464
FXUS65 KMSO 112120
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
320 PM MDT TUE AUG 11 2026
DISCUSSION
KEY MESSAGES:
* REDUCED VISIBILITY AND DIMINISHED AIR QUALITY TO CONTINUE ACROSS
THE NORTHERN ROCKIES
* THUNDERSTORMS CAPABLE OF 50+ MPH WIND GUSTS ACROSS SOUTHWEST
MONTANA AND EXTREME NORTHWEST MONTANA, WEDNESDAY EVENING
* GUSTY NORTHWEST WIND WEDNESDAY AFTERNOON AND EVENING TO INCREASE
WAVE ACTIVITY ON FLATHEAD LAKE
FIRE WEATHER, AIR QUALITY, AND WIND CHANGES:
A PERSISTENT DRY AIRMASS AND DAILY LATE AFTERNOON GUSTY WINDS WILL
CONTINUE THROUGH WEDNESDAY ACROSS THE NORTHERN ROCKIES. THE
AFTERNOON WINDS MAY PROVIDE LOCALIZED TEMPORARY RELIEF FROM HIGHLY
CONCENTRATED WILDFIRE SMOKE, HOWEVER STATUS QUO IN SMOKE CONDITIONS
WILL CONTINUE FOR THE NEXT FEW DAYS. IN FACT, WINDS ACROSS NORTHWEST
MONTANA ARE PROJECTED TO SHIFT TO THE NORTH-NORTHEAST THIS EVENING
THROUGH THURSDAY EVENING, HOWEVER THE AIRMASS NORTH AND EAST OF THE
REGION HAS SIMILAR CONCENTRATIONS OF LOCAL SMOKE. THE MOST
SIGNIFICANT IMPACT FROM THE NORTHEAST WINDS WILL BE INCREASED WAVE
ACTIVITY ON AREA LAKES.
THUNDERSTORMS BEGINNING WEDNESDAY:
MOISTURE FROM WEST AND SOUTH OF THE NORTHERN ROCKIES WILL BEGIN TO
CREEP OVER THE REGION ON WEDNESDAY AFTERNOON AND EVENING, WITH
MAINLY DRY THUNDERSTORMS CAPABLE OF 50+ MPH WIND DEVELOPING OVER
SOUTHWEST MONTANA AND ACROSS EXTREME NORTHWEST MONTANA. LITTLE
APPRECIABLE RAINFALL IS EXPECTED WITH THE WEDNESDAY STORMS, HOWEVER
MOISTURE WILL BECOME MUCH MORE AVAILABLE FOR SUBSEQUENT DAYS THROUGH
THE WEEKEND. IN FACT, A MARGINAL RISK OF EXCESSIVE RAINFALL ARRIVES
AS SOON AS THURSDAY, WITH RECENT AND ONGOING WILDFIRES HAVING THE
HIGHEST RISK OF RUNOFF AND FLOOD IMPACTS. THE PRESENCE OF WILDFIRE
SMOKE WILL BE A BIT OF WILD CARD IN THE EFFICIENCY OF
THUNDERSTORM DEVELOPMENT.
BUT DOES THE WILDFIRE SMOKE SITUATION IMPROVE?
THERE WILL BE SOME IMPROVEMENT IN THE WILDFIRE SMOKE WEDNESDAY
THROUGH THE WEEKEND, HOWEVER THE IMPROVEMENT WILL BE ONLY
INCREMENTAL FOR MOST LOCATIONS. THE INCREASED FLOW ALOFT DOES HAVE
THE POTENTIAL TO LIFT MUCH OF THE EXISTING SMOKE, HOWEVER WEST AND
SOUTHWEST WINDS ALOFT SIMPLY REPLACE THE SMOKE FROM UPSTREAM FIRES
IN WASHINGTON AND OREGON. THE BEST CASE SCENARIO IS FOR MOST SMOKE
TO BE CONCENTRATED OVER TERRAIN AND ONLY OCCASIONALLY FILTERING DOWN
TO THE VALLEY FLOORS.
BIGGER PATTERN CHANGE TO COME?
LONG RANGE MODEL ENSEMBLES SUGGEST THAT A LOW PRESSURE TROUGH WILL
PERSIST OFF COASTAL WESTERN US NEXT WEEK. MOST PATTERN SOLUTIONS
FEATURE EITHER SOUTHWEST FLOW ALOFT OR A RIDGE OF HIGH PRESSURE OVER
THE NORTHERN ROCKIES. EITHER WAY, THE MOISTURE FROM TROPICAL STORMS
IN THE PACIFIC OCEAN WILL PLAY A FACTOR IN WHETHER TEMPERATURES
RETURN TO SUMMERTIME WARMTH OR NOT. WILDFIRE SMOKE IS STILL A BIG
QUESTION MARK NEXT WEEK.
AVIATION
WILDFIRE SMOKE WILL CONTINUE TO LIMIT VISIBILITY ACROSS THE NORTHERN
ROCKIES AIR SPACE DURING THE NEXT 24 HOURS. TERRAIN WILL BE OBSCURED
FROM SMOKE AT TIMES. ANOTHER WEATHER IMPACT DURING THIS TIME WILL BE
WINDS SHIFTING TO NORTHEAST FROM NORTH TO SOUTH ACROSS WESTERN
MONTANA TONIGHT THROUGH WEDNESDAY. 30 KNOT WINDS WILL EXIST OVER THE
TERRAIN ALONG THE PORTION OF THE CONTINENTAL DIVIDE JUST EAST OF
KGPI, WITH LESSER WIND SPEEDS FURTHER SOUTH. CLOUDS AND
PRECIPITATION CHANCES WILL BEGIN TO INCREASE AFTER 12/1800Z,
FURTHER OBSCURING TERRAIN ALONG THE DIVIDE. LIGHTNING CHANCES
INCREASE FOR KGPI AND KBTM AFTER 12/1800Z AS WELL.
MSO WATCHES/WARNINGS/ADVISORIES
MT...RED FLAG WARNING UNTIL 9 PM MDT THIS EVENING FOR DEERLODGE/WEST
BEAVERHEAD...EAST BEAVERHEAD.
ID...NONE.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page