328 FXUS65 KMSO 261917 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 117 PM MDT Sat Jul 26 2025 .DISCUSSION... KEY MESSAGES: - KMSO Radar or the local Missoula MT weather radar will continue to be offline due to scheduled maintenance through 1st week of August. - Thunderstorm chances will gradually increase each day, moving from south to north, continuing into next week. - There is a 30 to 40 percent probability for strong outflow gusts in excess of 40 mph through Monday. Another round of showers and thunderstorms will impact many of the same areas as yesterday, with coverage extending slightly north and west into the southern Bitterroot and Sapphire Ranges. There remains a 20% probability of isolated wind gusts exceeding 50 mph from Georgetown Lake through Deer Lodge, southward to Butte, as well as across Lemhi County. The majority of wind gusts are expected to remain in the 30 to 40 mph range. While the northern Bitterroot and Missoula valleys may not see thunderstorms today, gusty outflows in excess of 30 mph will still be possible. The overall risk of flash flooding remains low over recent burn scars and flood-prone terrain due to sufficient steering flow from today through Sunday. However, isolated runoff issues cannot be entirely ruled out. The latest high-resolution models are coming into better agreement regarding nocturnal thunderstorms developing over north-central Idaho (Idaho and Clearwater Counties) and moving into west-central Montana tonight. On Sunday, the threat for scattered thunderstorms remains in the forecast, with expected coverage over a larger geographical area of western Montana and north-central Idaho. Sunday`s thunderstorms will have similar impacts, including gusty outflow winds, frequent lightning, and brief heavy rainfall. By the middle of next week, ensemble guidance continues to indicate an increase in atmospheric moisture associated with anomalously high values. Simultaneously, a large-scale trough is forecast to move onshore over the Pacific Northwest, enhancing wind shear and destabilizing the environment. Precipitable water values are projected to range from 160 to 180 percent of climatological normals, increasing the potential for more efficient rainfall production. Under these conditions, the threat of runoff, debris flows, and localized flash flooding over steep terrain and burn scars will increase. Current 48-hour rainfall probabilities show a 20 to 40 percent chance of exceeding 0.50" for areas along and north of I-90 in western Montana. Additional hazards could include frequent lightning, small hail, and strong wind gusts. Individuals with outdoor plans today through next week should remain weather-aware and be prepared to modify activities in response to increasing thunderstorm potential across western Montana and north-central Idaho. && .AVIATION...Scattered showers and thunderstorms will develop across Lemhi County, Idaho and southwest Montana, including terminals KSMN and KBTM, through roughly 27/0200Z. Seasonally warm temperatures and elevated cloud bases will favor strong convective downdrafts, with isolated outflow wind gusts exceeding 35 kts possible (20% chance) in association with the more robust storms. Heavy downpours and abundant lightning are also threats with any storms that develop today. Widespread afternoon winds will impact all terminals through 27/0300Z. Nocturnal convection is likely for KGIC, KHRF, KMSO, with a lesser threat at KBTM and KSMN. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && $$