A winter storm arriving before dawn Wednesday is expected to bring several inches of snow to the Sierra. Because of the forecast, Highway 120 in Yosemite will be closed from 6 p.m. Tuesday.

The Lake Tahoe area is also expecting colder temperatures, rain and some snow, but the brunt of the wintry weather will be south of Highway 50. Snow is not expected to accumulate below about 7,000 feet in the Tahoe area.

A winter weather advisory issued by the National Weather Service forecasts two to five inches of snow above 6,000 feet Wednesday from Yosemite south to the Lake Isabella area. Motorists are warned of possible “treacherous conditions,” especially on passes from Ebbetts (Highway 4) southward.

Temperatures in Yosemite Valley are expected to dip near 20 Tuesday and Wednesday nights; Wednesday’s daytime high will be around 35. Snow is expected to decrease Thursday morning.

The Yosemite closure — Highway 120 east of Crane Flat — will remain in effect “until further notice,” the park information system says.

From 1970-2009, the average date on which the road was closed for the remainder of the winter was in mid-November, but this decade it has been trending later, according to figures compiled by the environmental group Mono Lake Committee.

Because of the government shutdown, Yosemite National Park itself remains closed. Through traffic will still be allowed on roads other than Highway 120, but stopping is not allowed.

The park’s website is inactive because of the shutdown; recorded road and weather information is offered at (209) 372-0200.

The National Weather Service website Weather.gov remains in operation.