000
FXUS65 KMSO 311823
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
1223 PM MDT MON AUG 31 2026
DISCUSSION
KEY MESSAGES:
- WIDESPREAD SHOWERS AND THUNDERSTORMS TUESDAY AFTERNOON AND
EVENING, WITH GUSTY OUTFLOW WINDS OF 30-50 MPH, MODERATE TO
HEAVY RAINFALL, AND LIGHTNING, STRONGEST STORMS SOUTH OF
HIGHWAY 200.
- ANOTHER ROUND OF STORMS WEDNESDAY CAPABLE OF 30-50 MPH OUTFLOWS
AND HEAVY RAIN RATES UP TO 0.5 INCHES PER HOUR.
- PERSISTENT ACTIVE PATTERN LATE WEEK INTO THE WEEKEND UNDER
SOUTHWESTERLY FLOW, WITH A 15% CHANCE OF A TROPICAL MOISTURE
TAP ON SUNDAY.
TODAY THROUGH TUESDAY NIGHT:
A RIDGE OF HIGH PRESSURE WILL BE OVER THE REGION TODAY, RESULTING
IN A WARMING AND DRYING TREND WITH MINIMAL WIND ACROSS THE
NORTHERN ROCKIES. HIGH TEMPERATURES WILL CONTINUE TO REBOUND
FOLLOWING CHILLY MORNING CONDITIONS.
CONDITIONS SHIFT BY TUESDAY AFTERNOON AS AN ATMOSPHERIC
DISTURBANCE PUSHES NORTHWARD OUT OF LEMHI COUNTY AND SOUTHERN
IDAHO COUNTY INTO WESTERN MONTANA. THIS FEATURE WILL TRIGGER
WIDESPREAD SHOWERS AND THUNDERSTORMS ACROSS THE AREA. THE
STRONGEST CONVECTIVE ACTIVITY IS ANTICIPATED SOUTH OF HIGHWAY 200
IN WESTERN MONTANA, WHERE STORMS WILL BE CAPABLE OF PRODUCING
GUSTY OUTFLOW WINDS OF 30 TO 50 MPH, LIGHTNING, AND BRIEF MODERATE
TO HEAVY RAINFALL. STORM ACTIVITY WILL MOVE OUT OF THE FORECAST
AREA BY MIDNIGHT TUESDAY NIGHT.
WEDNESDAY THROUGH WEEKEND:
A STRONGER DISTURBANCE WILL TRAVERSE THE NORTHERN ROCKIES
WEDNESDAY MORNING THROUGH THE AFTERNOON. STORMS ON WEDNESDAY WILL
ONCE AGAIN POSE A THREAT FOR GUSTY OUTFLOW WINDS REACHING 30 TO
50 MPH. HEAVY RAIN POTENTIAL APPEARS ENHANCED WITH THIS SYSTEM,
WITH RAINFALL RATES UP TO 0.5 INCHES PER HOUR POSSIBLE UNDER
STRONGER CORES. EXTREME SOUTHWEST MONTANA WILL ALSO BE DEALING
WITH GUSTY WINDS AND LOW AFTERNOON HUMIDITY WEDNESDAY AFTERNOON
AND EVENING POTENTIALLY CREATING CRITICAL FIRE WEATHER CONDITIONS.
SOUTHWESTERLY FLOW ALOFT WILL PERSIST THURSDAY INTO FRIDAY AS AN
UPPER-LEVEL TROUGH OF LOW PRESSURE SETTLES OVER THE PACIFIC
NORTHWEST. THIS SETUP WILL KEEP TEMPERATURES NEAR TO SLIGHTLY
BELOW AVERAGE FOR LATE SUMMER, ALONG WITH PERIODIC SHOWERS AND
THUNDERSTORMS, PARTICULARLY DURING PRESSURE TROUGH OVER THE REGION
THROUGH THE WEEKEND. ROUGHLY 15% OF ENSEMBLE GUIDANCE INDICATES
THE POTENTIAL FOR A TAP OF SIGNIFICANT TROPICAL MOISTURE ON
SUNDAY. REGARDLESS OF WEATHER THIS MOISTURE PLUME MATERIALIZES,
THE NORTHERN ROCKIES WILL REMAIN EMBEDDED IN AN ACTIVE, UNSETTLED
WEATHER PATTERN THROUGH THE WEEKEND.
AVIATION
HIGH PRESSURE WILL CONTINUE TO BRING VFR CONDITIONS
AND LIGHT, DIURNALLY DRIVEN WINDS TODAY. CONVECTION RETURNS
TUESDAY AFTERNOON, AS SHOWERS AND THUNDERSTORMS DEVELOP ACROSS
CENTRAL IDAHO BY EARLY AFTERNOON, SPREADING NORTHEASTWARD INTO
WESTERN MONTANA THROUGH THE EARLY EVENING. GUSTY OUTFLOW WINDS AND
LIGHTNING WILL BE THE PRIMARY STORM THREATS, WITH PROBABILITIES
FOR OUTFLOW WINDS IN EXCESS OF 35 MPH REACHING 50-70% PERCENT ALONG
AND SOUTH OF HIGHWAY 200.
MSO WATCHES/WARNINGS/ADVISORIES
MT...FIRE WEATHER WATCH FROM WEDNESDAY AFTERNOON THROUGH WEDNESDAY
EVENING FOR EAST BEAVERHEAD.
ID...NONE.
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