Slang], a tornado that does not arise from organized storm-scale rotation and therefore is not associated with a wall cloud (visually) or a mesocyclone (on radar). Landspouts typically are observed beneath Cbs or towering cumulus clouds (often as no more than a dust whirl), and essentially are the land-based equivalents of waterspouts.
A small, weak tornado, which is not formed by a storm-scale rotation. It is generally weaker than a supercell tornado and is not associated with a wall cloud or mesocyclone. It may be observed beneath cumulonimbus or towering cumulus clouds and is the land equivalent of a waterspout.
A landspout is a slang-term coined by meteorologist Howard Bluestein for a tornado not associated with the mesocyclone of a thunderstorm.http://ams.allenpress.com/perlserv/?request=get-document&doi=10.1175%2F1520-0434%281999%29014%3C0558%3AAHOSSI%3E2.0.CO%3B2 Known officially as "dust-tube tornadoes" by the National Weather Service, they form during the growth stage of convective clouds by the ingestion and tightening of boundary layer vorticity by the cumuliform tower's updraft. Landspouts most often occur in drier areas with high-based storms and considerable low-level instability. They generally are smaller and weaker than supercellular tornadoes, though many persist in excess of 15 minutes and some have produced F3 damage.