Investigation of Near-Storm Environments for Tornado Events and Warnings

Abstract

In this study, a 13-yr climatology of tornado event and warning environments, including metrics of tornado intensity and storm morphology, is investigated with particular focus on the environments of tornadoes associated with quasi-linear convective systems and right-moving supercells. The regions of the environmental parameter space having poor warning performance in various geographical locations, as well as during different times of the day and year, are highlighted. Kernel density estimations of the tornado report and warning environments are produced for two parameter spaces: mixed-layer convective available potential energy (MLCAPE) versus 0–6-km vector shear magnitude (SHR6), and mixed-layer lifting condensation level (MLLCL) versus 0–1-km storm-relative helicity (SRH1). The warning performance is best in environments characteristic of severe convection (i.e., environments featuring large values of MLCAPE and SHR6). For tornadoes occurring during the early evening transition period, MLCAPE is maximized, MLLCL heights decrease, SHR6 and SRH1 increase, tornadoes rated as 2 or greater on the enhanced Fujita scale (EF2+) are most common, the probability of detection is relatively high, and false alarm ratios are relatively low. Overall, the parameter-space distributions of warnings and events are similar; at least in a broad sense, there is no systematic problem with forecasting that explains the high overall false alarm ratio, which instead seems to stem from the inability to know which storms in a given environment will be tornadic.

Severe Convective Storms across Europe and the United States. Part II: ERA5 Environments Associated with Lightning, Large Hail, Severe Wind, and Tornadoes

“…Other studies have also focused on specific convective phenomena with the need to improve their forecasting (Thompson et al 2012;Gropp and Davenport 2018;Anderson-Frey et al 2018;Coffer et al 2019). A consistent result between all studies has been the clear dependence of the severity of thunderstorms on the covariate relationship of CAPE and vertical wind shear (Rasmussen and Blanchard 1998;Craven and Brooks 2004;Brooks 2009Brooks , 2013Allen and Karoly 2014;Púčik et al 2015;Anderson-Frey et al 2016;Taszarek et al 2017Taszarek et al , 2019Ingrosso et al 2020).…”

“…Other studies have also focused on specific convective phenomena with the need to improve their forecasting (Thompson et al 2012;Gropp and Davenport 2018;Anderson-Frey et al 2018;Coffer et al 2019). A consistent result between all studies has been the clear dependence of the severity of thunderstorms on the covariate relationship of CAPE and vertical wind shear (Rasmussen and Blanchard 1998;Craven and Brooks 2004;Brooks 2009Brooks , 2013Allen and Karoly 2014;Púčik et al 2015;Anderson-Frey et al 2016;Taszarek et al 2017Taszarek et al , 2019Ingrosso et al 2020). A notable focus in recent years has been also on high shear low CAPE (HSLC) environments with an enhanced potential of producing severe weather, typically during cold-season as evidenced for western and central Europe and the southeastern U.S. (Sherburn and Parker 2014;Sherburn et al 2016;Gatzen et al 2020;Anderson-Frey et al 2019;Mathias et al 2019;Celiński-Mysław et al 2020).…”

“…DOI 10.1175/JCLI-D-20-0346.1. Sugden 2014; Tippett et al 2015;Anderson-Frey et al 2018). Brooks et al (2003) conducted a pioneering study using model data to estimate global climatology of environments leading to severe convective storms.…”

Processes Preventing the Development of a Significant Tornado in a Colorado Supercell on 26 May 2010

“…Unfortunately, it is difficult to forecast exactly when and where a tornado will occur. For example, from 2003 to 2015, only about two-thirds of tornadoes occurred in tornado-warned areas and about three-fourths of tornado warnings were never associated with a tornado (Anderson-Frey et al 2016). One way to improve the probability of detection for tornadoes and reduce the number of false alarms is to better understand the conditions and processes that result in tornadogenesis or tornadogenesis failure.…”

A Challenging Tornado Forecast in Slovakia

“…While many of the aforementioned studies looked at mostly high convective available potential energy (CAPE) and strongly sheared environments, Lawson (2019) [33] noted that explicit simulations of storm intensity exhibit large uncertainty in environments with low CAPE but strong vertical wind shear. This type of environment, as in the present case, is notorious for both lower tornado prediction and warning performance across the U.S. [34,35].…”