026
FXUS65 KMSO 090909
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
309 AM MDT THU OCT 9 2025
DISCUSSION
KEY MESSAGES:
- WARM TEMPERATURES CONTINUE INTO FRIDAY.
- INCREASING CONFIDENCE FOR WIDESPREAD MOUNTAIN SNOW LATE
SATURDAY INTO EARLY NEXT WEEK.
- GROWING RISK FOR A STRONG COLD FRONT, WITH VALLEY SNOW CHANCES
ACROSS NORTHWEST MONTANA MONDAY INTO TUESDAY.
A LARGE RIDGE OF HIGH PRESSURE, CENTERED OVER THE CENTRAL ROCKIES
WILL MAINTAIN WARM AND DRY CONDITIONS ACROSS THE AREA TODAY.
SOUTH-SOUTHEAST ARE EXPECTED WITH A SURFACE HIGH EAST OF THE
DIVIDE AND A THERMAL TROUGH IN CENTRAL IDAHO/EASTERN WASHINGTON.
GOES SATELLITE IMAGERY SHOWS A LARGE CLOSED LOW OFF THE OR/WA
COAST THIS MORNING. FORECAST MODELS PROJECT THIS LOW TO SLOWLY
MOVE INLAND THE NEXT COUPLE OF DAYS, WITH INCREASING MID-UPPER
LEVEL CLOUD COVER IN SOUTHERLY FLOW BEGINNING FRIDAY. MOISTURE AND
INSTABILITY WILL INCREASE ACROSS NORTH-CENTRAL IDAHO WITH SHOWERS,
AND PERHAPS A THUNDERSTORM OR TWO FORMING ACROSS IDAHO COUNTY
FRIDAY LATE AFTERNOON/EVENING.
THIS BROAD LOW WILL MOVE ACROSS THE NORTHERN ROCKIES FRIDAY NIGHT
INTO SATURDAY, WITH A COLD FRONT BRINGING A STARK COOLING TREND,
ALONG WITH WIDESPREAD SHOWER ACTIVITY AND PRECIPITATION. AS THIS
TROUGH MOVES INLAND, A SECOND SYSTEM EMBEDDED WITHIN NORTHERLY
FLOW WILL DIVE SOUTH FROM BRITISH COLUMBIA AND ALBERTA. THOSE
PLANNING TO HEAD INTO THE BACKCOUNTRY SHOULD PREPARE FOR COLD AND
RAW CONDITIONS, WITH SNOW COVERED ROADS ABOVE 5,000 FEET BY
SATURDAY NIGHT. THE THREAT FOR WINTER DRIVING CONDITIONS ACROSS
AREA MOUNTAIN PASSES INCREASES EARLY SUNDAY MORNING.
FORECAST MODELS ARE COMING INTO STRONGER AGREEMENT WITH A
STRONGER COLD FRONT MOVING ALONG AND WEST OF THE DIVIDE INTO
NORTHWEST MONTANA LATE SUNDAY INTO MONDAY. SNOW LEVELS HAVE
TRENDED LOWER WITH RECENT MODEL RUNS, WITH A 50-60% CHANCE FOR
VALLEY SNOW ALONG THE US-93 CORRIDOR FROM THE FLATHEAD VALLEY
NORTHWARD TO THE CANADIAN BORDER. VALLEY AREAS IN THE
KOOTENAI/CABINET REGION AND MISSION VALLEYS SEE PROBABILITIES NEAR
20-25% FOR VALLEY SNOW. THIS RISK FOR VALLEY SNOW IS BEING DRIVEN
BY THE INTERSECTION BETWEEN COLD AIR DIGGING SOUTHWARD FROM
CANADA AND PACIFIC MOISTURE WITHIN SOUTH-SOUTHWEST FLOW ALOFT.
CONFIDENCE IS HIGHER FOR WIDESPREAD SNOW IN GLACIER PARK REGION,
WITH A >80% CHANCE FOR 4 INCHES OR MORE. THE MAIN PIECE OF
UNCERTAINTY WITHIN MODEL GUIDANCE IS THE TRACK OF THE SECONDARY
LOW AS IT MOVES SOUTHWARD TOWARDS THE NORTHERN ROCKIES. ROUGHLY
HALF OF ENSEMBLE MEMBERS TRACK THE LOW ACROSS CENTRAL WA/OR, WITH
A FAVORABLE FEED OF MOISTURE OVERRUNNING THE COLD AIR MOVING
ACROSS THE DIVIDE, WHILE THE OTHER HALF TRACK THE LOW FURTHER
WEST, LEADING TO A DRIER, BUT STILL COLD SOLUTION ACROSS NORTHWEST
MONTANA. STAY TUNED!
AVIATION
SOUTH-SOUTHEAST WINDS WILL DEVELOP ACROSS THE NORTHERN
ROCKIES AIRSPACE TODAY WITH A SURFACE HIGH CENTERED EAST OF THE
DIVIDE. GUSTS UP TO 15KTS ARE EXPECTED ALONG THE DIVIDE AND IN
LEMHI COUNTY. WAVES OF HIGH CLOUDS WILL MOVE SOUTH TO NORTH
THROUGH THE AIRSPACE THROUGH THIS AFTERNOON AND EVENING.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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