Captain's Tips

All About Waterspouts

Captain's Tips


Mariners and weather enthusiasts alike are no doubt familiar with a waterspout. Similarly, mariners know (or at least should know) these weather dangers are to be avoided at all costs, but what exactly is a waterspout? Is it simply a tornado over the water? Or is it something more than that? Let's take a look at this rather interesting phenomenon to find out a little more.

Like tornadoes, waterspouts are intense vortices that appear as a funnel-shaped cloud over the water. Unlike tornadoes, which typically descend from their parent cloud mass, they tend to develop on the sea surface and move skyward drawing water from the ocean surface. While typically weaker than their land-based counterparts (tornadoes), stronger waterspouts can typically form from smaller-scale cyclones. Most waterspouts however, tend to form in an even smaller scale environment that is typically no more than 1 to 2 kilometers in total areal coverage. Most waterspouts form within tropical climates and in the lee of land masses, off the Florida coast and across the Florida Keys, for example. Generally speaking, waterspouts will most likely form late in the afternoon or early in the evening.

Waterspouts go through a five-stage life cycle. First, we find the formation of a dark spot over the water, followed by the  formation of light and dark bands spiraling out from the dark spot. A dense swirling ring of sea spray then forms around the dark spot making the waterspout visible from the sea surface to the cloud mass overhead, then reaching its maximum intensity (its mature phase). Finally, the waterspout begins its decay phase leading to its dissipation. The entire life cycle of a waterspout will typically last no more than 15 to 20 minutes.

While waterspouts tend to be smaller and weaker than tornadoes, make no mistake. Most are potentially lethal and are to be avoided at all costs. While typically brief, winds associated with waterspouts have been known to bring life threatening winds as high as hurricane force. Various government agencies provide warnings and advisories on waterspouts as they form, while some are spotted by observers in the area. Private weather companies and weather consulting firms also keep mariners aware of the potential of waterspouts impacting local areas by checking local radar trends as thunderstorms move in.

Always be aware of weather dangers, wherever they may be. Be informed and stay safe as you are traveling to your next destination.Visit:


David Cannon is a yacht manager and senior meteorologist at Weather Routing Inc. (WRI), and also serves as WRI's racing and tournament specialist. WRI has been providing mariners forecasts and routing advice for more than 50 years.

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