On Thursday, the storm was bringing heavy snow and strong winds to the Sierra Nevada and heavy rainfall over parts of coastal southern California.

Violent tornadoes ripped through parts of the U.S., wiping out schools and toppling semitractor-trailers in several states, part of a monster storm that killed at least 18 people as more severe weather was expected late Saturday.

A powerful storm system that unleashed severe weather for millions of Americans from coast to coast this week is now taking aim at the nation’s midsection, bringing blizzard conditions to the northern Plains, thunderstorms and the threat of tornadoes to the Midwest and South and an elevated risk of wildfires to the southern Plains.