593 FXUS65 KMSO 130811 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 211 AM MDT Fri Jun 13 2025 .DISCUSSION... KEY MESSAGES: - Thunderstorms again today, some storms may be strong. - A weak ridge builds over the region Sunday, causing fewer showers over the region. A trough moving across the region today will cause another round of thunderstorms. There is some uncertainty about how strong they will be which comes down to timing. Current model forecasts have the peak lift from the short wave enhancing storms in the morning and early afternoon. That means that there won`t be much time for the Sun to heat things up and build up instability, which would support stronger storms. The earlier arrival of the trough will also cause more cloud cover, which will somewhat inhibit the heating of the day. If however the trough arrives later in the day, conditions will be more unstable and the storms will be stronger with more shear to support hail growth. Current timing favors stronger storms east of the Continental Divide. Sunday, a weak ridge builds over the region. Models are showing some drying, so it won`t be as humid and there won`t be as much moisture to support thunderstorms. However, the ridge isn`t very strong and it is embedded in a much larger trough pattern over the region with southwest flow. As a result, some thunderstorms and showers are still possible, especially over the mountains in areas with up-slope aligned winds. && .AVIATION...A shortwave moving into the region this morning will cause increasing cloud cover, showers, and thunderstorms. With the morning and early afternoon timing of the trough, severe storms are not expected due to less diurnal heating. The stronger storms are expected east of and along the Continental Divide, that means in our area terminal KBTM is the most likely to see stronger convection. Unlike recent days, the presence of a well defined trough and a jet streak will provide more shear if any strong updrafts do get started. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && $$