145
FXUS65 KMSO 180922
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
322 AM MDT SAT JUL 18 2026
DISCUSSION
KEY MESSAGES:
- STRONG TO SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING,
BRINGING THE THREAT OF STRONG WINDS, LARGE HAIL, AND HEAVY RAIN.
- ELEVATED FIRE WEATHER THIS WEEKEND FROM HOT, DRY, AND BREEZY
CONDITIONS, ESPECIALLY IN NORTHWEST MONTANA.
HIGH RESOLUTION MODELS SHOW CONVECTION FORMING OVER THE SOUTHERN
BITTERROOT MOUNTAINS AROUND 2 TO 3PM, AND WILL MOVE NORTHEASTWARD
INTO WEST-CENTRAL AND SOUTHWEST MONTANA. GUSTY WINDS WILL BE THE
MAIN CONCERN WITH THESE STORMS, WITH GUSTS 40 TO 50 MPH
ANTICIPATED WITH STRONGER CELLS. WHILE LOW (10 TO 15 PERCENT),
THERE IS A CHANCE THUNDERSTORMS COULD FORM AS FAR NORTH AS
NORTHWEST MONTANA THIS EVENING.
LIKE YESTERDAY, STORMS WILL ALSO BE CAPABLE OF VERY HEAVY RAINFALL
WITH RATES IN EXCESS OF 0.50 INCHES PER HOUR. SENSITIVE FLOOD-
PRONE AREAS AND RECENT BURN SCARS, PARTICULARLY IN LEMHI COUNTY
AND SOUTHWEST MONTANA, COULD HAVE FLOOD CONCERNS IF THEY TAKE A
DIRECT HIT FROM A THUNDERSTORMS.
TODAY, THE LOW PRESSURE SYSTEM THAT HAS BEEN SITTING OFF THE
PACIFIC NORTHWEST COAST SLOWLY MOVES THROUGH SOUTHERN BRITISH
COLUMBIA AND ALBERTA, FLATTENING THE RIDGE OF HIGH PRESSURE AND
BRINGING MORE WESTERLY FLOW ALOFT. THIS WILL SHIFT THUNDERSTORM
POTENTIAL PRIMARILY TO LOCATIONS SOUTH OF INTERSTATE 90. FURTHER
NORTH ACROSS NORTHWEST MONTANA, BREEZY WESTERLY WINDS WILL
DEVELOP. THIS COUPLED WITH MUCH DRIER AIR COULD ENHANCE FIRE
WEATHER CONCERNS. BY SUNDAY, MUCH DRIER AIR MOVES OVER ALL OF
WESTERN MONTANA AND NORTH CENTRAL IDAHO, WITH HOT, DRY AND BREEZY
CONDITIONS ANTICIPATED.
LONG-RANGE WEATHER MODELS SUGGEST THE NEXT SURGE OF MONSOON
MOISTURE WILL ARRIVE BY THE MIDDLE OF NEXT WEEK. CHANCES FOR
SHOWERS AND THUNDERSTORM WILL TREND HIGHER EACH DAY AS MOISTURE
LEVELS REACH OVER ONE INCH.
AVIATION
THE ATMOSPHERE OVER THE NORTHERN ROCKIES WILL REMAIN
UNSTABLE TODAY, WITH AFTERNOON THUNDERSTORMS DEVELOPING OVER KSMN
AND KBTM BY 18/2000Z THIS AFTERNOON. GUSTY OUTFLOWS WILL AGAIN BE
A CONCERN, WITH GUSTS 30 TO 40 KNOTS DEVELOPING BETWEEN 18/2200Z
AND AND 19/0300Z FOR KMSO, KBTM, KSMN, KHRF. HEAVY RAINFALL WILL
ALSO ACCOMPANY THESE THUNDERSTORMS, THAT WILL BRING LOW VISIBILITY
FOR A SHORT PERIOD OF TIME.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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