287
FXUS65 KMSO 231844
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
1244 PM MDT SAT MAY 23 2026
DISCUSSION
KEY MESSAGES:
- A WARMING TREND CONTINUES THROUGH THE WEEKEND WITH ISOLATED
STORMS IN NORTHWEST MONTANA THIS AFTERNOON AND EVENING.
- SHOWERS AND THUNDERSTORMS CHANCES INCREASE REGION-WIDE BY LATE
MONDAY.
- A LARGE, SLOW-MOVING WEATHER SYSTEM WILL BRING WIDESPREAD RAIN
AND COOLER TEMPERATURES TUESDAY THROUGH MUCH OF NEXT WEEK,
WITH A 50 TO 70 PERCENT CHANCE OF AT LEAST A QUARTER INCH OF
RAIN BY WEDNESDAY MORNING.
SCATTERED SHOWERS WILL DEVELOP THIS AFTERNOON AND EVENING,
PRIMARILY ACROSS NORTHWEST MONTANA AND ALONG THE CONTINENTAL
DIVIDE. IMPACTS WILL STAY LARGELY LIMITED TO BRIEF RAIN SHOWERS
AND LOCALIZED WIND GUSTS UP TO 30 MPH. THERE IS ENOUGH ATMOSPHERIC
ENERGY TO SUPPORT AN ISOLATED THUNDERSTORM OVER GLACIER NATIONAL
PARK. BY TONIGHT, SHOWERS WILL DIMINISH AS A RIDGE OF HIGH
PRESSURE BUILDS INTO THE NORTHERN ROCKIES. THIS RIDGE WILL PROVIDE
A DRY, SUNNY WEEKEND WITH TEMPERATURES CLIMBING 10 TO 15 DEGREES
ABOVE NORMAL FOR LATE MAY.
A MAJOR PATTERN SHIFT BEGINS ON MONDAY AS A LARGE AREA OF LOW
PRESSURE DROPS INTO THE PACIFIC NORTHWEST. THIS WILL SWITCH OUR
WINDS TO THE SOUTHWEST, DRAWING MOISTURE AND INSTABILITY INTO THE
REGION. WIDESPREAD SHOWERS AND THUNDERSTORMS WILL DEVELOP BY
MONDAY AFTERNOON. STORMS ON MONDAY COULD PRODUCE GUSTY WINDS,
FREQUENT LIGHTNING, AND SMALL HAIL.
BY MONDAY NIGHT, A COLD FRONT WILL CROSS WESTERN MONTANA AND
NORTH-CENTRAL IDAHO. AS THE FRONT PUSHES EAST, WRAP-AROUND
MOISTURE WILL FILL INTO THE REGION. TUESDAY IS CURRENTLY FORECAST
TO BE THE WETTEST AND COOLEST DAY OF THE WEEK, WITH HIGH
TEMPERATURES STRUGGLING TO REACH THE 50S AND 60S.
HEADING INTO WEDNESDAY AND THURSDAY, THE LOW-PRESSURE SYSTEM IS
MOST LIKELY TO STALL TO OUR SOUTH OVER THE GREAT BASIN. THIS SETUP
WILL PULL UNUSUALLY HIGH LEVELS OF MOISTURE NORTHWARD FROM THE
PLAINS INTO MONTANA. FORECAST MODELS SUGGEST ATMOSPHERIC MOISTURE
WILL REACH 150 PERCENT OF NORMAL FOR LATE MAY. THIS MOISTURE
CONNECTION WILL INTRODUCE THE THREAT OF HEAVY RAINFALL AND
EMBEDDED THUNDERSTORMS THURSDAY AND FRIDAY.
AVIATION
A DRY AND STABLE AIRMASS WILL MAINTAIN VFR CONDITIONS
ACROSS THE NORTHERN ROCKIES AIRSPACE THROUGH THE WEEKEND, WITH ONE
MINOR EXCEPTION THIS AFTERNOON. SUFFICIENT INSTABILITY NEAR
GLACIER NATIONAL PARK MAY TRIGGER AN ISOLATED THUNDERSTORM OR
ROBUST SHOWER BETWEEN 21Z AND 03Z. THIS ACTIVITY COULD RESULT IN
LOCALIZED MVFR CONDITIONS AND ERRATIC WIND GUSTS UP TO 25 KNOTS
IMPACTING THE KGPI TERMINAL. OTHERWISE, ANTICIPATE LIGHT, TERRAIN-
DRIVEN DIURNAL WINDS AT KMSO, KBTM, KSMN, AND KHRF THROUGH SUNDAY.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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