Big Storm Brings Thunder, Cooler Temps & Mountain Snow

Posted at 5:18 PM, May 03, 2023
and last updated 2023-05-03 19:48:16-04

A FLOOD WARNING is in effect for the Clark Fork near Missoula.
A FLOOD WATCH has been issued for the Bitterroot Valley, and for the Yaak River near Troy.

It's been an unbelievable stretch of warm and dry weather from the last few days of April into the beginning of May. A large area of high pressure sitting over southern Canada has helped keep Montana sunny with above average temperatures, but this high pressure has also slowed the progression of a big low pressure over California. Eventually this storm will bring changes across Montana later this week and this weekend. Already there have been a few thunderstorms pop on Tuesday and then again Wednesday. There will be one more day with warm and mainly dry conditions before the changes. Thursday the high pressure moves a bit more to the east. Most of the day, most of the state will be completely dry but by late afternoon into the evening, scattered thunderstorms will move southern Montana. A few of these storms will come close to Helena later in the evening. Highs again will be warm in the 70s to around 80. Low pressure will move into Montana on Friday with more widespread showers and thunderstorms along with cooler temperatures in the 50s and 60s. Rain and a few rumbles will move slowly north through the morning into the afternoon. Helena will likely have a wet morning, but the rain should move out just before the Vigilante Day Parade begins at noon. The showers and storms will make for a stormy afternoon and evening for places like Great Falls and Lewistown. Mostly cloudy skies will continue on Saturday with widespread showers and even a return of mountain snow. Highs will be down in the 40s and 50s. Sunday will be somewhat drier to start but another round of showers will move through with some higher elevation snow. Highs will be cool in the 50s to around 60, skies will be partly to mostly cloudy. Another round of wet and cooler weather will move through on Monday and Tuesday. Snow levels could drop below 5000' Monday night into Tuesday morning. Please be aware of possible flooding and cold/fast moving water. Snowmelt continues with well above average temperatures, and now thunderstorms and more rain will increase the amount of water in the creeks, rivers, canals and streams.

Curtis Grevenitz
Chief Meteorologist