A waterspout is a funnel cloud over water. It is a nonsupercell tornado over water. Waterspouts do not suck up water; the water seen in the main funnel cloud is actually water droplets formed by condensation. It is weaker than most of its land counterparts.
Waterspouts that are not associated with a rotating updraft of a supercell thunderstorm, are known as "nontornadic" or "fair-weather waterspouts", and are by far the most common type.
Fair-weather waterspouts occur in coastal waters and are associated with dark, flat-bottomed, developing convective cumulus towers.
A winter waterspout, also known as a snow devil, an icespout, an ice devil, a snonado, or a snow spout, is a very rare meteorological phenomenon in which a vortex from snow develops that looks like a waterspout. One does not know much about this rare happening and there are only six known pictures of this event so far.
There are three main things that produce a winter waterspout:
Very cold temperatures present over a body of warm water enough to produce fog that looks like steam above the water's surface. This usually needs temperatures of -18 °C or colder if the water temperature is no warmer than 5 °C. Lake-effect snows in a small, enclosed or banded formation must be present and going on. The wind speed has to be slow, usually less than 5 knots (9.25 km/h).