660
FXUS65 KMSO 101951
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
151 PM MDT THU SEP 10 2026
DISCUSSION
KEY MESSAGES:
- NORTHEAST WINDS FRIDAY NIGHT THROUGH SATURDAY WILL CREATE
CHOPPY CONDITIONS ON AREA LAKES.
- A CUTOFF LOW PRESSURE SYSTEM BRINGS WIDESPREAD RAIN, WITH SNOW
ABOVE 6,000 FEET SATURDAY NIGHT THROUGH MONDAY MORNING.
A FAST-MOVING TROUGH WILL DROP SOUTH OUT OF CANADA TODAY, BRINGING
UPPER-LEVEL ENERGY WITH IT THIS EVENING AND OVERNIGHT. THIS WILL PUSH A
BAND OF SHOWERS AND ISOLATED THUNDERSTORMS THROUGH WESTERN MONTANA AND
NORTH-CENTRAL IDAHO BY EARLY FRIDAY MORNING. EXPECT BREEZY WESTERLY WINDS
GUSTING 15 TO 25 MPH, ALONG WITH BRIEF, LIGHT TO MODERATE RAINFALL OF 0.10
TO 0.40 INCHES BY SUNRISE FRIDAY MORNING.
BEHIND THIS TROUGH, A COLD FRONT WILL MOVE SOUTH OUT OF ALBERTA, CANADA,
BRINGING BREEZY EAST TO NORTHEAST WINDS FRIDAY EVENING. THESE WINDS WILL
REMAIN OVER THE AREA THROUGH THE DAY ON SATURDAY. TEMPERATURES FRIDAY AND
SATURDAY WILL RUN 5 TO 10 DEGREES BELOW NORMAL FOR THIS TIME OF YEAR. IT
WILL FEEL EVEN COOLER SATURDAY AFTERNOON WITH EAST WINDS GUSTING AROUND 20
MPH. THE EAST WINDS WILL INCREASE AFTER SUNSET SATURDAY EVENING, WITH GUSTS
UP TO 30 MPH IN THE FAVORED EAST-WEST GAPS AND CANYONS.
WE CONTINUE TO TRACK A CUTOFF LOW PRESSURE SYSTEM THAT IS FORECAST TO MOVE
ONSHORE OF THE PACIFIC NORTHWEST ON SATURDAY, PASSING OVER THE NORTHERN
ROCKIES SATURDAY EVENING AND SUNDAY. THIS SYSTEM WILL BRING WIDESPREAD RAIN
AND HIGH MOUNTAIN SNOW AND MUCH COOLER TEMPERATURES THAT WILL MAKE IT FEEL
MORE LIKE FALL THAN LATE SUMMER. THE CHALLENGING PART OF THE FORECAST HAS
BEEN THE EXACT TRACK OF THE LOW, WHICH WILL PLAY A HUGE ROLE IN WHERE THE
HEAVIEST RAIN AND SNOW WILL FALL. THE TRACK HAS BEEN TRENDING SLIGHTLY
NORTH THE PAST 24 HOURS, WITH THE CENTER OF THE LOW NOW MOVING OVER
NORTHWEST MONTANA. IN THIS SCENARIO, THE MOST WIDESPREAD AND PERSISTENT
RAIN WILL BE NORTH OF I-90, BRINGING SNOW LEVELS DOWN TO AROUND 6,000 FEET
IN GLACIER NATIONAL PARK AND ALONG THE CONTINENTAL DIVIDE. WHEREVER THE
TRACK OF THE LOW ENDS UP BEING, WET, COOL, AND BREEZY CONDITIONS WILL BE
PRESENT THROUGHOUT THE NORTHERN ROCKIES, INCREASING THE HYPOTHERMIA RISK IN
THE BACKCOUNTRY OF WESTERN MONTANA AND NORTH-CENTRAL IDAHO. AS IT STANDS
NOW, WE EXPECT ANYWHERE FROM 0.50 TO 1.25 INCHES OF RAIN TO FALL ACROSS
MOST OF THE REGION THROUGH MONDAY MORNING, WITH SOUTHWEST MONTANA BEING ON
THE DRIER END OF THE SYSTEM, WHERE ONLY ABOUT 0.25 INCHES ARE EXPECTED.
THERE IS A 10 TO 20 PERCENT PROBABILITY THIS NORTHERLY TREND IN THE TRACK
WILL CONTINUE. IN THAT CASE, RAIN AND SNOW AMOUNTS COULD BE CONSIDERABLY
LESS. STAY TUNED.
TEMPERATURES WILL BEGIN TO MODERATE BY MID-WEEK NEXT WEEK, WITH AFTERNOON
TEMPERATURES WARMING BACK CLOSER TO NORMAL FOR THIS TIME OF YEAR, ALONG
WITH A MIX OF CLOUDS AND SUNSHINE.
AVIATION
BREEZY SOUTHWEST WINDS WILL CONTINUE THROUGHOUT THE
NORTHERN ROCKIES, BRINGING GUSTS AROUND 20 TO 25 KNOTS TO ALL AREA
AVIATION SITES IN WESTERN MONTANA AND NORTH-CENTRAL IDAHO. AN
INCREASING MID-LEVEL CLOUD DECK WILL BEGIN TO MOVE SOUTH AND EAST
OVER THE NORTHERN ROCKIES LATE THIS AFTERNOON AND EVENING AS AN
UPPER-LEVEL TROUGH MOVES SOUTH OUT OF BRITISH COLUMBIA. THIS
TROUGH WILL BRING AN INCREASING CHANCE OF RAIN SHOWERS THROUGHOUT
THE REGION OVERNIGHT, ALONG WITH A 20 PERCENT PROBABILITY OF
LIGHTNING BETWEEN 11/0600Z AND 11/1200Z FOR KGPI, KMSO, AND KHRF
TONIGHT AND EARLY FRIDAY.
MSO WATCHES/WARNINGS/ADVISORIES
MT...RED FLAG WARNING UNTIL 9 PM MDT THIS EVENING FOR EAST BEAVERHEAD.
ID...NONE.
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