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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