596
FXUS65 KMSO 081939
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
139 PM MDT MON SEP 8 2025
DISCUSSION
KEY MESSAGES:
- THUNDERSTORMS EACH DAY THROUGH THURSDAY FEATURING GUSTY OUTFLOW
WINDS AND HEAVY RAIN, FOCUSED AFTERNOON/EVENING HOURS
- GRADUAL COOLING OF DAYTIME TEMPERATURES MID/LATE THIS WEEK
A RINSE AND REPEAT PATTERN OF DAILY SHOWERS AND THUNDERSTORMS IS
ANTICIPATED THIS WEEK AS AN UPPER LOW SLOWLY WOBBLES THROUGH THE
PACIFIC NORTHWEST. SHOWERS AND THUNDERSTORMS WILL BE MOST FOCUSED
IN THE AFTERNOON/EVENING HOURS, ENHANCED BY DAYTIME HEATING. BUT
SCATTERED SHOWERS/FEW THUNDERSTORMS WILL BE POSSIBLE EVEN DURING
THE OVERNIGHT AND MORNING HOURS EACH DAY AS WEAK DISTURBANCES PASS
THROUGH THE NORTHERN ROCKIES. EACH DAY SHOULD SEE A GRADUAL
INCREASE IN SHOWER/THUNDERSTORM COVERAGE THROUGH THURSDAY.
THERE IS A SLIGHT CONCERN (10-20% CHANCE) OF DEBRIS FLOWS/FLASH
FLOODS ON BURN SCARS AND FLOOD PRONE AREAS. PRECIPITABLE WATER
VALUES OF 0.8 TO 1.1 INCHES AND SLOW STORM CELL MOVEMENT WILL
ALLOW FOR BRIEF HEAVY RAIN RATES OVER 1 INCH/HR UNDER STRONGER
CELLS. ADDITIONAL THUNDERSTORM CONCERNS WILL BE GUSTY OUTFLOW
WINDS OF 40-50 MPH, SMALL HAIL, AND LIGHTNING.
OTHERWISE, DAYTIME TEMPERATURES WILL GRADUALLY COOL EACH DAY
MID/LATE THIS WEEK. IT WILL BE INTERESTING TO SEE THE TRACK AND
ORGANIZATION OF THE MAIN UPPER LOW AS IT COMES ACROSS THE NORTHERN
ROCKIES THURSDAY INTO THE WEEKEND. WIDESPREAD STEADY RAIN IS
CERTAINLY A POSSIBILITY BY FRIDAY BUT CONFIDENCE IS LOW ON THE
DETAILS. LOOKING FURTHER AHEAD, ANOTHER UPPER LOW IS LIKELY (70%
POTENTIAL) TO DROP INTO THE PACIFIC NORTHWEST LATE NEXT WEEKEND-
EARLY THE FOLLOWING WEEK (SEPT 14-16TH) CONTINUING THE COOL AND
SHOWERY PATTERN.
AVIATION
ANOTHER ROUND OF SCATTERED SHOWERS AND THUNDERSTORMS
IS ANTICIPATED THIS AFTERNOON/EVENING AS SOUTHWEST FLOWS BRING
MID- LEVEL MOISTURE ACROSS THE NORTHERN ROCKIES. GUSTY OUTFLOW
WINDS TO 35 KTS, SMALL HAIL, BRIEF HEAVY RAIN, AND LIGHTNING WILL
BE THE CONCERNS. SCATTERED SHOWERS AND A FEW THUNDERSTORMS MAY
CONTINUE INTO EARLY TUESDAY. WATCH FOR PATCHY VALLEY FOG,
ESPECIALLY WHERE RAIN OCCURS TODAY. TUESDAY WILL FEATURE A SIMILAR
PATTERN OF AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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