534
FXUS65 KMSO 250850
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
150 AM MST TUE NOV 25 2025
DISCUSSION
KEY MESSAGES:
- UNSETTLED HOLIDAY TRAVEL (WEDNESDAY & THANKSGIVING): LIGHT SNOW
RETURNS TONIGHT/WEDNESDAY MORNING. SNOW LEVELS RISE AND
PRECIPITATION TRANSITIONS TO A RAIN/SNOW MIX LATER ON WEDNESDAY
FOR MOST VALLEYS. NORTHWEST MONTANA VALLEYS REMAIN SNOW INTO
THURSDAY MORNING.
- POTENTIAL ARCTIC INTRUSION LATE WEEK (NOV 28-30): PLEASE
MONITOR THE FORECAST CLOSELY IF YOU HAVE POST-THANKSGIVING
TRAVEL PLANS.
TODAY THROUGH THANKSGIVING: ANY REMAINING EARLY MORNING SHOWERS
WILL DIMINISH, LEADING TO A QUIET START TO THE DAY. HOWEVER,
CONDITIONS WILL DETERIORATE BY THIS EVENING AS A STREAM OF
SUBTROPICAL MOISTURE BRINGS WIDESPREAD LIGHT PRECIPITATION TO
NORTH-CENTRAL IDAHO AND FAR NORTHWEST MONTANA. LIGHT SNOW WILL
GRADUALLY SPREAD EASTWARD INTO WEDNESDAY MORNING. SNOW LEVELS ARE
EXPECTED TO START AROUND 2,000 FEET THIS EVENING BEFORE RISING
ABOVE 4,000 FEET BY WEDNESDAY AFTERNOON ALONG AND SOUTH OF I-90.
SLICK TRAVEL IS A PRIMARY CONCERN FOR PASSES SUCH AS LOOKOUT, LOLO, AND
LOST TRAIL, AS WELL AS HIGHER VALLEY TOWNS IN IDAHO (INCLUDING
PIERCE AND ELK CITY) WHERE 2 TO 5 INCHES OF NEW SNOW IS FORECAST.
WHILE LOWER VALLEYS OF WESTERN MONTANA SHOULD SEE AN INCH OR LESS
OF ACCUMULATION, FORECAST ROAD TEMPERATURES NEAR FREEZING SUGGEST
A RISK OF LOCALIZED SLICK SPOTS FOR THE WEDNESDAY MORNING COMMUTE.
MODELS CONTINUE TO INDICATE THAT COLD AIR MAY REMAIN TRAPPED IN NORTHWEST
MONTANA VALLEYS THROUGH THURSDAY MORNING. CONSEQUENTLY, SNOW LEVELS MAY
LINGER NEAR VALLEY FLOORS IN THESE AREAS AS MOISTURE CONTINUES TO STREAM
OVERHEAD. WHILE SNOW AMOUNTS REMAIN GENERALLY LIGHT, MINOR TRAVEL IMPACTS
ARE POSSIBLE, PARTICULARLY DURING THE MORNING HOURS.
FRIDAY: THERE IS STRONG MODEL AGREEMENT ON MODIFIED ARCTIC AIR SPILLING
OVER THE DIVIDE INTO NORTHWEST MONTANA BY EARLY FRIDAY MORNING, DRIVING
SNOW LEVELS BACK DOWN TO VALLEY FLOORS. THERE IS A 50-70% CHANCE OF
WIDESPREAD ACCUMULATING SNOW BY FRIDAY EVENING FOR WESTERN MONTANA
VALLEYS AS THE COLD AIR WORKS SOUTHWARD. MOUNTAIN PASSES, ESPECIALLY
ALONG THE ID/MT BORDER, NORTHWEST MONTANA RANGES AND ALONG THE
DIVIDE, WILL LIKELY EXPERIENCE PERIODS OF MODERATE TO HEAVY SNOW.
SATURDAY THROUGH SUNDAY: FORECAST CONFIDENCE DECREASES SIGNIFICANTLY
REGARDING THE DEPTH AND WESTWARD PROGRESSION OF A POTENTIAL ARCTIC
INTRUSION. THE SCENARIO BREAKS DOWN AS FOLLOWS:
-FRIDAY EVENING: THERE IS MEDIUM-TO-HIGH CONFIDENCE (70%
CHANCE) THAT ARCTIC AIR WILL BANK ALONG THE DIVIDE IN
NORTHWEST MONTANA.
-SATURDAY: UNCERTAINTY PEAKS REGARDING THE WESTWARD PUSH OF
THIS AIRMASS. APPROXIMATELY 30% OF ENSEMBLE CLUSTERS DEPICT
ARCTIC AIR RUSHING ACROSS WESTERN MONTANA. HOWEVER, THE
MAJORITY (70%) SUGGEST A SLOWER PROGRESSION, RESULTING IN ONLY
A 50% CHANCE OF THE DEEPER COLD AIR REACHING THE FLATHEAD
VALLEY BY SATURDAY AFTERNOON.
-SUNDAY: A SECONDARY SHORTWAVE WITHIN THE NORTHWEST FLOW MAY
HELP DISLODGE THE ARCTIC AIR AND PULL IT OVER THE DIVIDE
SATURDAY NIGHT INTO SUNDAY (50% CHANCE TO REACH THE ID/MT
BORDER) BUT PROBABILITIES HAVE TRENDED SLIGHTLY LOWER ON THIS
OCCURRENCE.
TEMPERATURE IMPACTS: CURRENT PROBABILITIES INDICATE A 70-90%
CHANCE OF LOWS DIPPING INTO THE SINGLE DIGITS (OR COLDER) ALONG
THE DIVIDE BY SUNDAY MORNING, WITH A 40-60% CHANCE FOR THE
REMAINING WESTERN MONTANA VALLEYS.
EXTENDED OUTLOOK (NEXT WEEK): AN ACTIVE NORTHWEST FLOW PATTERN CONTINUES
INTO NEXT WEEK, BRINGING RENEWED SNOW CHANCES AND POTENTIAL EPISODES OF
ARCTIC AIR SPILLING OVER THE DIVIDE.
AVIATION
PATCHY FOG AND STRATUS REMAIN A CONCERN THIS MORNING, WITH
MOUNTAIN OBSCURATIONS CONTINUING NORTH OF I-90. ANY LINGERING SHOWERS WILL
DIMINISH EARLY. OTHERWISE, VFR CONDITIONS AND LIGHT WINDS WILL PREVAIL
ACROSS MUCH OF THE NORTHERN ROCKIES TODAY.
CONDITIONS CHANGE THIS EVENING AS A WEAK SUBTROPICAL MOISTURE TAP AND WARM
AIR ADVECTION BRING FAIRLY WIDESPREAD SNOW TO NORTH-CENTRAL IDAHO AND FAR
NORTHWEST MONTANA, SPREADING EASTWARD INTO WEDNESDAY MORNING. SNOW LEVELS
WILL START NEAR 2000 FEET AND GRADUALLY RISE FROM SOUTH TO NORTH ON
WEDNESDAY. EXPECT LIGHT TO MODERATE SNOW INTENSITY, RESULTING IN LOWER
CEILINGS AND REDUCED VISIBILITY.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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