Winter Weather in Lower Clark Fork Region, Montana

Snowfall totals of 2 to 5 inches created icy and hazardous conditions across the region. At Lookout Pass, a crash was reported at 1518MST, with webcams showing vehicle slide-offs by 1630MST. Chains were required at the pass by 1650MST. Later that evening, a crash blocked both eastbound lanes of Interstate 90 east of Alberton starting at 2100MST, where road conditions showed ice. Near the Idaho border, a crash blocked both lanes of Montana Highway 200 between mileposts 0 and 2 near Heron at 2253MST.

Lingering arctic air was overrun by a moist plume of subtropical moisture on December 1 and 2. The northwest flow pattern brought snow to both valley and mountain locations. Although the air temperature drop was gradual, road temperatures were above freezing initially. This caused the initial snowfall to melt and then re-freeze, creating a layer of ice beneath the snow. These slick road surfaces led to several vehicle accidents.