917
FXUS65 KMSO 200957
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
357 AM 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
TWO WEAK DISTURBANCES WILL BE INTERACTING OVER THE NORTHERN
ROCKIES TODAY INTO SUNDAY. THE FIRST DISTURBANCE IS LOCATED OVER
THE GREAT BASIN REGION PUSHING IN SOME MONSOONAL MOISTURE INTO
LEMHI COUNTY AND SOUTHWEST MONTANA. THE OTHER DISTURBANCE WILL BE
DROPPING OUT OF BRITISH COLUMBIA TODAY INTO SUNDAY, LIMITED THE
NORTHWARD PROGRESSION OF THE MONSOONAL MOISTURE. THIS AFTERNOON
THE BEST CHANCE OF SHOWER AND THUNDERSTORM ACTIVITY WILL BE MAINLY
ACROSS LEMHI COUNTY INTO SOUTHWEST MONTANA, BUT A FEW STORMS COULD
DEVELOP AS FAR NORTH AS MISSOULA UP TO SEELEY LAKE/OVANDO REGION.
THESE STORMS 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 CAUSING WRAP AROUND SHOWER ACTIVITY
ACROSS NORTHWEST MONTANA. THIS DISTURBANCE WILL ALSO PUSH IN
COOLER AIR CAUSING TEMPERATURES TO BE NEAR SEASONAL AVERAGES FOR
SUNDAY INTO 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 POTENTIALLY 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 VALLEYS OF NORTH
CENTRAL IDAHO BREAKING THE CENTURY MARK.
THE FAR 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 TO PUSH INTO LEMHI COUNTY 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 AND KHRF 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...
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page