A massive Arctic blast is delivering the coldest temperatures of the winter season to much of the US, while Gulf Coast and Southeast states face a rare winter storm. The National Weather Service warns this could be the coldest air in several years, with nearly all Lower 48 states—except for South Florida—seeing freezing temperatures.
Nearly 300 million Americans are set to experience below-average temperatures, with some areas seeing temperatures drop up to 45 degrees below normal and wind chills as low as minus 55 degrees. Around 30 million people from Texas to northern Florida and the Carolinas may face an unusual mix of snow, sleet, and freezing rain. Up to 10 inches of snow is possible in typically milder areas. See detailed forecasts for across the US here (w/clickable map).
The culprit is a shift in the polar vortex—a mass of low-pressure, cold air that rotates above the Earth’s polar regions. A weakened polar jet stream changes wind patterns and temporarily brings Arctic air southward (see the science).
