Storm types#tornado#coast
Waterspout
At a glance
A tornado over water. 'Fair weather' waterspouts are weak and come from growing cumulus; 'tornadic' ones are the full thing that just happens to be over the sea.
Deep dive
Fair-weather waterspouts form under rapidly growing cumulus clouds where surface vorticity under weak synoptic flow is tilted and stretched. Common off south and west UK coasts in autumn when cold pools of air pass over warmer seas.
Tornadic waterspouts are bona fide supercell tornadoes over water. Any waterspout making landfall is treated as a tornado for classification and damage surveying.