934
FXUS65 KMSO 252125
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
225 PM MST THU DEC 25 2025
DISCUSSION
KEY MESSAGES:
- SNOW IMPACTS TRAVEL: FRIDAY THROUGH SATURDAY, DEFINITELY ON
PASSES BUT VALLEYS BECOME PROBLEMATIC BEGINNING FRIDAY EVENING.
- HIGH WIND/OUTAGE RISK (FRIDAY): SOUTHWESTERLY GUSTS OF 30-45
MPH (VALLEYS) AND 60+ MPH (MOUNTAINS) ARRIVE FRIDAY AFTERNOON.
SATURATED SOILS WILL MAKE TREES MORE PRONE TO FALLING,
INCREASING THE RISK OF POWER OUTAGES.
- SATURDAY ARCTIC PUSH: FLASH FREEZE POTENTIAL AS BITTERLY COLD
AIR MOVES WEST OF THE DIVIDE SATURDAY MORNING. STRONG NORTHEAST
WINDS WILL DEVELOP IN PRONE CANYONS AND GAP AREAS (E.G., BAD
ROCK CANYON).
TODAY THROUGH FRIDAY MORNING: TRANSITION PERIOD
FOG AND LOW STRATUS WILL GRADUALLY LIFT TODAY, THOUGH ELEVATED
INSTABILITY MAINTAINS SCATTERED SHOWERS, PRIMARILY ACROSS NW
MONTANA. A WEAK COLD FRONT ARRIVING LATE THIS EVENING WILL LOWER
SNOW LEVELS TO 4,000 FEET BY FRIDAY MORNING.
-MOUNTAIN PASSES: MINOR IMPACTS LIKELY FRIDAY MORNING DUE TO
SLUSHY ACCUMULATIONS.
-LEMHI COUNTY: COLD AIR TRAPPED IN VALLEYS MAY SUPPORT A BRIEF
WINTRY MIX (SNOW/FREEZING RAIN) FRIDAY MORNING.
-WIND: SOUTHWEST WINDS INCREASE FRIDAY MORNING. A WIND ADVISORY IS
IN EFFECT FOR SOUTHWEST MONTANA, INCLUDING THE BITTERROOT VALLEY
AND BUTTE/BLACKFOOT REGION, FOR GUSTS UP TO 55 MPH.
FRIDAY AFTERNOON THROUGH SATURDAY: POTENT COLD FRONT
A ROBUST PACIFIC FRONT ARRIVES FRIDAY AFTERNOON, BRINGING A HIGH-IMPACT
COMBINATION OF WIND AND SNOW.
-SNOW/SQUALLS: WIDESPREAD PASS-LEVEL SNOW BEGINS FRIDAY AFTERNOON.
TRANSITION TO CONVECTIVE SNOW SHOWERS WITH A FEW SNOW SQUALLS IS
EXPECTED FRIDAY NIGHT INTO SATURDAY MORNING, IMPACTING BOTH
MOUNTAINS AND VALLEYS. SNOW SQUALLS WILL PRIMARILY OCCUR ALONG
THE CONTINENTAL DIVIDE, SW MONTANA, AND LEMHI COUNTY, HOWEVER
MOST ALL LOCATIONS WILL RECEIVE SNOW BY SATURDAY MORNING. A RAPID
TRANSITION FROM WET, TO SLUSHY/ICY SURFACES IS ANTICIPATED.
-WIND: VALLEY GUSTS OF 30 TO 45 MPH (CONVECTIVE GUSTS 50+ MPH)
ARE EXPECTED WITH THE FRONTAL PASSAGE. RIDGES WILL SEE 50 TO 65+
MPH. GIVEN SATURATED SOILS AND RECENT STRESS, EXPECT A HIGHER-
THAN- NORMAL RISK FOR DOWNED TREES AND POWER OUTAGES.
SATURDAY: ARCTIC INTRUSION (MARIAS PASS & FLATHEAD VALLEY)
ARCTIC AIR WILL SPILL SOUTH ALONG THE DIVIDE AND BLEED WESTWARD THROUGH
GAPS (E.G., MARIAS PASS) INTO NW MONTANA ON SATURDAY.
-WINDS: SHARP SHIFT TO N/NE WINDS, ACCELERATING THROUGH CANYONS. BAD
ROCK CANYON AND THE NORTHERN FLATHEAD VALLEY WILL SEE THE
STRONGEST GUSTS.
-FLASH FREEZE: TEMPERATURES DROPPING INTO THE TEENS AND LOW 20S
WILL FREEZE WET/SLUSHY ROADS.
-UNCERTAINTY: THE SOUTHWARD AND WESTWARD EXTENT OF THE ARCTIC BOUNDARY
REMAINS THE PRIMARY FORECAST CHALLENGE; FURTHER REFINEMENTS ARE
LIKELY.
SUNDAY THROUGH MID-WEEK: BUILDING RIDGE
HIGH PRESSURE BUILDS OVER THE PACIFIC NORTHWEST, LEADING TO DRIER
CONDITIONS. HOWEVER, NORTHWEST FLOW ALOFT MAY ALLOW MINOR
DISTURBANCES TO CLIP THE REGION, KEEPING LOW-END CHANCE FOR
PRECIPITATION AND FOG/STRATUS IN THE FORECAST. CONFIDENCE
DECREASES BY LATE WEEK AS MODELS HINT AT A POTENTIAL ATMOSPHERIC
RIVER EVENT.
AVIATION
VALLEY FOG AND LOW STRATUS CONTINUE TO LINGER AT SOME TERMINALS
THIS AFTERNOON, THOUGH SLOW IMPROVEMENT IS EXPECTED INTO THE
LATER AFTERNOON. ATTENTION IS QUICKLY SHIFTING TOWARD A POTENT
INCOMING STORM SYSTEM ARRIVING LATE TONIGHT INTO FRIDAY. STRONG
SOUTHWESTERLY FLOW INCREASES OVERNIGHT CREATING WIDESPREAD LOW
LEVEL WIND SHEAR AND MECHANICAL TURBULENCE, NOTABLY INCLUDING 45
KNOTS OF SHEAR AT TERMINALS SUCH AS KBTM BY 26/0700Z. WHILE
SURFACE GUSTS BEGIN TO INCREASE ELSEWHERE FRIDAY MORNING, VALLEY
DECOUPLING WILL HELP TO ENHANCE THOSE SHEAR PROFILES ESPECIALLY AT
KSMN, KMSO, AND KHRF FOR A A COUPLE HOURS OVERNIGHT AND INTO THE
MORNING BEFORE THOSE GUSTS MIX DOWN TO THE SURFACE. SNOW AND
FREEZING LEVELS BEGIN TO FALL THROUGH THE DAY ON FRIDAY TOWARD
VALLEY FLOORS. ANTICIPATE LOWERING CEILINGS, WIDESPREAD MOUNTAIN
OBSCURATIONS, AND REDUCED VISIBILITY THROUGH SATURDAY MORNING
ACROSS MUCH OF THE REGION.
MSO WATCHES/WARNINGS/ADVISORIES
MT...WINTER WEATHER ADVISORY FROM 8 AM FRIDAY TO 2 PM MST SATURDAY
FOR LOWER CLARK FORK REGION.
WINTER WEATHER ADVISORY FROM 5 AM FRIDAY TO 8 PM MST SATURDAY
FOR BITTERROOT/SAPPHIRE MOUNTAINS.
WINTER WEATHER ADVISORY FROM NOON FRIDAY TO 5 PM MST SATURDAY
FOR KOOTENAI/CABINET REGION.
WINTER WEATHER ADVISORY FROM 8 AM FRIDAY TO 5 PM MST SATURDAY
FOR WEST GLACIER REGION.
WINTER WEATHER ADVISORY FROM 8 PM FRIDAY TO 8 PM MST SATURDAY
FOR FLATHEAD/MISSION VALLEYS.
WIND ADVISORY FROM 5 AM TO 5 PM MST FRIDAY FOR
MISSOULA/BITTERROOT VALLEYS.
WINTER WEATHER ADVISORY FROM 2 AM TO 5 PM MST SATURDAY FOR
MISSOULA/BITTERROOT VALLEYS.
WIND ADVISORY FROM 6 AM FRIDAY TO 5 AM MST SATURDAY FOR
BUTTE/BLACKFOOT REGION.
WINTER WEATHER ADVISORY FROM 5 AM TO 8 PM MST SATURDAY FOR
BUTTE/BLACKFOOT REGION.
WIND ADVISORY FROM 8 AM FRIDAY TO MIDNIGHT MST FRIDAY NIGHT FOR
POTOMAC/SEELEY LAKE REGION.
WINTER WEATHER ADVISORY FROM 11 AM FRIDAY TO 8 PM MST SATURDAY
FOR POTOMAC/SEELEY LAKE REGION.
ID...WINTER WEATHER ADVISORY FROM 7 AM FRIDAY TO 1 PM PST SATURDAY
FOR NORTHERN CLEARWATER MOUNTAINS.
WINTER WEATHER ADVISORY FROM 4 AM FRIDAY TO 7 PM PST SATURDAY
FOR SOUTHERN CLEARWATER MOUNTAINS.
WINTER WEATHER ADVISORY FROM 4 PM FRIDAY TO 10 AM PST SATURDAY
FOR OROFINO/GRANGEVILLE REGION.
WINTER WEATHER ADVISORY FROM 2 AM FRIDAY TO 8 PM MST SATURDAY
FOR EASTERN LEMHI COUNTY...WESTERN LEMHI COUNTY.
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