What airlines do to prepare for winter weather and keep passengers safe

Snow began falling over Donner Summit on Monday, slicking Sierra roads and slowing traffic as an early season storm continued to move through Northern Nevada and California.

By midafternoon, no chain controls were in effect on Interstate 80, but Caltrans was screening eastbound trucks at Applegate and requiring westbound brake checks near Nyack -- standard precautions during major Sierra weather.

The Nevada Department of Transportation, meanwhile, reported chain controls on State Route 431 (Mt. Rose Highway) between Incline Lake Recreation Area and Mt. Rose for all vehicles except four-wheel drives with snow tires.

The California Highway Patrol Truckee office reported slick roads and several vehicles sliding off I-80 near Donner Summit late Monday morning, urging drivers to slow down and give extra space as snow continued to fall.

At nearby Soda Springs, researchers at the UC Berkeley Central Sierra Snow Lab noted light snowfall Monday morning -- less than 0.2 inches, below their measurement threshold -- but said they expected measurable accumulation within 24 hours.

The National Weather Service in Reno said snowfall would intensify through Monday night and early Tuesday, bringing 6 to 12 inches above 7,000 feet and up to 18 inches along the Sierra crest. Lighter snow of 1 to 3 inches is possible at lake level, with ridge gusts up to 60 mph and travel impacts likely on Donner and Carson passes.

The heaviest snowfall is expected Tuesday morning through late afternoon, with gusty winds at higher elevations. Road conditions are likely to remain hazardous through the Tuesday morning commute.

In the Reno-Sparks area, rain showers will continue through Tuesday, with highs in the low- to mid-50s. Skies should clear by Wednesday, with warmer, drier weather returning later in the week.

Forecast for Donner Pass on I-80

The National Weather Service in Sacramento said a Winter Storm Warning remains in effect through 5 a.m. Wednesday for Donner Pass and the western slope of the Sierra.

Forecasters expect 4 to 8 inches of snow along the I-80 and U.S. 50 corridors, with 1 to 2 feet south of Highway 50. Snow levels will hover between 5,500 and 6,500 feet, with the heaviest snowfall late Monday night into Tuesday.

Road conditions are expected to be hazardous during the Monday evening and Tuesday morning commutes, the agency said, with slippery roads likely to continue into Tuesday.

Sierra storm brings snow, slick roads over Donner Summit and Tahoe area