The Record Breaking South
Dakota Tornado Outbreak
of 24 June, 2003
A record 67 tornados hit the ground over eastern South Dakota on this day. Of all the storms that threatened the state two main areas dominated with persistent tornados for hours. The first area was in far southeast SD and the second which produced the larger long track funnels was further north, over east central SD. During this wild ride of severe weather over 350 warnings were issued producing at least one tornado as strong as F-4 with winds as high as 260 M.P.H. I set a personal record of witnessing 14 tornados in one day and photographing most of them.
Our chase began in western Nebraska after spending the
night at Lexington. We had been following a cluster of tornadic storm into the
night when we gave up the effort as the storms crossed I-80 into cooler air.
John Noble was my chase partner on this day. Our goal was to drop an acoustic
sounder in advance of the tornadic cell to measure low frequency sound when it
moved by the equipment. The forecast for the next day look exceptionally
favorable for and area from eastern Nebraska northward into Minnesota. During
the midmorning the area of interest had been reduced to one location, the city
of Mitchell in eastern SD. It was a long drive across Nebraska and by the time
we crossed the Missouri River giant towering clouds were forming near the city
of Yankton. It was tempting to stay with these exploding cells but another
storm, very small at this time, was streaming an anvil across the sky to our
NW. This cell was isolated and located in the target area, so we pressed north.
I through we had time, the storm was so quite small and seemed to be
struggling, but early in its lifecycle it developed a crescent shape on radar
and the anvil was huge, signs the updraft was very intense. In the distance we
could see the base of the storm, with all our efforts it appeared we were late,
the show had already started. We couldn't see precipitation from the distant
storm, the haze was awful, but we could make out an extensive wall cloud
structure. We were traveling north on highway 37 toward Mitchell. The first
shots are mostly video captures as we tried to get ahead of the
This event will be broken up into separate pages as if they were different storm days. Actually, when chasing this day it seemed as if the transitions from storm to storm were different storm days. Each storm and mesocyclone was a show in itself providing more action than we usually see on any storm day.
All images and text © copyright Gene Moore unless otherwise indicated.
The NOAA satellite image shows the early development of this
spectacular storm event. Only one cell had lit off at this time in eastern
South Dakota. In this image it is the single anvil over SE South Dakota. A
combination of outflow boundaries (OFB) and a cold front increased convergence
over the part of the state. The main core of the jet stream was further north
over Minnesota, but enough energy extend south to power the storms. Deep
moisture in the form of cumulus clouds dotted all of NE Nebraska and SE South
Images courtesy of WeatherTap Inc.
Small but packing a wallop, the Mount Vernon storm develops. During this radar sequence the lone supercell just east of Mitchell is intensifying rapidly. Note the arc or crescent shape to the echo early on the life cycle of the storm. Since the radar shows precipitation what we don't see is the long anvil streaming off the the ENE. Further south, storms over extreme NE Nebraska are developing; this complex will also produce many tornadoes.
We watched the distant tornado for about 5 minutes before a clear shot developed over the western horizon. Our goal was to move north in advance of the tornado to deploy our equipment. The tornado was down from 5:12 CDT until 5:35 CDT, although we were not able to observe the funnel during all of this time due to hilly terrain.
This was our best view of the approaching tornado as it moved NNE and to the east of the populated area of Mount Vernon. This tornado moved more north than east making it difficult to get in the path of the funnel.
The Mount Vernon tornado has become large in this image while another funnel tries to form nearby. It is not known if the funnel in the foreground touched down, but the National Weather Service logged numerous tornado occurrences in the Mitchell area. It is possible many of these reports were different sightings of the Mount Vernon tornado from the city of Mitchell as it mover over the Interstate west of town.