Thanksgiving is forecast to be colder and with more snow than usual across large swathes of the U.S., threatening to snarl what the AAA is projecting to be record holiday traffic.
The big picture: The National Weather Service warns the "polar vortex," an area of cold air around the Arctic, could expand southwards and combine with two other factors to bring "cooler than normal temperatures" from Seattle to Dallas and across to Chicago this Thanksgiving week.
