Unprecedented Cold Snap: Polar Vortex Displacement Brings Prolonged Winter Chill to the US
With over 170 million Americans facing below average temperatures, even colder air may be on the horizon thanks to the displacement of the polar vortex that will lock in a deep winter feel and park the coldest air over North America. Meanwhile, Florida will join the rest of the eastern half of the country with temperatures dropping into the 20s Friday.
According to experts, the polar vortex, a circulation of strong winds that normally keeps cold air trapped near the poles, has been stretched or elongated, rather than significantly weakened. This unusual phenomenon allows cold air to spread across a large area, leading to prolonged cold spells.
Understanding the Polar Vortex
Typically, a strong polar vortex keeps the coldest air locked up around the North and South poles. When it weakens, it allows for cold air intrusions into the lower latitudes, opening a window for cold air to flow into the U.S. 
This animation shows what a polar vortex is and where it comes from.
In the current circumstances, the displaced polar vortex will keep the coldest air over North America and bring prolonged periods of cold to the eastern portion of the Lower 48 through the end of January. 
This graphic displays how the polar vortex is impacting temperatures this week.
Cold Air Invasion: Florida and the Southeast
After a quick January thaw for most across the Lower 48, winter will roar back with temperatures crashing well below average from the Upper Midwest and stretching into Florida this week. By Thursday, the jet stream will dip south and drop temperatures 10 to 20 degrees below average for the entire state, except for Miami, which will remain closer to its seasonal average. 
This graphic displays the cold air surging south from Canada driving cold air into Florida by Friday.
Friday morning may be the coldest of the week, with freezing temperatures reaching as far south as Jacksonville and Daytona Beach. To provide perspective on the intensity of the cold, Tallahassee is forecast to be 26 degrees; meanwhile, Denver—located 1,630 miles away and at an elevation 5,155 feet higher—is forecast to be 27 degrees that same morning.
Impacts and Forecasts
This first shot of arctic air will plunge over 170 million Americans into below-average temperatures Tuesday. While parts of the Great Lakes and Northeast will feel the chill, the most significant shift will occur across the Southeast; cities like Nashville, Atlanta, and Louisville may not even reach 40 degrees for an afternoon high. 
This graphic displays the forecast wind chill temperatures in the East on Friday.
On Saturday, a second shot of bitter cold air will hit the Upper Midwest, where high temperatures may struggle to reach 10 degrees. This deep freeze will persist through the weekend and into early next week. To make matters worse, wind chills are expected to plunge to -10 to -20 degrees in Minneapolis and Chicago on Sunday.
For more information on the polar vortex and its impacts, visit Here
Image Source: www.foxweather.com
