622
FXUS65 KMSO 040830
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
230 AM MDT THU JUN 4 2026
DISCUSSION
KEY MESSAGES:
- DRYING TREND THIS AFTERNOON INTO FRIDAY WITH BUILDING HIGH
PRESSURE.
- SHOWERS AND THUNDERSTORMS RETURN THIS WEEKEND, FOCUSING ALONG
THE DIVIDE, LEMHI COUNTY, AND SOUTHWEST MONTANA.
- MONITORING TREND FOR WIDESPREAD PRECIPITATION BY WEDNESDAY AND
THURSDAY NEXT WEEK WITH CLOSED LOW.
RADAR IMAGES THIS MORNING SHOWS A LINE OF SHOWERS MOVING ACROSS
THE MONTANA-IDAHO BORDER TOWARDS THE DIVIDE. AN UPPER LEVEL
TROUGH PASSAGE THIS MORNING IS DRIVING SHOWER DEVELOPMENT, WITH
HIGH-RESOLUTION MODELS IN STRONG AGREEMENT FOR ACTIVITY TO PASS
EAST OF THE DIVIDE BY LATE MORNING. THE HIGHEST PRECIPITATION
AMOUNTS HAVE BEEN FOUND IN NORTHWEST MONTANA, WITH 0.45 INCHES
NEAR WHITEFISH LAKE, 0.34 INCHES IN LIBBY, AND 0.30 INCHES IN
EUREKA. DRIER AIR IN THE LOW LEVELS HAS LIMITED PRECIPITATION
SOUTH OF THE I-90 CORRIDOR.
DRY AIR WILL MOVE INTO THE NORTHERN ROCKIES AS THE TROUGH EXITS
EASTWARD. HIGH PRESSURE WILL ALSO BEGIN TO BUILD INTO THE AREA,
WITH SKIES CLEARING BY AFTERNOON INTO THE EVENING. TEMPERATURES
WILL TREND HIGHER ON FRIDAY AS SOUTHWEST FLOW DEEPENS AHEAD OF THE
NEXT SYSTEM ENTERING INTO THE PACIFIC NORTHWEST. WINDS WILL
INCREASE AREAWIDE, AS A MID-UPPER LEVEL JET MOVES OVERHEAD. VALLEY
GUSTS WILL RANGE FROM 20-35 MPH, WITH HIGHER PEAKS REACHING 30-45
MPH. THIS WILL BRING ELEVATED FIRE WEATHER CONDITIONS ACROSS LEMHI
COUNTY INTO SOUTHWEST MONTANA.
MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT WITH A UPPER LEVEL
TROUGH AND SURFACE COLD FRONT TRACKING ACROSS THE NORTHERN ROCKIES
THIS WEEKEND. THE TROUGH WILL SPLIT ACROSS OUR AREA, LIMITING
SHOWER COVERAGE AND PRECIPITATION AMOUNTS. TEMPERATURES WILL TREND
LOWER ON SATURDAY ACROSS NORTHWEST MONTANA AND NORTH-CENTRAL IDAHO
AS THE FRONT PASSES. THE FRONT WILL TRACK SOUTHEASTWARD ACROSS
WEST-CENTRAL MONTANA THROUGH SOUTHWEST MONTANA BY SUNDAY. OVERALL,
THIS WILL BE A DRY FRONTAL PASSAGE, GIVEN THE SPLITTING NATURE OF
THE PARENT TROUGH. NONETHELESS, THIS TROUGH WILL PROVIDE ENOUGH
MOISTURE AND INSTABILITY FOR SHOWERS AND THUNDERSTORMS, WITH
ACTIVITY FOCUSED ALONG THE DIVIDE, LEMHI COUNTY, AND SOUTHWEST
MONTANA.
ENSEMBLE MODEL GUIDANCE HAS BEEN HINTING FOR ANOTHER CLOSED LOW TO
MOVE INTO THE WESTERN US BY WEDNESDAY INTO THURSDAY NEXT WEEK. IN
FACT, RECENT MODEL RUNS HAVE BEEN INCREASING THE PROBABILITIES FOR
WIDESPREAD PRECIPITATION. THE LATEST NBM HAS A 60-70% CHANCE FOR
0.50 INCHES OR MORE OF PRECIPITATION, FOCUSED ALONG AND SOUTH OF
I-90 AND ALONG THE DIVIDE. OVERALL CONSENUS IS BEGINNING TO
INCREASE FOR THIS CLOSED LOW SOLUTION AND WE WILL MONITOR THIS
CLOSELY, GIVEN THE POTENTIAL FOR THESE SYSTEMS TO BRING
SIGNIFICANT PRECIPITATION. THE MIDDLE OF THE ROAD FORECAST
SUGGESTS A FAVORABLE PATTERN FOR WIDESPREAD SHOWERS AND
THUNDERSTORM ACTIVITY MONDAY INTO TUESDAY AHEAD OF THE LOW.
AVIATION
A LINE OF SHOWERS ARE MOVING EASTWARD FROM THE
MONTANA-IDAHO BORDER TOWARDS THE CONTINENTAL DIVIDE EARLY THIS
MORNING. THIS SHOWER ACTIVITY IS BEING DRIVEN BY THE PASSAGE OF AN
UPPER LEVEL TROUGH. HIGH-RESOLUTION MODELS ARE IN STRONG AGREEMENT
FOR SHOWERS TO PUSH EAST OF THE DIVIDE BY 04/1600-1800Z. SATELLITE
IMAGES SHOW DRY AIR UPSTREAM BEHIND THIS TROUGH, WHICH INCREASING
CONFIDENCE FOR A CLEARING TREND THIS AFTERNOON AND EVENING. WEST-
NORTHWEST SURFACE WINDS ARE EXPECTED THIS AFTERNOON, WITH GUSTS
REACHING 15-20KTS.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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