BOZEMAN – Ready for a wild weekend weather pattern? It begins Friday afternoon but a bigger impact is coming Saturday through Monday.
Strong SW flow aloft and the atmosphere is slightly unstable which could produce a few strong thunderstorms Friday afternoon and evening. Forecast models show a low probability for severe storms over SW Montana and a better chance for stronger storms north of our region.
Next, is a pacific storm rolling in Saturday late morning. Scattered showers and thunderstorms are likely and some slower moving storms could produce very heavy rainfall. Area of greatest concern is west of I-15. Wisdom, Wise River, Anaconda, Georgetown Lake, Philipsburg, Deer Lodge, Avon, MacDonald Pass and Butte could see a half an inch to 2 inches of rain. If this verifies watch for possible flash flooding, urban flooding, and rivers and streams jumping out of their banks.
Saturday afternoon into Saturday evening thunderstorms will develop over SW Montana east of the divide. Bozeman, Ennis, West Yellowstone and Dillon look for stronger thunderstorms Saturday afternoon into Saturday evening. Some storms could produce locally heavy rain. If this occurs look for flash flooding, urban flooding, and area river systems jumping up to minor flood stage.
Once this first system passes through the pattern will settle down into Sunday morning but by Sunday late morning a slow-moving trough will push into the region produce scattered rain with a few isolated thunderstorms. Colder air will dig into the state by Sunday morning and this will help snow levels drop down to 6,000’. Snow accumulations are likely for most mountain ranges this weekend but forecast models show the best chance for heavy wet snow will be west of I-15, in the Big Sky area, down into Yellowstone National Park.
As skies begin to clear Monday night look for colder morning lows Tuesday morning with below freezing temperatures possible.
