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 . Waterspouts that are not associated with a rotating updraft of a supercell thunderstorm , are known as `` non-tornadic '' or `` fair-weather waterspouts '' , and are by far the most common type .