989
FXUS65 KMSO 072124
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
224 PM MST FRI NOV 7 2025
DISCUSSION
KEY MESSAGES:
- SNOW SHOWERS OVER MOUNTAINS AND PASSES POSSIBLE INTO THIS
EVENING.
- HIGH PRESSURE BUILDS THIS WEEKEND; RISK FOR FOG AND LOW CLOUDS
SUNDAY AND MONDAY MORNINGS.
BREEZY AND SHOWERY CONDITIONS CONTINUE THIS AFTERNOON BEHIND THE
PASSAGE OF A COLD FRONT, WHICH OCCURRED EARLY THIS MORNING.
SHOWER ACTIVITY WILL PRIMARILY BE FOCUSED OVER THE HIGHER TERRAIN
AND MAY IMPACT HIGH ELEVATION MOUNTAIN PASSES AT TIMES WITH A
LIGHT DUSTING OF SNOW. BREEZY WESTERLY WINDS WILL CONTINUE INTO
THE EVENING. THE WIND HAS BROUGHT DRIER AIR INTO THE VALLEYS,
WHICH WILL LIKELY HELP LIMIT THE EXTENT OF FOG/STRATUS DEVELOPMENT
INTO SATURDAY MORNING. LOCATIONS THAT DO SEE CLEARING TONIGHT CAN
EXPECT TEMPERATURES TO DROP INTO THE UPPER TEENS TO 20S BY
SATURDAY MORNING.
HIGH PRESSURE BEGINS TO BUILD OVER WESTERN MONTANA AND NORTH
CENTRAL IDAHO FOR THE WEEKEND. WITH A STABLE AIRMASS OVER THE
REGION, THE DEVELOPMENT OF VALLEY INVERSIONS IS ANTICIPATED. WHILE
MOUNTAINS AND THE HIGHER TERRAIN WILL SEE PERIODS OF SUN AND
ABOVE NORMAL TEMPERATURES, VALLEY LOCATIONS WILL LIKELY SEE THE
DEVELOPMENT OF FOG AND LOW CLOUDS (STRATUS), ESPECIALLY ACROSS
PORTIONS OF NORTHWEST MONTANA, WEST-CENTRAL MONTANA AND NORTH-
CENTRAL IDAHO. THIS BECOMES MORE LIKELY SUNDAY INTO MONDAY WHEN
THE RIDGE REACHES PEAK STRENGTH. AREAS WITH PERSISTENT FOG WILL BE
5-10 DEGREES COOLER THAN CURRENTLY FORECAST, THOUGH PINPOINTING
SPECIFIC LOCATIONS REMAINS DIFFICULT. LOCALLY DENSE FOG MAY
DEVELOP IN THE EARLY MORNING HOURS, WHICH COULD CAUSE DIFFICULT
DRIVING CONDITIONS DUE TO LOWER VISIBILITY AND ICE.
FORECAST MODELS ARE GENERALLY IN AGREEMENT THAT THE RIDGE WILL
BEGIN TO FLATTEN AROUND TUESDAY NEXT WEEK. THIS WILL INCREASE
WINDS OVER THE HIGHER TERRAIN AND MAY HELP TO WEAKEN ANY
INVERSIONS THAT HAVE DEVELOPED OVER THE WEEKEND. IN ADDITION,
FORECAST MODELS CONTINUE TO SHOW A DECAYING PLUME OF PACIFIC
MOISTURE WILL MOVE OVERHEAD, LEADING TO SHOWERS AND LIGHT HIGH
ELEVATION SNOW (6000-7000 FT).
AVIATION
BREEZY WESTERLY WINDS WILL CONTINUE INTO THIS EVENING
ACROSS ALL OF WESTERN MONTANA AND NORTH CENTRAL IDAHO, WITH GUSTS
20 TO 25 KTS FAIRLY WIDESPREAD. IN ADDITION, ONGOING MOUNTAIN
SHOWERS WILL CAUSE LOCALLY LOWERED VISIBILITY AND CEILING,
OBSCURING TERRAIN. WINDS AND SHOWER ACTIVITY WILL DECREASE AFTER
SUNSET THIS EVENING. DEVELOPING HIGH PRESSURE WILL ALLOW FOR MORE
STABLE CONDITIONS TO SET UP OVER THE REGION INTO THE WEEKEND.
DRIER AIR THAT MIXED DOWN WITH AFTERNOON WINDS THIS AFTERNOON,
SHOULD KEEP THE DEVELOPMENT OF WIDESPREAD FOG AT BAY THROUGH
SATURDAY MORNING. HOWEVER, LOCALIZED VALLEY FOG CANNOT BE RULED
OUT, ESPECIALLY ACROSS NORTHWEST MONTANA (KGPI) AND NORTH CENTRAL
IDAHO.
AIR STAGNATION
STABLE CONDITIONS WILL DEVELOP OVER WESTERN
MONTANA AND NORTH CENTRAL IDAHO THIS WEEKEND AS HIGH PRESSURE
INFLUENCES THE REGION. THE RIDGE WILL LIKELY REACH PEAK STRENGTH
SUNDAY INTO MONDAY, BEFORE FLATTENING AND INTRODUCING SOME WIND
ALOFT AND A PLUME OF DECAYING PACIFIC MOISTURE ON TUESDAY. VALLEY
FOG AND LOW STRATUS IS LIKELY TO DEVELOP, ESPECIALLY SUNDAY INTO
MONDAY AND MAY LEAD TO DEGRADING AIR QUALITY. AIR STAGNATION
ADVISORIES ARE NOT CURRENTLY ANTICIPATED DUE TO THE RELATIVELY
WARM AND EARLY SEASON NATURE OF THIS EVENT, WITH MIXING HEIGHTS
GENERALLY LOWERING TO AROUND 1500 TO 2000 FT AGL.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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