501
FXUS65 KMSO 170924
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
224 AM MST MON FEB 17 2025
DISCUSSION
KEY MESSAGES:
- HEAVIER SNOWFALL IS EXPECTED TO CONTINUE THROUGH MONDAY NIGHT,
SIGNIFICANTLY IMPACTING TRAVEL ACROSS THE REGION.
- ACTIVE WEATHER CONTINUES THROUGH THE WEEKEND, WITH SNOW LEVELS
AT TIMES ABOVE VALLEY FLOORS THIS WEEKEND.
THE HEAVIEST SNOW THIS MORNING HAS BEEN FOCUSED ALONG THE I-90
CORRIDOR, ESPECIALLY EAST OF MISSOULA INCLUDING THE SEELEY VALLEY.
TIMING OF HEAVIEST SNOW ENDING IS ROUGHLY 7 TO 9PM ALONG I-90 AND
IN THE SEELEY VALLEY. WHILE THAT IS EXPECTED TODAY A WRINKLE WILL
BE ADDED AS AN ARCTIC FRONT PROGRESSES THROUGH WESTERN MONTANA.
EVEN WITHIN HOURS OF THE EVENT HAPPENING, THERE IS STILL SOME
MODEL DISCREPANCY WITH THE SOUTHERLY EXTENT OF THE FRONT.
SO WHAT WILL THE ARCTIC WRINKLE LOOK LIKE? SNOW BANDS ARE BEING
DEMONSTRATED WITHIN THE MODELS ALONG AND SOUTH OF THE FRONT, WHICH
COULD CAUSE VERY HEAVY PERIOD OF SNOW, SIGNIFICANTLY DEGRADED
VISIBILITY, AND BLOWING OF SNOW. THIS FRONT IS VERY DRY, SO A
QUICK CUTOFF OF PRECIPITATION IS ALSO LIKELY AS AND IF THE FRONT
MOVES THROUGH YOUR AREA. WINDS ARE A QUESTION MARK, BUT TYPICAL
GAPS/ CANYONS COULD SEE GUSTS 20 TO 30 MPH. THE HIGHEST
RESOLUTION MODELS HAVE THESE GAP WINDS DEVELOPING IN THE NORTHERN
FLATHEAD LATE THIS MORNING, MT-200 OVANDO TO LINCOLN THIS
EVENING, AND FINALLY I-90 GARRISON JUNCTION TO DRUMMOND EARLY
TUESDAY MORNING. WEAKER WINDS 10 TO 20 MPH MAY BLAST THROUGH
HELLGATE CANYON 2 TO 4 AM TUESDAY.
WITH SUFFICIENT CLEARING WEDNESDAY MORNING MAY BE QUITE COLD. THE
COLDEST AIR WILL STAY EAST OF THE DIVIDE BUT ON OUR SIDE ALONG THE
DIVIDE COULD DROP INTO THE SINGLE DIGITS BELOW ZERO, SINGLE DIGITS
WEST OF THE DIVIDE TO MISSOULA, WITH TEENS IN MISSOULA AND POINTS
SOUTH. THIS COLD AIR IS NOT EXPECTED TO AFFECT NORTH-CENTRAL ID,
WHICH WILL HAVE A SEASONALLY COLD START TO THE DAY.
THE NEXT SYSTEM WILL BEGIN TO AFFECT OUR REGION WITH SNOW ON
WEDNESDAY. THIS SYSTEM WILL BE LACKING MOISTURE WITH UP TO AN INCH
OF SNOW IN VALLEYS AND 3 TO 6 INCHES IN THE HIGHEST TERRAIN OF
THE CLEARWATER MOUNTAINS ID.
A COMBINATION OF A FLAT RIDGE, RISING HEIGHTS, AND 30 TO 40KT MID
LEVEL WINDS WILL CAUSE SNOW LEVELS TO RISE ABOVE VALLEYS WITH
LIGHT PRECIPITATION THIS WEEKEND. WE WILL CONTINUE TO MONITOR
THIS AS OVERNIGHT TEMPERATURES MAY FALL BELOW FREEZING AND ALLOW
FOR WET SURFACES TO FREEZE UP. NO HYDROLOGIC ISSUES ARE EXPECTED
FROM THIS SYSTEM AS MOISTURE WILL BE LIMITED.
AVIATION
A ONGOING WINTER STORM WILL CONTINUE THROUGH TUESDAY. MODEL
CROSS- SECTIONS AND FORECAST SOUNDINGS INDICATE AN EXTENDED PERIOD
OF MODERATE SNOW DEVELOPING THIS AFTERNOON AT KMSO AND KBTM, WITH
FREQUENT DROPS IN VISIBILITY TO 1/2SM. WIDESPREAD LOW CEILINGS
AND REDUCED VISIBILITY ARE EXPECTED TO CONTINUE THROUGH MONDAY
NIGHT REGION WIDE. EASTERLY ARCTIC WINDS HAVE FORMED JUST WEST OF
THE DIVIDE, WITH THE FRONT ANTICIPATED TO ADVANCE ACROSS WESTERN
MONTANA FROM MIDDAY MONDAY THROUGH MONDAY NIGHT. THIS WILL BRING
STRONGER WINDS AND INCREASED SNOWFALL AS THE SYSTEM MOVES IN.
MSO WATCHES/WARNINGS/ADVISORIES
MT...WINTER STORM WARNING UNTIL 9 AM MST TUESDAY FOR
BITTERROOT/SAPPHIRE MOUNTAINS...BUTTE/BLACKFOOT REGION...
LOWER CLARK FORK REGION...MISSOULA/BITTERROOT VALLEYS...
POTOMAC/SEELEY LAKE REGION.
WINTER WEATHER ADVISORY UNTIL 11 AM MST THIS MORNING FOR
FLATHEAD/MISSION VALLEYS...WEST GLACIER REGION.
WINTER STORM WARNING FROM 11 AM THIS MORNING TO 9 AM MST TUESDAY
FOR FLATHEAD/MISSION VALLEYS...WEST GLACIER REGION.
WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING FOR
KOOTENAI/CABINET REGION.
ID...WINTER STORM WARNING UNTIL 8 AM PST TUESDAY FOR NORTHERN
CLEARWATER MOUNTAINS...SOUTHERN CLEARWATER MOUNTAINS.
WINTER WEATHER ADVISORY UNTIL 10 AM PST MONDAY FOR LOWER HELLS
CANYON/SALMON RIVER REGION...OROFINO/GRANGEVILLE REGION.
WINTER STORM WARNING FROM 10 AM MONDAY TO 8 AM PST TUESDAY FOR
OROFINO/GRANGEVILLE REGION.
WINTER WEATHER ADVISORY UNTIL 9 AM MST TUESDAY FOR EASTERN LEMHI
COUNTY...WESTERN LEMHI COUNTY.
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