Charles E. Konrad II Maggie M. Kovach Christopher M. Fuhrmann Jordan McLeod Southeast Regional Climate Center Department of Geography University of North Carolina – Chapel Hill

Background Number of Killer Tornado EventsAnnual Tornado Reports Ashley 2007 Dixie Alley

Mobile Homes Tornado fatalities by location (1985–2005) Sutter, Daneil., Kevin M. Simmons The likelihood of fatality is 20 times greater in mobile homes than in other structures (Brooks and Doswell 2002) Sutter and Simons 2012

Research Question What are the regional variations in tornado outbreak vulnerability? How vulnerable are people in the immediate vicinity of a tornado? Once a tornado has touched down, how vulnerable are individuals? How does population, mobile home density, poverty, and numbers of senior citizens affect vulnerability in the path of a tornado? What are the secular trends in tornado vulnerability?

Data Tornado data from 1980 to 2010 obtained from Storm Prediction Center (SPC) using the online SeverePlot tool. – Beginning & ending lat/lon, F/EF level of tornado, # deaths & injuries of every reported tornado. – Underreporting of tornadoes not an issue during the study period.

Census data Tract level: 1990 & 2000 Data (continued) # of mobile homes Population Pover Poverty Senior Citizens

A. Estimate the population and # of mobile homes in a 500 m buffer around each tornado track in the database. Tornadoes observed Early period:  1990 census Late period:  2000 census B. Record/calculate the following for each tornado: 1. EF-level 2. Track length 3. Adjusted Fujita miles (Track length * EF-level) 4. Number of deaths 5. Number of deaths per km of track 6. Exposed population, elderly, poverty 7. Exposed population/km, elderly/km, poverty/km 8. Exposed mobile homes 9. Exposed mobile homes/km Methodology

C. Compare differences between the early and late period. - Stratify by EF level (EF1-3 vs. EF4-5) and night/day occurrence - Compare differences at the regional scale Methodology (con’d)

Results 1.Deaths per km along track of tornadoes 2.Secular trends in: a. Deaths b. Population, # elderly, #poverty, number of mobile homes in the immediate vicinity of tornadoes

The Paths of Killer Tornadoes ( )

ALL Deaths/kmEF1-3 Deaths/km FL TN NC OH AL GA PA TX NE States AR IL OK MO MS SC LA IN KN WV/VA/DE/MD IA SD ND NE Vulnerability when a tornado is on the ground

State ALL Deaths/kmEF1-3 Deaths/km Mobile homes/km Pop/kmElderly/kmPoverty/Km FL TN NC OH AL GA PA TX NE States AR IL OK MO MS SC LA IN KN WV/VA/DE/MD IA SD ND NE Deaths per Km in the immediate vicinity of tornadoes

Percentage Change in Quantity  Changes significant at the.10 and.05 level are in blue and bolded blue, respectively. STUDY AREA ALLEF4-5EF1-3DaytimeNight NUMBER OF DEATHS EF-level Track length AEF_MILES Deaths Death/km Pop exposed Pop exposed/km Exposed Mobile Homes Exposed Mobile Homes/km Elderly exposed Elderly exposed/km Poverty exposed Poverty exposed/km

Regional Breakdown Southeast Southern Plains Northern Plains Midwest NE

Summary Focus on vulnerability in the immediate vicinity of a tornado Greatest in South, especially FL (.039/km), lowest in Northern Plains (.0025) Association with pop density, # mobile homes. Secular changes: vs for entire region 31%  in deaths overall. 57%  for EF1-EF3 tornadoes 24%  in track length 52%  in mobile homes 6%  deaths/ km 16%  mobile homes/km 14%  elderly/km 17%  poverty/km

Summary (continued) Greatest secular increases observed in nocturnal tornadoes, especially South and Midwest 56%  in deaths overall. 57%  for EF1-EF3 tornadoes 31%  in track length 72%  in mobile homes 19%  deaths/ km 16%  mobile homes/km 5%  elderly/km 8%  poverty/km

Current work Apply a much larger buffer (100 km around each tornado track) and compare with 1km buffer. Rationale: Large buffer identifies the region within which each tornado may have tracked given slightly different initial conditions (e.g. location of supercell development). This addresses the vagaries of where tornadoes just happen to develop.

Example of 100 km buffer for tornado that tracks from downtown Tampa through downtown Orlando

Study area ALLEF4-5EF1-3DaytimeNight NUMBER OF DEATHS Pop exposed Pop exposed/km Exposed Mobile Homes Exposed Mobile Homes/km Elderly exposed Elderly exposed/km Poverty exposed Poverty exposed/km Percentage Change in Quantity  Pop exposed Pop exposed/km Exposed Mobile Homes Exposed Mobile Homes/km Elderly exposed Elderly exposed/km Poverty exposed Poverty exposed/km km buffer 1 km buffer

Questions? Chip Konrad