A Wobbly Polar Vortex Could Make for a Bitter Thanksgiving Across Much of the U.S.

Much of the contiguous U.S. could be in for a very chilly Thanksgiving as a wobbly polar vortex threatens to send a blast of Arctic air southward.

According to the European Centre for Medium-Range Weather Forecasts (ECMWF), a sudden stratospheric warming (SSW) event may be just around the corner. These rare, rapid temperature increases in the upper atmosphere weaken the stratospheric polar vortex—a large area of low pressure and frigid air that swirls around the Arctic. When disrupted, this air creeps down to lower latitudes, causing temperatures to plummet in parts of the northern hemisphere.

The Climate Prediction Center’s outlook for November 24 to 30 reflects these conditions, with below-normal temperatures expected across the majority of the western U.S. during the week of Tha