467
FXUS65 KMSO 151845
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
1245 PM MDT SAT AUG 15 2026
DISCUSSION
KEY MESSAGES:
- CHANCES FOR THUNDERSTORMS THIS AFTERNOON FOR NORTH-CENTRAL
IDAHO, AND WEST-CENTRAL AND SOUTHWEST MONTANA. ABOUT 10% CHANCE
FOR STORMS TO BECOME SEVERE.
- SHOWER AND THUNDERSTORM ACTIVITY WILL CONTINUE EACH AFTERNOON
THROUGH EARLY NEXT WEEK.
- WARMING AND DRYING LATTER PART OF NEXT WEEK UNDER A RIDGE OF
HIGH PRESSURE.
SOUTHWESTERLY FLOW ALOFT WILL BRING MOISTURE INTO THE NORTHERN
ROCKIES THIS AFTERNOON. THE MOISTURE FEED WILL COINCIDE WITH A
SHORTWAVE DISTURBANCE MOVING SOUTHWEST TO NORTHEAST OVER NORTH-
CENTRAL IDAHO INTO WESTERN MONTANA THIS AFTERNOON AND EVENING.
MODEL SOUNDINGS INDICATE ENOUGH INSTABILITY TO FUEL THUNDERSTORM
DEVELOPMENT IN THE AFOREMENTIONED AREAS. HIGH RESOLUTION MODELS
SHOW STORMS TRACKING WITH THE SHORTWAVE, SOUTHWEST TO NORTHEAST
ALONG APPROXIMATELY U.S. HIGHWAY 12. PRIMARY THREATS FROM
THUNDERSTORMS WILL BE SMALL HAIL, GUSTY OUTFLOW WINDS OF ABOUT
40-50 MPH, HEAVY RAIN, AND FREQUENT LIGHTNING. THERE IS ABOUT A 10
PERCENT CHANCE THAT STORMS BECOME SEVERE, MEANING ONE-INCH
DIAMETER HAIL AND GUSTS OF 50-60 MPH.
UPPER LEVEL FLOW TRANSITIONS TO WESTERLY ON SUNDAY AS A BROAD
RIDGE OF HIGH PRESSURE BUILDS OVER THE WESTERN U.S. THE MOISTURE
FEED STAYS UNINTERRUPTED, THOUGH, AND WILL CONTINUE TO SUPPORT
SOME THUNDERSTORM ACTIVITY IN THE AFTERNOON. AS NEXT WEEK
PROGRESSES, A TROUGH OF LOW PRESSURE AMPLIFYING OVER THE EASTERN
PACIFIC WILL BRING SOUTHWESTERLY FLOW ALOFT TO THE NORTHERN
ROCKIES. THIS SETUP WILL KEEP AFTERNOON THUNDERSTORMS IN THE
FORECAST FOR THE FIRST PART OF THE WORK WEEK. HIGH PRESSURE
COINCIDING WITH A MUCH DRIER AIRMASS WILL MOVE BACK IN FOR THE
LATTER PART OF THE WEEK.
AVIATION
FAIR WEATHER EARLY TODAY WILL TRANSITION TO MORE
UNSETTLED WEATHER LATER THIS AFTERNOON AND EVENING IN THE FORM OF
THUNDERSTORMS. STORMS WILL MOVE FROM SOUTHWEST TO NORTHEAST,
STARING OUT IN THE VICINITY OF KSMN BY ABOUT 15/2100Z. PRIMARY
THREATS FROM THUNDERSTORMS WILL BE ERRATIC, GUSTY WINDS OF ABOUT
35-45 KNOTS, HEAVY RAIN DROPPING VISIBILITY TO ABOUT 4 SM, SMALL
HAIL, AND FREQUENT LIGHTNING. STORMS WILL HAVE ABOUT A 10 PERCENT
CHANCE OF BECOMING SEVERE (DAMAGING HAIL AND GUSTS OF 45-55
KNOTS). FOG WILL BE AN ISSUE ON SUNDAY MORNING IN AREAS THAT
RECEIVE HEAVY RAIN TONIGHT. THERE'S NOT ENOUGH CONFIDENCE THIS
AFTERNOON FOR FOG TO INCLUDE IN 15/1800Z TAFS. SUNDAY AFTERNOON
WILL BE SIMILAR TO TODAY AS FAR AS CONVECTION.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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