698 FXUS65 KMSO 270905 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 305 AM MDT Sun Jul 27 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 continue each day, but Monday through Wednesday may become terrain driven. - There is a 30 to 40 percent probability for strong thunderstorm outflow gusts in excess of 40 mph today. An area of showers and thunderstorms moved into north-central ID around midnight and will allow for some nocturnal storms through mid-morning today, spreading eventually into western MT. The question now becomes how much residual cloud cover will we have? With sufficient clearing an analysis of the atmosphere demonstrates increasing moisture today compared to Saturday. Threats for today will continue with gusty outflow winds with a 20 to 30% chance of gusts 40+ mph, generally in the Bitterroot and Missoula Valleys, and I-90 east of Missoula. The increased moisture and modest shear will allow for small hail and isolated heavy downpours. Coverage of storms will expand through all but far NW MT, IE the Yaak and NW portions of US-2. The overall risk of flash flooding remains low over recent burn scars and flood-prone terrain due to sufficient steering flow. However, isolated runoff issues cannot be entirely ruled out. Overnight Sunday into Monday the signal for nocturnal thunderstorms is stronger than this evening, so an adjustment to probability of thunderstorms will be made in the forecast to reflect the potential. Monday through Wednesday the forecast becomes intriguing and challenging. The models would suggest weak high pressure folds over the region. At the same time atmospheric moisture continues to increase. Showers and thunderstorms will continue but may require the lifting of higher terrain to initiate. Also, steering winds that are currently 35 to 40 mph, will decrease 20 to 25 mph. Any heavy showers that form will move slower over any location, we`ll continue to monitor concerns for flash flooding, mainly in vulnerable drainages and new burn scars. The gusty wind outflow threat will decrease except in cases of thunderstorm cores that collapse into valleys due to lack of lift. As HIRES models become available (48-hours or less) they may depict weak waves ejecting off the overall Pacific trough, these would allow for valley storms. By Thursday, atmospheric moisture remains elevated. Models vary widely on timing and actual feature, but almost all depict atmospheric waves moving through the region pushing the ridge east. This will add lift and produce cooler temperatures, with widespread shower and thunderstorm activity. More to come as the forecast evolves. && .AVIATION...An area of showers has moved into north-central ID. Little precipitation is being observed at local weather stations, however brief terrain obscurations with some lightning can be expected. This area of showers moves into Western Montana later this morning. This afternoon, the atmosphere destabilizes again and strong storms develop at KSMN, KHRF, KMSO, and KBTM between 27/1900z and 28/0300z. The wide range in times reflects the potential for two distinct periods of storms to form, early and then again late afternoon. Gusty outflow winds up to 40 kts and heavy downpours reducing visibilities are possible, with a low probability of small hail. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && $$