A cold front will move south out of Canada on Tuesday night, opening the door to much colder air to move down into Montana.
At the same time, moisture is spreading over the state, and rain is expected to develop during the overnight hours.
As the colder air moves in, the rain will change over to snow through Wednesday morning. This could result in slick, icy roads in some areas as temperatures drop below freezing during the day on Wednesday.
The National Weather Service has issued a Winter Storm Warning for parts of central Montana, affecting elevations above 5000 feet. This includes most mountain passes.
This warning means severe winter weather conditions are expected. Drivers are advised to use extreme caution if venturing into the higher terrain through Wednesday.
Visibility may also be limited at times, making it difficult to view changing conditions on the roads.
The National Weather Service has also issued a Winter Weather Advisory for several counties, affecting elevations below 5000 feet. This includes Great Falls, Helena, Lewistown, and Cut Bank.
The advisory is issued when snow will cause travel difficulties.
STORMTracker meteorologist Mike Rawlins says these lower elevation areas will receive 1-3 inches of snow through Wednesday. At higher elevations, 5-12" of snow is expected, with a few places picking up as much as 18" of snow.
Colder air will move in for Wednesday and temperatures will drop well below average.
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Additional snow is expected with yet another storm system arriving late in the work week.
Low pressure moving off the Pacific Ocean will provide the needed lift for more widespread snow to form over the Northern Rockies and spread across Montana on Thursday and Friday.
Rawlins says an additional 12-24" of snow is likely in the mountains, with 3-8" of snow for lower elevations.
Anyone planning to travel on Friday or Saturday should pay close attention to the forecast as significant travel impacts are anticipated.