460
FXUS65 KMSO 231821
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
1221 PM MDT FRI OCT 23 2026
DISCUSSION
KEY MESSAGES:
- OCTOBER WEATHER HAS ARRIVED! SEASONAL TEMPERATURES MEAN COOL
AFTERNOONS AND COOLER MORNINGS.
- CONFIDENCE IS INCREASING FOR POTENTIAL WINTER DRIVING
CONDITIONS AT MOUNTAIN PASS LEVEL TUESDAY NIGHT INTO
WEDNESDAY.
PRECIPITATION WILL CONTINUE THIS AFTERNOON ENDING FROM NORTHWEST
TO SOUTHEAST LATE AFTERNOON INTO EARLY EVENING. OBSERVATIONS FROM
AROUND THE REGION ALSO DEMONSTRATE SNOW LEVELS ARE SLOWLY
LOWERING. PRECIPITATION MAY LINGER IN SOUTHWEST MT AS SNOW LEVELS
LOWER TO OR BELOW MOUNTAIN PASSES, 6000 FEET OR LOWER. WINTER
WEATHER ADVISORIES REMAIN IN EFFECT FOR THIS EVENINGS RUSH HOUR TO
HIGHLIGHT THE POTENTIAL FOR SLICK DRIVING CONDITIONS OVER
HOMESTAKE AND MACDONALD PASSES.
A NORTHEASTERLY GRADIENT CONTINUES OVER NIGHT AS A COLD CANADIAN
AIR MASS SETTLES INTO CENTRAL MT. IF THE GRADIENT RELAXES AND
CLOUDS CLEAR, EFFICIENT RADIATIONAL COOLING WILL ALLOW FOR PATCHY
TO AREAS OF VALLEY FOG OR LOW STRATUS CLOUDS TO DEVELOP.
SATURDAY THROUGH MONDAY WILL FEEL LIKE OCTOBER WITH SEASONABLE
TEMPERATURES, COOL AFTERNOONS AND COLD MORNINGS. SUNDAY AND MONDAY
VALLEY FOG AND LOW STRATUS CHANCES WILL CONTRACT BACK TO MORE
TYPICAL VALLEYS.
THE MODELS ARE COALESCING AROUND A SOLUTION THAT BRINGS ANOTHER
WEATHER SYSTEM ON TUESDAY. ANOTHER ROUND OF VALLEY RAIN AND
MOUNTAIN SNOW IS EXPECTED. SNOW LEVELS ARE FORECAST TO LOWER BELOW
MOUNTAIN PASSES OVERNIGHT TUESDAY AND WINTER DRIVING CONDITIONS
MAY BE PRESENT AT MOST REGIONAL PASSES WEDNESDAY MORNING WHILE
ONLY LOST TRAIL PASS HAS THE POTENTIAL TO RECEIVE SNOW FOR TUESDAY
MORNINGS COMMUTE. ALSO WEDNESDAY MORNING, ALONG THE CONTINENTAL
DIVIDE THE CHANGE OVER TO SNOW IN VALLEYS MAY ALLOW FOR MINOR
ACCUMULATIONS ON VEGETATION.
AVIATION
WIDESPREAD PRECIPITATION IS PRODUCING VARYING
CATEGORIES FOR VISIBILITY AND CEILINGS AT ALL TERMINALS THROUGH
23/2100Z. THE PRECIPITATION TYPE IS EXPECTED TO TRANSITION OVER
TO SNOW AT KBTM THIS AFTERNOON, AT TIMES VISIBILITY WILL BE
REDUCED TO A MILE OR LESS. LOW LEVEL MOISTURE, WEAKENING EASTERLY
GRADIENT, AND RADIATIONAL COOLING SATURDAY MORNING COULD PRODUCE
PATCHY FOG OR LOW LEVEL STRATUS AT ANY TERMINAL. ANY TERMINAL
THAT DOES DEVELOP FOG OR STRATUS MAY BE SLOW TO LIFT, WITH
CONDITIONS REMAINING THROUGH 24/1800Z.
MSO WATCHES/WARNINGS/ADVISORIES
MT...WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO MIDNIGHT MDT
TONIGHT FOR BUTTE/BLACKFOOT REGION.
ID...NONE.
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