157
FXUS65 KMSO 072045
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
245 PM MDT WED MAY 7 2025
DISCUSSION
KEY MESSAGES:
- SLIGHTLY COOLER, ISOLATED THUNDERSTORMS SOUTHWEST MT AND
BREEZY ALL LOCATIONS FOR THURSDAY
- FRIDAY INTO SATURDAY WARMEST TEMPERATURES SO FAR THIS YEAR,
CAUSING SIGNIFICANT INCREASE IN RIVER/STREAM FLOWS
- SCATTERED THUNDERSTORMS SATURDAY AND SUNDAY AFTERNOONS,
POTENTIALLY A FEW STRONG STORMS
AFTER A WARM AND DRY WEDNESDAY, A WEAK DISTURBANCE TRANSITS THE
NORTHERN ROCKIES THURSDAY. THE MOST NOTABLE ELEMENT OF THIS SYSTEM
WILL BE AN INCREASE IN SOUTHWEST WINDS WITH GUSTS 20 TO 30 MPH IN
MOST VALLEYS, WHILE 30 TO 35 MPH IN HIGHER TERRAIN. THOSE
RECREATING ON AREA LAKES SHOULD PLAN FOR AFTERNOON WINDS AND THE
POTENTIAL OF CHOPPY CONDITIONS. THIS IS A DRY COLD FRONT BUT AFTER
MIDNIGHT A FEW SHOWERS MAY DEVELOP IN NORTHWEST MT, THEN BY
AFTERNOON THE AXIS OF INSTABILITY WILL BE OVER SOUTHWEST MT WHERE
ISOLATED THUNDERSTORMS WILL BE POSSIBLE. ANY VIRGA SHOWER OR
THUNDERSTORM WILL BE CAPABLE OF ERRATIC OUTFLOW WINDS GUSTING 30
TO 40 MPH.
DRY AND WARM CONDITIONS RETURN FRIDAY AND SATURDAY, WITH THE
CAVEAT THAT SUFFICIENT INSTABILITY WILL BE PRESENT FOR ISOLATED
AFTERNOON THUNDERSTORMS.
THIS WARM PERIOD WILL ACCELERATE SNOWPACK MELT OFF, WITH STREAM
AND RIVER FLOWS EXPECTED TO RISE SIGNIFICANTLY IN RESPONSE.
CURRENT RIVER/ STREAM FLOW MODELING DOES HAVE A COUPLE LOCATIONS
RISING CLOSE TO ACTION STAGE BUT NO FLOODING IS EXPECTED.
SUNDAY THE RIDGE BREAKDOWN IS EXPECTED WITH A SIGNAL OF INCREASED
INSTABILITY. SHOWERS AND THUNDERSTORMS WILL BE PRESENT ALONG THE
PACIFIC COLD FRONT. A STRONG STORM CAN NOT BE RULED OUT IN THIS
ENVIRONMENT.
NEARLY ALL ENSEMBLE MODELS (ABOUT 90%) CONTINUE TO SHOW A LARGE
SCALE TROUGH OVER THE PACIFIC NORTHWEST EARLY NEXT WEEK (MAY
12-14) WITH A RETURN TO SEASONABLE TEMPERATURES AND SHOWERY
CONDITIONS. GIVEN THE TIME OF YEAR, CLOSED LOWS ARE COMMON IN THIS
PATTERN, WHICH WOULD BRING WIDESPREAD PRECIPITATION, STAY TUNED!
AVIATION: VFR CONDITIONS ARE ANTICIPATED TODAY AS WEAK RIDGING
REMAINS IN PLACE. WINDS TURN SOUTHWESTERLY THIS AFTERNOON WITH
GUSTS OF 15-20 KTS FOR TERMINAL SITES. A WEAK COLD FRONT WILL
BRING A FEW LIGHT SHOWERS EARLY THURSDAY MORNING ACROSS NORTH-
CENTRAL IDAHO AND NORTHWEST MONTANA. BY THURSDAY AFTERNOON, THE
AXIS OF INSTABILITY WILL BE IN SOUTHWEST MT AND FUTURE TERMINAL
AERODROME FORECASTS MAY NEED VICINITY THUNDERSTORMS ADDED TO KBTM
ROUGHLY BETWEEN 08/2100Z AND 09/0300Z.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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