Winter Weather in Lower Clark Fork Region, Montana

Up to 4 inches of snow fell in the mountain generally above 6000 feet. On the morning of May 18, low temperatures ranged from 27 degrees in Nine Mile to 32 degrees in Trout Creek, causing frost formation. On May 19, temperatures ranged from 32 degrees in Haugan to 38 degrees along Highway 200.

An unseasonably cold upper-level trough, originally an Aleutian Low/Gulf of Alaska low, was dislodged and sagged south over the Pacific Northwest and Northern Rockies. This system brought a prolonged period of late-season winter weather, including persistent graupel showers, accumulating mountain snow, and record or near-record cold temperatures leading to widespread frost and hard freezes across Western Montana.