Polar vortex: Your questions answered

CNN's Jennifer Gray explains what is a "Polar Vortex" and what to do if you find yourself in very cold temperatures.

Posted: Jan 28, 2019 2:04 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.

Terre Haute
Clear
75° wxIcon
Hi: 90° Lo: 72°
Feels Like: 75°
Robinson
Clear
73° wxIcon
Hi: 90° Lo: 70°
Feels Like: 73°
Indianapolis
Few Clouds
76° wxIcon
Hi: 82° Lo: 72°
Feels Like: 76°
Rockville
Clear
71° wxIcon
Hi: 87° Lo: 71°
Feels Like: 71°
Casey
Clear
77° wxIcon
Hi: 91° Lo: 72°
Feels Like: 78°
Brazil
Clear
75° wxIcon
Hi: 85° Lo: 71°
Feels Like: 75°
Marshall
Clear
75° wxIcon
Hi: 88° Lo: 71°
Feels Like: 75°
The Heat Continues
WTHI Planner
WTHI Temps
WTHI Radar

WTHI Events

 

Illinois Coronavirus Cases

(Widget updates once daily at 7 p.m. CT)

Confirmed Cases: 147865

Reported Deaths: 7026
CountyConfirmedDeaths
Cook927814630
Lake10007423
DuPage9364475
Kane7877275
Will6957320
Winnebago310996
McHenry212097
St. Clair2037137
Kankakee131165
Rock Island106129
Madison104269
Kendall100021
Champaign96015
Boone61021
DeKalb58220
Peoria56728
Sangamon45532
Jackson34019
Randolph2887
McLean28513
Stephenson2785
Ogle2754
Clinton24217
Macon23622
LaSalle22817
Union19619
Whiteside19615
Coles17817
Grundy1775
Iroquois1645
Tazewell1528
Knox1470
Warren1450
Monroe13713
Cass1367
Williamson1334
Adams1311
Morgan1303
Jefferson10717
Lee1032
McDonough10215
Henry981
Pulaski790
Vermilion792
Marion700
Macoupin583
Perry581
Douglas540
Unassigned530
Livingston522
Montgomery491
Christian474
Jasper477
Jo Daviess471
Ford401
Woodford362
Jersey351
Franklin310
Bureau302
Menard250
Mercer250
Fayette233
Mason230
Wabash230
Alexander220
Carroll212
Washington210
Johnson200
Piatt200
Effingham191
Hancock191
Moultrie190
Shelby191
Crawford180
Logan180
Cumberland170
Bond161
Clark150
Fulton150
Massac150
Wayne141
Schuyler130
De Witt120
Marshall110
Brown100
Edgar100
Greene90
Saline90
Henderson80
White80
Lawrence70
Hamilton60
Richland40
Stark40
Gallatin30
Out of IL30
Pike30
Clay20
Edwards20
Calhoun10
Hardin10
Pope10
Putnam10
Scott10

Indiana Coronavirus Cases

(Widget updates once daily at 8 p.m. ET)

Confirmed Cases: 48524

Reported Deaths: 2698
CountyConfirmedDeaths
Marion11682684
Lake5180242
Elkhart330146
Allen2798132
St. Joseph196466
Cass16389
Hamilton1563101
Hendricks1410100
Johnson1288118
Porter73237
Tippecanoe7268
Madison65964
Clark65544
Bartholomew58644
LaPorte58026
Howard57757
Kosciusko5494
Vanderburgh5486
Marshall4904
Noble48228
Jackson4723
LaGrange4709
Hancock45035
Boone44543
Delaware44550
Shelby42625
Floyd38144
Morgan32931
Monroe30028
Grant29526
Montgomery29420
Clinton2892
Henry27415
Dubois2736
White26510
Decatur25032
Lawrence24625
Dearborn23823
Vigo2358
Harrison21822
Warrick21829
Unassigned193193
Greene18932
Miami1832
Jennings17611
Putnam1698
DeKalb1624
Scott1627
Daviess14317
Wayne1406
Orange13623
Perry1299
Steuben1292
Franklin1248
Jasper1212
Ripley1177
Wabash1122
Carroll1102
Fayette997
Newton9810
Starke933
Whitley925
Gibson812
Huntington812
Randolph794
Wells731
Fulton721
Jefferson722
Jay680
Washington671
Pulaski661
Knox640
Clay604
Rush583
Adams501
Owen491
Benton480
Sullivan451
Posey420
Brown391
Spencer381
Blackford372
Crawford320
Fountain322
Tipton321
Switzerland270
Parke230
Martin220
Ohio170
Vermillion140
Warren141
Union130
Pike110