There have been a lot of waterspouts seen in the Tampa Bay area lately. The 10 News TV weather team has tracked five in just the past month. Waterspouts are are more frequent in Tampa Bay during the wet season.
While they look scary, fair weather waterspouts are generally weak, with 50 mph winds. They are built differently compared to more powerful supercell tornadoes. Waterspouts typically last about 20 minutes and weaken quickly on shore, after getting cut off from warm water fuel. At that point, the name changes to tornado.
Most only toss lawn furnitureor snap tree limbs, but some of the winter tornadic waterspouts can bring winds up to 100 mph. Tampa Bay leads the nation with these types of damaging waterspouts, according to 10 News. It is also believed to lead the nation in lightning strikes on boats.
Cold season waterspouts are more damaging, because they often develop with supercells. That is the name given to a type of thunderstorm that is more organized than our typical summertime storms. Supercells are driven by shear aloft and high levels of buoyant air. Rotating columns of air become tilted vertically, which is what produces tornadoes.
The recent weather pattern has supported just the right ingredients to set up funnels that have caught our attention. It includes: warm water, light winds, and high humidity.
Tampa Bay is 88 degrees now and the warm surface waters create instability by combining with colder air aloft. Waterspouts generate along outflow boundaries. Unequal heating of land and water, or even the irregular shape of the coastline can cause these boundaries of unequal air masses. Rolling horizontal air currents develop next to these features.
If the winds are light, updrafts develop with rapidly rising air tilting these rolls vertically. Funnels spin up to the parent cloud. Dropping pressure causes the vortex to darken as moisture condenses and at the base, a spray ring develops in mature waterspouts.