What are waterspouts?
Wikipedia tells us: A waterspout is officially defined by the US National Weather Service simply as a tornado over water. However, researchers typically distinguish “fair weather” waterspouts from tornadic waterspouts.

• Fair weather waterspouts are less severe but far more common, and are similar in dynamics to dust devils and landspouts. They form at the bases of cumulus congestus cloud towers in tropical and semitropical waters. They have relatively weak winds, smooth laminar walls, and typically travel very slowly, if at all.[13] They occur most commonly in the Florida Keys.
• Tornadic waterspouts are more literally “tornadoes over water”. They can form over water like mesocyclonic tornadoes, or be a land tornado which crosses onto water. Since they form from severe thunderstorms and can be far more intense, faster, and longer-lived than fair weather waterspouts, they are considered far more dangerous.

Where do waterspouts occur?
The Florida Keys “are the greatest, natural vortex lab in the world,” says Joseph Golden, a senior National Oceanic and Atmospheric Administration scientist who has studied waterspouts extensively. “Waterspouts probably occur more frequently in the Florida Keys than anywhere in the world.”

Waters around the Keys, especially from Marathon past Key West on westward to the Dry Tortugas, probably see 400 or 500 waterspouts a year. Since they are so common, most go unreported unless they cause damage.

Golden suspects so many waterspouts hit the Florida Keys because the weather and geography supply two necessary ingredients.

First, the islands and the shallow water along them help heat the air. During the summer, waterspout season, the air is extremely humid with temperatures in the mid-80s into the low 90s. The heat causes the air to rise. As it rises, the air’s humidity condenses into the tiny water droplets that make up clouds.

As water vapor condenses, it releases more heat that makes the air rise even faster. Rising air currents are needed for waterspout formation.

The second important waterspout ingredient in the Keys seems to be the regular east or northeast “trade winds” that blow right down the islands. These winds help line up the clouds. Lines of clouds encourage waterspouts. Exactly how is one of the questions researchers are trying to answer.

What to do when you encounter a waterspout?
As with any kind of weather hazard, safety begins by staying informed . One of the special radios that pick up weather broadcasts should always be aboard your boat. And, you should listen to it regularly.

Waterspouts tend to come from clouds with a dark, flat bottom when there is just the first hint of rain.

If one heads your way, try to escape by going at right angles to its path. And if it’s about to hit your boat, the best bet might be to dive overboard. Flying debris is the big killer in tornadoes and waterspouts.

Waterspout footage

sources: USA Today, Wikipedia