waterspout

A waterspout is a rapidly rotating column of air and spray that forms over a body of water, connected at its base to a cloud, typically a cumulus or cumulonimbus, and extending down to the surface. It is a type of vortex and can vary in size, duration, and intensity.

There are two main types: fair-weather waterspouts and tornadic waterspouts. Fair-weather waterspouts typically form in warm, humid conditions over warm water with light to moderate winds and little vertical wind shear. They originate from a pre-existing cumulus cloud and a developing low-level vortex, often appearing as slender funnels and sometimes remaining largely invisible except for a spray ring. They usually dissipate within minutes and rarely cause damage on land. Tornadic waterspouts are associated with severe thunderstorms and are essentially tornadoes that move over water. They are typically more powerful, can produce stronger winds and debris, and may move onshore, posing greater danger.

Formation and behavior: Waterspouts develop in environments with sufficient instability and moisture, and some low-level wind shear. They commonly form within several kilometers of shore and can move with prevailing winds or drift unpredictably. Lifetimes range from a few minutes to about 20–30 minutes, though longer-lived cases are known.

Hazards and safety: On water, waterspouts can capsize small boats and scatter spray and debris. If a waterspout is sighted or forecast, vessels should seek safe shelter and avoid the funnel’s path; if onshore, seek sturdy shelter away from the water’s edge. Related topics include tornadoes and severe weather phenomena.