Mount Baker Highway was closed from early Thursday morning to Friday morning because of avalanche danger, the Washington state Department of Transportation said.

"The safety of the traveling public is our top priority, so WSDOT will close the highway at milepost 37, east of Glacier, at 4 a.m. due to anticipated avalanche risk," WSDOT spokeswoman Andrea Petrich said in an email.

Mount Baker Highway, also called state Highway 542, was last closed for avalanche danger in 2009, Petrich said.

A powerful sub-tropical storm is dumping rain in the Whatcom County lowlands and heavy snow in the higher elevations of the North Cascades, the Nation Weather Service said in online forecasts.

But rain was likely Thursday through Saturday above 3,000 feet as the storm blows off the Pacific with warmer temperatures.

Mt. Baker Ski Area said at its website that it was closing Thursday because of avalanche danger and because the highway is its only access road.

Avalanche danger was listed as "high" Thursday in the Mount Baker wilderness, the Northwest Avalanche Center said at its website.

At 4 p.m. Wednesday, WSDOT reported at its website that it was snowing heavily at 4,250 feet with compact snow and ice on the road.

Some 2 feet of snow fell from Tuesday into Wednesday at the ski area and rain on top of that could create dangerous avalanche conditions, ski area officials said online.

"Looking forward the forecast is for warming starting in the early hours of (Thursday) morning coupled with a few inches of rain," the ski area said.

Normal operations were expected to resume Friday at the ski area.