Unusually Devastating Tornadoes Tyler Fricker Department of Geography, Florida State University April 3, 2019 Tyler Fricker Unusually Devastating Tornadoes 1 / 17 

Who Survives? Credit: Dayton Daily News Tyler Fricker Unusually Devastating Tornadoes 2 / 17 

Why the Difference? 1999 Blue Ash, Ohio tornado Intensity: ∼ 350 GW (EF3 tornado) Population Density: ∼ 600 people per square kilometer Casualties: 69 2002 Canton, Ohio tornado Intensity: ∼ 350 GW (EF3 tornado) Population Density: ∼ 600 people per square kilometer Casualties: 2 Tyler Fricker Unusually Devastating Tornadoes 3 / 17 

Objectives Provide a framework for systematically identifying the most unusually devastating tornadoes from the historical record Examine the characteristics of communities impacted by unusually devastating tornadoes Socioeconomic profiles Demographic profiles Tyler Fricker Unusually Devastating Tornadoes 4 / 17 

Factors Related to Tornado Casualties Physical factors Maximum damage rating (EF-scale) Damage path area Tornado energy (strength) Socioeconomic and demographic factors Population density Mobile Homes Race, poverty, and female-headed households Tyler Fricker Unusually Devastating Tornadoes 5 / 17 

The Usefulness of Statistical Models Researchers have used statistical models to: Determine what factors are important in explaining the number or rate of tornado casualties Quantify the effect a single factor has on tornado casualties while controlling for the effect of the other factors Tyler Fricker Unusually Devastating Tornadoes 6 / 17 

Defining Unusually Devastating Tornadoes An unusually devastating tornado is defined as one in which the difference between observed and predicted casualties exceeds some large value (L) Statistically, given by: UDTT = CT − ˆ CT > L (1a) ˆ CT ∼ f (xT ), (1b) where CT is the observed number of tornado casualties, ˆ CT is the predicted casualty rate, and f is some regression model Tyler Fricker Unusually Devastating Tornadoes 7 / 17 

Casualty Model The regression model includes a number of physical, socioeconomic, and demographic variables: Tornado energy (strength) Population density Mobile homes Year of occurrence Month of occurrence Hour of occurrence Tyler Fricker Unusually Devastating Tornadoes 8 / 17 

Casualty-Producing Tornadoes 0 500 1000 1500 km Tyler Fricker Unusually Devastating Tornadoes 9 / 17 

How Good is the Model? Spencer, SD Camilla, GA Camilla, GA Smithville, MS/Shottsville, AL Garland−Rowlett, TX 10 100 1000 10000 30 100 300 1000 Observed Number of Casualties Predicted Rate Tyler Fricker Unusually Devastating Tornadoes 10 / 17 

Top 10 Unusually Devastating Tornadoes Location Date (Day-Month-Year) Observed Predicted Difference (Observed - Predicted) Joplin, MO 22-05-2011 1308 131 1177 Garland-Rowlett, TX 26-12-2015 478 81 397 Gainesville, GA 20-03-1998 183 10 173 Camilla, GA 13-02-2000 186 20 166 Camilla, GA 20-03-2003 206 46 160 Spencer, SD 30-05-1998 156 22 134 Smithville, MS/Shottsville, AL 27-04-2011 160 41 119 Columbus County, NC 07-11-1995 122 3 119 Copeville, TX 26-12-2015 121 6 115 Marmaduke, AR/Caruthersville, MO 02-04-2006 179 90 89 Tyler Fricker Unusually Devastating Tornadoes 11 / 17 

Where do Unusually Devastating Tornadoes Occur? Underprediction 50 100 500 1,000 1,500 0 500 1000 1500 km Tyler Fricker Unusually Devastating Tornadoes 12 / 17 

Examples of Unusually Devastating Tornadoes Spencer, SD Garland−Rowlett, TX Camilla, GA Smithville, MS/Shottsville, AL Tyler Fricker Unusually Devastating Tornadoes 13 / 17 

Examples of Unusually Devastating Tornadoes Variable Spencer, SD Garland-Rowlett, TX Camilla, GA Smithville, MS/Shottsville, AL Age (Under 18) 30% 30% 30% 23% Age (18-24) 2% 9% 11% 9% Age (25-44) 19% 29% 27% 25% Age (45-64) 25% 24% 19% 26% Age (Over 65) 24% 8% 13% 17% Race (White) 97% 62% 25% 95% Race (Black) 1% 14% 70% 3% Race (Other) 2% 24% 5% 2% Median Household Income $21,250 $76,657 $22,485 $32,676 Poverty (Total family) 7% 9% 35% 10% Poverty (Total population) 11% 12% 38% 15% Tyler Fricker Unusually Devastating Tornadoes 14 / 17 

Beauregard-Smiths Station, AL Tornado Tyler Fricker Unusually Devastating Tornadoes 15 / 17 

Summary An unusually devastating tornado is one in which the difference between observed and predicted casualties is large Unusually devastating tornadoes can occur anywhere in the United States, but are most consistent across portions of the rural Southeast Examples of unusually devastating tornadoes can provide insight into communities at risk to high casualty counts Tyler Fricker Unusually Devastating Tornadoes 16 / 17 

What questions do you have? Tyler Fricker Unusually Devastating Tornadoes 17 / 17