Polar vortex: Your questions answered

Article Image

The coldest air in a generation is spilling out across the US thanks to a breakdown in the polar vortex.The icy blast it's sending southward is the bi...

Posted: Jan 28, 2019 2:10 PM
Updated: Jan 28, 2019 2:45 PM

The coldest air in a generation is spilling out across the US thanks to a breakdown in the polar vortex.

The icy blast it's sending southward is the biggest visitor from the North Pole since Santa Claus. The gifts it brings, however, are chilling and generally unwelcome.

Seventy-five percent of the continental US will dip below freezing at some point this week, leading to record low temperatures across the country. CNN meteorologists Brandon Miller and Judson Jones answer a few pressing questions about this phenomenon.

What is a polar vortex? What distinguishes it?

The polar vortex, as its scary name suggests, is a circulation of strong, upper-level winds that normally surround the northern pole, moving in a counterclockwise direction -- a polar low-pressure system.  These winds tend to keep the bitter cold air locked in the Arctic regions of the Northern Hemisphere. It's not a single storm. On occasion, this vortex can become distorted and dip much farther south than you would normally find it, allowing cold air to spill southward.

How often does this polar vortex distortion occur?

The upper-level winds that make up the polar vortex change in intensity from time to time. When those winds decrease significantly, it can allow the vortex to become distorted, and the result is a jet stream that plunges deep into southern latitudes, bringing the cold, dense Arctic air spilling down with it.

This oscillation is known as the Arctic Oscillation and it can switch from a positive phase to negative phase a few times per year. This oscillation -- namely the negative phase where the polar winds are weaker -- tends to lead to major cold air outbreaks in one or more regions of the planet.

Where on Earth can this happen?

The polar vortex can lead to major cold air outbreaks in any portion of the Northern Hemisphere -- North America, Europe and Asia.

How dangerous is a polar vortex distortion as compared to a tornado or hurricane?

They are completely different types of systems. A cold air outbreak caused by the polar vortex is much more widespread and lasts longer than a single storm. With the widespread drop in temperature, however, you can see significant winter storms develop, especially when the cold air is initially advancing into a previously warm region -- much like the nor'easter during the past week.

When did the last one hit a densely populated area?

Serious cold snaps happen several times a year, though in different regions of the world and with different degrees of severity. Most notable was the polar vortex in the winter of 2014 when cold arctic air spilled out across North America.

It was the first year that the phrase polar vortex was used extensively in the mainstream media. The term took off, especially on Twitter, and meteorologists have been trying to clarify what the name means.

If you get caught up in one, what should you do?

Again, it's not a 'storm' that you get caught in. But when faced with significant cold temperatures, you should stay inside whenever possible, layer clothing if you must be outside, winterize your home and car, etc.

Is it a side effect of global warming and should we expect more events like this?

This is a hotly researched topic. In short, yes, it could be. It seems counterintuitive that global warming could cause significant cold snaps like this one, but some research shows that it could.

We know that different types of extreme weather can result from the overall warming of the planet, melting of the Arctic Sea ice, etc.

This includes extreme distortions of the jet stream, which can cause heat waves in summer and cold snaps in winter.

Indiana Coronavirus Cases

Data is updated nightly.

Confirmed Cases: 34211

Reported Deaths: 2125
CountyConfirmedDeaths
Marion9761576
Lake3573186
Allen160069
Cass15877
St. Joseph126634
Elkhart126228
Hendricks116671
Hamilton115493
Johnson1097108
Madison58659
Porter53428
Bartholomew50834
Clark49741
LaPorte43023
Howard40428
Tippecanoe3933
Delaware38536
Jackson3821
Shelby37122
Hancock33127
Floyd31839
Boone31635
Morgan27824
Vanderburgh2662
Montgomery23817
White2338
Noble22821
Clinton2271
Decatur22431
Grant21022
Dubois1993
Harrison19422
Henry17211
Greene16924
Vigo1688
Dearborn16821
Monroe16712
Warrick16628
Lawrence15924
Miami1401
Putnam1367
Jennings1304
Kosciusko1271
Orange12622
Scott1193
Franklin1108
Ripley1086
Marshall1021
Carroll932
Daviess8516
Steuben832
Wayne785
Fayette777
Newton7710
Wabash772
LaGrange762
Jasper661
Washington521
Clay511
Jay500
Fulton491
Randolph473
Rush462
Pulaski460
Jefferson451
Whitley413
Starke393
DeKalb371
Sullivan351
Owen341
Brown331
Perry320
Wells310
Benton300
Knox280
Huntington272
Tipton251
Blackford252
Crawford240
Fountain212
Switzerland200
Spencer201
Parke170
Adams171
Posey160
Gibson152
Ohio130
Warren121
Martin110
Vermillion100
Union90
Pike60
Unassigned0167
West Lafayette
Clear
63° wxIcon
Hi: 73° Lo: 50°
Feels Like: 63°
Kokomo
Clear
58° wxIcon
Hi: 70° Lo: 47°
Feels Like: 58°
Rensselaer
Clear
59° wxIcon
Hi: 70° Lo: 48°
Feels Like: 59°
Fowler
Clear
59° wxIcon
Hi: 71° Lo: 50°
Feels Like: 59°
Williamsport
Clear
63° wxIcon
Hi: 73° Lo: 50°
Feels Like: 63°
Crawfordsville
Clear
62° wxIcon
Hi: 72° Lo: 50°
Feels Like: 62°
Frankfort
Broken Clouds
64° wxIcon
Hi: 71° Lo: 49°
Feels Like: 64°
Delphi
Clear
59° wxIcon
Hi: 71° Lo: 48°
Feels Like: 59°
Monticello
Clear
59° wxIcon
Hi: 71° Lo: 47°
Feels Like: 59°
Logansport
Clear
57° wxIcon
Hi: 70° Lo: 46°
Feels Like: 57°
Cooler, less humid weather continues Sunday
WLFI Radar
WLFI Temps
WLFI Planner

COVID-19 Important links and resources

As the spread of COVID-19, or as it's more commonly known as the coronavirus continues, this page will serve as your one-stop for the resources you need to stay informed and to keep you and your family safe. CLICK HERE

Closings related to the prevention of the COVID-19 can be found on our Closings page.

Community Events