774
FXUS65 KMSO 220742
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
142 AM MDT WED JUL 22 2026
DISCUSSION
KEY MESSAGES:
- MONSOON MOISTURE DRIVES THUNDERSTORMS THROUGH THURSDAY, BRING
A LOCALIZED FLASH FLOOD THREAT.
- HOT, DRY, AND BREEZY CONDITIONS THIS WEEKEND WILL BE A CONCERN
FOR CRITICAL FIRE WEATHER CONDITIONS.
- SMOKE FROM THE PACIFIC NORTHWEST WILDFIRES WILL CONTINUE TO
IMPACT AIR QUALITY, POTENTIALLY WORSENING OVER THE WEEKEND.
THE SOUTHWEST MONSOON CONTINUES TO BUILD A RIDGE OF HIGH PRESSURE OVER THE
WESTERN U.S. WHILE DRAWING IN ABUNDANT MOISTURE. TODAY AND THURSDAY, THAT
MOISTURE WILL WORK ITS WAY INTO SOUTHERN IDAHO, ALL OF LEMHI COUNTY IN
IDAHO, AND SOUTHWEST MONTANA. THE RESULT WILL BE WIDESPREAD SHOWERS AND
THUNDERSTORMS IN THESE REGIONS. THE ABUNDANT MOISTURE AND SLOW-MOVING
NATURE OF THESE STORMS MAKE HEAVY RAIN AND LOCALIZED FLASH FLOODING THE
PRIMARY RISKS.
LATE THURSDAY AND INTO THE WEEKEND, A BROAD AREA OF LOW PRESSURE OVER THE
NORTHEAST PACIFIC OCEAN PUSHES THE HIGH-PRESSURE RIDGE FURTHER EAST,
BRINGING IN MUCH DRIER AIR. THIS LOW-PRESSURE SYSTEM WILL ALSO BRING
STRONGER WINDS ALOFT OVER THE NORTHERN ROCKIES, WHICH WILL IN TURN PRODUCE
GUSTY WESTERLY WINDS OVER WESTERN MONTANA AND NORTH-CENTRAL IDAHO ON FRIDAY
AND SATURDAY. CURRENTLY, SATURDAY LOOKS LIKE THE WINDIER DAY, WITH
WIDESPREAD GUSTS BETWEEN 15 TO 30 MPH. THERE IS A 20 TO 30 PERCENT
PROBABILITY GUSTS WILL REACH 40 MPH IN THE TERRAIN AND VALLEYS OF WESTERN
MONTANA SATURDAY AFTERNOON AND EVENING. THESE WINDS, ALONG WITH EXPECTED
RELATIVE HUMIDITY VALUES IN THE UPPER SINGLE DIGITS AND LOW TEENS, WILL
PRESENT A MAJOR CONCERN FOR CRITICAL FIRE WEATHER CONDITIONS.
ANOTHER POTENTIAL PROBLEM WITH THE WESTERLY WINDS WILL BE
WIDESPREAD SMOKE FROM SEVERAL WILDFIRES CURRENTLY BURNING IN
WASHINGTON AND OREGON.
AVIATION...A SOUTHWESTERLY FLOW WILL CONTINUE TO TRANSPORT MONSOON MOISTURE
OVER THE NORTHERN ROCKIES, BRINGING SCATTERED SHOWERS AND THUNDERSTORMS TO
PORTIONS OF SOUTHWEST MONTANA AND NORTH-CENTRAL IDAHO. CURRENTLY, KBTM AND
KSMN HAVE THE HIGHEST POTENTIAL FOR IMPACTS DUE TO THUNDERSTORMS. TIMING
FOR THE THUNDERSTORMS WILL BE BETWEEN 2100Z TODAY AND 0200Z THURSDAY FOR
KBTM AND KSMN. WITH THE HIGH AVAILABLE MOISTURE CONTENT AND THE SLOW
MOVEMENT OF THESE STORMS, HEAVY RAINFALL AND FREQUENT LIGHTNING WILL BE THE
MAIN IMPACTS. CURRENT HIGH-RESOLUTION MODELS KEEP THE ACTIVITY SOUTH OF THE
I-90 CORRIDOR, NOT DIRECTLY IMPACTING KMSO AND AVIATION TERMINALS FURTHER
NORTH. ANY IMPACTS TO KMSO WILL MOST LIKELY BE GUSTY OUTFLOW WINDS FROM THE
SOUTH.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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