A polar vortex dipping down from Siberia will bring a cold front with frigid temperatures to nearly 300 million Americans.

Friends of Carla Thomas say her death was more than a tragedy: It was utterly preventable, foreseeable — and forewarned. This advertisement has not loaded yet, but your article continues below.

Multiple bursts of increasingly brutal, cold Arctic air will overspread the eastern two-thirds of the country over the next few days, dropping temperatures to dangerous lows by next week.