183
FXUS65 KMSO 091832
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
1232 PM MDT WED SEP 9 2026
DISCUSSION
KEY MESSAGES:
- TODAY AND THURSDAY WILL BE THE WARMEST DAYS BEFORE THE CHANGE
BACK TO FALL-LIKE WEATHER.
- CHOPPY LAKE CONDITIONS ON LAKES FOR THURSDAY DUE TO WESTERLY
WINDS BETWEEN 15 AND 25 MPH, AND LOCALLY HIGHER SPEEDS EXPECTED
OVER THE DIVIDE.
- STIFF NORTHEAST WINDS ARE POSSIBLE FRIDAY NIGHT THROUGH
SATURDAY CREATING CHOPPY CONDITIONS ON AREA LAKES.
- CUTOFF LOW BRINGS WIDESPREAD RAIN, WITH SNOW ABOVE 6000 FEET
SATURDAY NIGHT INTO SUNDAY.
NORTHWESTERLY FLOW ALOFT BEHIND A DEPARTING TROUGH OF LOW PRESSURE
WILL KEEP NEAR-NORMAL DAYTIME HIGH TEMPERATURES IN THE FORECAST
FOR THIS AFTERNOON. EXPECT CLEAR SKIES ACROSS THE NORTHERN ROCKIES
TODAY AND TONIGHT. UPPER LEVEL FLOW FLATTENS OUT, BECOMING MORE
WESTERLY ON THURSDAY AS A BROAD TROUGH OF LOW PRESSURE MOVES ALONG
THE CANADIAN BORDER. THERE WILL BE ENOUGH MOISTURE INVOLVED TO
KEEP SOME CHANCES FOR PRECIPITATION IN THE FORECAST FOR NORTHWEST
MONTANA IN THE MORNING. ELSEWHERE, THURSDAY LOOKS WARM AND DRY
WITH INCREASED WESTERLY WINDS. WINDS WILL BE GUSTY ENOUGH TO
CREATE CHOPPY CONDITIONS ON FLATHEAD LAKE AND ELEVATED FIRE
WEATHER CONCERNS FOR SOUTHWEST MONTANA.
BY THURSDAY NIGHT, A WEAK FRONT WILL BECOME THE IMPETUS FOR
SHOWERS THAT CONTINUE THROUGHOUT THE DAY FRIDAY. NORTHEAST WINDS
DEVELOP BY FRIDAY EVENING WHICH WILL ENHANCE SHOWER ACTIVITY OVER
THE GLACIER REGION, AND ALSO COULD CAUSE LAKE MACDONALD TO BECOME
CHOPPY.
AN IMPRESSIVE PRESSURE GRADIENT SETS UP ON SATURDAY IN RESPONSE
TO THE INCOMING LOW PRESSURE SYSTEM MOVING ONSHORE OVER OREGON.
THERE IS A 50% CHANCE THAT SUSTAINED WINDS COULD EXCEED 15 MPH AND
GUSTS EXCEED 25 MPH OVER FLATHEAD LAKE. OTHER AREAS, ESPECIALLY
CHANNELED LOCATIONS COULD ALSO EXPERIENCE ELEVATED WINDS.
A CUT-OFF LOW PRESSURE SYSTEM WILL TRACK FROM SOUTHWEST IDAHO
SATURDAY NIGHT TO EAST OF GREAT FALLS BY SUNDAY EVENING, BRINGING
WIDESPREAD LIGHT TO MODERATE PRECIPITATION TO CENTRAL IDAHO AND
WESTERN MONTANA. THE HEAVIEST PRECIPITATION WILL BE ROUGHLY 100
MILES NORTH AND SOUTH FROM A LINE FROM GRANGEVILLE, IDAHO TO
MISSOULA TO GREAT FALLS WITH A RANGE FROM 0.60" TO 1.60" OF TOTAL
PRECIPITATION. THE MOUNTAINS WITHIN THIS LINE COULD RECEIVE 1 TO 2
INCHES. THIS UPPER TROUGH IS A BIT COLDER THAN THE RECENT SYSTEM,
SO SNOW LEVELS COULD FALL TO AROUND 6000 FEET BY DAYBREAK SUNDAY
MORNING. IT COULD FEEL VERY WINTRY IN THE BACKCOUNTRY, ESPECIALLY
ALONG THE CONTINENTAL DIVIDE AND IN GLACIER NATIONAL PARK. A
MODERATING AND DRYING TREND IS EXPECTED BY EARLY NEXT WEEK.
AVIATION
VFR CONDITIONS AND LIGHT DIURNALLY DRIVEN WINDS
CONTINUE INTO THIS EVENING. PATCHY VALLEY FOG IS ONCE AGAIN
POSSIBLE ON THURSDAY MORNING BUT LESS COVERAGE THAN EXPERIENCED
THIS MORNING. HIGH AND MID LEVEL CLOUDS INCREASE FROM THE
NORTHWEST ON THURSDAY WITH A FEW LIGHT SHOWERS IN NORTHWEST
MONTANA. WESTERLY WINDS ALSO PICK UP WITH GUSTS OF 20-30 KTS ON
THURSDAY AFTERNOON.
MSO WATCHES/WARNINGS/ADVISORIES
MT...RED FLAG WARNING FROM NOON TO 9 PM MDT THURSDAY FOR EAST
BEAVERHEAD.
ID...NONE.
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