690
FXUS65 KMSO 111829
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
1229 PM MDT FRI SEP 11 2026
DISCUSSION
KEY MESSAGES:
- EASTERLY GAP WINDS DURING THE OVERNIGHTS THROUGH SUNDAY
MORNING: CHOPPY LAKES AND STRONG CANYON WINDS.
- WIDESPREAD RAIN AND MOUNTAIN SNOW ABOVE 7,000 FEET LATE
SATURDAY NIGHT, THROUGH SUNDAY, INTO MONDAY.
- DRYING AND WARMING CONDITIONS BY MID-WEEK.
ISOLATED SHOWERS WILL CONTINUE OVER HIGH TERRAIN EAST OF HIGHWAY
93 THIS AFTERNOON BEFORE DIMINISHING. AN EASTERLY SURFACE PRESSURE
GRADIENT WILL BUILD TONIGHT AND PERSIST THROUGH SUNDAY MORNING,
GENERATING EAST-TO-NORTHEAST WIND GUSTS TOWARD 30 MPH THROUGH
FAVORED CANYONS, ON THE WEST SLOPES OF MAJOR MOUNTAIN RANGES, AND
ON REGIONAL LAKES INCLUDING FLATHEAD LAKE. SATURDAY THROUGH THE
EARLY EVENING WILL REMAIN MOSTLY DRY AND SLIGHTLY WARMER THAN
FRIDAY AHEAD OF THE MAIN INCOMING SYSTEM.
A CLOSED UPPER-LEVEL LOW TRACKING ACROSS THE REGION WILL PUSH
WIDESPREAD SHOWERS AND EMBEDDED THUNDERSTORMS FROM WEST TO EAST
STARTING AFTER MIDNIGHT SATURDAY NIGHT AND CONTINUING THROUGH
SUNDAY. RECENT MODEL GUIDANCE HAS SHIFTED THE LOW TRACK SLIGHTLY
FARTHER NORTH, ALSO SLIGHTLY INCREASING PRECIPITATION FORECASTS
ACROSS NORTH- CENTRAL IDAHO AND NORTHWEST MONTANA WHERE 0.50 TO
1.25 INCHES OF RAINFALL IS EXPECTED. SOUTHWEST MONTANA WILL REMAIN
ON THE DRIER PERIPHERY AND WITHIN A FETCH OF ELEVATED WEST AND
SOUTHWEST WINDS, AGAIN FOSTERING NEAR-CRITICAL FIRE WEATHER
CONDITIONS BASED SOLELY OFF OF RH AND WINDS. SNOW LEVELS DROP TO
AROUND 7,000 FEET SUNDAY INTO MONDAY MORNING, CREATING WET, COLD,
AND RAW CONDITIONS IN THE BACKCOUNTRY INCREASING THE RISK FOR
HYPOTHERMIA TO THOSE WHO ARE UNPREPARED.
THE LOW EXITS EAST BY TUESDAY, YIELDING TO A SPLIT-FLOW PATTERN
ALOFT BY MID-WEEK. TEMPERATURES WILL REBOUND TOWARD AND ABOVE SEASONAL
AVERAGES ALONGSIDE A GENERAL DRYING TREND, THOUGH MINOR EMBEDDED
DISTURBANCES WILL MAINTAIN LOW-END SHOWER CHANCES.
AVIATION
VFR FLIGHT CATEGORIES WILL PREVAIL ACROSS REGIONAL
TERMINALS THROUGH SATURDAY AFTERNOON. HOWEVER, ISOLATED
THUNDERSTORMS ARE POSSIBLE NEAR KGPI BETWEEN 11/2100Z AND
12/0100Z, CAPABLE OF BRIEF REDUCTIONS IN LOCAL VISIBILITY DUE TO
LIGHT RAIN. AN EASTERLY SURFACE PRESSURE GRADIENT WILL DEVELOP
THIS EVENING BETWEEN 12/0100Z AND 12/0600Z ACROSS THE REGION,
WITH NORTHEAST WINDS STRENGTHENING AT KGPI AFTER 12/0800Z WITH
GUSTS UP TO 20 KNOTS. THIS NEAR-SURFACE EASTERLY FLOW WILL
GENERATE LOCALIZED TURBULENCE AND LOW-LEVEL WIND SHEAR DOWNWIND OF
CANYON EXITS INTO SATURDAY MORNING. WIDESPREAD RAIN SHOWERS AND
LOWERING MVFR/IFR CEILINGS WILL ARRIVE FROM WEST TO EAST NEAR AND
AFTER 13/0600Z SATURDAY NIGHT INTO SUNDAY.
MSO WATCHES/WARNINGS/ADVISORIES
MT...FIRE WEATHER WATCH FROM SUNDAY AFTERNOON THROUGH SUNDAY EVENING
FOR EAST BEAVERHEAD.
ID...NONE.
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