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and Parker 2019 ; Flournoy and Coniglio 2019 ; Boyer and Dahl 2020 ; Marion and Trapp 2021 ) suggests that QLCS tornadogenesis can be characterized in two general ways, based on what appear to be the dominant processes. The first encompasses the sequence of processes involving mesocyclonic rotation thought to lead to tornadoes in most supercells (e.g., Davies-Jones et al. 2001 ), and accordingly, this is classified herein as pre-tornadic mesocyclone dominant (PMD). In generally reverse
and Parker 2019 ; Flournoy and Coniglio 2019 ; Boyer and Dahl 2020 ; Marion and Trapp 2021 ) suggests that QLCS tornadogenesis can be characterized in two general ways, based on what appear to be the dominant processes. The first encompasses the sequence of processes involving mesocyclonic rotation thought to lead to tornadoes in most supercells (e.g., Davies-Jones et al. 2001 ), and accordingly, this is classified herein as pre-tornadic mesocyclone dominant (PMD). In generally reverse
disrupt low-level flows and preclude tornadogenesis in instances that might otherwise yield tornadoes over flat terrain and/or whether significant mountain tornadoes are relatively underreported because fewer people live in the mountains, damage surveys are more difficult to conduct, and fewer structures can be damaged. Although generally not explicitly stated in studies on tornado climatology, anecdotal evidence is that rough terrain is viewed as an inhibitor of tornado occurrence in mountain
disrupt low-level flows and preclude tornadogenesis in instances that might otherwise yield tornadoes over flat terrain and/or whether significant mountain tornadoes are relatively underreported because fewer people live in the mountains, damage surveys are more difficult to conduct, and fewer structures can be damaged. Although generally not explicitly stated in studies on tornado climatology, anecdotal evidence is that rough terrain is viewed as an inhibitor of tornado occurrence in mountain
increased rotation in the mesocyclone led to upward pressure gradient forces that were responsible for generating a strong low-level updraft. In turn, this low-level updraft tilted baroclinically generated horizontal vorticity into the vertical and then stretched it leading to tornadogenesis. WW95 was unable to explain the development of rotation next to the surface and they did not discuss the cause of the midlevel mesocyclone intensification responsible for low-level updraft intensification. Most of
increased rotation in the mesocyclone led to upward pressure gradient forces that were responsible for generating a strong low-level updraft. In turn, this low-level updraft tilted baroclinically generated horizontal vorticity into the vertical and then stretched it leading to tornadogenesis. WW95 was unable to explain the development of rotation next to the surface and they did not discuss the cause of the midlevel mesocyclone intensification responsible for low-level updraft intensification. Most of
1. Introduction It has been surmised that tornadogenesis results when near-surface convergence acts on existing (i.e., prior to the tornado) vertical vorticity, amplifying it to tornadic levels (e.g., Ward 1972 ). However, less understood is the development of rotation close to the surface prior to its contraction to the tornadic scale as well as the processes leading to the final contraction in some storms and not others (e.g., Davies-Jones 1982 ; Davies-Jones et al. 2001 ; Markowski and
1. Introduction It has been surmised that tornadogenesis results when near-surface convergence acts on existing (i.e., prior to the tornado) vertical vorticity, amplifying it to tornadic levels (e.g., Ward 1972 ). However, less understood is the development of rotation close to the surface prior to its contraction to the tornadic scale as well as the processes leading to the final contraction in some storms and not others (e.g., Davies-Jones 1982 ; Davies-Jones et al. 2001 ; Markowski and
tornadic environments was 10°F (5.6 K). In a tropical cyclone environment, the boundary layer relative humidity is typically high, and thus the LCL height and surface dewpoint depressions are typically low. These conditions, along with strong low-level wind shear and sufficient buoyancy, will create an environment favorable for tornadogenesis. It is uncertain whether the critical values of LCL height and surface dewpoint depression in the Great Plains studies by Rasmussen and Blanchard (1998) and
tornadic environments was 10°F (5.6 K). In a tropical cyclone environment, the boundary layer relative humidity is typically high, and thus the LCL height and surface dewpoint depressions are typically low. These conditions, along with strong low-level wind shear and sufficient buoyancy, will create an environment favorable for tornadogenesis. It is uncertain whether the critical values of LCL height and surface dewpoint depression in the Great Plains studies by Rasmussen and Blanchard (1998) and
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. Tornadogenesis within supercells Owing to the disproportionate number of significant tornadoes 1 produced by supercells compared to other storm modes
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. Tornadogenesis within supercells Owing to the disproportionate number of significant tornadoes 1 produced by supercells compared to other storm modes
1. Introduction Important unresolved issues pertaining to supercell tornadogenesis include its triggering factor and vorticity sources. Although the development of a low-level mesocyclone in a supercell often precedes tornadogenesis, the existence of the low-level mesocyclone is not a sufficient condition for tornadogenesis (e.g., Burgess et al. 1993 ; Trapp 1999 ; Trapp et al. 2005 ; Markowski et al. 2011 ). To address these issues, extensive field observations have been conducted over the
1. Introduction Important unresolved issues pertaining to supercell tornadogenesis include its triggering factor and vorticity sources. Although the development of a low-level mesocyclone in a supercell often precedes tornadogenesis, the existence of the low-level mesocyclone is not a sufficient condition for tornadogenesis (e.g., Burgess et al. 1993 ; Trapp 1999 ; Trapp et al. 2005 ; Markowski et al. 2011 ). To address these issues, extensive field observations have been conducted over the
1. Introduction Tornadogenesis and, particularly, the manner by which tornado-strength rotation makes contact with the ground have long been a topic of deep interest to the meteorological community. Several early idealized numerical simulations and observational studies initially suggested that the evolution of strong vertical vorticity associated with tornado formation occurred in a rather slow [time scales O (∼5–10) min ( Mitchell et al. 1998 ; Trapp 1999 )], top-down manner by which
1. Introduction Tornadogenesis and, particularly, the manner by which tornado-strength rotation makes contact with the ground have long been a topic of deep interest to the meteorological community. Several early idealized numerical simulations and observational studies initially suggested that the evolution of strong vertical vorticity associated with tornado formation occurred in a rather slow [time scales O (∼5–10) min ( Mitchell et al. 1998 ; Trapp 1999 )], top-down manner by which
1. Introduction Our knowledge of the dynamics of tornadogenesis in supercells is limited to a large extent by our restricted ability to observe tornadogenesis near the ground. Much of what we have learned in the last 25 years is based on Doppler radar measurements that have enabled us to visualize the wind field near tornadoes, but on spatial scales that do not explicitly resolve the tornado very well or at all. For example, early fixed-site dual-Doppler studies of tornadic storms described the
1. Introduction Our knowledge of the dynamics of tornadogenesis in supercells is limited to a large extent by our restricted ability to observe tornadogenesis near the ground. Much of what we have learned in the last 25 years is based on Doppler radar measurements that have enabled us to visualize the wind field near tornadoes, but on spatial scales that do not explicitly resolve the tornado very well or at all. For example, early fixed-site dual-Doppler studies of tornadic storms described the
1. Introduction Despite increased understanding of how environmental profiles of temperature, humidity, and winds affect the tornadic potential of convective storms, much is still unknown about what ultimately differentiates between seemingly similar nontornadic and tornadic supercells. Observations and simulations of nontornadic supercells show remarkable similarity to their tornadic counterparts, with operationally unobservable differences ultimately leading to tornadogenesis failure. While
1. Introduction Despite increased understanding of how environmental profiles of temperature, humidity, and winds affect the tornadic potential of convective storms, much is still unknown about what ultimately differentiates between seemingly similar nontornadic and tornadic supercells. Observations and simulations of nontornadic supercells show remarkable similarity to their tornadic counterparts, with operationally unobservable differences ultimately leading to tornadogenesis failure. While
