Weather Answers: Why Destructive Tornadoes Happen In The Middle Of Winter

As a meteorologist, I like to share information about the weather and educate people on what we've learned about seasonal patterns. Today's blog shares an informative blog from two Weather Underground Meteorologists about why tornadoes form in the winter.

(Image: Confirmed tornadoes and reports of tornadoes in five separate outbreaks from Nov. 4, 2022, through Jan. 12, 2023. (Note: Not all confirmed tornadoes may show up on this map, particularly on the Jan. 12, 2023, map which was created before many NWS damage surveys were completed. Credit: Weather Underground)

Why Destructive Tornadoes Happen In The Middle Of Winter 

Chris Dolce and Jonathan Erdman Weather Underground Published: January 13, 2023

Destructive tornadoes, even outbreaks, can occur in parts of the United States in December, January and February, despite winter's bone-chilling reputation.

That's certainly been the case recently, with three tornado outbreaks since mid-December, and five since early November.

The most recent outbreak on Jan. 12 included a destructive tornado in Selma, Alabama, and a deadly twister in Autauga County.

How This Happens In Winter 

Severe thunderstorms and tornadoes need a mix of ingredients.

First, they typically need strong wind shear, a sharp change in wind speed and/or direction from the ground to the jet stream. Since the jet stream is strongest in the U.S. in winter, this first ingredient is almost always sufficient. That was certainly the case on Jan. 12, when a 125-mph jet stream punched across the Deep South.

T​hen, you need it to be at least somewhat warm and humid. T​his is why severe thunderstorms in winter are relatively rare in the Northeast, Midwest or Northern Plains. It's just too cold. 

(Severe weather set up. Credit: Weather Underground) 

I​f Arctic cold air dominates the country in winter, that shuts off the threat of severe thunderstorms everywhere. B​ut, the Deep South isn't always cold in the winter. High temperatures can soar into the 60s, 70s or even low 80s, as happened during the Jan. 12 outbreak.

Its close proximity to the Gulf of Mexico means the Deep South can quickly become humid, fueling the instability needed to generate thunderstorms.

I​f that warm, humid air is in place ahead of a strong low-pressure system accompanied by a powerful jet stream, you get severe thunderstorms and tornadoes.

Tornadoes Are Typical, Even In Winter 

W​hile tornadoes in the U.S. are usually infrequent in winter, it is typical for at least some to touch down each season. Over the last 20 years, an average of 123 tornadoes have occurred in the U.S. from December through February.

However, t​hat average masks a lot of variability. A​ December record 232 tornadoes tore through the U.S. in 2021, mainly from two large outbreaks in less than a week.

But some winter months only manage a handful of tornadoes, if that. February 2015 produced three tornadoes, and January 2014 only had four.

These winter tornadoes are often deadly. T​here's been at least one deadly winter tornado in the U.S. every year since 2005, according to data from NOAA's Storm Prediction Center.

Since 1991, only three years – 1992, 1994 and 2004 – didn't have a single deadly winter tornado.

Usually A Southern Thing In Winter 

T​his probably isn't surprising, given the most recent outbreaks, but winter tornadoes favor a corridor of the South, especially the lower Mississippi Valley, Deep South and northern Gulf Coast. Occasionally, some tornadoes can occur farther north into the Ohio or Mississippi valleys.