Winter Storm in Southern Clearwater Mountains, Idaho

Montana Department of Transportation (on the east side of Highway 12) reported severe driving conditions. Lolo Pass Visitor Center reported 59 inches of storm total snow. Rock slides occurred between Grangeville and Elk City. A power outage event was reported in Elk City.

An intense and prolonged atmospheric river (AR) impacted the Northern Rockies, directed primarily at North-Central Idaho. This event was characterized by a deep moisture plume and an unseasonably warm air mass, which transitioned mountain snow to a heavy rain-on-snow event. Total precipitation across the Clearwater Basin ranged from 2.5 to over 5.0 inches. Impacts from this storm included power outages and impacts to travel. The biggest impact, however, was flooding in Clearwater County near Orofino. By the morning of March 13, several days of moderate rain and mild temperatures had completely saturated the soil. With the ground unable to absorb any more water and temperatures remaining above freezing overnight, continued rainfall and rapid snowmelt triggered immediate runoff. This surge of water overwhelmed culverts, destabilized hillsides, and caused rapid rises on small streams and the Clearwater River.