A powerful storm dropping drenching rain on flood-prone Southern California is raising concern among forecasters that it could produce a dangerous, widespread outbreak of tornadoes, damaging winds and fires along with a blizzard as it crosses the entire United States in the coming days.

California braced for the arrival of a massive storm on Wednesday, evacuating residents in areas at risk of mudslides and debris flows.

A strong storm system is expected to “blast through” Los Angeles and Orange County tonight, bringing a heavy dose of rain over a short period of time and prompting evacuation orders, flood warnings and road closures.

Incoming heavy rain from an atmospheric river-fueled storm that slammed into the West Coast early Wednesday is threatening mudslides and debris flows in Southern California and has already prompted evacuations in the Los Angeles area.