A tornado that forms over a lake or ocean
If 
a tornado forms over an ocean, lake, or even a river, it is... [DOC] [TLE] Video: Massive spinning column of water forms over Lake Michigan ... [PAR] Sep 25, 2011 ... A tornado-like waterspout forms over Lake Michigan, near Milwaukee, ... 
Waterspouts are essentially tornadoes that develop at sea, in which a... [DOC] [TLE] waterspout - National Geographic Society [PAR] Mar 29, 2013 ... A waterspout descends from a cumulus cloud to an ocean or a lake.