Of all the thunderstorms, Supercell thunderstorms are the least likely. However they are the most likely to produce severe weather. A thunderstorm is classified as severe if it produces at least 58 mph wind or 1” diameter hail or larger. Supercells are the most likely to produce tornadoes as well.
A Supercell thunderstorm is different from other storms because it rotates. The rotation is caused by a change in wind speed and wind direction with height. Stronger wind speeds at the top of the storm cause it to tilt. As a result, the warm, moist air feeding the storm is separated from the precipitation falling out of the storm. This “balance” can allow the storm to last for hours.
During our severe weather coverage, you will hear us talk about a rotating storm or Supercell. Here are three common symbols you will see appear on the screen while we are tracking storms especially Supercells:
The first marker (in yellow) indicates a mesocyclone or rotating thunderstorm. As a result, we will immediately give this storm more attention and track its movement.
The hail marker indicates a hail producing storm and also estimates hail size.
The last marker is called a TVS. The acronym stands for Tornado Vortex Signature. This pinpoints an area with an enhanced risk for tornado development.