A winter storm descended on the mountains of Southern Oregon this afternoon and likely will complicate travel over the passes through the evening.

A winter storm descended on the mountains of Southern Oregon this afternoon and likely will complicate travel over the passes through the evening.

The National Weather Service in Medford issued a winter weather advisory alerting drivers to watch for heavy snow in the mountains tonight.

A wreck west of Lake of the Woods on a slippery Highway 140 briefly blocked the road this afternoon, and transportation officials imposed chain restrictions on towing and heavy vehicles.

The advisory says drivers should expect 6 to 8 new inches of snow tonight above 5,000 feet, with 2 to 3 inches at 4,500 feet. Eight to 10 inches are possible near Crater Lake and Mount Ashland.

Heavy snow was falling this afternoon at Lake of the Woods, over the Siskiyou Summit on Interstate 5 and on the Greensprings Highway east of Ashland.

Forecasters this morning had predicted snow as low as 1,500 feet tonight, but this afternoon's forecast raises that to 2,000 feet after midnight.

See travel details at www.tripcheck.com.

— Staff reports