What is a landspout tornado?

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What is a landspout tornado?
funnel extends from cloud, creating a cloud of debris around its base

Landspout tornado over Hale County in Texas (NOAA).

“Landspout” is slang for a tornado that, unlike most tornadoes, is not associated with the mesocyclone of a thunderstorm. The name reflects the fact that these tornadoes look “like a weak Florida Keys waterspout over land.”

The official name, “dust-tube tornado,” comes from the National Weather Service.

Landspout tornadoes form as a growing convective cloud ingests and tightens a rotating boundary layer during intense 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 longer than 15 minutes and some have produced severe damage.

Landspouts resemble waterspouts in appearance and mechanism, and usually comprise a translucent and highly laminar helical tube. Both landspouts and waterspouts are classified as tornadoes since they are defined by an intensely rotating column of air in contact with both the surface and a cumuliform cloud.

Not all landspouts are visible, and many are first sighted as debris swirling at the surface before they eventually fill in with condensation and dust.

Steven A. Ackerman and Jonathan Martin are professors in the Department of Atmospheric and Oceanic Sciences at UW-Madison, are guests on the Larry Meiller‘s WHA-AM radio show the last Monday of each month at 11:45 a.m.