Session 7A.2 Hazards of long-lived, convectively generated high wind events in the United States

Tuesday, 5 October 2004: 4:45 PM
Walker S. Ashley, University of Georgia, Athens, GA; and T. L. Mote

Presentation PDF (116.0 kB)

Assessing the human and economic impacts of derechos has received considerably less attention in comparison to “large-impact” events such as floods, hurricanes, and tornadoes. By consolidating and extending the climatological record of U.S. derechos, this investigation quantitatively and qualitatively reveals the impacts derechos have had on the U.S. from 1986-2003. Results indicate that derecho hazards (defined as derechos that result in injury, death, or economic loss) can be as substantial as hurricanes and tornado hazards.

For the 18-yr period investigated, derechos were responsible for 153 fatalities and over 2,600 injuries. Derecho fatalities are comparable to those produced by recent U.S. hurricanes and exceed the fatalities caused by more than 88 % of the tornadoes that have affected U.S from 1986-2003. However, results suggest that derechos do not account for a majority of the casualties owing to convectively induced non-tornadic winds in the U.S.

Insured losses from many derechos and derecho families (i.e., a series of derecho events) were found to exceed $100 million dollars with one event (31 May 1998) nearing $0.5 billion in estimated insured losses. These estimated losses are comparable to some of the U.S.’s most noteworthy hurricanes in the last 18 yr and are equivalent to the most damaging tornadoes in the U.S. history.

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