE.
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