752
FXUS65 KMSO 081210 CCA
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
428 AM MDT MON SEP 8 2025
DISCUSSION
KEY MESSAGES:
- THUNDERSTORMS THIS AFTERNOON/EVENING FEATURING GUSTY OUTFLOW
WINDS AND HEAVY RAIN.
- PATTERN CHANGE TO COOLER AND WETTER WEATHER TUESDAY ONWARD
YESTERDAY, SCATTERED THUNDERSTORMS BROUGHT HEAVY RAIN, LIGHTNING,
AND SMALL HAIL TO NORTH-CENTRAL IDAHO. SHOWERS AND STORMS LINGERED
INTO THE OVERNIGHT HOURS AND SHIFTED NORTHEASTWARDS TOWARDS
FLATHEAD LAKE. SEVERAL NEW FIRE STARTS OCCURRED AS A RESULT OF THE
LIGHTNING. A FEW PLACES SAW TRAINING SHOWERS, INCLUDING JUST SOUTH
OF ST. REGIS WHERE THE RADAR ESTIMATED OVER 1.50 INCHES OF
RAINFALL IN ONE HOUR!
TODAY, A LARGE UPPER LEVEL LOW WILL MOVE ONSHORE OVER OREGON AND
NORTHERN CALIFORNIA. THIS SYSTEM WILL TAKE ITS SWEET TIME,
WOBBLING IN A COUNTER-CLOCKWISE FASHION EAST AND NORTH, ENDING UP
IN EASTERN MONTANA BY NEXT WEEKEND! THIS PLODDING SYSTEM WILL
GENERATE MULTIPLE ROUNDS OF SHOWERS AND THUNDERSTORMS, INCREASED
MOISTURE (GOOD FOR AREA WILDFIRES), COOLER TEMPERATURES, AND A
DEFINITE NEED FOR A RAIN JACKET/UMBRELLA AT TIMES.
HIGH RESOLUTION MODELS DEPICTS SHOWERS AND THUNDERSTORMS
DEVELOPING ACROSS THE BITTERROOT MOUNTAINS AND SHIFTING NORTH AND
EAST THIS AFTERNOON AND EVENING. WIND GUSTS TO 40 MPH ARE
POSSIBLE, ALONG WITH HEAVY RAIN AND SMALL HAIL. ON TUESDAY, A MORE
ROBUST UPPER WAVE WILL BRING WIDELY SCATTERED STORMS THAT COULD BE
STRONGER RELATIVE TO MONDAY. BUT WITH SHEAR LACKING, HAIL IS
EXPECTED TO REMAIN LESS THAN ONE INCH. OTHER THREATS INCLUDE GUSTY
WINDS TO 45 MPH, HEAVY RAIN, AND LIGHTNING.
LOCALLY HEAVY RAIN IS A POSSIBILITY WITH A VERY SLIGHT CHANCE
(5-10%) OF DEBRIS FLOWS NEAR BURN SCARS OR FLOOD PRONE AREAS.
OTHERWISE, BENEFICIAL RAIN IS ANTICIPATED WITH A 50-70% CHANCE OF
AT LEAST 0.50 INCH OF RAIN FOR MUCH OF THE AREA, A SLIGHTLY LOWER
40-50% CHANCE IN SOUTHWEST MONTANA AND EASTERN SANDERS COUNTY.
FORECAST MODELS CONTINUE TO SHOW A CLOSED LOW WITH WIDESPREAD RAIN
BY LATE WEEK BUT MUCH WILL DEPEND ON THE TRACK AS TO THE IMPACT
FOR THE NORTHERN ROCKIES. ASIDE FROM THE RAIN, DAYTIME
TEMPERATURES WILL COOL TO SEASONABLE LEVELS WITH VALLEY HIGHS
GENERALLY IN THE 70S.
AVIATION
THIS MORNING, SHOWERS ARE POSSIBLE TOWARDS GLACIER
NATIONAL PARK. PATCHY FOG IS POSSIBLE ACROSS NORTH-CENTRAL IDAHO
INCLUDING IN LEMHI COUNTY. BY THIS AFTERNOON, SHOWERS AND
THUNDERSTORMS ARE POSSIBLE ACROSS THE BITTERROOT MOUNTAINS AND
ACROSS NORTHWEST MONTANA. GUSTY WINDS TO 35 KNOTS, SMALL HAIL,
HEAVY RAIN AND LIGHTNING ARE POSSIBLE. SHOWERS AND A FEW
THUNDERSTORMS ARE POSSIBLE TONIGHT (MONDAY NIGHT).
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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