062
FXUS65 KMSO 010649
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
1249 AM MDT THU OCT 1 2026
DISCUSSION
KEY MESSAGES:
- PATCHY VALLEY FOG THIS MORNING, ESPECIALLY NORTHWEST MONTANA.
- WARMING AND DRYING TREND FRIDAY THROUGH SUNDAY.
- INCREASING WESTERLY WINDS ON MONDAY AND POTENTIAL ISOLATED
AFTERNOON STORMS AS A WEAK DISTURBANCE FLATTENS THE RIDGE.
- STRONG HIGH PRESSURE RE-ESTABLISHES LATE NEXT WEEK, MAINTAINING
A PROLONGED WARM AND DRY PATTERN.
TODAY THROUGH FRIDAY NIGHT: PATCHY MORNING VALLEY FOG WILL DISSIPATE BY
MID- TO LATE MORNING. OTHERWISE, ZONAL FLOW ALOFT WILL BRING PERIODIC MID-
AND HIGH-LEVEL CLOUD COVER THROUGH FRIDAY, ALONG WITH A FEW LIGHT SPRINKLES
ACROSS NORTHWEST MONTANA TODAY. WINDS WILL REMAIN LIGHT AND DIURNALLY
DRIVEN THROUGH FRIDAY MORNING; HOWEVER, A WEAK DISTURBANCE TRACKING ALONG
THE CANADIAN BORDER FRIDAY AFTERNOON WILL INCREASE WESTERLY GUSTS UP TO 25
MPH. HIGH TEMPERATURES TODAY WILL BE NEAR SEASONAL AVERAGES, WARMING TO
AROUND 10 DEGREES ABOVE NORMAL BY FRIDAY.
SATURDAY THROUGH NEXT WEEK: AN UPPER-LEVEL HIGH-PRESSURE RIDGE WILL BUILD
OVERHEAD THIS WEEKEND, MAINTAINING WIDESPREAD SUNSHINE AND PERSISTENT WARM
DAYTIME TEMPERATURES. STRONG RADIATIONAL COOLING UNDER CLEAR SKIES WILL
ALLOW VALLEY OVERNIGHT LOWS TO DROP BELOW BLENDED MODEL GUIDANCE, PROMOTING
LOCALIZED FROST IN HIGHER VALLEYS AND TYPICAL COLD SPOTS. MONDAY INTO
TUESDAY, LONG-RANGE GUIDANCE DEPICTS A WEAK SHORTWAVE TROUGH SLIDING EAST
ALONG THE CANADIAN BORDER, TEMPORARILY FLATTENING THE RIDGE. THIS SYSTEM
WILL TRIGGER AN UPTICK IN WESTERLY WINDS ACROSS THE NORTHERN ROCKIES.
MODEST AFTERNOON DESTABILIZATION MAY ALSO SUPPORT ISOLATED, NON-SEVERE
THUNDERSTORMS ON MONDAY AFTERNOON. ONCE THIS DISTURBANCE DEPARTS, THE
STRONG UPPER-LEVEL RIDGE WILL REBUILD ACROSS THE REGION THROUGH MID-TO-LATE
WEEK, BRINGING A RETURN TO WARM AND DRY CONDITIONS. ENSEMBLE CLUSTER
GUIDANCE HAVE TRENDED TOWARD A POTENTIAL DISTURBANCE AROUND
OCTOBER 9TH-10TH (~50% CLUSTER SUPPORT), WHICH COULD INTRODUCE A
BRIEF PERIOD OF COOLER TEMPERATURES, INCREASED WINDS, AND A
CHANCE OF SHOWERS.
AVIATION
LOCALIZED MORNING VALLEY FOG MAY BRIEFLY REDUCE VISIBILITIES
TODAY, BUT WIDESPREAD VFR CONDITIONS WILL PREVAIL THROUGH FRIDAY
AS ZONAL FLOW PERSISTS. MID- AND HIGH-LEVEL CLOUDS WILL REMAIN
COMMON TODAY, PARTICULARLY ALONG AND NORTH OF THE I-90 CORRIDOR,
ACCOMPANIED BY LIGHT MOUNTAIN SPRINKLES ACROSS NORTHWEST MONTANA.
WINDS WILL REMAIN LIGHT AND TERRAIN-DRIVEN THROUGH FRIDAY MORNING
BEFORE INCREASING FRIDAY AFTERNOON, BRINGING WESTERLY GUSTS UP TO 20
KNOTS.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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