122
FXUS65 KMSO 101848
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
1248 PM MDT SAT OCT 10 2026
DISCUSSION
KEY MESSAGES:
- COLD, WET CONDITIONS THROUGH MONDAY MORNING AND A WINTER STORM
FOR THE FRONT RANGE AND SOUTHWEST MONTANA.
- HARD FREEZE POTENTIAL EARLY NEXT WEEK.
- WARMING UP TO ABOVE NORMAL LATE NEXT WEEK.
OVERVIEW & WINTER IMPACTS: AN UPPER-LEVEL TROUGH SETTLING OVER
THE PACIFIC NORTHWEST WILL ADVECT MOISTURE ACROSS THE NORTHERN
ROCKIES. CONCURRENTLY, A COLD FRONT IS GRADUALLY SPILLING OVER THE
CONTINENTAL DIVIDE, DRIVING GUSTY EAST-TO-NORTHEAST WINDS AND
PUSHING MUCH COLDER AIR SOUTH AND WEST. THIS SYNOPTIC SETUP WILL
YIELD A HIGHLY ACTIVE WEEKEND, FEATURING ACCUMULATING SNOW
PRIMARILY FOCUSED ABOVE 4,000 FEET. EXPECT NOTABLE TRAVEL IMPACTS
OVER REGIONAL MOUNTAIN PASSES, INCLUDING ROGERS, MACDONALD,
HOMESTAKE, AND LOST TRAIL. TOTAL SNOWFALL ACCUMULATIONS THROUGH
MONDAY MORNING ARE FORECAST TO RANGE FROM 6 TO 10 INCHES ACROSS
THE BACKCOUNTRY OF SOUTHWEST AND WEST-CENTRAL MONTANA, WHILE LOWER
VALLEY LOCATIONS WILL GENERALLY SEE LESS THAN AN INCH.
HOWEVER, FORECAST MODELS CONTINUE TO SHOW SPREAD REGARDING THE
INLAND EXTENT OF REMNANT MOISTURE FROM TROPICAL STORM RACHEL
SUNDAY NIGHT. SHOULD THIS MOISTURE TRACK FURTHER WEST THAN CURRENT
CONSENSUS DICTATES, GRASSY SURFACES IN THE LOWER VALLEYS OF WEST-
CENTRAL AND SOUTHWEST MONTANA COULD SEE LOCALLY HIGHER SNOWFALL
TOTALS BY MONDAY MORNING.
ROAD & BACKCOUNTRY HAZARDS: RECENT ANOMALOUS WARMTH HAS RESULTED
IN ELEVATED GROUND TEMPERATURES, COMPLICATING SNOW ACCUMULATION.
PRECIPITATION WILL INITIALLY MELT ON PAVED SURFACES; HOWEVER, AS
DIURNAL COOLING TAKES OVER AFTER SUNSET OR WHERE INTENSE SNOWFALL
RATES OVERCOME GROUND HEAT, SLUSHY CONDITIONS WILL QUICKLY
TRANSITION TO SNOW-COVERED ROADS, PARTICULARLY OVER THE PASSES.
THIS COMBINATION OF WET SNOW, FALLING TEMPERATURES, AND GUSTY
WINDS WILL CREATE AN ELEVATED RISK FOR HYPOTHERMIA FOR BACKCOUNTRY
RECREATIONISTS. THOSE HEADING OUTDOORS SHOULD BE FULLY PREPARED
FOR RAPIDLY DETERIORATING, RAW, AND WINTER-LIKE CONDITIONS.
LOCALIZED WIND THREAT: A SECONDARY, YET SIGNIFICANT, CONCERN IS
THE POTENTIAL FOR LOCALIZED STRONG EAST WIND GUSTS EXCEEDING 50
MPH, FOCUSED ALONG THE EAST AND SOUTHEAST SHORES OF FLATHEAD LAKE
AND THE LAKE BLAINE AREA. THESE CROSSWINDS COULD LEAD TO MINOR
TREE DAMAGE AND LOCALIZED POWER OUTAGES, WITH HIGHWAY 35 BEING
PARTICULARLY VULNERABLE. RECENT HIGH-RESOLUTION MODEL GUIDANCE
INDICATES BOTH AN EARLIER ONSET (MID-AFTERNOON TODAY) AND A
PROLONGED DURATION (LASTING THROUGH AT LEAST SUNDAY AFTERNOON).
CONSEQUENTLY, THE EXISTING WIND ADVISORY HAS BEEN UPDATED TO
REFLECT THIS EXPANDED TIMEFRAME.
EARLY WEEK FREEZE: LOOKING AHEAD TO EARLY NEXT WEEK (MONDAY
THROUGH WEDNESDAY MORNINGS), THERE IS HIGH CONFIDENCE IN A
WIDESPREAD HARD FREEZE ACROSS THE WESTERN MONTANA VALLEYS, ALONG
WITH NEAR-FREEZING TEMPERATURES FOR THE LOWER ELEVATIONS OF NORTH-
CENTRAL IDAHO. THE PRIMARY FORECAST WILD CARD FOR MONDAY MORNING
IS THE EXTENT OF LINGERING CLOUD COVER, WHICH COULD INHIBIT
RADIATIONAL COOLING AND KEEP TEMPERATURES SLIGHTLY WARMER THAN
CURRENT PROBABILISTIC GUIDANCE SUGGESTS.
IN THE EXTENDED FORECAST, ENSEMBLES REMAIN IN STRONG AGREEMENT
THAT UPPER-LEVEL RIDGING WILL QUICKLY REBOUND ACROSS THE REGION.
BY LATE NEXT WEEK, EXPECT AFTERNOON HIGH TEMPERATURES TO RECOVER
INTO THE 60S ACROSS WESTERN MONTANA AND THE 70S FOR THE LOWER
ELEVATIONS OF CENTRAL IDAHO.
AVIATION
AN UPPER-LEVEL TROUGH SITUATED OVER THE PACIFIC NORTHWEST
IS DRAWING MOISTURE ACROSS THE NORTHERN ROCKIES, WHILE A COLD
FRONT SIMULTANEOUSLY PUSHES MUCH COLDER AIR OVER THE CONTINENTAL
DIVIDE. THIS SYNOPTIC SETUP WILL USHER IN EARLY WINTER-LIKE
CONDITIONS ACROSS THE AIRSPACE. EXPECT PERIODIC PRECIPITATION TO
RESULT IN PROLONGED PERIODS OF DEGRADED FLIGHT CATEGORIES (MVFR TO
LOCALIZED LIFR), PRIMARILY DRIVEN BY LOWERED CEILINGS AND REDUCED
VISIBILITIES, ALONGSIDE WIDESPREAD MOUNTAIN OBSCURATION.
* KBTM (BUTTE): WILL LIKELY EXPERIENCE THE MOST SIGNIFICANT
AVIATION IMPACTS. PERIODS OF ACCUMULATING SNOW ARE EXPECTED TO
DRIVE SUDDEN DROPS IN VISIBILITY AND PROLONGED IFR CONDITIONS.
BEFORE THE SNOW ARRIVES THIS EVENING, ENOUGH INSTABILITY EXISTS
FOR A FEW BRIEF THUNDERSTORMS.
* REGIONAL TERMINALS: SURROUNDING TERMINALS ARE GENERALLY
FORECAST TO SEE PRECIPITATION FALL AS LIGHT RAIN OR WET, NON-
ACCUMULATING SNOW, KEEPING IMPACTS COMPARATIVELY LOWER.
MSO WATCHES/WARNINGS/ADVISORIES
MT...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM MDT
MONDAY FOR BITTERROOT/SAPPHIRE MOUNTAINS...POTOMAC/SEELEY
LAKE REGION...WEST GLACIER REGION.
WIND ADVISORY FROM 3 PM THIS AFTERNOON TO 3 PM MDT SUNDAY FOR
FLATHEAD/MISSION VALLEYS.
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 AM MDT MONDAY
FOR BUTTE/BLACKFOOT REGION.
ID...NONE.
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