Tornadoes happen in every month of the year and at any time — they may show up at three in the morning in May or three in the afternoon in January. Winter tornadoes are less common than their spring counterparts, but they are caused by the same weather ingredients as warm-season tornadoes and are just as deadly. We’ll see what can cause a winter tornado and why there have been more cold-season twisters in recent years.
What Causes Tornadoes?
Forecasters can often pinpoint a tornado outbreak several days in advance because there is a recipe nature uses to craft these swirling snakes of woe, including:
- Warm air: Warm air rises and helps shape the updraft needed for a tornado.
- Humid air: Storms use moisture for fuel; a storm simply will not form if it’s too dry.
- Wind shear: A change of wind direction or speed with height helps the air spin; the greater the rotation in the air, the easier it is for a tornado to form.
- Cold air aloft: If you have cold air over warm air, it makes it easier for the warm air below to rise and create a violent updraft.
Meteorologists track these changes with satellite imagery, weather analysis charts, and computer modeling.
Tornado Season vs. Winter Tornadoes
About 1,240 tornadoes occur each year in the U.S. More than half of these happen in March, April, May, and June; these four months are often called tornado season. Conversely, winter tornadoes in the period from December through February are about 20% as common with an average of about 120 twisters. The lack of winter tornadoes is because:
- Warm air rises with greater speed and higher into the atmosphere, which is essential to producing updrafts. Think of the updraft as the storm’s engine. Since it’s typically much colder in the winter than in the spring, energy is usually lacking for severe storms and big updrafts.
- The air is generally much drier in the winter because winds are blowing out of the north, keeping Gulf of Mexico moisture out at sea. No moisture, no storm.
Winter Tornadoes and Climate Change
There’s little doubt that our Earth is warming; we can simply look at the data over the past 140 years or so. A single snowstorm or heatwave does not equal climate change, but when you see the trends moving consistently in one direction, it’s an open-and-shut case. We’re not here today to have a political discussion; the scientific truth is that our weather is changing:
- Natural cycles, such as solar changes and ocean currents, account for some of these effects.
- Human activity is creating more carbon dioxide and methane, which traps heat.
- Earth’s climate has changed many times over the millennia from natural forces. What makes this time different is the rate of change: It’s 10 times faster than any previous climate shift.
Trends suggest that an increase in winter tornadoes may be the new normal thanks to climate change, providing more heat and moisture to spawn severe thunderstorms.
Big Winter Tornadoes — Too Many Both Recent And Tragic
Most major tornadoes rated EF3 and higher happen in the spring when the atmosphere is warm and moist with high wind shear. However, there have been several recent exceptions where big twisters showed up in the winter. Most winter tornadoes happen in the Southern U.S., where the air is likely to be warmer.
Central U.S. EF-4 Tornadoes
One of the longest-track tornadoes in history took place on December 10, 2021 — it traveled some 165 continuous miles on the ground from northern Tennessee into western and central Kentucky. This mammoth EF4 tornado, with 190 mph winds, was over a mile wide at times, remained continuously on the ground for more than 2 hours, and killed nearly 80 people. It laid waste to much of Mayfield, Kentucky, population 10,000, in a mere 3 horrifying minutes. The track could even be seen from space!
Mid-South December Outbreak
Some 40 tornadoes ravaged several southern states — primarily Louisiana, Mississippi, and Arkansas, on Dec 16-17, 2019. There were miraculously only three fatalities despite 14 of these tornadoes having wind speeds of at least 111 mph.
Rowlett EF4 Tornado
It was just one night after Santa’s visit in 2015 when things turned tragic in the Dallas/Fort Worth Metroplex. An EF4 tornado (winds of 166 to 200 mph) crashed across the Dallas suburbs of Garland and Rowlett. Eight people were killed, and the damage exceeded $1 billion.
Tornado Storm Safety
Be it July or January, tornadoes are dangerous. Sensible storm-safety precautions and weather awareness are essential:
- Understand the difference between different types of tornado alerts and what you should do during each one.
- Track the weather with a personal weather station that monitors for severe weather indications like lightning detection, rapid pressure drops, and strong winds or rapidly shifting winds. The AcuRite Atlas® with lightning detection can help you and your family prepare for approaching storms with alerts and notifications sent right to your smartphone.
- Act quickly. A number of people who died in the Mayfield tornado perished in a candle factory. Take immediate shelter when a tornado warning is issued — that’s the safest choice.
- Keep winter weather gear handy in your home and in your vehicle since a winter tornado offers the added challenge of finding warm shelter after the storm.
Have you ever experienced a winter tornado? Let us know what steps you took to stay safe in the comments!
Steve LaNore is a certified broadcast meteorologist with more than 30 years’ forecasting and technical experience. He has provided meteorological consulting for everything from insurance adjusters to court cases and is a nine-time award-winning author and broadcaster. LaNore has authored two books, available on Amazon. He resides in north Texas near beautiful Lake Texoma.