489
FXUS65 KMSO 091831
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
1231 PM MDT FRI OCT 9 2026
DISCUSSION
KEY MESSAGES:
- GUSTY WEST WINDS THIS AFTERNOON WILL CREATE CRITICAL FIRE
WEATHER CONDITIONS ACROSS SOUTHWEST MONTANA, CHOPPY CONDITIONS
AT AREA LAKES, AND HAZARDOUS CROSSWINDS FOR HIGH-PROFILE
VEHICLES ON I-90 FROM DEER LODGE TO BUTTE, AND I-15 SOUTH OF
BUTTE.
- STRONG NORTHEAST WINDS WILL DEVELOP SATURDAY, CAUSING CHOPPY
WAVES THAT COULD POSE A DANGER TO DOCKS AND BOATS ON THE
SOUTHWESTERN PORTION OF FLATHEAD LAKE. ISOLATED POWER OUTAGES
ARE POSSIBLE ACROSS NORTHWEST MONTANA THROUGH SUNDAY MORNING.
- THE FIRST WINTER STORM OF THE SEASON IS EXPECTED TO BRING WET,
HEAVY SNOW, COLD TEMPERATURES, AND GUSTY NORTHEAST WINDS TO THE
MOUNTAINS AND HIGH VALLEYS OF WEST-CENTRAL, SOUTHWEST, AND
CENTRAL MONTANA LATE SATURDAY THROUGH MONDAY MORNING. THIS
HEAVY SNOW COULD DAMAGE TREES AND POWER LINES, AND WILL
SIGNIFICANTLY IMPACT BACKCOUNTRY RECREATION, HUNTERS, AND
TRAVEL.
IT WILL BE A BREEZY FRIDAY ACROSS THE NORTHERN ROCKIES. SOUTHWEST WINDS
WILL INCREASE TO 15 TO 25 MPH, BRINGING A 1- TO 2-FOOT CHOP TO FLATHEAD
LAKE THIS AFTERNOON. STRONGER WINDS OF 20 TO 30 MPH WITH GUSTS UP TO 45 MPH
ARE POSSIBLE FROM LEMHI COUNTY TO SOUTHWEST MONTANA. IN ADDITION TO
DANGEROUS CROSSWINDS ON NORTH-SOUTH HIGHWAYS, THE DRY AND WINDY CONDITIONS
WILL CREATE CRITICAL FIRE WEATHER CONDITIONS ACROSS SOUTHWEST MONTANA.
ON SATURDAY, AS A LOW PRESSURE SYSTEM MOVES ONSHORE OVER WASHINGTON AND
OREGON, NORTHEAST WINDS WILL INCREASE ACROSS MUCH OF THE REGION. AT THE
SAME TIME, COLD, BELOW-FREEZING AIR WILL PUSH SOUTH FROM ALBERTA, CANADA,
FURTHER INCREASING THE NORTHEAST WINDS. FLATHEAD LAKE WILL AGAIN EXPERIENCE
CHOPPY CONDITIONS, BUT FROM THE NORTHEAST BY SATURDAY AFTERNOON. NORTHEAST
WINDS OF 15 TO 25 MPH WITH GUSTS TO 35 MPH COULD POSE A DANGER TO DOCKS AND
BOATS FROM YELLOW BAY SOUTH AND WEST TOWARD THE NARROWS AND BIG ARM.
ISOLATED HIGHER GUSTS NEAR 50 MPH WILL BE POSSIBLE ALONG HIGHWAY 35 ON THE
EAST SIDE OF FLATHEAD LAKE.
MOISTURE WRAPPING AROUND THE LOW PRESSURE SYSTEM OVER OREGON WILL MOVE OVER
THE COLD AIR PUSHING SOUTH ACROSS WESTERN MONTANA SATURDAY NIGHT. SNOW
LEVELS WILL FALL TO THE VALLEY FLOORS ALONG AND WEST OF THE DIVIDE. THE
COLD AIR WILL WEAKEN AS IT REACHES THE IDAHO/MONTANA BORDER, SO SNOW LEVELS
IN CENTRAL IDAHO WILL REMAIN HIGHER, GENERALLY ABOVE 4000 FEET.
TEMPERATURES FALLING INTO THE 20S AT MACDONALD PASS, COMBINED WITH GUSTY
NORTHEAST WINDS AND WET, HEAVY SNOW, WILL ACCUMULATE ON WARM GROUND AND
MAKE TRAVEL CONDITIONS SLICK. THIS WET, HEAVY SNOW MAY ALSO CAUSE IMPACTS
TO POWER LINES AND TREES. OTHER LOCATIONS, INCLUDING GEORGETOWN LAKE,
BUTTE, AND HOMESTAKE PASS, WILL ALSO EXPERIENCE WINTER-LIKE CONDITIONS.
THESE AREAS HAVE THE HIGHEST CHANCES FOR 3 OR MORE INCHES OF SNOW.
THE HEAVIEST RAIN AND SNOW WILL FALL IN A NARROW BAND CURRENTLY FORECAST
OVER THE ANACONDA/PINTLER RANGE AND SPREADING EAST OVER HOMESTAKE AND
MACDONALD PASSES. IF THIS BAND SHIFTS FURTHER NORTH, AREAS AROUND SEELEY
LAKE AND THE BOB MARSHALL WILDERNESS COULD SEE HIGHER IMPACTS, WHICH WOULD
ALSO ALLOW RAIN TO CHANGE OVER TO SNOW IN PLACES LIKE MISSOULA. HOWEVER,
IMPACTS WILL BE MINIMAL IN THE LOWER ELEVATIONS, ASIDE FROM COLD
TEMPERATURES.
LOWER ELEVATIONS, INCLUDING BUTTE AND ANACONDA, WILL ALSO SEE ACCUMULATING
SNOW, THOUGH TO A LESSER EXTENT THAN THE MOUNTAIN PASSES. ACCUMULATING SNOW
IS ALSO POSSIBLE FOR THE MOUNTAINS NORTH AND WEST OF THIS REGION, INCLUDING
THE BITTERROOT AND SAPPHIRE RANGES AND THE SEELEY-SWAN REGION.
ON SUNDAY, MOISTURE FROM THE REMNANTS OF HURRICANE RACHEL (CURRENTLY
SOUTHWEST OF BAJA CALIFORNIA) IS STILL ON TRACK TO MOVE NORTHWARD TOWARD
YELLOWSTONE AND WYOMING. FORECAST MODELS ARE STILL DIVIDED ON HOW THE LOW
PRESSURE SYSTEM WILL EVOLVE LATER SUNDAY INTO SUNDAY NIGHT. THIS KEY
FEATURE WILL DETERMINE HOW FAR NORTH AND WEST THE MOISTURE WILL SPREAD. WE
CONTINUE TO BE ON THE EDGE OF IT, WITH LINGERING SNOW POSSIBLE SUNDAY INTO
SUNDAY NIGHT. SNOW AND GUSTY EAST WINDS WILL ALSO IMPACT HIGHWAY 2 FROM
ESSEX TO MARIAS PASS AND GLACIER NATIONAL PARK, WITH WINTER WEATHER IMPACTS
LINGERING THROUGH MONDAY MORNING.
AS FOR THE HIGHLIGHTS, THE WINTER STORM WATCH FOR SOUTHWEST MONTANA HAS
BEEN UPGRADED TO A WINTER STORM WARNING. A WINTER WEATHER ADVISORY WAS
ADDED TO ENCOMPASS HIGHWAY 2 FROM ESSEX TO MARIAS PASS AND GLACIER NATIONAL
PARK. AND LASTLY, A WIND ADVISORY HAS BEEN ISSUED FOR THE FLATHEAD VALLEY,
INCLUDING FLATHEAD LAKE FOR SATURDAY NIGHT.
AS THE WEATHER SYSTEM PULLS AWAY, MONDAY MAY BRING THE FIRST WIDESPREAD
HARD FREEZE OF THE SEASON. WESTERN MONTANA MAY SEE LOWS IN THE UPPER TEENS
TO LOW 20S, WHILE THE LOWER ELEVATIONS IN NORTH-CENTRAL IDAHO GET CLOSE TO
FREEZING. IF CLOUD COVER AND PRECIPITATION LINGER INTO MONDAY MORNING, THE
COLDEST MORNING FOR THE WEEK MAY BE PUSHED BACK TO TUESDAY.
AVIATION
A DRY COLD FRONT WILL BRING GUSTY WEST TO SOUTHWEST
WINDS THIS AFTERNOON. TERMINALS KGPI, KMSO, AND KBTM MAY
EXPERIENCE THE STRONGEST GUSTS BETWEEN 25 AND 35 KNOTS, ALTHOUGH
HIGH CLOUD COVER MAY LIMIT THESE GUSTS SOMEWHAT. LIGHT SHOWERS
GRADUALLY WORK NORTH TO SOUTH THROUGH THE REGION TONIGHT INTO
SATURDAY WITH BRIEF MVFR CONDITIONS POSSIBLE AT KMSO AND KHRF
ALONG WITH MOUNTAIN OBSCURATIONS AT TIMES. GUSTY NORTHEAST WINDS
WILL DEVELOP ON SATURDAY AFTERNOON ACROSS NORTHWEST MONTANA AND
SPREAD SOUTH AND WEST ON SATURDAY NIGHT WITH GUSTS OF 15 TO 25
KTS AT WESTERN MONTANA TERMINAL SITES, CLOSER TO 35 KTS FOR KGPI.
A WINTER STORM WILL BRING LOW CEILINGS, VISIBILITY AND SNOW ALONG
THE DIVIDE AND POINTS WEST SATURDAY NIGHT THROUGH SUNDAY NIGHT.
MSO WATCHES/WARNINGS/ADVISORIES
MT...WINTER WEATHER ADVISORY FROM 6 PM SATURDAY TO 6 AM MDT MONDAY
FOR BITTERROOT/SAPPHIRE MOUNTAINS...POTOMAC/SEELEY LAKE
REGION...WEST GLACIER REGION.
LAKE WIND ADVISORY UNTIL 9 PM MDT THIS EVENING FOR
FLATHEAD/MISSION VALLEYS.
WIND ADVISORY FROM 6 PM SATURDAY TO 6 AM MDT SUNDAY FOR
FLATHEAD/MISSION VALLEYS.
WINTER STORM WARNING FROM 6 PM SATURDAY TO 6 AM MDT MONDAY FOR
BUTTE/BLACKFOOT REGION.
ID...NONE.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page