744
FXUS65 KMSO 141917
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
117 PM MDT SUN SEP 14 2025
DISCUSSION
KEY MESSAGES:
- WIDESPREAD SHOWERS THIS AFTERNOON INTO MONDAY FOR MOST OF THE
NORTHERN ROCKIES.
- WARMING AND DRYING BY MID WEEK.
AN UPPER LEVEL TROUGH ALONG THE WEST COAST WILL USHER IN A COLD
FRONT THIS AFTERNOON. SHOWERS AND ISOLATED THUNDERSTORMS WILL
INCREASE FROM WEST TO EAST ACROSS THE NORTHERN ROCKIES. WIND GUSTS
AROUND 20 MPH WILL BE POSSIBLE (20-40%) THROUGH THIS EVENING
ACCOMPANYING THE FRONT AND SHOWERS. AREAS OF SHOWERS WILL CONTINUE
TONIGHT THROUGH MUCH OF MONDAY AS A WEAK MID LEVEL LOW DEVELOPS
AND ROTATES OVER THE NORTHERN ROCKIES.
THE PROBABILITY OF A WETTING RAIN (>0.10") THIS EVENING THROUGH
THE DAY MONDAY REMAINS HIGH, 70-100% FOR THE MAJORITY OF THE
NORTHERN ROCKIES, EXCLUDING FAR NORTHWEST MONTANA WHERE CHANCES
ARE FALL TO AROUND 50%. THE PROBABILITY FOR AT LEAST 0.25 INCH OF
RAINFALL IS 70-90% ACROSS NORTH-CENTRAL IDAHO AND 50-70% FOR WEST-
CENTRAL MONTANA. OVERALL, WIDESPREAD SHOWERS ARE ANTICIPATED WITH
A BENEFICIAL RAIN FOR MANY LOCATIONS. ADDITIONALLY, IT WILL BE
MUCH COOLER WITH DAYTIME HIGHS 5-10 DEGREES BELOW NORMAL ON MONDAY
WITH SNOW LEVELS DROP TO AROUND 8500 FEET.
PATCHY FOG WILL BE POSSIBLE TOMORROW MORNING FOR VALLEY LOCATIONS
ACROSS NORTHWEST MONTANA AND NORTH-CENTRAL IDAHO, AND LOCATIONS
ADJACENT TO BODIES OF WATER FOR WEST-CENTRAL MONTANA.
CONFIDENCE REMAINS HIGH WITH NEARLY 100% OF FORECAST ENSEMBLE
MODELS SHOWING A SHORTWAVE RIDGE OF HIGH PRESSURE BUILDING OVER
THE NORTHERN ROCKIES BY WEDNESDAY, USHERING IN A WARMING AND
DRYING TREND. BY THIS COMING WEEKEND, THE RIDGE WILL WEAKEN AS A
WESTERLY FLOW DEVELOPS, BRINGING AN INCREASE IN WESTERLY WIND.
MOST LOCATIONS WILL REMAIN DRY, BUT MORE SEASONABLE TEMPERATURES
WILL RETURN.
AVIATION
SHOWERS AND SCATTERED THUNDERSTORMS WILL INCREASE
FROM WEST TO EAST ACROSS THE NORTHERN ROCKIES LATER THIS
AFTERNOON AHEAD OF AND ALONG A COLD FRONT. WIND GUSTS AROUND 20
KTS WILL BE COMMON MID THROUGH EARLY EVENING ACCOMPANYING THE
FRONT AND SHOWERS. TIMING FOR THUNDERSTORMS WILL BE BETWEEN
14/2100Z-15/0200Z FOR KSMN, KHRF, KMSO AND KBTM. AREAS OF
SHOWERS, PERIODIC LOWERED CEILINGS/VISIBILITY AND MOUNTAIN
OBSCURATIONS WILL CONTINUE TONIGHT THROUGH MUCH OF MONDAY AS A
WEAK MID LEVEL LOW ROTATES THROUGH. PATCHY VALLEY FOG MAY BRING
BRIEF REDUCTIONS IN VISIBILITY AND CEILINGS FOR KGPI BETWEEN
15/1000Z-15/1500Z TOMORROW MORNING.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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