If you're heading out of town for Thanksgiving, be prepared for plenty of snow on area roads.

The National Weather Service said a winter weather advisory will be in effect from 4 p.m. Tuesday to 10 a.m. Wednesday. Snow levels are expected to get as low as 3,500 feet by Wednesday.

More storms are expected to drop snow throughout Oregon Thursday through Sunday, but weather forecasters said those storms were a little too far away Monday for accurate forecasting.

Snow is expected to accumulate Tuesday and Wednesday on roads and passes in the Southern Oregon Cascades, Siskiyous and the Mount Shasta area, the advisory said.

Areas named in the advisory include Diamond Lake, Crater Lake, Highway 62 near Crater Lake, Highway 58 at Willamette Pass, Highway 230, Highway 138 at Diamond Lake, Highway 140 near Lake of the Woods, Highway 66 and the Mount Ashland Ski Road. Light snow may also impact motorists on the Siskiyou Summit.

Snow is expected to start falling late Tuesday afternoon at about 4,500 feet. By late evening, the level will drop to about 4,000 feet. Snow levels are expected to hit 3,500 feet by Wednesday morning.

Up to 6 inches are forecast to fall in the Cascades and Siskiyous near Mount Ashland. Up to 3 inches are possible on the Siskiyou Summit, while up to 9 inches could fall at Crater Lake.

Southern winds of up to 20 mph, with 25 mph gusts, are expected Tuesday afternoon and evening, decreasing overnight.

"Visibility may be reduced in blowing snow, especially Tuesday evening when winds will be gusty," the advisory said.

"It is a little too early to pin down any favorable windows for travel (or particularly dangerous ones)" from Thursday through Sunday, the National Weather Service office in Medford said on its Facebook page. But "it looks particularly stormy, so please start preparing now for wintry conditions if you're planning on traveling over any mountain passes."

— Reach reporter Ryan Pfeil at 541-776-4468 or rpfeil@mailtribune.com. Follow him at www.twitter.com/ryanpfeil.