550
FXUS65 KMSO 220757
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
157 AM MDT TUE SEP 22 2026
DISCUSSION
KEY MESSAGES:
- SUMMER-LIKE CONDITIONS THIS WEEK
- CHANCE FOR SHOWERS/THUNDERSTORMS IN LEMHI COUNTY AND SOUTHWEST
MONTANA TODAY
- COLD FRONT FRIDAY TO BRING A CHANGE: SHOWERS AND THUNDERSTORMS,
GUSTY WINDS, THEN COOLER, FALL-LIKE CONDITIONS THIS WEEKEND.
- FROSTY MORNINGS TO FOLLOW THIS WEEKEND INTO EARLY NEXT WEEK.
LOW PRESSURE SPINNING OVER NEVADA THIS MORNING WILL TRACK
NORTHEAST TODAY, SENDING MOISTURE INTO LEMHI COUNTY AND SOUTHWEST
MONTANA, INCLUDING BUTTE, THIS AFTERNOON AND EVENING. THERE WILL
BE ENOUGH MOISTURE AND INSTABILITY TO FUEL SHOWERS AND
THUNDERSTORMS. WIND GUSTS TO 30 MPH AND LIGHTNING WILL BE THE
MAIN THREATS. OTHERWISE, EXPECT FAIR WEATHER ACROSS THE NORTHERN
ROCKIES FEATURING ABOVE-NORMAL TEMPERATURES, LIGHT WINDS, AND
CLEAR SKIES, THROUGH THURSDAY UNDER DRY SOUTHWESTERLY FLOW ALOFT.
ON FRIDAY, A COLD FRONT WILL DISRUPT OUR RECENT WARM AND DRY
WEATHER. DESPITE TIMING DIFFERENCES WITH THE FRONT PASSAGE, THERE
IS A CHANCE FOR SHOWERS AND POSSIBLY THUNDERSTORMS IF WE'RE ABLE
TO WARM UP ENOUGH. IF WE WERE TO GET A SQUALL LINE FORMING WITH
THE FRONT WITH EMBEDDED THUNDER, THEN STRONG GUSTY WINDS COULD BE
POSSIBLE IMPACTING RECREATION ON AREA LAKES.
ON SATURDAY, IT COULD REMAIN QUITE BREEZY ACROSS THE REGION, BUT
IT WILL BE MUCH COOLER WITH HIGHS IN THE 60S. SOME LOCATIONS
ACROSS NORTHWEST MONTANA MAY REMAIN SHOWERY WITH SOME CLOUD COVER.
THESE AREAS COULD EXPERIENCE TEMPERATURES IN THE 50S UNTIL ANY
SUN BREAKS OUT. BOTH SATURDAY AND SUNDAY TEMPERATURES WILL BE NEAR
TO BELOW SEASONAL LEVELS. WITH THE COLDER NIGHT-TIME
TEMPERATURES, FROST WILL AGAIN BE IN THE CARDS.
AVIATION
HIGH PRESSURE WILL KEEP FAIR WEATHER IN THE FORECAST
FOR TODAY. THIS MORNING, CHANCES FOR FOG ARE LINGERING AT KGPI
(AND, TO A LESSER EXTENT, KSMN), WHERE DEW POINT DEPRESSION IS
ABOUT WHERE IT WAS LAST NIGHT WITH CALM WINDS AND CLEAR SKIES.
DURATION OF FOG HAS BEEN DECREASING EACH MORNING, SO EXPECT THAT
TREND TO CONTINUE THIS MORNING. THIS AFTERNOON, MOISTURE FROM THE
SOUTHWEST WILL ENTER INTO LEMHI COUNTY AND SOUTHWEST MONTANA,
BRINING CHANCES FOR SHOWERS AND THUNDERSTORMS TO KSMN AND KBTM.
THUNDERSTORMS THAT DO FORM WILL BE CAPABLE OF GUSTY WINDS OF ABOUT
25 KNOTS, LIGHTNING, AND BRIEF HEAVY RAIN DROPPING VISIBILITY.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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