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.

A cross-country tornado snow blitz threatens 100 million Americans with the ‘most severe’ storm outbreak of the year. ‘Dangerous, damaging and life-threatening’ weather conditions spanning half a million square miles will smash the US into mid-month.

Severe thunderstorms, flooding rainfall, damaging winds, wildfires, record temperatures and snow are all possible across the United States.