065
FXUS65 KMSO 090852
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
252 AM MDT SAT MAY 9 2026
DISCUSSION
KEY MESSAGES:
- RAPIDLY BUILDING HEAT WILL BRING WIDESPREAD 70S AND 80S THIS
WEEKEND WITH TEMPERATURES POTENTIALLY REACHING CLOSE TO 90
DEGREES BY TUESDAY.
- DANGEROUSLY COLD WATER CONTINUES TO BE THE PRIMARY HAZARD, AS
RIVER TEMPERATURES IN THE 40S AND 50S CAN TRIGGER COLD-WATER
SHOCK.
A RIDGE OF HIGH PRESSURE WILL AMPLIFY OVER THE REGION. CONFIDENCE
IS EXCEPTIONALLY HIGH FOR A PROLONGED PERIOD OF MOSTLY DRY,
UNSEASONABLY WARM CONDITIONS THROUGH AT LEAST EARLY TO MIDDLE-PART
OF NEXT WEEK. TUESDAY REMAINS ON TRACK TO BE THE HOTTEST DAY OF
THE SEASON SO FAR. CURRENT FORECASTS OF TEMPERATURES NEARING 90
DEGREES (25% CHANCE FOR MISSOULA AND BITTERROOT VALLEYS, 70%
CHANCE FOR LOWER RIVER VALLEYS OF IDAHO) WOULD BEGIN TO ENCROACH
ON DAILY HIGH TEMPERATURE RECORDS FOR MANY LOCATIONS.
DESPITE THE "SUMMER" FEEL OF THE AIR, LOCAL WATERWAYS REMAIN
EXTREMELY HAZARDOUS. RIVERS ARE CURRENTLY RUNNING FAST AND HIGH
WITH NEAR-PEAK MOUNTAIN SNOWMELT ONGOING. DEBRIS AND HAZARDS MAY
BE OBSCURED OR HIDDEN UNDER THE WATER'S SURFACE. WATER
TEMPERATURES BETWEEN 40 AND 50 DEGREES CAN PARALYZE MUSCLES AND
TRIGGER INVOLUNTARY GASPING (COLD-WATER SHOCK) IN MINUTES EVEN FOR
STRONG AND EXPERIENCED SWIMMERS. RECREATIONISTS ARE URGED TO WEAR
LIFE JACKETS AND STAY BACK FROM SLIPPERY, UNSTABLE BANKS.
MODEL UNCERTAINTY INCREASES BY WEDNESDAY AS THE RIDGE COULD BEGIN
TO BREAK DOWN. THERE IS CURRENTLY A ROUGHLY 50% CHANCE OF A
TRANSITION TO A SLIGHTLY COOLER AND MORE ACTIVE PATTERN BY MID WEEK.
AVIATION
VFR WEATHER CONDITIONS WILL PREVAIL ACROSS THE
NORTHERN ROCKIES THROUGH THE FORECAST PERIOD. TYPICAL AFTERNOON
WESTERLY WINDS(EXCEPT FOR THE SOUTHERLY AT GPI DUE TO THE FLATHEAD
LAKE BREEZE) WILL GUST BETWEEN 10 AND 20 KNOTS BEFORE BECOMING
LIGHT AND VARIABLE OVERNIGHT.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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