236 FXUS65 KMSO 290852 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 252 AM MDT Mon Jun 29 2026 .DISCUSSION... KEY MESSAGES: - Potential for rapidly rising water levels in small creeks and streams across northwest Montana this afternoon and evening, due to heavy rain showers and thunderstorms. Localized rockfall and/or debris flows are possible as well. - Hypothermia risk continues through the day Monday in the backcountry. - Near seasonable temperatures along with daily thunderstorm chances are possible Tuesday through Friday of next week. Satellite and radar observations show a large low pressure system spinning over central Montana, near Great Falls this morning, that is spreading moderate to heavy rainfall across western Montana. Moderate snowfall is also occurring for elevations above 6,500 feet across the Northern Rockies. As such, Winter Storm Warnings remain in effect through mid-morning. Along with impassable backcountry Forest Service roads, the risk for hypothermia for unprepared recreationists remains due to the cold and wet conditions. Rainfall totals over the past 36 hours ending this morning have ranged between 0.30 to 1.50 inches across the Northern Rockies. The highest totals have fallen in the terrain along the Continental Divide from the Canadian Border, south to Butte. Several inches of snow have also been reported across the region with 6 inches at Lost Trail Pass, 7 inches near Porters Corner in Granite County, Montana, and 8 inches near Cobalt in Lemhi County, Idaho. Widespread moderate to heavy rain at times will continue through mid-morning today. Rainfall rates this morning will generally range from 0.10 to 0.20 inches per hour. These rates are expected to increase later this afternoon and evening, when heavy showers and thunderstorms develop between 2 PM and 10 PM. During this time, rates of 0.50 inches per hour or more are expected under the heavier showers. The latest forecast ensemble models show additional rainfall totals through Tuesday morning ranging between 0.75 and 1.50 inches across the Northern Rockies. The higher terrain along the Continental Divide and the Mission Range has additional expected amounts of 1 to 2 inches. Some of these totals account for the potential for heavy rainfall with scattered thunderstorms this afternoon and evening, so not everyone will see these higher amounts. This will be on top of what has already fallen. Small streams and creeks may experience rapid rises this evening with the expected additional rain, along with the threat for rockfall and/or debris flows. The highest risk for these impacts is most likely to occur in the higher terrain along the divide and the Mission Range, north of Missoula. Additional Flood Watches may need to be issued this morning to account for these risks. Given the widespread precipitation, fog and low clouds could cause travel issues across the region Tuesday morning. The lingering moisture will also support scattered showers later in the day. A moderating trend is expected later this week with possible thunderstorms each day. With the added low-level moisture from all the rain, this could enhance instability each day. && .AVIATION...Satellite and radar observations show a large low pressure system spinning over central Montana, near Great Falls this morning, that is spreading moderate to heavy rainfall across western Montana. Moderate snowfall is also occurring for elevations above 6,500 feet across the Northern Rockies. The widespread rainfall will periodically reduce visibility and ceiling for all aviation sites throughout the day, along with mountain obscurations. This afternoon heavier showers and scattered thunderstorms are expected to develop between 29/2000Z and 30/0400Z this evening. These showers and thunderstorms will be capable of producing short bursts of 0.50" per hour rainfall rates as they pass overhead. KGPI, KMSO, and KHRF will have the highest risk for these heavier showers. Given the recent widespread precipitation, fog and low clouds could cause travel issues across the region Tuesday morning. Afternoon showers will remain in the forecast, through the widespread persistent precipitation will have ended by sunrise Tuesday. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...Winter Storm Warning until 9 AM MDT this morning for Bitterroot/Sapphire Mountains...Butte/Blackfoot Region. Flood Watch until 3 AM MDT early this morning for Flathead/Mission Valleys...Potomac/Seeley Lake Region... West Glacier Region. Lake Wind Advisory until 3 AM MDT early this morning for Flathead/Mission Valleys. ID...Winter Storm Warning until 9 AM MDT this morning for Eastern Lemhi County...Western Lemhi County. && $$