953
FXUS65 KMSO 211824
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
1224 PM MDT THU MAY 21 2026
DISCUSSION
KEY MESSAGES:
- WARMING AND DRYING TREND EXPECTED THROUGH THE WEEKEND.
- COLD FRONT MONDAY-TUESDAY MAY USHER IN COOLER, BREEZY AND
UNSETTLED WEATHER FOR MUCH OF NEXT WEEK.
THROUGH FRIDAY: NORTHERLY FLOW AND WEAK ATMOSPHERIC INSTABILITY
WILL SUPPORT ISOLATED CONVECTIVE SHOWERS THIS AFTERNOON, PRIMARILY
ALONG THE CONTINENTAL DIVIDE. OTHERWISE, TEMPERATURES WILL REMAIN
UNSEASONABLY COOL ACROSS SOUTHWEST MONTANA, WITH HIGHS RESTRICTED
TO THE 50S (ROUGHLY 10 DEGREES BELOW NORMAL FOR BUTTE). WESTERN
MONTANA WILL SEE HIGHS IN THE 60S, WHILE THE LOWER ELEVATIONS OF
NORTH-CENTRAL IDAHO WILL APPROACH 80 DEGREES.
FRIDAY WILL FEATURE A WARMING TREND, WITH AFTERNOON TEMPERATURES
INCREASING BY 5 TO 7 DEGREES ACROSS THE NORTHERN ROCKIES. SCATTERED
SHOWERS ARE EXPECTED FRIDAY AFTERNOON AND EVENING ACROSS NORTHWEST
MONTANA AND ALONG THE DIVIDE. IMPACTS WILL REMAIN LIMITED TO BRIEF,
LOCALIZED RAINFALL AND WIND GUSTS UP TO 25 MPH. HOWEVER, SUFFICIENT
INSTABILITY MAY TRIGGER AN ISOLATED THUNDERSTORM WITHIN GLACIER
NATIONAL PARK.
THIS WEEKEND/WATER SAFETY:
A SIGNIFICANT WARMING TREND WILL BRING SUMMER-LIKE TEMPERATURES TO
THE REGION BY THE WEEKEND. WITH THE WARM AIR TEMPERATURES,
OUTDOOR RECREATION WILL LIKELY INCREASE AROUND AREA LAKES AND
RIVERS. PLEASE BE AWARE THAT LOCAL WATERWAYS CONTINUE TO RUN
EXTREMELY COLD DUE TO ONGOING MOUNTAIN SNOWMELT. PLUNGING INTO
COLD WATER WITHOUT ACCLIMATIZATION CAN INDUCE COLD WATER SHOCK,
WHICH DRASTICALLY ALTERS BREATHING, HEART RATE, AND BLOOD
PRESSURE, CREATING LIFE- THREATENING CONDITIONS. ALWAYS WEAR A
LIFE JACKET TO STAY AFLOAT AND EXERCISE CAUTION. FOR MORE
INFORMATION ON COLD WATER HAZARDS, VISIT
WEATHER.GOV/SAFETY/COLDWATER.
EARLY TO MID-NEXT WEEK:
BY EARLY NEXT WEEK, A PACIFIC TROUGH WILL INTRODUCE AN UNSETTLED
WEATHER PATTERN ACROSS THE PACIFIC NORTHWEST, EVENTUALLY PROGRESSING
INTO CENTRAL IDAHO AND WESTERN MONTANA. CONSIDERABLE SPREAD REMAINS
AMONG DETERMINISTIC MODELS REGARDING THE FINER SYNOPTIC DETAILS.
CURRENT ENSEMBLE CLUSTER ANALYSIS FOR MONDAY INDICATES A 61%
PROBABILITY OF A SLOWER, MILDER PROGRESSION, WHILE THE REMAINING 39%
OF MEMBERS FAVOR A FASTER, COOLER, AND WETTER SOLUTION.
THIS TROUGH IS EXPECTED TO EVENTUALLY CUT OFF AND MEANDER OVER THE
REGION, MAINTAINING SHOWERY CONDITIONS THROUGH MID-WEEK. THOSE WITH
OUTDOOR PLANS NEXT WEEK SHOULD MONITOR THE FORECAST CLOSELY AND BE
PREPARED WITH RAIN GEAR IN THE EVENT THE WETTER SOLUTIONS MATERIALIZE.
AVIATION
PREDOMINANTLY VFR CONDITIONS WILL PREVAIL ACROSS ALL
REGIONAL TERMINALS THROUGH FRIDAY. DIURNAL CUMULUS DEVELOPMENT
WILL BE COMMON OVER THE HIGHER TERRAIN BOTH THIS AFTERNOON AND
FRIDAY AFTERNOON, WHILE VALLEYS REMAIN MOSTLY CLEAR TO PARTLY
CLOUDY. ISOLATED SHOWERS ARE EXPECTED NEAR THE CONTINENTAL DIVIDE
THIS AFTERNOON, WITH SHOWER ACTIVITY EXPANDING INTO NORTHWEST
MONTANA BY FRIDAY AFTERNOON. SUFFICIENT INSTABILITY MAY SUPPORT AN
ISOLATED THUNDERSTORM NEAR GLACIER NATIONAL PARK ON FRIDAY
AFTERNOON. EXPECT LOCALIZED WIND GUSTS OF 20-25 KNOTS NEAR ANY
THUNDERSTORM OR STRONGER SHOWER ACTIVITY. OTHERWISE, LIGHT AND
DIURNALLY DRIVEN WINDS WILL CONTINUE AT ALL TERMINAL SITES.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page