Large storm to impact western Montana
A large storm is developing south of Montana. It will bring widespread valley rain and mountain snow to the region.
The focus of the heaviest precipitation will be in areas along and south of I-90 from Missoula to Butte and Bozeman. The rain and snow will be periodic from now through Thursday night.
WINTER WEATHER ADVISORY from 4 am Thursday to 6 am Friday for the passes in Gallatin, Madison and Beaverhead Counties. That includes Monida, Big Hole, Chief Joseph, Raynolds and Targhee Passes along with the West Yellowstone area. Snowfall of 6 to 12 inches at Big Hole and Chief Joseph Passes and 3 to 5 inches at the other passes and West Yellowstone.
Rainfall will generally range from a quarter to half inch across the region. However, heavier amounts are likely with possibly a half to one inch in places like Bozeman and Salmon, Idaho.
Heavier rain in the mountains may create mud and rock slides with water running over various roads. The highways most susceptible to this will be #2 and #12.
The precipitation will linger across southwest Montana Friday around Butte and Bozeman, with improving conditions in Missoula and Kalispell.
A nice break will occur from the rain late Friday and Saturday before more showers develop Sunday. Models indicate another impressive storm Sunday through Tuesday.