934
FXUS65 KMSO 080651
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
1251 AM MDT THU MAY 8 2025
DISCUSSION
KEY MESSAGES:
- SLIGHTLY COOLER, ISOLATED THUNDERSTORMS SOUTHWEST MT AND BREEZY
ALL LOCATIONS TODAY
- 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
THE RIDGE WILL BE KNOCKED DOWN TODAY AS A WEAK DISTURBANCE AND
ASSOCIATED COLD FRONT WORKS ACROSS THE NORTHERN ROCKIES. THE MAIN
IMPACT WILL BE GUSTY WINDS OF 20 TO 30 MPH, STRONGEST ACROSS
NORTHWEST MONTANA. THOSE RECREATING ON AREA LAKES SHOULD PLAN FOR
THESE WINDS AND THE POTENTIAL OF CHOPPY CONDITIONS. THIS WILL BE A
MOSTLY DRY COLD FRONT WITH ONLY A FEW LIGHT SHOWERS. BY THIS
AFTERNOON, THE AXIS OF INSTABILITY WILL BE OVER SOUTHWEST MT WHERE
ISOLATED THUNDERSTORMS MAY OCCUR. ANY VIRGA SHOWER OR
THUNDERSTORM THIS AFTERNOON WILL BE CAPABLE OF ERRATIC OUTFLOW
WINDS GUSTING 30 TO 40 MPH.
RIDGING BUILDS BACK IN FRIDAY AND SATURDAY WITH WARM AND MOSTLY DRY
CONDITIONS. THERE WILL BE ENOUGH INSTABILITY FOR ISOLATED
AFTERNOON THUNDERSTORMS. SATURDAY STANDS OUT FROM I-90 SOUTHWARD
WITH A POTENTIAL OF STRONG, GUSTY OUTFLOW WINDS AS CLOUD BASES
WILL BE FAIRLY HIGH ALLOWING FOR CONSIDERABLE EVAPORATIVE COOLING
FROM ANY 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 AND MOISTURE. SHOWERS AND THUNDERSTORMS WILL BE
PRESENT AHEAD OF AND ALONG A PACIFIC COLD FRONT. A STRONG STORM OR
TWO CAN NOT BE RULED OUT IN THIS ENVIRONMENT. ALSO AHEAD OF THE
FRONT, WATCH FOR GUSTY WINDS OF 30-40 MPH ACROSS LEMHI COUNTY AND
SOUTHWEST MONTANA ON SUNDAY AFTERNOON.
ENSEMBLE MODEL CLUSTERS CONTINUE IN VERY GOOD AGREEMENT (NEAR
100%) WITH A LARGE TROUGH OVER THE PACIFIC NORTHWEST EARLY NEXT
WEEK. THIS PATTERN SIGNALS BELOW NORMAL TEMPERATURES WITH VALLEY
HIGHS IN THE 50S AND 60S ALONG WITH CONSIDERABLE SHOWERS. THIS
TIME OF YEAR IS PRIME TIME FOR CLOSED LOW FORMATION, WHICH OPENS
THE DOOR FOR WIDESPREAD PRECIPITATION. PLEASE STAY TUNED AS
DETAILS COME MORE INTO FOCUS!
AVIATION: A WEAK COLD FRONT WILL BRING A FEW LIGHT SHOWERS THIS
MORNING ACROSS NORTH- CENTRAL IDAHO AND NORTHWEST MONTANA. BY THIS
AFTERNOON, THE AXIS OF WEAK INSTABILITY WILL SHIFT INTO SOUTHWEST
MT/LEMHI COUNTY, THERE MAY BE A THUNDERSTORM OR TWO ALONG WITH
HIGH BASED SHOWERS. ASIDE FROM OCCASIONAL MOUNTAIN OBSCURATIONS
AND A FEW SHOWERS, THIS FRONT WILL BRING LIMITED IMPACTS ASIDE
FROM GUSTY WINDS OF 20-25 KTS. THESE WINDS WILL BE STRONGEST IN
NORTHWEST MONTANA, DIMINISHING AROUND SUNSET AREAWIDE. VFR
CONDITIONS ARE EXPECTED ON FRIDAY WITH TYPICAL AFTERNOON WIND
GUSTS OF 15-20 KTS.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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