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Tornado deaths: What the past tells us about the future

Tornado deaths: What the past tells us about the future. Harold Brooks NOAA/NSSL Harold.brooks@noaa.gov. General History of Death. >20000 people have died in US tornadoes (~400 years) Deadliest decade-1920s (95 min, 4 years>200, 3169 total) 1986-1995: 419 deaths 2000-2009: 558 deaths

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Tornado deaths: What the past tells us about the future

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  1. Tornado deaths: What the past tells us about the future Harold Brooks NOAA/NSSL Harold.brooks@noaa.gov

  2. General History of Death • >20000 people have died in US tornadoes (~400 years) • Deadliest decade-1920s (95 min, 4 years>200, 3169 total) • 1986-1995: 419 deaths • 2000-2009: 558 deaths • Only 3 years since 1974 > 100, max is 130 (1998)

  3. 10 Years of Tornado Fatalities by County Avg. Fatalities ~2.5 Avg. Injuries ~21 Avg. Prop. Dmg. ~$18M Avg. Track ~18 miles Avg. Width ~500 yards Avg. Rating ~(E)F2.5 631 Total Fatalities 1999-2008

  4. What happened in 1925? • Seminal weather events that changed society • 1888 Blizzard • 1900 Galveston Hurricane • 1927 Mississippi River flood • 1930s Dust Bowl • 1925 Tri-State tornado

  5. Mobile Home Permanent Home

  6. Brooks and Doswell (2001) Highlight role of education in reducing 3 May 1999 deaths Question whether downward trend (post-1925) stopped Model death rate as function of mobile home fraction

  7. Model Tornado Deaths (Brooks and Doswell 2001) Mobile home contribution to overall death rate

  8. Mobile Home Permanent Home

  9. Warning/response system • Warning • Decision • Dissemination • Reception • Response • Preparation • Options • Action

  10. Warning performance • Lead time? • Lead time for warned tornadoes hasn’t changed in 25 years

  11. Warning performance • Lead time? • Lead time for warned tornadoes hasn’t changed in 25 years • POD has increased • Sutter and Simmons-decrease in fatalities up to 15 minutes • Hoekstra • Preferred mean lead time 34 minutes • Given 1 hour lead time, respondents less likely to act immediately, more likely to flee • Stalker-Long lead-people prepared to take action • False alarms? • Many convolved factors (SE primarily) • What do people think is a warning for them?

  12. What are the issues? • Organization of storms (warning challenges) • Ashley (2007) summarizes many aspects • Mobile homes • Nocturnal/visibility • Poverty • Preparation/response

  13. Nocturnal Tornado Death Fraction Mobile Home Fraction by County Forest Cover Fraction in Poverty (Ashley 2007)

  14. Compare to lightning • Which kills more in US?

  15. Compare to lightning • Which kills more in US? • 1976-90: Lightning (m=90), tornado (53), lightning more in 13 years • 1996-2010: Lightning (41), tornado (63), lightning more in 3 years • Lightning deaths dropped dramatically starting ~1990 • Education-“30-30 rule” • Training-ER docs less likely to kill you now than 25 years ago

  16. Final thoughts • Reducing deaths won’t come by improving forecast quality (lead time, POD, FAR) • Non-meteorological problem • Education/preparation • Choices for appropriate action • Communication of messages

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