057
FXUS65 KMSO 182021
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
121 PM MST WED DEC 18 2024
DISCUSSION
KEY MESSAGES:
- HIGH PRESSURE BRING POTENTIAL FOR FOG AND LOW CLOUDS TO DEVELOP
THURSDAY INTO THE WEEKEND.
- MIXED VALLEY PRECIPITATION AND MOUNTAIN PASS LEVEL SNOW SATURDAY
NIGHT AND SUNDAY.
GUSTY WINDS ARE EXPECTED TO CONTINUE THIS AFTERNOON AS A COLD
FRONT, SUPPORTED BY AN UPPER-LEVEL JET, MOVES THROUGH THE REGION.
UPSTREAM OBSERVATIONS INDICATE WIDESPREAD WIND GUSTS EXCEEDING 50
MPH, WITH ISOLATED REPORTS OF 60-70 MPH. MODEL GUIDANCE CONTINUES
TO SUPPORT THESE WIND SPEEDS THROUGH THE AFTERNOON. WINDS WILL
PERSIST INTO THE EVENING BUT GRADUALLY WEAKEN.
HIGH PRESSURE WILL REBUILD OVER THE REGION ON THURSDAY,
ACCOMPANIED BY LOW CLOUDS AND MORNING FOG. SHORTWAVE TROUGHS ARE
FORECAST TO TRAVERSE THE RIDGE THROUGH THE END OF THE WEEK,
PRIMARILY BRINGING INCREASED CLOUD COVER. LIGHT PRECIPITATION IS
POSSIBLE, PARTICULARLY IN NORTHWEST MONTANA.
ENSEMBLE AND DETERMINISTIC MODELS INDICATE A DEEPER TROUGH
ARRIVING SATURDAY NIGHT INTO SUNDAY. THIS SYSTEM IS EXPECTED TO
BRING HIGH SNOW LEVELS, WITH THE POTENTIAL FOR FREEZING RAIN IN
VALLEY AREAS DEPENDING ON THE STRENGTH OF INVERSIONS. MOUNTAIN
PASSES AND HIGHER TERRAIN ARE LIKELY TO SEE ACCUMULATING SNOW.
NEXT WEEKS WEATHER PATTERN LOOKS ACTIVE, WITH FREQUENT TROUGH
PASS= AGES. MIXED PRECIPITATION IN VALLEYS AND MOUNTAIN SNOW WILL
BE LIKELY WITH EACH SYSTEM.
AVIATION
A STRONG COLD FRONT WILL CONTINUE TO BRING STRONG
GUSTY WINDS TO AREA MOUNTAINS AND VALLEYS ACROSS THE NORTHERN
ROCKIES THROUGH THE EVENING. KGPI, KMSO, KHRF AND KBTM WILL SEE
THE STRONGEST WINDS FROM 18/2200Z-19/0500Z THIS EVENING. 35-40
KNOT WINDS HAVE ALREADY OCCURRED AND THERE IS A 40 TO 50 PERCENT
PROBABILITY THE ABOVE AVIATION SITES COULD SEE GUSTS UP TO 50KTS
DURING THIS TIME PERIOD. SCATTERED RAIN AND SNOW SHOWERS WILL
BRIEFING REDUCE VISIBILITY AND CREATE MOUNTAIN OBSCURATIONS
DURING THE EVENING HOURS AS WELL.
MSO WATCHES/WARNINGS/ADVISORIES
MT...WIND ADVISORY UNTIL 11 PM MST THIS EVENING FOR KOOTENAI/CABINET
REGION...LOWER CLARK FORK REGION.
WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING FOR WEST
GLACIER REGION.
HIGH WIND WARNING UNTIL 11 PM MST THIS EVENING FOR
BITTERROOT/SAPPHIRE MOUNTAINS...BUTTE/BLACKFOOT REGION...
FLATHEAD/MISSION VALLEYS...MISSOULA/BITTERROOT VALLEYS...
POTOMAC/SEELEY LAKE REGION.
ID...WIND ADVISORY UNTIL 11 PM MST /10 PM PST/ THIS EVENING FOR
EASTERN LEMHI COUNTY...SOUTHERN CLEARWATER MOUNTAINS...
WESTERN LEMHI COUNTY.
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