National Weather Service United States Department of Commerce

Dangerous, Record-Breaking Heat to Continue in the Central and Eastern U.S.; Severe Thunderstorms in the Upper Midwest; Critical Fire Weather in the Four Corners

Dangerous, record-breaking heat will continue across most of the central and eastern U.S this week. Heat indices will exceed 100 degrees. Severe storms will be possible from the northern Plains into the Midwest and Great Lakes regions, as well as across the southern Appalachians Thursday, with the primary threat large to very large hail. Critical fire weather to continue in the Four Corners Region Read More >

Overview

On June 29, 2019 a surface boundary was located across south central South Dakota. Very strong instability along the boundary was realized when a thunderstorm exploded along it. The thunderstorm updraft stretched energy along the boundary into a very slow moving tornado near Allen, SD.

The tornado was visible for many miles. It was unusual because it only moved within a two mile area, but lasted about 40 minutes. Fortunately, it spun over corn fields most of the time. It damaged a house, blew over a couple of grain bins, snapped power poles, and carried grain bags. The tornado was rated EF-1 by an NWS storm survey team.

More information about the environment of the Allen tornado can be found here

Tornado near Allen, SD
Courtesy Chris O.
Tornado near Allen, SD Tornado near Allen, SD Tornado near Allen, SD
Courtesy Gail S. Courtesy Josie D. Courtesy Ang G.
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