A WINTER STORM WARNING has been issued for Lewis and Clark, Madison, Jefferson, Broadwater, Meagher, Gallatin, and Beaverhead Counties, and above 5500' in Cascade and Judith Basin Counties.
This will be the biggest snowstorm for parts of Montana since Thanksgiving. This is a complicated storm with rich moisture streaming in from the Pacific. The position and flow of moisture from the northwest will first favor the mountains with limited to no snow in the lower elevations east of the Continental Divide. Travel over the mountain passes on Thursday will be snowy and slippery, but the valleys east of the Divide and really much of I-15 will be decent until late in the day. That's when snow will increase in the lower elevations like Great Falls, Helena and Townsend. Snow will continue through Thursday night into Friday. The worst travel conditions will be Friday morning, when there will be widespread snow covering the roads. Snow will wind down through the day with cleaner roads by afternoon and evening. Wind over the mountain passes will create drifting snow throughout the day. Saturday another powerful low pressure will move right across Montana with snow and wind. While the snow totals won't be as significant, healthy snowfall rates and a gusty wind will make for another potent storm. Travel conditions may be worse with reduced visibility. Sunday will be a sunny but chilly day. Another round of snow showers will move through Sunday night into Monday morning. A more significant snow with arctic air and subzero temperatures will begin moving into the state on Tuesday. This is the stormiest stretch of winter 2019-2020 right here.
Have a great day.