Tornadoes Are More Powerful Than We Realize

A South Dakota tornado stood still for at least half an hour Saturday afternoon, producing a mesmerizing sight for miles into northern Nebraska.

The tornado first developed around 2:30 p.m. MDT near Allen, South Dakota, about 85 miles southeast of Rapid City.

Roughly 30 minutes after the tornado was first reported, it was still in progress in western Bennett County. Unlike most tornadoes, though, it had barely moved.

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One house was damaged but there were no reports of injuries, according to the South Dakota Highway Patrol and Bennett County Sheriff's Office.

Meteorologists from the National Weather Service will survey the damage on Sunday to estimate the tornado's intensity and path.

The relatively flat, treeless terrain allowed many to view the tornado from miles away.

For some, the view resembled a landspout tornado, with a narrow funnel near the cloud base and a hose of churned-up dust, giving the tornado a two-part look.

You could see the parent thunderstorm's broader rotation, what meteorologists call the mesocyclone, swirling at the base of the cloud from which the almost perfectly vertical tornado extended.

This tornado was spawned from a lone supercell thunderstorm which developed rapidly along a boundary of converging winds created by a push of cooler air that moved southeast of the Black Hills near Rapid City.

Despite high temperatures near 100 degrees Saturday, this wind boundary was apparently needed to overcome a cap, or lid on thunderstorm development, lifting the air just enough to trigger the supercell.

Relatively light winds aloft kept the parent thunderstorm virtually parked in place for some time.

It was the nation's only tornado on Saturday.

In mid-June, South Dakota's first tornado of 2019 was a rare, clockwise-rotating tornado in Deuel County, near the Minnesota border.