harold brooks noaa/nssl harold.brooks@noaa.gov tornado deaths: what the past tells us about the...

HAROLD BROOKSNOAA/NSSL

HAROLD.BROOKS@NOAA.GOV

Tornado deaths: What the past tells us about the future

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

Only 3 years since 1974 > 100, max is 130 (1998)

10 Years of Tornado Fatalities by County

631 Total Fatalities

1999-2008

Avg. Fatalities ~2.5

Avg. Injuries ~21

Avg. Prop. Dmg. ~$18M

Avg. Track ~18 miles

Avg. Width ~500 yards

Avg. Rating ~(E)F2.5

8harold.brooks@noaa.gov

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

Mobile Home

Permanent Home

harold.brooks@noaa.gov

13harold.brooks@noaa.gov

Mobile Home Fraction of Total Housing

0

2

4

6

8

10

12

14

16

18

1950 1960 1970 1980 1990 2000

Year

%

SoutheastOK-KS-NERest of US

14harold.brooks@noaa.gov

Brooks and Doswell (2001)

Highlight role of education in reducing 3 May 1999 deaths

Question whether downward trend (post-1925) stoppedModel death rate as function of mobile home fraction

Model Tornado Deaths (Brooks and Doswell 2001)

Mobile home contribution to overall death rate

Mobile Home

Permanent Home

17harold.brooks@noaa.gov

Warning/response system

Warning Decision Dissemination Reception

Response Preparation Options Action

18harold.brooks@noaa.gov

Warning performance

Lead time? Lead time for warned tornadoes hasn’t changed in 25 years

19harold.brooks@noaa.gov

0 0.2 0.4 0.6 0.8 10

0.2

0.4

0.6

0.8

1

Tornado Warning Performance by Watch

Overall (1986-2007)TornadoSevereNo Watch

SR (1-FAR)

POD

21harold.brooks@noaa.gov

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?

22harold.brooks@noaa.gov

What are the issues?

Organization of storms (warning challenges)Ashley (2007) summarizes many aspects

Mobile homes Nocturnal/visibility Poverty

Preparation/response

Nocturnal Tornado Death Fraction Mobile Home Fraction by County

Forest Cover Fraction in Poverty

(Ashley 2007)

24harold.brooks@noaa.gov

Compare to lightning

Which kills more in US?

1975 1980 1985 1990 1995 2000 2005 20100

20

40

60

80

100

120

140

Annual US Deaths from Hazards

TornadoLightning

Year

Dea

ths

26harold.brooks@noaa.gov

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

27harold.brooks@noaa.gov

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