National Weather Service United States Department of Commerce

Isaias Rapidly Moving North with Tropical Storm Impacts; Critical Fire Weather Conditions in the West

Isaias speed will increase some as it heads into New England, including New York City and other larger New England cities today and tonight; and the center is forecast to be in Canada by Wednesday morning. Very heavy rain and flash flooding, damaging winds, storm surge, and isolated tornadoes can be expected. In the West, critical fire conditions continue due to hot, dry, and breezy conditions. Read More >

Slide 3

A Brief History of Highway Overpass Incidents

The first significant instance of which the authors are aware where someone gained notoriety by seeking shelter from a tornado underneath an overpass bridge was in Wichita Falls TX on 10 April 1979. In this event, a man became trapped in a traffic jam and lay flat on the embankment underneath a bridge, surviving the F4 intensity tornado with only minor injuries. This man's story garnered some publicity. However, the currently widespread public perception that seeking shelter from tornadoes and severe storms underneath highway overpasses is a proper action to take is a result of several factors. The most important factor apparently stems from the widespread distribution of a video taken by a Kansas television crew during a violent tornado outbreak in the central and southern Great Plains region on 26 April 1991. However, there have also been several other videos that have also gained widespread distribution, including a video taken on 19 April 1996 in central Illinois by a Minnesota television crew. Another factor which has also contributed to this perception likely includes the natural human instinct to seek shelter in a covered location (in this case, an overpass). In addition, there has even been some information distributed by the National Weather Service over the years that has indirectly endorsed this practice.

The image on the left is a picture of the overpass on the Kansas Turnpike where the video was taken, looking northeast. The image on the right is a photograph taken from the shoulder of I-35, looking underneath the east side of the overpass where the people sought shelter on 26 April 1991. Of particular note, the reader's attention should go to the construction of this particular overpass. Note the small crawl space where the underside of the bridge meets the embankment, and the presence of the large girder beam that might provide at least a handhold. The unique construction of this bridge is in stark contrast to the construction of most overpass bridges. As will be shown in slides 7 through 10, the overpasses affected in Oklahoma on 3 May 1999 are not constructed in the same way as the overpass in the now-famous video.

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