![]() ![]() A 15-yr dataset helps partially offset the strong influence of individual tornado outbreaks when compared with a briefer period of study (although, for instance, the 27 April 2011 outbreak still features prominently in the data) without moving into multidecadal time scales that are more likely to encompass significant secular (nonmeteorological) shifts in the data. In addition to this forecast evaluation approach, this paper divides a relatively long-term tornado event, warning, and environment dataset by intensity, time of day, season, and storm mode, providing a wealth of directly comparable information that previously has been spread across several datasets and different times of record.ĭefining the southeastern United States as in the following section, we make use of 4133 tornado events (refer to section 2 for the definition of an “event”) and 16 429 tornado warnings from 2003 to 2017. Previous work, however, has not explicitly associated tornado warning skill with near-storm environmental parameters in this region. Past studies have been centered on identifying and characterizing the physical attributes of southeastern tornadoes and their environments as inputs for ingredients-based forecasting and updates for conceptual models, with a special focus on the atypical tornadic environments common in this region (e.g., environments with marginal instability but large wind shear). (2013) examined nine years of tornado near-storm environments in the context of the spatial distribution of convective mode. 2016) or much shorter-term environmental studies (generally comprising fewer than five years of data e.g., Davis and Parker 2014 Sherburn and Parker 2014 Sherburn et al. 1978 Grazulis 1990 Bounds and Soulé 1993 Boruff et al. ![]() tornadoes has either focused on multidecadal summaries of nonenvironmental factors (seasonal and diurnal data, latitude, longitude, path width e.g., Kelly et al. Much of the previous research into the unique characteristics of southeastern U.S. ![]() 2014) with, frequently, a disproportionately high loss of life versus comparable events in the Great Plains ( Sims and Baumann 1972 Ashley 2007). Both of these have resulted in several prominent devastating tornado outbreaks in the region (e.g., Kincer 1936 Grazulis 1990 Egentowich et al. 2008 Sutter and Simmons 2010 Sherman-Morris 2013 Wallace et al. 2018) and social risk factors (e.g., large segment of population in poverty, high population of elderly residents, high concentration of mobile homes Grazulis 1990 Ashley 2007 Ashley et al. 2003 Coleman and Dixon 2014 Davis and Parker 2014 Sherburn and Parker 2014 Agee et al. 1978 Bounds and Soulé 1993 Egentowich et al. More focused research has emphasized the Southeast’s unique juxtaposition of physical risk factors (e.g., relatively high frequency of nocturnal tornadoes, disproportionate percentage of long-track tornadoes, low visibility of tornadoes in forested regions, a less easily defined storm season Skaggs 1969 Kelly et al. 1980), also has been identified as a region of particular concern when it comes to tornado risk. In addition to this prominent Great Plains–centric discussion, the southeastern United States, nicknamed “Dixie Alley” ( Schaefer et al. 2003 Coleman and Dixon 2014 Anderson-Frey et al. The common perception of tornadoes in the United States has historically been dominated by Tornado Alley, a region centered on the Great Plains in which tornadoes overwhelmingly occur in the late afternoon and early evening during springtime months ( Kelly et al. ![]() On average, however, the tornadoes with the lowest POD also tend to be those that are weakest and least likely to be deadly for the most part, the most dangerous storms are indeed being successfully warned. The Southeast also has nearly double the CONUS percentage of deadly tornadoes, with the highest percentage of these deadly tornadoes occurring during the spring, the winter, and around local sunset. These measures of warning skill remain consistent even when we consider only HSLC tornadoes. We also examine tornado warning skill in the form of probability of detection (POD percent of tornadoes receiving warning prior to tornado occurrence) and false alarm ratio (FAR percent of tornado warnings for which no corresponding tornado is detected), and find that, on average, POD is better and FAR is worse for tornadoes in the Southeast than for the CONUS as a whole. Through this analysis of 4133 tornado events and 16 429 tornado warnings in the southeastern United States, we find that tornadoes in the Southeast do indeed have, on average, higher shear and lower CAPE than tornadoes elsewhere in the contiguous United States (CONUS). The southeastern United States has become a prime area of focus in tornado-related literature due, in part, to the abundance of tornadoes occurring in high-shear low-CAPE (HSLC) environments. ![]()
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