Polar Vortex spills Arctic weather into North America

What

in the world is a polar

vortex? On Earth, it’s a large area of low pressure and extremely cold

air that usually swirls over the Arctic, with strong counter-clockwise winds

that trap the cold around the Pole. But disturbances in the jet stream and the

intrusion of warmer mid-latitude air masses can disturb this polar vortex and

make it unstable, sending Arctic air south into middle latitudes.

That

has been the case in late January 2019 as frigid weather moves across the

Midwest and Northern Plains of the United States, as well as interior Canada. Forecasters

are predicting that air temperatures in parts of the continental United States

will drop to their lowest levels since at least 1994, with the potential to

break all-time record lows for January 30 and 31. With clear skies, steady

winds, and snow cover on the ground, as many as 90 million Americans could

experience temperatures at or below 0 degrees Fahrenheit (-18° Celsius),

according to the National Weather Service (NWS).

The Goddard

Earth Observing System Model above shows this air temperature

movement at 2 meters (around 6.5 feet above the ground) from January 23-29. You

can see some portions of the Arctic are close to the freezing

point—significantly warmer than usual for the dark of mid-winter—while masses

of cooler air plunge toward the interior of North America.

Science Behind the Polar

Vortex / Credit: NOAA

Meteorologists predicted that steady northwest winds (10 to 20 miles per hour)

were likely to add to the misery, causing dangerous wind chills below -40°F

(-40°C) in portions of 12 states. A wind chill of -20°F can cause frostbite in

as little as 30 minutes, according to the weather service.

Not sure how cold

that is? Check out the low temperatures on January 30, 2019 in some of the

coldest places on Earth—and

a planetary neighbor:

 -46°F (-43°C) – Chesterfield,

Newfoundland

-36°F (-33°C) – Yukon

Territory, Canada

-33°F (-27°C) – Fargo,

North Dakota (Within the Polar Vortex)

-28°F (-18°C) –

Minneapolis, Minnesota (Within the Polar

Vortex)

-27°F (-33°C) – Amundsen-Scott

South Pole Station, Antarctica

-24°F (-31°C) – Chicago,

Illinois (Within the Polar Vortex)

-15°F (5°C) – Barrow,

Alaska 

-99°F (-73°C) – Mars

Learn more about the science behind the polar

vortex and how NASA is modeling it here:

https://go.nasa.gov/2Wtmb43.

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