622 FXUS65 KMSO 292039 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 239 PM MDT Mon Jun 29 2026 .DISCUSSION... KEY MESSAGES: - Flooding of small streams and creeks due to ongoing heavy rain is imminent or occurring in the Mission valley and in Glacier National Park - Strong showers and thunderstorms capable of rainfall rates of 0.50" to 0.75" per hour possible for locations along and north of I90 in northwest Montana through this evening - Widespread heavy rain tapers off late tonight, however an active pattern supportive of showers and thunderstorms with locally heavy rain continues through Friday Widespread prolonged rainfall continues this afternoon as anomalous moisture (200 percent of normal) continues to rotate around an upper level low pressure system moving slowly through central Montana. Observed 24 hour precipitation amounts of 1 to 2 inches of rain are common across much of western Montana and north central Idaho with focused amounts of 3 to 6 inches occurring in the higher terrain along the Continental Divide in Glacier National Park as well as the Mission and Swan Ranges. With additional amounts of 1 to 3 inches of rain possible through Tuesday morning in these locations, areal flood warnings have been posted for small streams and creeks of Glacier National Park and in the Mission valley. High resolution forecast models show an area of instability through portions of Sanders, Lake, Lincoln, Flathead and Missoula counties this afternoon and evening, which may allow for convective precipitation (thunderstorms and strong showers) to develop. This activity will be capable of 0.50 to 0.75 inch per hour rainfall rates, which could accentuate ongoing flooding or potentially impact additional flood prone basins/burn scars. Precipitation intensity is expected to decrease late tonight into Tuesday morning as the low pressure system exits the region. However, a general trough with a wave of energy will move through the region Tuesday afternoon and evening. Anomalous moisture will remain in the atmosphere, which may allow for thunderstorms capable of localized heavy rain. This will mainly be focused through Idaho county, Lemhi County and southwest Montana. 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 through Friday. && .AVIATION...Low pressure continues to spin east of the Continental Divide this afternoon, sending wraparound moisture into the Northern Rockies airspace. Precipitation will continue, lowering visibility and ceilings into Tuesday morning. Heavier rainfall producing short bursts of 0.50 inches per hour rates will last through about 30/0400Z, reducing visibility down to IFR at times. Expect terrain to be obscured over the entire Northern Rockies airspace well into Tuesday. Fog could also form over KMSO and KGPI early Tuesday morning, though confidence was not yet high enough to include fog in the 29/1800Z TAFs. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...Flood Watch through late tonight for Flathead/Mission Valleys... West Glacier Region. ID...None. && $$