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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 1:35 PM
Updated: Jan 28, 2019 1:45 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.

Mississippi Coronavirus Cases

Data is updated nightly.

Cases: 309223

Reported Deaths: 7153
CountyCasesDeaths
DeSoto21005250
Hinds19989411
Harrison17590303
Rankin13388277
Jackson13169243
Madison9965212
Lee9900170
Jones8319161
Forrest7554149
Lauderdale7232237
Lowndes6306144
Lamar614685
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Washington5296133
Bolivar4778130
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Pearl River4447142
Warren4310119
Marshall4302103
Pontotoc417672
Monroe4063132
Union405175
Neshoba4009176
Lincoln3892109
Hancock373785
Leflore3471124
Sunflower332090
Tate325984
Pike3226105
Scott311973
Yazoo305369
Alcorn301566
Itawamba297977
Copiah294365
Coahoma290779
Simpson290486
Tippah285368
Prentiss276659
Marion266479
Leake262473
Wayne261541
Grenada257385
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Adams247082
Newton246161
George238947
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Holmes187272
Clay183354
Stone179733
Clarke178177
Tallahatchie176240
Calhoun165632
Yalobusha160236
Smith159734
Walthall131143
Greene129633
Lawrence126823
Noxubee126634
Montgomery125842
Perry125238
Amite121041
Carroll121026
Webster113932
Jefferson Davis105932
Tunica103425
Claiborne101430
Benton97525
Kemper95728
Humphreys94732
Franklin83123
Quitman78916
Choctaw74417
Wilkinson65329
Jefferson64928
Sharkey49817
Issaquena1686
Unassigned00

Alabama Coronavirus Cases

Cases: 522512

Reported Deaths: 10790
CountyCasesDeaths
Jefferson755371494
Mobile39129799
Madison34124500
Tuscaloosa25408444
Montgomery24059573
Shelby23225242
Baldwin20730302
Lee15638166
Calhoun14358311
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Jackson6762110
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Franklin421382
Chilton4130110
Covington4069115
Tallapoosa3922148
Escambia390374
Dallas3528150
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Clarke347360
Marion3076100
Pike306676
Lawrence296395
Winston273272
Bibb256761
Marengo248561
Geneva246475
Pickens233259
Barbour227155
Hale218675
Butler213268
Fayette209660
Henry188444
Cherokee182744
Randolph177841
Monroe173140
Washington165538
Macon156548
Clay150255
Crenshaw149557
Cleburne147041
Lamar140034
Lowndes137353
Wilcox124727
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A strong cold front will pass through our area this evening. This will bring some very unseasonably cold air into our area for a few days. We will see some potential for some frosty conditions for tonight and for our Wednesday night.
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