POLAR VORTEX RETURNS (But What Does That Really Mean?)

Friday morning

The term "polar vortex" became frozen in our minds last winter when it became very cold and stayed that way. Meteorologists have always known about the circumpolar vortex. It is a general area of low pressure aloft that it is typically close to the North Pole in summer but spreads out and changes shape in winter. The launch pad for the widespread use of polar vortex came when last winter's circumpolar cortex expanded southward, but one part of it stretched out much more than usual. Cold air then had a straight shot from northwestern Canada right into the Midwest and on eastward.

Now, however, it seems someone is bringing up "polar vortex" every time it gets cold. In a way, saying there is a polar vortex is as useful as saying there are cars on the highway. Cars are used to get places. They're all over the place. However, if there is an accident with fatalities or injuries and backed up traffic, it is a very serious matter. The polar vortex steers winds around the globe. Sometimes it brings very cold air to us and sometimes it causes the weather to become warm, but it would be silly to say that a warm spell is brought to us by a polar vortex even though that is a common way to get a reprieve from wintry cold!

In this video, I show the forecast layout on a different map base than usual. The map is too big to show minute details, but it should help you picture why it should turn cold in the Midwest and Northeast as we go through next week.

It will turn colder in the Midwest then the Northeast between Tuesday and Thursday. One test of how cold it gets will be whether any new records are set. In Chicago, there have been no new record lows in November since 1991, 23 years ago. Before I play the climate change card on this one, I will point out there have been no new record highs in November since 15 years ago!