RENO — White out conditions and jack-knifed trucks forced the closure of nearly 100 miles of U.S. Interstate 80 west of Reno for several hours on Tuesday as the most significant winter storm of the season pounded the Sierra with heavy snow.

It also brought much needed rain to the valleys of western Nevada but forecasters said the rain in the Reno-Carson City area would change to snow later Tuesday. Several inches of snow was expected in the valleys overnight.

The Lake Tahoe region and Reno-Sparks area remained under a winter storm warning through Wednesday morning.

The storm barreled in late Sunday, and the National Weather Service said higher elevations could receive as much as 4 feet of snow by Wednesday.

The California Highway Patrol originally closed about a 30-mile stretch of I-80 in both directions from the Nevada-California line to Truckee, Calif., because blowing snow led to zero visibility Tuesday afternoon.

The closure later was expanded another 60 miles west to Applegate, Calif., because eight to 10 tractor-trailer rigs had jack-knifed in that stretch, the patrol said.

The interstate was not expected to open until at least 9 p.m.

Chains or snow tires were required on all other mountain passes, U.S. Highway 50 over Echo Summit, U.S. 395 north of Reno and the Mount Rose Highway that connects Reno to Lake Tahoe.

Travel restrictions also were posted for Washoe Valley south of Reno.