A huge storm system crossing the U.S. threatens to unleash tornadoes Friday in the Mississippi Valley, blizzards in the northern Plains and dry, gusty conditions in Texas and Oklahoma that pose an extreme risk of wildfires.

A powerful storm is dropping drenching rain on flood-prone Southern California and heavy snow on the state’s mountains. It’s the first act of a storm that will unleash a severe thunderstorm outbreak,

Forecasters warned heavy snow could make roads slick and reduce visibility, making travel in some areas "very difficult to impossible."

A major storm continued to wallop much of Southern California on Thursday morning, bringing evacuation warnings, fears of mudslides and heavy mountain snow.

New video shows the moment a tornado touched down in Pico Rivera early Thursday morning, leaving behind a trail of destruction. At around 3:15 a.m., an EF-0 level tornado with wind speeds of up to 85 mph,