Weather School: Tornadoes

Weather School: Tornadoes
Weather School: Tornadoes (WFXG)

AUGUSTA, GA (WFXG) - Tornadoes can happen any time of the year, but they tend to be most common in April, May, and June. Spring is a time of year when the ingredients come together most often to form tornadoes.

The truth is, we don't fully understand how they form, but here's what we do know. There are four main ingredients needed: moisture, lift, instability, and shear.

During severe weather outbreaks, south winds transport warm moist air from the Gulf of Mexico. At the same time, west winds bring in cool dry air thousands of feet above the ground. This change in temperature with height causes instability. The more drastic the change, the greater the instability.

A trigger, like a front, brings lift, forcing the air up. Rising air cools and condenses, leading to clouds, rain, and with enough instability, thunderstorms.

To get tornadoes, you need one more thing: wind shear. The change in wind direction from south to west with height causes a rolling rotation in the atmosphere. If the wind speed gets faster with height, that causes an even stronger roll.

Rising air within a thunderstorm can tap into that rotation and tilt it. Rotating thunderstorms, known as supercells, can produce tornadoes.

More research is being done to learn why some supercells produce tornadoes and others don't.

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