BILOXI, Miss. (WLOX) -Summertime thunderstorms are a normal part of life in South Mississippi. While these pop-up storms can bring much needed relief from the heat, they do pose the risk of producing waterspouts.
Waterspouts are tornadoes over water, but they fall under two different categories based on how they form: fair weather waterspouts and tornadic waterspouts
Fair weather waterspout
Fair weather waterspouts are the more common ones that occur in the summer and are generally weaker than tornadic waterspouts and usually dissipate when they move onto land.
They happen when winds merge from opposite directions near the surface, creating a small area of spin. When thunderstorms rise, they stretch the column of spinning air, causing it to rotate faster. Sometimes it rotates fast enough a funnel appears from the base of the thunderstorm cloud to the surface.
Tornadic waterspouts are caused by rotating thunderstorms called supercells. These thunderstorms rotate due to the change in speed and direction of winds as you go up with height, which is caused by the jet stream and strong upper-level low pressure systems. These are typically stronger and can survive over the water and on land.
If a supercell thunderstorm produces a tornado over land, and the tornado moves over water, it is then called a tornadic waterspout.
If a fair weather waterspout or tornadic waterspout move onto land, they are called tornadoes.