935 FXUS65 KMSO 092043 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 243 PM MDT Fri Aug 9 2019 .DISCUSSION...Widespread rain showers and isolated thunderstorms will continue to spread from the south to north across the Northern Rockies through the evening hours. Brief heavy rain and occasional lightning will be the main threats this evening. We continue to watch for the potential for strong to severe thunderstorms developing across west-central and southwest Montana, as well as north-central Idaho tomorrow afternoon and evening. Thunderstorms will begin to form in north-central Idaho in the late morning, and strengthen as they move north into western Montana later in the afternoon. Storms that become severe in nature will have the potential to produce strong damaging wind gusts in excess of 50 mph. Winds gusts of these speeds may topple trees and power lines. These strong storms can also produce large hail in excess of 1 inch in diameter. Another impact from these storms will be very heavy rain. Area burn scars will be susceptible for rock and mudslides, along with flooding in some urban locations and other flood prone areas. A Flash Flood Watch has been issued for certain locations with these vulnerabilities. Details can be found at our website www.weather.gov/mso. Scattered thunderstorms will continue to move across the region through midnight Saturday night, but these storms that move overhead after sunset are not expected to be severe in nature. As the upper level trough moves through the area on Sunday, widespread rain will develop, particularly across the Idaho panhandle and northwest Montana. Precipitation amounts of a quarter of an inch or more will be possible in these areas. Thunderstorms will also be possible in the afternoon, and will be capable of brief heavy rain and small hail. Temperatures will run roughly 15 degrees cooler than normal for this time of year. A weak ridge of high pressure is expected over the region to start next week, with temperatures slowly warming though still running somewhat below seasonal normals. As the flow becomes more southwesterly by mid week, the chance for showers and thunderstorms will increase. && .AVIATION...Rain will dissipate at KGPI, KMSO, and KBTM by 10/0200Z and a short break in unsettled weather will last through Saturday morning. The exception will be KSMN as some isolated storms overnight are not out of the question. Saturday will bring active weather to all terminals in the afternoon as many ingredients come together for strong convection. Expect a decrease in visibility as widespread showers and thunderstorms bring heavy rain, lightning, gusty winds, and a chance of hail to all terminals. Storms will start at KSMN by about 10/2000Z, spread north and northeast to KBTM and KMSO, then continue to KGPI by about 10/2200Z. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...Flash Flood Watch from Saturday afternoon through Saturday evening Bitterroot/Sapphire Mountains...Butte/Blackfoot Region...Missoula/Bitterroot Valleys...Potomac/Seeley Lake Region. Flash Flood Watch from Saturday afternoon through Saturday evening Flathead/Mission Valleys...Kootenai/Cabinet Region...West Glacier Region. ID... Flash Flood Watch from Saturday morning through Saturday afternoon Lower Hells Canyon/Salmon River Region... Orofino/Grangeville Region...Southern Clearwater Mountains. && $$