098
FXUS65 KMSO 062044
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
244 PM MDT THU AUG 6 2026
DISCUSSION
KEY MESSAGES:
- WARMING TREND THROUGH THE REST OF THE WEEK.
- WILDFIRE SMOKE WILL CONTINUE TO IMPACT THE REGION UNTIL
FURTHER NOTICE.
- RIDGE OF HIGH PRESSURE FLATTENS HEADING INTO THE WEEKEND. NEAR-
CRITICAL TO CRITICAL FIRE WEATHER EXPECTED DUE TO HOT, DRY AND
BREEZY CONDITIONS.
A BUILDING UPPER-LEVEL RIDGE WILL MAINTAIN HOT, DRY, AND STABLE
CONDITIONS ACROSS WESTERN MONTANA AND NORTH-CENTRAL IDAHO.
TEMPERATURES WILL WARM SIGNIFICANTLY FRIDAY AND SATURDAY, WITH
LOWER ELEVATIONS REACHING THE 90S AND LOCALIZED SPOTS EXCEEDING
100 DEGREES. AS THE RIDGE FLATTENS INTO ZONAL FLOW THIS WEEKEND,
AFTERNOON SURFACE WINDS WILL INCREASE. HOT TEMPERATURES, LOW
RELATIVE HUMIDITY, GUSTY WINDS, AND CRITICALLY DRY FUELS WILL
MAINTAIN NEAR-CRITICAL TO CRITICAL FIRE WEATHER CONDITIONS,
PEAKING FRIDAY INTO SATURDAY. THE MAIN FOCUS FOR THE MOST CRITICAL
CONDITIONS IS EXPECTED ACROSS SOUTHWEST AND WEST-CENTRAL MONTANA
ALONG WITH THE PALOUSE AND HELLS CANYON REGION OF NORTH- CENTRAL
IDAHO WITH FIRE WEATHER WATCHES ISSUED.
WILDFIRE SMOKE REMAINS A KEY FORECAST CHALLENGE FOR AIR QUALITY
AND VISIBILITY. STRONG RADIATIONAL COOLING UNDER SMOKY SKIES WILL
YIELD SHARP NOCTURNAL VALLEY INVERSIONS EACH MORNING, TRAPPING
SURFACE PARTICULATES. WHILE DAYTIME BOUNDARY LAYER MIXING WILL
TEMPORARILY DISPERSE VALLEY SMOKE EACH AFTERNOON, INCREASED
VENTILATION WILL ALSO INVIGORATE FIRE ACTIVITY AND GENERATE
THICKER PLUMES ALOFT. HIGH-RESOLUTION SMOKE MODELS PROJECT SURFACE
SMOKE PEAKING EARLY THIS AFTERNOON BEFORE MODESTLY IMPROVING BY
EARLY EVENING.
MONSOONAL MOISTURE TRACKING ALONG THE RIDGE PERIPHERY INTRODUCES
A SLIGHT CHANCE FOR ISOLATED HIGH-BASED CONVECTION FRIDAY
AFTERNOON THROUGH THE WEEKEND, PRIMARILY ACROSS SOUTHWEST MONTANA.
AN ANOMALOUSLY DRY SUB-CLOUD LAYER WILL POSE A RISK FOR DRY
LIGHTNING IGNITIONS AND ERRATIC MICROBURST GUSTS OF 40 TO 55 MPH.
FORECAST CONFIDENCE IS LOW TO MODERATE BUT TRENDING UPWARD
REGARDING MOISTURE RETURNING MID/LATE NEXT WEEK. AT THIS POINT,
THE MOISTURE DOESN'T APPEAR DEEP OR ORGANIZED ENOUGH FOR
WIDESPREAD RAINFALL. A SUBSTANTIAL SYNOPTIC SHIFT SUCH AS A DEEP
PACIFIC NORTHWEST TROUGH WILL BE REQUIRED TO SUPPRESS FIRE
ACTIVITY AND CLEAR SMOKE. ENSEMBLE GUIDANCE SHOWS A 20 TO 30%
CHANCE OF THIS TROUGH ARRIVING BY MID TO LATE NEXT WEEK.
AVIATION
WIDESPREAD WILDFIRE SMOKE REMAINS THE PRIMARY AVIATION HAZARD
OVER THE NEXT 24 HOURS. SHARP NOCTURNAL INVERSIONS AND STRONG RADIATIONAL
COOLING WILL TRAP SURFACE SMOKE IN VALLEY BASINS OVERNIGHT THROUGH
MID-MORNING, MAINTAINING PERIODS OF MVFR TO LOCALIZED IFR
VISIBILITIES (ALONG WITH LOCALLY REDUCED CEILINGS). DAYTIME
HEATING WILL PROMOTE BOUNDARY LAYER MIXING AND YIELD MODEST
SURFACE VISIBILITY IMPROVEMENTS BY AFTERNOON; HOWEVER, ENHANCED
VENTILATION WILL ALSO INVIGORATE REGIONAL FIRE ACTIVITY,
GENERATING THICKER SMOKE PLUMES ALOFT AND IMPACTING SLANT-RANGE
VISIBILITY. HIGH DENSITY ALTITUDE WILL BE A PROMINENT OPERATIONAL
CONCERN AS AFTERNOON TEMPERATURES REACH THE 90S AND LOW 100S.
SURFACE WINDS WILL REMAIN LIGHT AND TERRAIN- DRIVEN WITH A
WESTERLY GRADIENT BY FRIDAY AFTERNOON.
MSO WATCHES/WARNINGS/ADVISORIES
MT...FIRE WEATHER WATCH FROM FRIDAY AFTERNOON THROUGH SATURDAY
EVENING FOR BITTERROOT...DEERLODGE/WEST BEAVERHEAD...EAST
BEAVERHEAD...EAST LOLO.
FIRE WEATHER WATCH FROM SATURDAY AFTERNOON THROUGH SATURDAY
EVENING FOR FLATHEAD RESERVATION...WEST LOLO.
RED FLAG WARNING UNTIL 9 PM MDT THIS EVENING FOR DEERLODGE/WEST
BEAVERHEAD...EAST BEAVERHEAD.
ID...FIRE WEATHER WATCH FROM FRIDAY MORNING THROUGH SATURDAY EVENING
FOR PALOUSE/HELLS CANYON.
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