1. A Historical Look at Tornadoes: Damage and Death Harold E. Brooks NOAA/National Severe Storms Laboratory Norman, Oklahoma brooks@nssl.noaa.gov

2. Impacts of tornadoes on society What happens in an “average” year? –~40 deaths –~$400M in damage Looking backwards and forwards –Historical trends –Implications for the future

3. Adjusting historical tornado damage Damage numbers go up –Inflation, acquisition of things, population Adjust for inflation, total wealth (1997) Consumer Price Index Current-Cost Net Stock of Fixed Reproducible Tangible Wealth (1925- 1997)-“Stuff” $25,000,000,000,000 in 1997

5. Adjusting stuff outside of period Pure inflation (gap between curves stays same) Stuff grows with GNP

6. Inflation adjusted top ten 311 52 Worcester, MA 9 June 1953 321 89 Conyers, GA 31 Mar 1973 325 100 Xenia, OH 3 Apr 1974 380 12 Saint Louis, MO 26 May 1896 442 200 Windsor Locks, CT 3 Oct 1979 494 100 Topeka, KS 8 June 1966 558 135 Lubbock, TX 11 May 1970 745 250 Omaha, NE 6 May 1975 884 400 Wichita Falls, TX 10 Apr 1979 963 1000 Oklahoma City, OK 3 May 1999 Adjusted Value Raw Value ($M) PlaceDate

7. Stuff-adjusted Big Ten 11Oklahoma City 909(963) 10-4 all range from 1023-1141 –Lorain-Sandusky (28 June 1924), Lubbock, Gainesville, GA (6 April 1936), Topeka, Omaha, Worcester, Wichita Falls 3Tri-State (1925, raw-16)1392 2St. Louis (1927, raw-22) 1797 1St. Louis (1896, raw-12)2916 (2167)

11. Summary of Adjustments Big damage-combination of meteorological event and civilization Inflation still shows some era bias Saint Louis 1896 –Destroyed ~.01-.025% of national wealth –Comparable to Dallas-Fort Worth study

12. Tornado deaths First recorded death –1680 in Cambridge, Massachusetts Total of 19,814 (as of 23 April 2001) When do they occur? How have they changed through time?

14. Problems with death tolls Poor counting –Cultural biases (e.g., Natchez 1840) –Who was there (e.g., Saint Louis 1896)? “Indirect” fatalities –Big problem with hurricanes –At least 5 in Oklahoma City –None, apparently, in Plainfield (1991)

18. How has the decrease happened? Causes can’t be deconvolved Changes –Number of tornadoes –Frequency of “big deaths” –Number in big events “95 th percentile” killer

22. How has the decrease happened? Fewer fatal tornadoes –40/year in 1920s, 1930s –20/year in 1980s, 1990s –Increase in time between fatal tornadoes “High death” tornadoes are smaller –36-fatality tornadoes occurred once/year in 1920s, 1930s –95 th percentile death toll dropped from 20-25 to 10-15

23. Putting death and damage together Consider deaths per damage amount –Inflation –Wealth

26. 3 May 1999 Oklahoma City 36 deaths, 11 in mobile homes –>7000 permanent homes, 100 mobile homes Estimating the death toll before warnings? –Rate used to be ~15x today, so ~540 –Inflation-adjustment, ~700 –Wealth-adjustment, ~250 What happened?

29. Mobile Homes Previously –20x rate of deaths compared to permanent –Big increase in Oklahoma City What might the future hold?

33. Final Thoughts $1B tornadoes occur ~1/decade in US ~$3B tornado is “practically” worst case Can’t identify causes of decline in deaths Mobile home problem Big disaster situations? Education and communication