Winter Storm Warnings are covering much of western and central Montana, with snow already building and more expected through Monday in the Helena Valley, Madison River Valley, Missouri Headwaters, MacDonald Pass, Homestake Pass, Highway 12 Garrison to Elliston, Georgetown Lake, Butte and the Absaroka/Beartooth Mountains. Some of the highest totals could reach 30 inches in the heaviest mountain pockets, while lower valleys may end up with only a light dusting.
The search for snowfall totals in Montana is driven by how uneven this storm is. In the Helena Valley, Madison River Valley and Missouri Headwaters, another 3 to 7 inches is expected and winds may gust as high as 40 mph before the warning expires at 6 AM Monday. Farther southwest, the warning that begins at 6 PM Saturday for MacDonald Pass, Homestake Pass, Highway 12 Garrison to Elliston, Georgetown Lake and Butte calls for 3 to 9 inches overall, with 12 to 18 inches possible in the higher mountain areas and gusts up to 45 mph.
The storm does not stop at the passes. The Absaroka/Beartooth Mountains are under warning from 6 PM Saturday to noon Monday, with 10 to 18 inches forecast. Gates of the Mountains, Upper Blackfoot and MacDonald Pass, Southern High Plains and Southern Rocky Mountain Front remain under warning until 6 AM Monday with 10 to 20 inches expected. The East Glacier Park Region Zone and Northern High Plains also stay under warning until 6 AM Monday, with 10 to 20 inches forecast and the highest amounts in the mountains south of US Highway 2.
That split between mountain and valley snowfall is the part travelers need to watch. Snow totals are expected to stay above 4,000 feet through the weekend, while lower valleys in western Montana may see only a light dusting on grassy surfaces. Even so, travel could be very difficult in several warned areas, and the hardest roads to use will be the mountain routes and passes where the heaviest snow and strongest winds overlap. Travel into Cooke City will be hit by severe winter conditions, and isolated amounts approaching 30 inches are possible within the Bob Marshall Wilderness.
The warnings end at different times, which matters because conditions will not improve all at once. The first round expires at 6 AM Monday in several valleys and mountain zones, while the Absaroka/Beartooth Mountains hold on until noon Monday. After the snow, a widespread hard freeze is expected in the valleys Monday through Wednesday mornings, with Tuesday morning looking like the coldest stretch of the forecast.
