Docstoc

Issues in Severe Weather Climatology

Document Sample
Issues in Severe  Weather Climatology Powered By Docstoc
					A Historical Look at Tornadoes:
             Damage and Death


         Harold E. Brooks
NOAA/National Severe Storms Laboratory
         Norman, Oklahoma
       brooks@nssl.noaa.gov
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
 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
                  CPI and Wealth (1997 = 100)

        100
              CPI
              Wealth
Value




         10




          1
          1860 1880 1900 1920 1940 1960 1980 2000
                               Year
Adjusting stuff outside of period



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

• 11 Oklahoma 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
• 3 Tri-State (1925, raw-16) 1392
• 2 St. Louis (1927, raw-22)       1797
• 1 St. Louis (1896, raw-12) 2916 (2167)
                     30 Most Damaging Tornadoes (Adjusted)

                  3000

                  2500
Damage (1997$M)




                  2000
                                                                      Inflation
                  1500
                                                                      Wealth
                  1000

                  500

                     0
                     1880   1900   1920   1940   1960   1980   2000

                                          Year
   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
        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?
                                                 Probability of Tornado In U.S.

                   .50

                                                                  F2 or Greater Tornado
                   .45
                                                                  Death*3
                                                                  5 Death*10
                   .40


                   .35
p(Sig. Tor. Day)




                   .30


                   .25


                   .20


                   .15


                   .10


                   .05


                   .00
                     1-Jan   29-Jan 26-Feb 25-Mar 22-Apr 20-May 17-Jun   15-Jul   12-Aug   9-Sep   7-Oct   4-Nov   2-Dec   30-Dec
                                                                Day of Year
   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)
                Last Time Number of Tornado Deaths Occurred

         1000
                  Tri-State (MO/IL/IA)

                         Gainesville, GA
             Tupelo, MS            Woodward, OK
         100                             Flint, MI
                       Worcester, MA        Blackwell, OK/Udall, KS
                                                            Cary-Pugh City, MS
Deaths




                                              Wichita Falls, TX
                                                                Oklahoma City, OK

          10                                                       Englewood, AL
                                                              Pontotoc County, MS

                                                                         Agency,IA

           1                                                        Hoisington, KS
            1925            1940         1955          1970       1985          2000
                                                Date
                         US Tornado Deaths Per Year
                                                      Deaths
         800
                                                      Median/Boxcar
                                                      filtered
         700



         600



         500
Number




         400



         300



         200



         100



           0
           1875   1900          1925          1950        1975        2000
                                       Year
                           US Tornado Deaths/Million People
                  10




                   1
Deaths/Million




                  0.1




                 0.01
                    1875    1900      1925          1950   1975   2000

                                             Year
How has the decrease happened?

• Causes can’t be deconvolved
• Changes
 –Number of tornadoes
 –Frequency of “big deaths”
 –Number in big events
   • “95th percentile” killer
                                U.S.Killer Tornadoes Per Year (1800-2000)

            80

                     Raw Data
            70
                     Smoothed

            60



            50
Tornadoes




            40


            30



            20



            10



             0
             1800   1820   1840     1860   1880   1900   1920   1940   1960   1980   2000
                                                  Year
                                    Return Period for 20-Death Tornadoes


                       10000




                                                                                    5
                                                                                    4




                                                                                          Return Period (Years)
                        1000                                                        3
                                                                                    2
Return Period (Days)




                                                                                    1

                                                                                    1/2
                         100




                          10




                           1
                           1875   1900        1925          1950           1975   2000
                                                     Year
                        Deaths in 95th-Percentile Tornado

         45

                                                               Raw-5 year
         40
                                                               Filtered

         35


         30


         25
Deaths




         20


         15


         10


          5


          0
          1875   1900            1925          1950         1975            2000
                                        Year
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
  – 95th percentile death toll dropped
    from 20-25 to 10-15
Putting death and damage together


   • Consider deaths per damage
     amount
     –Inflation
     –Wealth
                                                        Death/Damage Ratio
                                                for Selected Major Tornado Events
                         100.000
                                                                       1953
(US$1M, 1997, Inflation-Adjusted)




                                    10.000
       Deaths/Damage




                                     1.000                                                     data
                                                                                               Pre-1953
                                                                                               Post-1953
                                                                                               OKC 3 May 1999
                                      .100




                                      .010




                                      .001
                                         1880   1900    1920    1940      1960   1980   2000

                                                                 Year
                                                    Death/Damage Ratio
                                            for Selected Major Tornado Events

                           10.000
                                                                    1953
(US$1M, 1997, Wealth-Adjusted)




                                 1.000
      Deaths/Damage




                                                                                          data
                                                                                          Pre-1953
                                  .100                                                    Post-1953
                                                                                          OKC 3 May 1999



                                  .010




                                  .001
                                     1880   1900    1920   1940      1960   1980   2000

                                                             Year
  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?
                           US Tornado Deaths/Million People
                  10
                                                           Mobile Homes




                   1
Deaths/Million




                  0.1




                                             Permanent Homes

                 0.01
                    1875    1900      1925          1950        1975      2000

                                             Year
       Mobile Homes

• Previously
 –20x rate of deaths compared to
  permanent
 –Big increase in Oklahoma City
• What might the future hold?
                              Fraction of Total Deaths in Mobile Homes

                    1.0


                    0.9


                    0.8


                    0.7
Fraction of Total




                    0.6


                    0.5


                    0.4


                    0.3


                    0.2


                    0.1


                    0.0
                      1975   1980          1985           1990           1995   2000
                                                  Year
                    Mobile Homes as Percentage of US Housing

    14
            Southeast
            OK-KS-NE
    12      Rest of US



    10



     8
%




     6



     4



     2



     0
     1950                1960         1970            1980     1990
                                      Year
                                  Modelled Tornado Death Rate

                   1




                                                                       Mobile Home
                                   Overall
Deaths/Million




                 0.1




                 0.01
                    1960   1970     1980        1990            2000           2010   2020
                                                Year
         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

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:5
posted:6/4/2012
language:English
pages:33