The promised major winter storm settled upon western Montana on Wednesday, with copious snowfall in mountains and valleys alike.
The National Weather Service says to expect the heaviest snowfall in the Missoula and northern Bitterroot valleys, south Mission Valley, Seeley-Swan/Potomac area and the lower Clark Fork.
That's where a dry arctic air mass will collide with abundant Pacific moisture, "a classic battle," in the Weather Service's words.
Look for valley accumulations of 8-12 inches, with Seeley Lake receiving 20 inches, by Thursday afternoon.
The mountains of western Montana will receive at least twice that amount, making travel over the passes extremely dangerous, according to the Weather Service.
"In addition to the heavy snowfall, strong westerly winds will produce blowing and significant drifting of snow across the mountains and over passes, which could result in near blizzard conditions at times," according to the Weather Service's winter weather warning.
There is still a chance of freezing rain on Thursday morning, as temperatures warm slightly. Should that happen, the Weather Service says travel will be even more dangerous and difficult.
The winter storm warning is in effect through Thursday.