579
FXUS65 KMSO 201821
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
1221 PM MDT SAT JUN 20 2026
DISCUSSION
KEY MESSAGES:
- THUNDERSTORMS RETURN TO LEMHI COUNTY, IDAHO, AND SOUTHWEST
MONTANA WITH THE WEATHER PATTERN DURING WEEKEND, BRINGING
LIGHTNING AND BRIEF, ERRATIC WIND GUSTS
- WARMING TREND TUESDAY THROUGH THURSDAY
- COOLER AND SHOWERY CONDITIONS EXPECTED NEXT WEEKEND
A DISTURBANCE PASSING TO THE SOUTH OF OUR REGION WILL INTERACT
WITH ANOTHER MORE NORTHERN DISTURBANCE THAT WILL DROP OUT OF
BRITISH COLUMBIA. SHOWER AND THUNDERSTORM ACTIVITY IS LIKELY
ACROSS NORTHWEST MONTANA THIS AFTERNOON AND EVENING, ALONG WITH
ONGOING SHOWER AND THUNDERSTORMS ACROSS SOUTHWEST MONTANA AND
SOUTHEAST IDAHO. IN ADDITION, A FEW STORMS COULD DEVELOP AS FAR
NORTH AS MISSOULA AND UP TO THE SEELEY LAKE/OVANDO REGION. ANY
STORMS THAT OCCUR TODAY WILL BE CAPABLE OF PRODUCING GUSTY ERRATIC
WINDS, LIGHTNING, AND BRIEF HEAVY RAIN. THE SHOWER ACTIVITY IS
EXPECTED TO DIMINISH AFTER SUNSET THIS EVENING.
THE BRITISH COLUMBIA DISTURBANCE WILL CONTINUE TO TRACK ALONG THE
CANADIAN BORDER ON SUNDAY, KEEPING THE CHANCE FOR WRAP-AROUND
SHOWER ACTIVITY ACROSS NORTHWEST MONTANA. IT WILL ALSO BRING IN
COOLER AIR, CAUSING TEMPERATURES TO BE NEAR SEASONAL AVERAGES FOR
SUNDAY AND MONDAY.
A RIDGE OF HIGH PRESSURE WILL BE BUILDING OVER THE REGION TUESDAY
THROUGH THURSDAY. TEMPERATURES WILL BE STEADILY CLIMBING EACH DAY
WITH WEDNESDAY AND THURSDAY BEING THE WARMEST DAYS SO FAR THIS
YEAR. MOST VALLEY LOCATIONS SHOULD BE IN THE UPPER 80S TO LOW 90S
BY WEDNESDAY AFTERNOON, WITH THE LOWER ELEVATION VALLEYS OF NORTH
CENTRAL IDAHO BREAKING 100 DEGREES.
THE VAST MAJORITY (OVER 75%) OF THE LONG TERM MODELS ARE SHOWING
A TROUGH OF LOW PRESSURE MOVING INTO THE PACIFIC NORTHWEST BY NEXT
WEEKEND, CAUSING COOLER CONDITIONS ALONG WITH WIDESPREAD SHOWER
ACTIVITY.
AVIATION
MOISTURE WILL CONTINUE ACROSS LEMHI COUNTY, ID AND
SOUTHWEST MONTANA TODAY, CAUSING SCATTERED SHOWERS. INSTABILITY
THIS AFTERNOON WILL LEAD TO THE POTENTIAL DEVELOPMENT OF
THUNDERSTORMS THAT COULD IMPACT KSMN AND KBTM. THESE STORMS WILL
BE CAPABLE OF PRODUCING GUSTY ERRATIC WINDS, LIGHTNING, AND BRIEF
HEAVY RAIN. KMSO, KHRF, AND KGPI HAVE A LOWER PROBABILITY OF
BEING IMPACTED BY THESE STORMS. THE SHOWER ACTIVITY IS EXPECTED TO
DIMINISH AFTER SUNSET THIS EVENING.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...
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