SACRAMENTO — There’s a week left in fall but forecasters said Tuesday a winter storm is about to roll into Northern California, carrying widespread rain and mountain snow.

The weather system is expected to arrive Wednesday afternoon and continue through Thursday, the National Weather Service said.

Sierra Nevada snow levels will start out at the higher pass levels and drop to as low as 4,500 feet (1,372 meters).

Travel is expected to be hazardous in the mountains.

Caltrans said it has imposed winter closures on Sonora Pass on State Route 108, Monitor Pass on State Route 89 and Ebbetts Pass on State Route 4. Several other roads are also under seasonal or storm closures.