408
FXUS65 KMSO 110915
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
315 AM MDT WED MAR 11 2026
DISCUSSION
KEY MESSAGES:
- PROLONGED ATMOSPHERIC RIVER EVENT FROM WEDNESDAY NIGHT THROUGH
SATURDAY.
-STRONG AND POTENTIALLY DAMAGING WINDS LATE WEDNESDAY NIGHT
THROUGH THURSDAY, WITH THE STRONGEST GUSTS EXPECTED ACROSS
NORTHWEST MONTANA AND ALONG THE CONTINENTAL DIVIDE.
-VERY DIFFICULT BACKCOUNTRY CONDITIONS DUE TO STRONG WINDS AND
HEAVY SNOW, LEADING TO LOCALIZED BLIZZARD CONDITIONS.
FORECAST CHANGES OVER LAST 24-HOURS:
AS WITH ALL FORECASTS THEY EVOLVE OVER TIME, THIS FORECAST IS NO
DIFFERENT. WINDS APPEAR TO HAVE SLIGHTLY WEAKENED FROM 24-HOURS
AGO, YET WILL STILL ATTAIN STRONG TO DAMAGING SPEEDS. PEAK WINDS
WILL STILL HAPPEN JUST AFTER MIDNIGHT TONIGHT THROUGH THURSDAY
AFTERNOON. BE PREPARED FOR THE POTENTIAL OF DOWNED TREES AND POWER
OUTAGES, AS SOILS ARE NOT FROZEN AND SOIL MOISTURE IS HIGH FOR
THIS TIME OF YEAR. PRECIPITATION AMOUNTS HAVE INCREASED,
ESPECIALLY IN THE CLEARWATER, BITTERROOT, AND SAPPHIRE MTNS.
SMALL STREAMS AND CREEKS WILL LIKELY SEE RAPID RISES AND NEED TO
BE MONITORED, PLEASE CHECK LOCAL CONDITIONS IF PLANNING OUTDOOR
ACTIVITIES. ADDITIONALLY, LOW LYING AND POOR DRAINAGE AREAS MAY
HAVE PONDING OF WATER ISSUES.
SHORT TERM FORECAST:
SATELLITE IS SHOWING A LONG FETCH OF SUBTROPICAL MOISTURE STREAMING
INTO THE PACIFIC NORTHWEST, THIS SYSTEM WILL BEGIN TO AFFECT OUR
REGION THIS EVENING LASTING INTO SATURDAY. PRECIPITATION COVERAGE
AND INTENSITY WILL INCREASE THIS EVENING AS SNOW LEVELS RISE.
NORTH OF I-90 SNOW LEVELS WILL RISE BETWEEN 4000 AND 4500 FEET,
BEFORE LOWERING INTO THE VALLEYS THROUGH SATURDAY. ELSEWHERE, SNOW
LEVELS WILL INITIALLY RISE 4500 TO 6000 FEET, BEFORE LOWERING
AGAIN BY THURSDAY EVENING. THE HIGHEST SNOW LEVELS WILL OCCUR IN
NORTH- CENTRAL ID, THIS IS ALSO THE LOCATIONS THAT WILL HAVE
LARGEST VARIATION IN SNOW LEVELS THROUGHOUT THE STORM. VALLEYS
EVEN IN NORTHWEST MT WILL BE EFFECTED BY DOWNSLOPING, HIGHER SUN
ANGLES, AND LONGER DAYS. THE ONLY VALLEYS THAT WILL LIKELY RECEIVE
SNOW ACCUMULATIONS WILL BE NORTHWEST MT AND ONLY DURING OVERNIGHT
PERIODS. EACH MORNING FRIDAY AND SATURDAY A WET, HEAVY
ACCUMULATION OF TRACE TO 3 INCHES IS POSSIBLE, DEPENDING ON
ELEVATION.
ALL OF OUR MOUNTAINS ARE STILL ON TRACK TO RECEIVE MULTIPLE FEET
OF SNOW, LOWEST STORM TOTALS CURRENTLY ARE IN LEMHI COUNTY ID AND
THE MOUNTAINS OF SOUTHWEST MT. BLIZZARD CONDITIONS WILL BE
POSSIBLE AT TIMES ON THURSDAY, MAINLY IN THE MOUNTAINS BUT
POTENTIALLY AT LOLO AND MARIAS PASSES AS WELL. THE CONSTANT WEST
WINDS AND HEAVY, WET NATURE OF THE SNOW WILL PRODUCE AVALANCHE
CONCERNS. PLEASE CHECK YOUR LOCAL AVALANCHE CENTER RECOMMENDATIONS
BEFORE TRAVELING OR RECREATING IN THE BACK COUNTRY.
LONG TERM FORECAST:
THE MOISTURE PLUME APPEARS TO EXIT THE REGION BY LATE SATURDAY,
BUT THE NORTHERN ROCKIES WILL REMAIN IN A BREEZY AND ACTIVE
WEATHER PATTERN THROUGH THE REMAINDER OF THE WEEKEND AND INTO NEXT
WEEK.
AVIATION
WINDS HAVE WEAKENED ACROSS THE NORTHERN ROCKIES DUE TO
THE JET STREAM SAGGING SOUTH, BUT WILL BEGIN TO INCREASE LATE
THIS AFTERNOON AS THE JET STREAM PUSHES NORTH AND INCREASES IN
INTENSITY. ADDITIONALLY, AFTER 12/0000Z LOW LEVEL WIND SHEAR WILL
BE PRESENT AT MOST TERMINALS DUE TO THE INCREASE IN RIDGE TOP
WINDS.
AN ATMOSPHERIC RIVER IS PUSHING INTO THE REGION THIS EVENING,
BRINGING INCREASED PRECIPITATION COVERAGE. PRECIPITATION IS
EXPECTED TO START AS SNOW BEFORE TRANSITIONING TO RAIN AS SNOW
LEVELS RISE.
LATE WEDNESDAY THROUGH SATURDAY, THE NORTHERN ROCKIES AIRSPACE
WILL BE IMPACTED BY A HIGH INTENSITY ATMOSPHERIC RIVER SYSTEM.
MSO WATCHES/WARNINGS/ADVISORIES
MT...WINTER STORM WARNING FROM 6 PM THIS EVENING TO NOON MDT SATURDAY
FOR BITTERROOT/SAPPHIRE MOUNTAINS...LOWER CLARK FORK
REGION...WEST GLACIER REGION.
HIGH WIND WARNING FROM MIDNIGHT TONIGHT TO MIDNIGHT MDT THURSDAY
NIGHT FOR BUTTE/BLACKFOOT REGION.
HIGH WIND WARNING FROM MIDNIGHT TONIGHT TO 6 PM MDT THURSDAY FOR
FLATHEAD/MISSION VALLEYS...KOOTENAI/CABINET REGION...
MISSOULA/BITTERROOT VALLEYS...POTOMAC/SEELEY LAKE REGION.
WINTER WEATHER ADVISORY UNTIL 6 PM MDT THIS EVENING FOR WEST
GLACIER REGION.
ID...WINTER STORM WARNING FROM 5 PM THIS AFTERNOON TO 11 AM PDT
SATURDAY FOR NORTHERN CLEARWATER MOUNTAINS...SOUTHERN
CLEARWATER MOUNTAINS.
WIND ADVISORY FROM 8 PM THIS EVENING TO 11 AM PDT THURSDAY FOR
LOWER HELLS CANYON/SALMON RIVER REGION...
OROFINO/GRANGEVILLE REGION.
HIGH WIND WARNING FROM MIDNIGHT TONIGHT TO MIDNIGHT MDT THURSDAY
NIGHT FOR EASTERN LEMHI COUNTY...WESTERN LEMHI COUNTY.
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