(Yuba-Sutter CA) — The National Weather Service has issued a winter storm warning for portions of the High Sierra, cautioning Northern Californians to avoid mountain travel this week.

The warning, which is effective until 11 a.m. today, covers areas above 55-hundred feet in High Sierra counties. Forecasters predict heaviest snowfall from Wednesday evening through Thursday, particularly impacting Donner Summit on Interstate 80 and Echo Summit on Highway 50.

Travelers should anticipate difficult conditions, including reduced visibility and slick roads, with chain controls and delays likely. Additionally, another storm is expected to bring heavy snow Friday into Saturday.