Waterspouts are tornadoes that form over ocean areas. This phenomenon consists of two types: tornadic in origin and locally induced. The difference between the two types is significant in that the tornadic type has potential for inducing substantial damage and injury over abroad area, while the local type has potential for causing only minor damage in a small area. The following information is provided to help you to better understand the two types of waterspouts. 1. Tornadic type: These waterspouts format the cloud and extend down to the surface. They originate from severe convective cells associated with a cold front, squall line, or large convective cluster. Whenever the conditions for tornado development are present over coastal areas and the triggering mechanism extends into the adja-cent maritime area, then potential for waterspout development is high. The tornadic waterspout has a relatively short life span and usually stays over water. However, when one does come ashore, there is potential for it to assume the characteristics of a tornado; although its life span is limited, the initial intensity is sufficient to cause property damage and injury to personnel. 

2. Local type: These waterspouts originate from convective clouds of moderate vertical extent which form a line or a small cluster. Their existence is sensitive to wind and temperature in that surface winds of 20 knots or greater, or a cooling of the atmosphere by precipitation, dissapates them. Additionally, when local waterspouts come ashore, the friction induced by the land rapidly dissipates them. The biggest threat posed by these waterspouts is to small craft, recreational boating, and to their support facilities such as harbor operations and marinas.

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