A potent winter storm arrived en force in western Montana early Friday, knocking out power to parts of Missoula and causing delays and cancellations at Missoula International Airport.

City crews raced throughout the morning to keep roadways clear, though the snow soon turned to rain, easing the local commute. Still, forecasters retained their snowfall prediction of eight to 18 inches and expected colder air to arrive by early afternoon.

“We're expecting it to get here soon,” said Ryan Leach, meteorologist with the National Weather Service in Missoula. “If you were to get off I-90 and go up Highway 200, you'd head into it shortly after you got off the interstate. It's right there, and we do still expect it to make it to Missoula and soon.”

A winter storm warning was extended to all of western Montana and the Idaho panhandle, with snowfall predictions ranging from 24 inches at Lookout Pass to a foot or more in Missoula and areas west of the Continental Divide.

By midday, Allegiant Airlines had canceled its Friday flight from Las Vegas into Missoula, as well as the outbound flight. Departures from Missoula to Salt Lake City and Minneapolis were delayed.

Shortly before sunrise, power went out in areas of south Missoula. NorthWestern Energy spokesman Butch Larcombe said a tree had fallen onto a power line, cutting service to 1,500 customers.

“That's residential and some business customers, so it affected a pretty good chunk of folks,” Larcombe said. “We've had a couple other smaller outages in the Missoula area, but no problems elsewhere just yet.”