Stephen M. Strader

Spatiotemporal Changes in Tornado Hazard Exposure: The Case of the Expanding Bull’s-Eye Effect in Chicago, Illinois

AbstractExposure has amplified rapidly over the past half century and is one of the primary drivers of increases in disaster frequency and consequences. Previous research on exposure change detection has proven limited since the geographic units of aggregation for decennial censuses, the sole measure of accurate historical population and housing counts, vary from one census to the next. To address this shortcoming, this research produces a set of gridded population and housing data for the Chicago, Illinois, region to evaluate the concept of the “expanding bull’s-eye effect.” This effect argues that “targets”—people and their built environments—of geophysical hazards are enlarging as populations grow and spread. A collection of observationally derived synthetic violent tornadoes are transposed across fine-geographic-scale population and housing unit grids at different time stamps to appraise the concept. Results reveal that intensifying and expanding development is placing more people and their possession...

Recipe for Disaster: How the Dynamic Ingredients of Risk and Exposure Are Changing the Tornado Disaster Landscape

AbstractTornado disasters and their potential are a product of both hazard risk and underlying physical and social vulnerabilities. This investigation appraises exposure, which is an important component and driver of vulnerability, and its interrelationship with tornado risk in the United States since the mid-twentieth century. The research demonstrates how each of these dynamic variables have evolved individually and interacted collectively to produce differences in hazard impact and disaster potential at the national, regional, and local scales. Results reveal that escalating tornado impacts are driven fundamentally by growing built-environment exposure. The increasing tornado disaster probability is not uniform across the landscape, with the mid-South region containing the greatest threat based on the juxtaposition of an immense tornado footprint risk and elevated exposure/development rates, which manifests—at least for one important impact marker—in the area’s high mortality rate. Contemporary, high-i...

Driving Blind: Weather-Related Vision Hazards and Fatal Motor Vehicle Crashes

AbstractVisibility-related weather hazards have significant impacts on motor vehicle operators because of decreased driver vision, reduced roadway speed, amplified speed variability, and elevated crash risk. This research presents a national analysis of fog-, smoke-, and dust storm–associated vehicular fatalities in the United States. Initially, a database of weather-related motor vehicle crash fatalities from 1994 to 2011 is constructed from National Highway Traffic Safety Administration data. Thereafter, spatiotemporal analyses of visibility-related (crashes where a vision hazard was reported at time of event) and vision-obscured (driver’s vision was recorded as obscured by weather, and a weather-related vision hazard was reported) fatal vehicular crashes are presented. Results reveal that the annual number of fatalities associated with weather-related, vision-obscured vehicular crashes is comparable to those of more notable and captivating hazards such as tornadoes, floods, tropical cyclones, and light...

The Expanding Bull's-Eye Effect

W eather hazards such as tornadoes and hurricanes affect thousands of people annually, often resulting in casualties and billions of dollars in damage. These extreme weather events can lead to disasters, which are a product of both hazard risk and societal exposure. Hazard risk describes the frequency and magnitude of a weather hazard, while societal exposure is defi ned as who and what is affected by an event. The NOAA reports that there have been nearly 180 weather and climate Th e EXPANDING BULL’S-EYE EFFECT

Observed and Projected Changes in United States Tornado Exposure

AbstractThis study examines how tornado risk and societal exposure interact to create tornado disaster potential in the United States. Finescale historical and projected demographic data are used in a set of region-specific Monte Carlo tornado simulations to reveal how societal development has shaped, and will continue to shape, tornado disaster frequency and consequences. Results illustrate that although the U.S. Midwest contains the greatest built-environment exposure and the central plains experience the most significant tornadoes, the midsouth contains the greatest tornado disaster potential. This finding is attributed to the relatively elevated tornado risk and accelerated growth in developed land area that characterizes the midsouth region. Disaster potential is projected to amplify in the United States due to increasing built-environment development and its spatial footprint in at-risk regions. In the four regions examined, both average annual tornado impacts and associated impact variability are p...

Projected 21st century changes in tornado exposure, risk, and disaster potential

While risk and associated hazard characteristics are important components of disaster formation, the consequences of hazards are often driven by underlying human and built-environment vulnerabilities. Yet, there has been little research conducted on how the evolving contributors of risk and vulnerability commingle to produce disaster potential. In this study, we assess the interaction of risk and vulnerability by investigating a single hazard, the tornado. How future changes in risk and vulnerability influence tornado disaster probability is estimated by integrating, for the first time, projected residential built environment data and modeled future severe weather environments. Results suggest that, although the projected twenty-first century escalation in tornado risk will play a role in increasing disaster consequences and frequency, growth in the human-built environment is projected to outweigh the effects of increased risk on future tornado disaster potential. While changes in societal exposure are projected to overshadow potential climate change-driven alterations in tornado risk, the combination of both an increase in risk and exposure may lead to a threefold increase in median annual tornado impact magnitude and disaster potential from 2010 to 2100.

Cloud-to-ground lightning signatures of long-lived tornadic supercells on 27-28 April 2011

This study integrates past research methodologies, data from the National Lightning Detection Network (NLDN), and geographic information system techniques to assess the lightning and severe weather hazard relationship for the 27–28 April 2011 United States tornado outbreak. NLDN and Doppler radar data are used to examine the cloud-to-ground (CG) lightning characteristics associated with seven supercell thunderstorms that produced long-track, significant and/or violent tornadoes. Analyses indicate that CG lightning flashes alone do not provide enough information for the detection of a lightning jump prior to tornadogenesis. All seven supercells were dominated by negative-polarity CG lightning flashes; which is expected due to the geographic location and elevated low-level moisture found in the outbreak environment. The correlation between low-level mesocyclone strength and total CG lightning flash rate was varied and inconsistent among all storms despite their formation and sustenance in similar environmental and geographic space. Additional case studies, as well as climatological approaches, are required to discover if the varying lightning–tornado relationships found in this study are consistent with other tornadic environments.