Characteristics of Tornado Events and Warnings in the Southeastern United States

Anderson-Frey, Alexandra K.; Richardson, Yvette; Dean, Andrew R.; Thompson, Richard L.; Smith, Bryan T.

doi:10.1175/waf-d-18-0211.1

Cited by 38 publications

(28 citation statements)

References 43 publications

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“…Between 1998and 2007, Schoen and Ashley (2011 found that more than 90% of tornado deaths were associated with supercells, and also that supercells resulted in a mean of three fatalities per fatal storm, while other storm modes resulted in values closer to one fatality per fatal storm. Anderson-Frey et al (2019) also found, for 2003-17, a higher mean percentage of deadly tornadoes with an RMS storm mode versus a QLCS storm mode.…”

Section: B Storm Modementioning

confidence: 69%

“…This paper employs a NOAA Storm Prediction Center dataset of 16 232 tornado events occurring during the 15-yr period from 2003 to 2017. Smith et al (2012) described the initial creation of this dataset, and the update of the data through 2017 was discussed and these data were applied in Anderson-Frey et al (2019). This dataset filters county tornado segment data, keeping only the highest (E)F-scale value occurring within a given hour and 40 km 3 40 km area; as a result, any tornadoes occurring within the same 1 h 3 40 km 3 40 km are grouped together as a single event.…”

Section: A Tornado Event Databasementioning

confidence: 99%

“…The horizontal grid spacing of these model data is 40 km, and the temporal data are hourly. Thompson et al (2012) and Anderson-Frey et al (2016) provided a more indepth discussion of the strengths and limitations of the dataset.…”

Section: A Tornado Event Databasementioning

confidence: 99%

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Tornado Fatalities: An Environmental Perspective

Anderson-Frey

Brooks

2019

Weather and Forecasting

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Deadly tornadoes are rare events, but that level of rarity varies with many factors. In this work, we summarize and update past research on tornado fatalities, and also discuss the environments of deadly tornadoes both from the perspective of proximity soundings (i.e., point-based) and self-organizing maps (i.e., two-dimensional). In our study of 16 232 tornado events from 2003 to 2017, we find that deadly tornadoes are disproportionately likely to have high (E)F-scale ratings, to have right-moving supercell parent storm modes (deadly QLCS tornadoes are exceptionally rare and tend to result in only one death when they do occur), and to occur during the winter and spring. Warning skill is generally higher for deadly tornadoes than for nondeadly tornadoes: 87% of deadly tornadoes were warned in advance, and nearly 95% of tornado deaths occurred within an active warning. The same environments are warned well for both deadly and nondeadly tornadoes, but the deadly tornadoes tend to occur in environments that are less conducive to weaker (E)F0–1 tornadoes. We identify four prototypical deadly tornado scenarios using self-organizing maps, ranging from marginal environments resulting in relatively few fatalities to major deadly outbreak events. Overall results indicate that the most dangerous tornadoes (i.e., those with high numbers of deaths per deadly tornado) also generally occur in environments and under conditions in which warning skill is high. While, generally speaking, the correct storms are being warned, we include some recommendations for additional research and further improvement.

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Section: B Storm Modementioning

confidence: 69%

Section: A Tornado Event Databasementioning

confidence: 99%

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Tornado Fatalities: An Environmental Perspective

Anderson-Frey

Brooks

2019

Weather and Forecasting

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“…SRH is an important parameter for characterizing the environments associated with both supercells and tornadoes, particularly for 0-1-and 0-3-km layers (Thompson et al 2003(Thompson et al , 2012Anderson-Frey et al 2016;Coffer et al 2019Coffer et al , 2020Coniglio and Parker 2020). ERA5 tends to overestimate SRH with ME of around 5 m 2 s 22 , whereas for MERRA-2 ME is close to zero, while MAE for both reanalyses is around 30 m 2 s 22 (Table 3, Fig.…”

Section: Wind Parametersmentioning

confidence: 99%

“…8). However, it can be also noted that MERRA-2 has overall better performance in sampling high-shear, low-CAPE environments (HSLC; Sherburn and Parker 2014;Anderson-Frey et al 2019;Gatzen et al 2020) than ERA5. Compared to observations, both reanalyses have more frequent situations with marginal both instability and wind shear.…”

Section: E Composite Parametersmentioning

confidence: 99%

Comparison of Convective Parameters Derived from ERA5 and MERRA-2 with Rawinsonde Data over Europe and North America

et al. 2021

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In this study we compared 3.7 mln rawinsonde observations from 232 stations over Europe and North America with proximal vertical profiles from ERA5 and MERRA2 to examine how well reanalysis depicts observed convective parameters. Larger differences between soundings and reanalysis are found for thermodynamic theoretical parcel parameters, low-level lapse rates and low-level wind shear. In contrast, reanalysis best represents temperature and moisture variables, mid-tropospheric lapse rates, and mean wind. Both reanalyses underestimate CAPE, low-level moisture and wind shear, particularly when considering extreme values. Overestimation is observed for low-level lapse rates, mid-tropospheric moisture and the level of free convection. Mixed-layer parcels have overall better accuracy when compared to most-unstable, especially considering convective inhibition and lifted condensation level. Mean absolute error for both reanalyses has been steadily decreasing over the last 39 years for almost every analyzed variable. Compared to MERRA2, ERA5 has higher correlations and lower mean absolute errors. MERRA2 is typically drier and less unstable over central Europe and the Balkans, with the opposite pattern over western Russia. Both reanalyses underestimate CAPE and CIN over the Great Plains. Reanalyses are more reliable for lower elevations stations and struggle along boundaries such as coastal zones and mountains. Based on the results from this and prior studies we suggest that ERA5 is likely one of the most reliable available reanalysis for exploration of convective environments, mainly due to its improved resolution. For future studies we also recommend that computation of convective variables should use model levels that provide more accurate sampling of the boundary-layer conditions compared to less numerous pressure levels.

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