Some Northwest Montana residents may spend another night in the dark as Flathead Electric Cooperative crews continue restoring power following Wednesday’s severe windstorm.

Roughly 10,000 co-op customers remained without electricity late Thursday afternoon after hurricane-force winds blasted the region. At the peak, about 30,000 homes were affected by outages that stretched from Libby to Essex, south through the Swan Valley and Rollins, and north to Whitefish.

All available co-op employees were working to restore power Thursday, with crews on rotating shifts, but because of the extent of damage to the power system, complete restoration was expected to take multiple days.

“Crews are now inspecting substations and main feeder lines, with the goal of restoring power to the greatest number of members as quickly and safely as possible,” a media release from the co-op stated. “However, crews must visually inspect each issue before determining what resources are needed, which may include tree crews, substation crews or traffic control. Because of the scale and complexity of this outage, estimated restoration times are not available.”

An emergency shelter was opened in Libby at the Memorial Center, and in Flathead County the Office of Emergency Services and the Red Cross were prepared to open a shelter at the fairgrounds.

Another round of strong wind was expected to hit the area Thursday night into Friday morning. A wind advisory for the Flathead and Mission valleys and the Kootenai and Cabinet regions warned that gusts of 50 mph could damage trees and cause more power outages. Mountains along the Continental Divide could see gusts up to 70 mph.

After the cold front passes, a transition to winter weather is likely beginning Thursday night.

A winter weather advisory was issued for the West Glacier region, where up to 12 inches of snow could accumulate from Essex to Marias Pass on U.S. 2.