273  
FXUS65 KMSO 300806  
AFDMSO  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MISSOULA MT  
206 AM MDT WED JUL 30 2025  
   
DISCUSSION  
 
KEY MESSAGES:  
 
- THE KMSO RADAR (MISSOULA, MT LOCAL WEATHER RADAR) WILL REMAIN  
OFFLINE DUE TO SCHEDULED MAINTENANCE THROUGH THE FIRST WEEK  
OF AUGUST.  
 
- SHOWERS AND THUNDERSTORMS EXPECTED EACH DAY THROUGH THE  
WEEKEND.  
 
- SLOW MOVING THUNDERSTORMS WILL HAVE THE TO POTENTIAL TO CAUSE  
EXCESSIVE RAINFALL IN FLOOD PRONE BASINS AND NEW BURN SCARS  
THIS EVENING.  
 
SIMILAR TO TUESDAY, LATE THIS AFTERNOON AND EVENING WE EXPECT  
DISORGANIZED SHOWERS AND THUNDERSTORMS TO FORM IN THE MOUNTAINS.  
AFTER 2 TO 3 PM, ACTIVITY WILL BLOSSOM BETWEEN LEMHI COUNTY ID AND  
THE ANACONDA RANGE. PROPAGATION WILL GENERALLY BE SLOWLY TO THE  
NORTH AND EAST, RELYING ON OUTFLOW WINDS OF FADING CELLS TO BUILD  
NEW CELLS ON ADJACENT TERRAIN. TUESDAY EVENING WE OBSERVED  
ISOLATED WEATHER STATIONS IN THE MOUNTAINS RECEIVING 0.50 TO 1" OF  
RAIN IN AN HOUR. WITH INCREASING ATMOSPHERIC MOISTURE TODAY  
SIMILAR RESULTS ARE EXPECTED THIS EVENING. ACTIVITY WILL FADE  
BETWEEN 10 AND MIDNIGHT. THESE STORMS OVER THE PAST FEW DAYS HAVE  
PRODUCED PLENTIFUL LIGHTNING, ATTEMPT TO FIND COVER IF OUTDOORS  
AROUND STORMS.  
 
THE NORTHERN ROCKIES WILL CONTINUE TO BE SANDWICHED BETWEEN COOL  
CANADIAN HIGH PRESSURE TO OUR EAST AND A SURFACE/ THERMAL TROUGH  
OVER THE SNAKE RIVER PLANE AND EASTERN WA. EAST WINDS WILL BE  
PRESENT ALL DAY AND AN INTENSIFICATION OF THOSE WINDS IS EXPECTED  
LATE AFTERNOON BETWEEN 6 AND 11 PM. FOR THAT REASON A LAKE WIND  
ADVISORY HAS BEEN ISSUED FOR FLATHEAD LAKE. BETWEEN BIGFORK AND  
WOODS BAY COULD BE AN AREA OF THE LAKE WHERE WIND GUSTS EXCEED 40  
MPH BETWEEN 8 AND 10 PM.  
 
THURSDAY AFTERNOON AN ATMOSPHERIC WAVE MOVES NORTH AND WILL  
PROVIDE THE REGION WIDE LIFT FOR WIDESPREAD CONVECTION TO DEVELOP.  
WHILE INITIAL STORMS MAY HAVE OUTFLOW GUSTS 30 TO 40 MPH, FOLLOW  
ON CELLS AND SHOWERS WILL HAVE THE CHANCE TO PRODUCE MODERATE TO  
HEAVY RAINFALL RATES AND SMALL HAIL. HIRES MODELS THAT CURRENTLY  
ONLY EXTEND OUT TO 6 PM THURSDAY, WOULD SUGGEST THE AREA FROM LOST  
TRAIL PASS NORTH THROUGH THE MISSION VALLEY, INCLUDING NORTH-  
CENTRAL ID COULD RECEIVE 0 TO 0.40 INCHES OF PRECIPITATION,  
HIGHER TERRAIN IN THIS AREA A 10% PROBABILITY OF EXCESS OF AN  
INCH. ACTIVITY WILL WANE AROUND MIDNIGHT WITH POLSON THE LIKELY NORTHERN  
EXTENT OF SHOWER ACTIVITY.  
 
FRIDAY A SIMILAR SETUP DEVELOPS WITH THE HEAVIEST PRECIPITATION  
NORTH OF I-90. THAT SAID, THE ENTIRE NORTHERN ROCKIES COULD SEE A  
MODERATE TO HEAVY SHOWER OR THUNDERSTORM.  
 
MUCH COOLER TEMPERATURES, AS MUCH AS 5 TO 10 DEGREES COOLER,  
ARE EXPECTED THIS WEEKEND. EXCEPT IN HELLS CANYON AND THE CAMAS  
PRAIRIE OF NORTH-CENTRAL ID WHERE ONLY MODESTLY COOLER  
TEMPERATURES, IE LOW 90S WILL BE PRESENT.  
 
THESE COOLER TEMPERATURES ALONG WITH DAILY SHOWER AND  
THUNDERSTORM ACTIVITY ARE IN THE FORECAST THROUGH THE START OF  
NEXT WEEK.  
 
 
   
AVIATION  
EAST OR NORTH WINDS WILL BE PRESENT AT TERMINALS  
TODAY. A SHARP INCREASE IN GUSTS IS EXPECTED BETWEEN 31/0000Z AND  
31/0400Z WITH GUSTS 20 TO 30 KTS AT TIMES. DISORGANIZED  
CONVECTION WILL AFFECT THE NORTHERN ROCKIES THIS AFTERNOON WITH  
OUTFLOW WINDS HELPING TO DEVELOP CONVECTION FROM SOUTH TO NORTH,  
MAINLY IN THE MOUNTAINS. THUNDERSTORMS OUTFLOW GUSTS OF 30-40 MPH  
MAY BE AN INITIAL CONCERN FOLLOWED BY MODERATE TO LOCALLY HEAVY  
RAINFALL. THE BEST CHANCES FOR SHOWERS AND THUNDERSTORMS WILL BE  
IN THE VICINITY OF KSMN, KBTM, AND KHRF. ACTIVITY AT OTHER  
TERMINALS IS LOW PROBABILITY BUT CANNOT BE RULED OUT. ANY SHOWER  
OR THUNDERSTORM WILL BE CAPABLE OF BRIEFLY (30-45 MINUTES)  
DEGRADING VISIBILITY TO 4SM. CONVECTIVE ACTIVITY WILL DIMINISH BY  
LATE EVENING.  
 
 
   
MSO WATCHES/WARNINGS/ADVISORIES  
 
MT...LAKE WIND ADVISORY FROM 6 PM TO 11 PM MDT WEDNESDAY FOR  
FLATHEAD/MISSION VALLEYS.  
 
ID...NONE.  
 
 
 
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