926
FXUS65 KMSO 260736
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
136 AM MDT SUN JUL 26 2026
DISCUSSION
KEY MESSAGES:
- HOT, DRY, AND SMOKY CONDITIONS CONTINUE THROUGH THIS WEEK.
- EVEN HOTTER, DRIER, AND WINDY CONDITIONS TO END NEXT WEEK.
- POTENTIAL COOL DOWN TO NEAR AVERAGE TEMPERATURES NEXT WEEKEND,
THOUGH IT REMAINS DRY.
OUR CURRENT PATTERN OF HIGH PRESSURE RIDGE TO OUR EAST AND THE
NORTHERN ROCKIES UNDER SOUTHWEST FLOW WILL REMAIN UNCHANGED FOR
THE TIME BEING. EXPECT VERY WARM AND DRY DAYS, UNSTABLE
ATMOSPHERE, AND SMOKEY CONDITIONS. OUR REGION LOOKS TO BE CUT OFF
FROM MONSOONAL FLOW BUT ISOLATED THUNDERSTORMS DURING THE
AFTERNOONS IN SOUTHWEST MT AND LEMHI COUNTY ID WILL BE POSSIBLE
BUT LOW PROBABILITY.
THE BIGGEST CONCERN IN THE SHORT TERM WILL BE DEGRADING AIR
QUALITY FROM LOCAL AND REGIONAL FIRES. EACH OVERNIGHT SMOKE WILL
LIKELY FILTER INTO VALLEYS, THEN DURING THE AFTERNOON SOLAR
HEATING WILL DESTABILIZE THE ATMOSPHERE ALLOWING FOR SOME
VENTILATION. UNFORTUNATELY, SMOKE INHERENTLY STABILIZES THE
ATMOSPHERE BY BLOCKING SOLAR ENERGY AND LIMITING SURFACE HEATING.
WITHOUT A COLD FRONT TO SCOUR OUT VALLEYS, EVENTUALLY SMOKE WILL
INCREASE TO THE POINT OF STABILIZING VALLEYS, DEGRADING VISIBILITY
AND AIR QUALITY. HIGH RESOLUTION GUIDANCE WOULD SUGGEST NORTHWEST
AND WEST-CENTRAL MT WILL BE AMONG THE FIRST VALLEYS FOR THIS TO
OCCUR OVER THE NEXT FEW DAYS.
RELIEF? THE MODELS ARE NOTORIOUS FOR TRYING TO BREAKDOWN HIGH
PRESSURE RIDGES TOO QUICKLY. CURRENT MODELS WOULD SUGGEST
SUCCESSIVE SHORT WAVES AND EVENTUALLY EJECTION OF THE MAIN
PACIFIC LOW PRESSURE TROUGH FLATTENING THE RIDGE, COULD HAPPEN AS
EARLY AS FRIDAY/ SATURDAY. LAST NIGHT I WROTE THURSDAY/ FRIDAY,
SO THE MODELS ARE ALREADY TRYING TO DELAY RIDGE BREAKDOWN.
WHEN BREAKDOWN OF THE RIDGE DOES HAPPEN, THIS WOULD LIKELY LEAD TO
A PERIOD OF HEIGHTENED FIRE WEATHER DUE TO AN INCREASE IN WINDS.
ADDITIONALLY, A COOLING OF TEMPERATURES AND CLEANING OUT OF SMOKE
FROM VALLEYS WOULD ALSO BE LOGICAL OUTCOMES.
AVIATION
WITH A STRONG RIDGE OVER THE REGION, THE MAIN
AVIATION IMPACTS WILL BE FROM WILDFIRE SMOKE BOTH REGIONALLY AND
LOCALLY. IMPACTS FROM THE SMOKE HAVE BEEN MINIMAL AT AREA
TERMINALS, WITH VISIBILITY GETTING AS LOW AS 5SM IN THE EARLY
MORNING HOURS, BUT GENERALLY IMPROVING THROUGH THE DAY. WITH THE
RIDGE BEING STATIONARY, WE EXPECT THIS PATTERN TO CONTINUE THROUGH
MOST OF THE COMING WEEK.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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