070
FXUS65 KMSO 061004
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
ISSUED BY NATIONAL WEATHER SERVICE BOISE ID
304 AM MST TUE JAN 6 2026
DISCUSSION
KEY MESSAGES:
- MODERATE TO HEAVY SNOW IMPACTS TRAVEL TODAY.
- WIND TODAY AND TONIGHT WILL CAUSE BLOWING AND DRIFTING SNOW
AND POOR VISIBILITY AT TIMES.
- A RIDGE OF HIGH PRESSURE WILL BUILD BACK IN THIS WEEKEND.
ZONAL FLOW, OR STRAIGHT WEST TO EAST FLOW, ACROSS THE REGION IS
CARRYING A PLUME OF MOISTURE THAT WILL CAUSE SOME SNOW IMPACTS.
IN ADDITION TO THE INCOMING MOISTURE PLUME, THERE IS ALSO A JET
STREAK THAT MOVES INTO THE REGION TONIGHT AND WILL CAUSE SOME
STRONGER WINDS. AFTER THE COLD FRONT YESTERDAY, SNOW LEVELS ARE
BACK DOWN THE VALLEY FLOORS ACROSS THE NORTHERN ROCKIES. AS A
RESULT, THE INCOMING PLUME OF MOISTURE WILL FALL AS SNOW. WINTER
WEATHER ADVISORIES AND WARNINGS HAVE ALREADY BEEN ISSUED TO COVER
THE AREAS WITH THE HIGHEST IMPACTS EXPECTED. THE WARNINGS ARE
FOCUSED ON THE REGION AROUND LOOKOUT PASS ON THE MONTANA / IDAHO
BORDER, SINCE THIS IS THE REGION WHERE THE MOST MOISTURE AND
STRONGEST LIFT WILL COMBINE TO CAUSE THE HEAVIEST SNOW RATES.
WITH THE FRESH SNOW AND THE INCOMING JET STREAK, BLOWING AND
DRIFTING SNOW WILL BE A CONCERN. NORTHWEST MONTANA AND THE
MOUNTAINS WILL BE THE HARDEST HIT. WITH THE COLDER AIR MASS IN
PLACE, WE EXPECT MORE IMPACTS FROM BLOWING AND DRIFTING SNOW
THAN THE REGION HAS SEEN SO FAR THIS WINTER. THE STRONGER WINDS
WILL BE TODAY, AND TO A LESSER EXTENT ON THURSDAY. THIS WILL BE
ONE OF THE STRONGEST WINTER STORMS (MEANING NOT RAIN) THAT THE
WESTERN PORTIONS OF MONTANA ALONG THE IDAHO BORDER HAVE SEEN SO
FAR THIS SEASON.
LONG TERM MODELS REMAIN CONSISTENT ABOUT BUILDING A RIDGE INTO
THE REGION THIS WEEKEND. WHILE THIS WILL CAUSE SIGNIFICANT
WARMING IN THE MOUNTAINS, IT WILL ALSO ESTABLISH VERY STABLE
CONDITIONS. THIS IN COMBINATION WITH DRIER AIR ALOFT AND THE
RECENT SNOW WILL CAUSE STRONGER COLD POOLS TO DEVELOP IN THE
VALLEYS. THE TEMPERATURE FORECAST IN THE VALLEYS IS PROBABLY A
LITTLE TOO WARM RIGHT NOW SINCE THIS IS THE BEST COLD POOL SET
WE’VE HAD SO FAR THIS YEAR. UNFORTUNATELY, THAT ALSO CAUSES
AIR STAGNATION AND POLLUTANTS TO BUILD UP.
AVIATION
A PLUME OF MOISTURE EMBEDDED IN ZONAL FLOW WILL START
TO IMPACT THE REGION TODAY AND CAUSE SOME MODERATE TO HEAVY SNOW
IN THE MOUNTAINS. VALLEYS WILL ALSO BE IMPACTED BY THESE SNOWS,
CAUSING SOME OBSCURATIONS AT AREA TERMINALS. TERMINAL KGPI WILL BE
HARDEST HIT WITH THE SNOW DUE TO ITS LOCATION IN NORTHWEST
MONTANA UNDER THE LEFT EXIT REGION OF THE UPPER LEVEL JET STREAK.
THE HEAVIEST SNOW AT TERMINAL KGPI IS EXPECTED TO BE BETWEEN
07/03Z AND 07/07Z. WEST-SOUTHWEST TO WESTERLY WINDS 40-50 KTS AT
THE 700MB LEVEL IMPLY SIMILAR WINDS AT MOUNTAIN TOP LEVEL. THAT
WILL CAUSE DOWNSLOPING AND RAIN SHADOW EFFECTS ESPECIALLY FOR
TERMINALS KMSO AND KHRF. LOW LEVEL WIND SHEAR IS ALSO A CONCERN
FOR THESE TERMINALS.
MSO WATCHES/WARNINGS/ADVISORIES
MT...WINTER WEATHER ADVISORY UNTIL 8 AM MST THIS MORNING FOR
BITTERROOT/SAPPHIRE MOUNTAINS...BUTTE/BLACKFOOT REGION...
MISSOULA/BITTERROOT VALLEYS.
WINTER WEATHER ADVISORY FROM NOON TODAY TO 11 AM MST WEDNESDAY
FOR KOOTENAI/CABINET REGION.
WINTER WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO 11 AM MST
WEDNESDAY FOR WEST GLACIER REGION.
WINTER STORM WARNING FROM 5 PM THIS AFTERNOON TO 11 AM MST
WEDNESDAY FOR LOWER CLARK FORK REGION.
ID...WINTER STORM WARNING FROM 11 AM THIS MORNING TO 10 AM PST
WEDNESDAY FOR NORTHERN CLEARWATER MOUNTAINS.
WINTER WEATHER ADVISORY UNTIL 7 AM PST THIS MORNING FOR
OROFINO/GRANGEVILLE REGION...SOUTHERN CLEARWATER MOUNTAINS.
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