737
FXUS65 KMSO 241935
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
135 PM MDT FRI APR 24 2026
DISCUSSION
KEY MESSAGES:
- NEAR RECORD OR RECORD COLD TEMPERATURES FORECAST FOR SATURDAY
AND POSSIBLY SUNDAY. PATCHY CLOUDS AND/OR EASTERLY WINDS OVER
THE DIVIDE/CHANNELED TERRAIN AND POINTS WEST COULD HELP
TEMPERATURES FROM GETTING TOO COLD IN SPOTS.
- SNOW SHOWERS WILL PERSIST ALONG THE DIVIDE AND POINTS WEST
THROUGH THE WEEKEND. ROADWAYS AND MOUNTAIN PASSES COULD BECOME
SNOW-COVERED AT TIMES.
- GRADUAL WARM-UP WITH AFTERNOON SHOWERS IS EXPECTED TUESDAY AND
WEDNESDAY. FROSTY MORNINGS ARE POSSIBLE.
- 70-80% CHANCE FOR HIGH TEMPERATURES REACHING THE 70S BY FRIDAY
ACROSS NORTH-CENTRAL IDAHO AND WESTERN MONTANA LOWER VALLEYS.
70-80% CHANCE FOR LOW 80S THROUGH HELLS CANYON AND WHITEBIRD BY
FRIDAY.
AN UNSEASONABLY COLD AIRMASS WILL REMAIN IN PLACE THROUGH EARLY
NEXT WEEK. HOW OFTEN DO WE SEE THE LEGIT POLAR VORTEX, NORMALLY
FOUND IN THE ARCTIC LATITUDES OR HUDSON BAY, OVER SOUTHERN
SASKATCHEWAN AND MONTANA IN LATE APRIL? THIS SYSTEM WILL CONTINUE
TO KEEP THE UPPER LEVELS COLD KEEPING IT UNSTABLE PRODUCING DAILY
SHOWERS. ALSO WITH THE COLDEST AIR FOUND EAST OF THE DIVIDE AND
LOWER PRESSURE TO OUR SOUTH AND WEST, EASTERLY WINDS WILL DEVELOP
NIGHTLY. SNOW SHOWERS COULD BE PERSISTENT OVER THE DIVIDE AND
POINTS WEST, INCLUDING THE GLACIER REGION.
FREEZE WARNINGS AND FROST ADVISORIES HAVE BEEN ISSUED FOR MANY
LOCATIONS. WE OPTED TO LEAVE OUT THE HIGHER VALLEYS ALONG THE
DIVIDE AS THOSE HAVE BEEN COLD ALREADY. PATCHY CLOUDS AND EASTERLY
WINDS THROUGH CHANNELED AREAS COULD HELP KEEP HARD FREEZES FROM
OCCURRING. OUTSIDE OF THE WIND AND CLOUDY AREAS, TEMPERATURES MAY
FALL INTO THE TEENS AND LOWER 20S WHICH COULD CAUSE DAMAGE TO
UNPROTECTED OUTDOOR PLUMBING AND IRRIGATION SYSTEMS. WE TRIED TO
GIVE MORE DETAIL IN THE WARNINGS ON THE AREAS THAT HAVE A HIGHER
PROBABILITY FOR THIS TO OCCUR.
PREVIOUS DAILY RECORD LOW TEMPERATURES FOR SATURDAY THAT COULD BE
TIED OR BROKEN INCLUDE:
EUREKA 18 DEGREES F. 2006
KALISPELL 21 DEGREES F. 1924
LIBBY 22 DEGREES F. 2002
MISSOULA 24 DEGREES F. 1988
BUTTE 12 DEGREES F. 1960
SALMON, IDAHO 12 DEGREES F. 2022
FENN, IDAHO 22 DEGREES F. 2013
GRANGEVILLE, IDAHO 25 DEGREES F. 1984
PIERCE, IDAHO 22 DEGREES F. 2009
MODELS CONTINUE TO SHOW A SECONDARY TROUGH SUNDAY NIGHT SITUATED
OVER IDAHO WHICH COULD BRING A PERIOD OF PRECIPITATION TO SOUTHERN
IDAHO COUNTY AND LEMHI COUNTY. THIS COULD BRING SNOW-COVERED
CONDITIONS AT LOST TRAIL PASS AND OTHER PASSES IN SOUTHWEST
MONTANA BY MONDAY MORNING.
WE'LL BE UNDER CYCLONIC FLOW THROUGH THURSDAY. THIS MEANS THE AIR
ALOFT IS MOVING IN A COUNTER-CLOCKWISE DIRECTION OVER THE REGION
RELATIVE TO THE CENTER OF THE POLAR VORTEX WHICH WILL SHIFT EAST
OVER THE GREAT LAKES REGION BY MID-WEEK. IT ALSO MEANS THAT
TEMPERATURES MAY BE A LITTLE SLOWER TO MODERATE, AFTERNOON INSTABILITY
CLOUDS AND SHOWERS ARE POSSIBLE, AND WE COULD BE LOOKING AT MORE
FROSTY MORNINGS.
A WARM RIDGE OF HIGH PRESSURE FINALLY BUILDS BY THE END OF THE
WEEK. PROBABILITIES ARE HIGH THAT 70S MAY RETURN TO WESTERN
MONTANA VALLEYS, AND NEAR 80 TOWARDS HELLS CANYON IN IDAHO.
AVIATION
THE WARM SPRING SUN AND A NEAR RECORD COLD AIR MASS
OVER THE REGION IS CAUSING CONVECTION AGAIN TODAY. THE AMOUNT OF
WATER AVAILABLE IN THE ATMOSPHERE FOR PRECIPITATION TODAY IS LESS
THAN YESTERDAY, SO WE EXPECT THE SHOWERS TO BE MUCH LESS INTENSE
TODAY. THE OVERALL AIR MASS IS MUCH COLDER AND WE EXPECT NEAR
RECORD LOW TEMPERATURES OVERNIGHT TONIGHT WITH LOWS IN THE LOW TO
MID 20S BY SATURDAY MORNING.
MSO WATCHES/WARNINGS/ADVISORIES
MT...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 8 AM MDT SUNDAY FOR
BITTERROOT/SAPPHIRE MOUNTAINS...FLATHEAD/MISSION VALLEYS...
LOWER CLARK FORK REGION...MISSOULA/BITTERROOT VALLEYS.
ID...FREEZE WARNING FROM MIDNIGHT MDT /11 PM PDT/ TONIGHT TO 8 AM MDT
/7 AM PDT/ SUNDAY FOR EASTERN LEMHI COUNTY...NORTHERN
CLEARWATER MOUNTAINS...SOUTHERN CLEARWATER MOUNTAINS.
WINTER WEATHER ADVISORY UNTIL 11 AM PDT THIS MORNING FOR
SOUTHERN CLEARWATER MOUNTAINS.
FROST ADVISORY FROM MIDNIGHT MDT /11 PM PDT/ TONIGHT TO 8 AM MDT
/7 AM PDT/ SUNDAY FOR OROFINO/GRANGEVILLE REGION...WESTERN
LEMHI COUNTY.
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