You Asked Us
I was recently on a Caribbean cruise and took the attached photo of what looked like a tornado forming over the Atlantic Ocean. Could you tell me what it was that I saw?

What you saw was not a tornado but a waterspout, and your sighting was a once in a lifetime event! A waterspout - which may look like a tornado but is in fact weaker - is a rotating column of air mixed with water that forms over the surface of the water.

Waterspouts form during unstable conditions when cool air moves over relatively warmer water. They occur any time during the day or night and throughout the year. In Canada, they are most frequently sighted during the month of September.

The earliest stage of a waterspout consists of a rotating column of spray near the water surface. It may or may not be accompanied by a funnel extending downward from a cumulus type cloud. As the waterspout strengthens, the funnel will lengthen downwards towards the water. The waterspout reaches its mature stage when the funnel touches the water surface. It is at this point that the waterspout is at its greatest strength with associated wind speeds greater than 95 km/h.

Waterspouts are sometimes seen in families of two or more. The confirmed world record is twelve waterspouts that formed in a row over Lake Huron in the 1980s. They can last up to 20 minutes and have diameters ranging from 15 to 50 metres. They also move between 15 to 25 km/h.

While the world waterspout "hot spot" is around the Florida Keys, waterspouts form over all oceans around the world, as well as large inland lakes like the Great Lakes. Here in Canada, Lake Erie sees the most waterspouts annually.

The greatest threat by waterspouts is to small boats as well as to people along the shoreline. Waterspouts can capsize a boat or toss individuals overboard. They have also been known to knock down large trees along the shoreline. If you are in a boat, move at a right angle to the movement of the waterspout. If onshore, move away from trees.

Until recently, no method existed to predict waterspouts. Now, Environment Canada is leading the way internationally in waterspout forecasting research with the development of a technique that can predict waterspouts up to two days in advance. This technique is currently being used in Canada and the United States, and is under consideration for use in other countries. An international effort led by an Environment Canada meteorologist is now underway to coordinate waterspout research through the establishment of the International Centre for Waterspout Research.

Related Link:

The Great Waterspout Outbreak of 2003