924
FXUS65 KMSO 071955
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
155 PM MDT FRI AUG 7 2026
DISCUSSION
KEY MESSAGES:
- NEAR-CRITICAL TO CRITICAL FIRE WEATHER EXPECTED DUE TO HOT, DRY
AND BREEZY CONDITIONS THROUGH SATURDAY.
- WILDFIRE SMOKE WILL CONTINUE TO IMPACT THE REGION UNTIL FURTHER
NOTICE.
TODAY THROUGH SUNDAY:
AN UPPER-LEVEL RIDGE OF HIGH PRESSURE WILL MAINTAIN HOT, DRY
CONDITIONS ACROSS WESTERN MONTANA AND NORTH-CENTRAL IDAHO INTO
EARLY NEXT WEEK. AS THE RIDGE FLATTENS THROUGH SATURDAY, MID-
LEVEL FLOW WILL INCREASE, YIELDING STRONGER AFTERNOON SURFACE
WINDS. THE COMBINATION OF HEAT, SINGLE-DIGIT TO LOW- DOUBLE-DIGIT
RELATIVE HUMIDITY, GUSTY WINDS, AND RECEPTIVE FUELS WILL DRIVE
CRITICAL FIRE WEATHER CONDITIONS. RED FLAG WARNINGS REMAIN ACTIVE,
WITH PEAK CONCERNS FOCUSED ACROSS SOUTHWEST AND WEST-CENTRAL
MONTANA, AS WELL AS THE PALOUSE AND HELLS CANYON REGIONS.
WILDFIRE SMOKE REMAINS THE PRIMARY FORECAST CHALLENGE. STRONG
OVERNIGHT VALLEY INVERSIONS WILL TRAP DENSE SMOKE EACH MORNING,
PARTICULARLY ACROSS NORTHWEST MONTANA. WHILE AFTERNOON SOLAR
HEATING WILL PROMOTE BOUNDARY LAYER MIXING AND TEMPORARILY IMPROVE
SURFACE VISIBILITY, INCREASED WINDS WILL SIMULTANEOUSLY
INVIGORATE FIRE ACTIVITY AND GENERATE SMOKE ALOFT. NOTABLY,
PERSISTENT SMOKE COVER MAY ATTENUATE SOLAR RADIATION AND SUPPRESS
ATMOSPHERIC MIXING, LOCALLY CAPPING MAXIMUM TEMPERATURES AND WIND
GUSTS BELOW CURRENT GUIDANCE.
SUBTLE MONSOONAL MOISTURE ADVECTING FROM THE SOUTH WILL INTRODUCE
A LOW CHANCE OF ISOLATED THUNDERSTORMS SATURDAY AFTERNOON, MAINLY
ACROSS SOUTHWEST MONTANA AND SOUTHERN LEMHI COUNTY. DUE TO AN
EXCEPTIONALLY DRY SUB-CLOUD LAYER, RAINFALL WILL LARGELY EVAPORATE
AS VIRGA, CREATING A HIGH RISK FOR DRY LIGHTNING IGNITIONS AND
SUDDEN, ERRATIC MICROBURST GUSTS BETWEEN 40 AND 55 MPH.
MONDAY THROUGH NEXT FRIDAY:
CONFIDENCE IS GRADUALLY INCREASING THAT MID-LEVEL MOISTURE WILL
SETTLE IN BY MID-TO-LATE NEXT WEEK, SUSTAINING PERIODIC
THUNDERSTORM CHANCES RATHER THAN PRODUCING WIDESPREAD, SOAKING
PRECIPITATION. HIGHER CONFIDENCE EXISTS FOR TEMPERATURES
MODERATING BACK TOWARD SEASONAL NORMALS IN THE MID-TO-UPPER 80S. A
MAJOR WEATHER PATTERN CHANGE, SUCH AS A STRONG, DEEP STORM SYSTEM
FROM THE PACIFIC NORTHWEST, IS NECESSARY TO SIGNIFICANTLY
SUPPRESS FIRE ACTIVITY AND CLEAR THE SMOKE. CURRENT FORECASTS SHOW
ONLY A 20 TO 30 PERCENT CHANCE OF SUCH A SYSTEM ARRIVING BY THE
MIDDLE TO LATE PORTIONS OF NEXT WEEK.
AVIATION
WIDESPREAD WILDFIRE SMOKE REMAINS THE PRIMARY AVIATION HAZARD
OVER THE NEXT SEVERAL DAYS. SHARP NOCTURNAL INVERSIONS AND STRONG
RADIATIONAL COOLING WILL TRAP SURFACE SMOKE IN VALLEY BASINS
OVERNIGHT THROUGH MID-MORNING EACH DAY, 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. MODELS SHOW THICK
SMOKE FROM EASTERN WASHINGTON FILLING INTO NORTHWEST MONTANA
AGAIN ON SATURDAY MORNING. AFTERNOON WIND GUSTS OF 15 TO 25 KTS
ARE ANTICIPATED THE NEXT FEW AFTERNOONS AT TERMINAL SITES BUT
THICK SMOKE MAY LIMIT MIXING AND GUST POTENTIAL. ADDITIONALLY,
HIGH DENSITY ALTITUDE WILL BE A PROMINENT OPERATIONAL CONCERN AS
AFTERNOON TEMPERATURES REACH THE 90S AND LOW 100S.
MSO WATCHES/WARNINGS/ADVISORIES
MT...RED FLAG WARNING UNTIL 9 PM MDT SATURDAY FOR BITTERROOT...
DEERLODGE/WEST BEAVERHEAD...EAST BEAVERHEAD...EAST LOLO.
RED FLAG WARNING FROM NOON TO 9 PM MDT SATURDAY FOR FLATHEAD
RESERVATION...WEST LOLO.
ID...RED FLAG WARNING UNTIL 11 PM PDT SATURDAY FOR PALOUSE/HELLS
CANYON.
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