680
FXUS65 KMSO 051921
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
121 PM MDT WED AUG 5 2026
DISCUSSION
KEY MESSAGES:
- CHILLY MORNINGS, HOT AFTERNOONS WITH GRADUAL WARMING TREND
THROUGH THE WEEK.
- SMOKE WILL CONTINUE TO IMPACT THE REGION UNTIL FURTHER NOTICE.
- RIDGE OF HIGH PRESSURE FLATTENS HEADING INTO THE WEEKEND.
ELEVATED AND LOCALIZED NEAR-CRITICAL FIRE WEATHER EXPECTED.
A RIDGE OF HIGH PRESSURE WILL CONTINUE TO BUILD OVER THE WESTERN
U.S. MAINTAINING WARM, DRY AND STABLE CONDITIONS. STRONG
RADIATIONAL COOLING UNDER DRY, "CLEAR" (BUT SMOKY) SKIES ALLOWED
KALISPELL TO SET A RECORD LOW OF 38 DEGREES THIS MORNING. THIS
COOLING IS CREATING SHARP NOCTURNAL VALLEY INVERSIONS WHICH CAN
AID IN TRAPPING SMOKE NEAR THE SURFACE WORSENING AIR QUALITY AND
VISIBILITY DURING THE MORNING HOURS. CONVERSELY, THERMAL BELTS ON
MID-SLOPES AND RIDGES WILL KEEP CONDITIONS WARM AND DRY WITH
INCREASINGLY POOR OVERNIGHT HUMIDITY RECOVERIES (25-35% RANGE),
CONTRASTING WITH EXCELLENT RECOVERIES IN DEEP VALLEY BOTTOMS.
AFTERNOON HEATING WILL REMAIN A DOUBLE-EDGED SWORD ALLOWING US TO
MIX INTO CLEANER AIR ALOFT OR ANY THICKER PLUMES THAT DEVELOP
FROM REGIONAL WILDFIRES AND GET TRANSPORTED OVERHEAD. CURRENT
HIGH-RESOLUTION SMOKE MODELING INDICATES HEAVIER NEAR-SURFACE
SMOKE CONCENTRATIONS PEAKING THURSDAY AFTERNOON IN THE NEAR-TERM.
TEMPERATURES WARM BACK INTO THE 90S (OR WARMER) FOR MANY LOWER
ELEVATIONS BY FRIDAY AND SATURDAY. AS THE RIDGE BEGINS FLATTENING
INTO A MORE ZONAL FLOW THIS WEEKEND, AFTERNOON SURFACE WINDS WILL
INCREASE. WHILE SYNOPTIC WINDS CURRENTLY LOOK TOO MARGINAL FOR
FIRE WEATHER / RED FLAG HIGHLIGHTS DURING ANY GIVEN SPECIFIC PERIOD
AT THIS TIME, HIGH TEMPERATURES, LOW HUMIDITY VALUES, BREEZY
CONDITIONS, AND LOW FUEL MOISTURE WILL CONTINUE TO KEEP FIRE
WEATHER ELEVATED IF NOT NEAR- CRITICAL.
A SLIGHT UPTICK IN AVAILABLE MOISTURE RIDING THE PERIPHERY OF THE
OVERHEAD RIDGE MAY INTRODUCE VERY SLIGHT CHANCES FOR ELEVATED
CONVECTION FROM FRIDAY THROUGH THE WEEKEND PARTICULARLY ACROSS
SOUTHWEST MONTANA. INCREDIBLY DRY SURFACE HUMIDITY COULD EASILY
DRIVE LOCALIZED ERRATIC OUTFLOW POTENTIAL INTO THE 30-50 KNOT
RANGE WITH A RISK FOR NEW LIGHTNING IGNITIONS.
LOOKING INTO NEXT WEEK, THERE IS LOW CONFIDENCE IN A SLOW UPTREND
OF AVAILABLE MOISTURE, BUT NO WIDESPREAD WETTING RAINS ARE
EXPECTED. A MAJOR PACIFIC NW CLOSED LOW SCENARIO WILL ULTIMATELY
BE REQUIRED TO INDUCE A RAPID DOWNTREND IN PREVAILING FIRE WEATHER
AND RESULTANT SMOKY CONDITIONS.
AVIATION
INCREASING AFTERNOON DENSITY ALTITUDES ARE
ANTICIPATED WITH WARMING TREND THROUGH THE REST OF THE WEEK.
SURFACE WINDS REMAIN LIGHT AND MOSTLY DIURNALLY/TERRAIN DRIVEN
WITH STABLE CONDITIONS UNDER A RIDGE OF HIGH PRESSURE. SMOKE PLUME
WATCH CONTINUES ACROSS THE AIRSPACE. MVFR VISIBILITY CONDITIONS
ARE ANTICIPATED TO DEVELOP IN NW MONTANA THROUGH THE DAY ON
THURSDAY PARTICULARLY AROUND KGPI, AND TO A LESSER EXTENT KMSO.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page