AMARILLO – Probably the most interesting weather phenomenon seen on the High Plains is the tornado. Tornadoes can be deadly but are quite fascinating at the same time.
Here’s a look at the process that can lead to their formation.
Tornadoes come from thunderstorms, for which you need enough moisture, instability in the atmosphere, and a source of lift to kick things off. The lift can come from a cold front, a warm front, a dryline, or even just day time heating in the afternoon.
As pockets of air rise because of the lift, the moisture condenses into clouds and the upward-moving air becomes known as the updraft, that keeps thunderstorms from dissipating. Rain droplets form and start falling when the updraft can no longer keep them suspended in the air. The rain and air falling from a cell are part of the downdraft. The rapid upward and downward movement of air builds up electrical charges in the atmosphere that cause lightning to occur.
When thunderstorms rotate, the potential for dangerous severe weather increases.
This happens when the wind direction and speed change with height, known as wind shear. A rotating thunderstorm with a well-defined circulation is called a supercell.
Rotating air underneath the supercell, thanks to the wind shear, gets forced upward because of the updraft, and a tornado may form. A wall cloud will lower from the base of the supercell, then a funnel cloud will lower from that. If the funnel cloud reaches the ground, then it is considered a tornado.
Tornadoes can last for a few minutes up to several hours. You find them under the updraft. The downdraft at the rear of the storm, known as the rear flank downdraft, can intensify a tornado. When these ingredients get out of balance, the tornado will dissipate.
Once the updraft is cut off by rain-cooled air, the storm will weaken but can cause other cells to pop up.
Our area averages 17 tornadoes per year, though some years they are more frequent while we’ve had some seasons with very few occurrences.
Thankfully, not every storm produces a tornado.