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: The influence of environmental low-level shear and cold pools on tornadogenesis: Insights from idealized simulations . J. Atmos. Sci. , 71 , 243 – 275 , doi: 10.1175/JAS-D-13-0159.1 . 10.1175/JAS-D-13-0159.1 Markowski , P. , J. Straka , and E. Rasmussen , 2003 : Tornadogenesis resulting from the transport of circulation by a downdraft: Idealized numerical simulations . J. Atmos. Sci. , 60 , 795 – 823 , doi: 10.1175/1520-0469(2003)060<0795:TRFTTO>2.0.CO;2 . 10
: The influence of environmental low-level shear and cold pools on tornadogenesis: Insights from idealized simulations . J. Atmos. Sci. , 71 , 243 – 275 , doi: 10.1175/JAS-D-13-0159.1 . 10.1175/JAS-D-13-0159.1 Markowski , P. , J. Straka , and E. Rasmussen , 2003 : Tornadogenesis resulting from the transport of circulation by a downdraft: Idealized numerical simulations . J. Atmos. Sci. , 60 , 795 – 823 , doi: 10.1175/1520-0469(2003)060<0795:TRFTTO>2.0.CO;2 . 10
operations, viewing radar-indicated evidence of tornadogenesis in finer temporal detail has resulted in the issuance of earlier warnings by up to 7.5 min, especially during classic supercell events ( Heinselman et al. 2015 ; Wilson et al. 2017 ). In the 2012 PARISE, forecasters achieving above-average tornado warning lead times applied conceptual models that depended on trends only observable in the 1-min PAR updates ( Heinselman et al. 2015 ). P13 emphasized the importance of these trends, reporting
operations, viewing radar-indicated evidence of tornadogenesis in finer temporal detail has resulted in the issuance of earlier warnings by up to 7.5 min, especially during classic supercell events ( Heinselman et al. 2015 ; Wilson et al. 2017 ). In the 2012 PARISE, forecasters achieving above-average tornado warning lead times applied conceptual models that depended on trends only observable in the 1-min PAR updates ( Heinselman et al. 2015 ). P13 emphasized the importance of these trends, reporting
of the bands CAPEs are likely to be significantly higher; however, these CAPEs are not as high as those soundings made far from any reflectivity features. c. The 1500-m vertical shear Novlan and Gray (1974) identified a threshold vertical shear of the horizontal wind from the surface to 850 mb that was correlated with tornadogenesis in hurricanes. Consequently, a similar shear value was calculated over the first 1500 m of each ODW profile by taking ∂ υ /∂ z from the 10-m estimate to the 1500-m
of the bands CAPEs are likely to be significantly higher; however, these CAPEs are not as high as those soundings made far from any reflectivity features. c. The 1500-m vertical shear Novlan and Gray (1974) identified a threshold vertical shear of the horizontal wind from the surface to 850 mb that was correlated with tornadogenesis in hurricanes. Consequently, a similar shear value was calculated over the first 1500 m of each ODW profile by taking ∂ υ /∂ z from the 10-m estimate to the 1500-m
typically have high CAPE. However, many nocturnal environments are characterized by decreased near-surface temperatures and a low-level inversion, leading to less surface-based instability and greater CIN. Logically, these conditions would be expected to inhibit strong tornadogenesis in some cases ( Leslie and Smith 1978 ; Nowotarski et al. 2011 ). Recent research has sought to describe the characteristics of environments in which nocturnal tornadoes form. For example, Davies and Fischer (2009
typically have high CAPE. However, many nocturnal environments are characterized by decreased near-surface temperatures and a low-level inversion, leading to less surface-based instability and greater CIN. Logically, these conditions would be expected to inhibit strong tornadogenesis in some cases ( Leslie and Smith 1978 ; Nowotarski et al. 2011 ). Recent research has sought to describe the characteristics of environments in which nocturnal tornadoes form. For example, Davies and Fischer (2009
1. Introduction a. Motivation The lion’s share of tornado research to date has been understandably focused on the tornadogenesis problem (e.g., Brandes 1978 ; Klemp and Rotunno 1983 ; Wicker and Wilhelmson 1995 ; Davies-Jones and Brooks 1993 ; Markowski and Richardson 2009 , 2014 ; Markowski et al. 2012 ; Coffer and Parker 2017 ). A much smaller subset of studies has focused, at least in part, on tornado maintenance or aspects of tornado evolution after development. The research
1. Introduction a. Motivation The lion’s share of tornado research to date has been understandably focused on the tornadogenesis problem (e.g., Brandes 1978 ; Klemp and Rotunno 1983 ; Wicker and Wilhelmson 1995 ; Davies-Jones and Brooks 1993 ; Markowski and Richardson 2009 , 2014 ; Markowski et al. 2012 ; Coffer and Parker 2017 ). A much smaller subset of studies has focused, at least in part, on tornado maintenance or aspects of tornado evolution after development. The research
at every scan below 8000 ft (∼2438 m); and 3) persisted at least two full volume scans. Previous studies have applied similar approaches to identify MVs via WSR-88D data interrogation ( Smith et al. 2015 ; Sessa and Trapp 2020 ). Qualitatively, these criteria follow the findings of Atkins et al. (2004) , which describe tornadic MVs as being “longer-lived and stronger at low levels” and deepening rapidly prior to tornadogenesis. In applying the above criteria, 42 unique MVs ( within 39
at every scan below 8000 ft (∼2438 m); and 3) persisted at least two full volume scans. Previous studies have applied similar approaches to identify MVs via WSR-88D data interrogation ( Smith et al. 2015 ; Sessa and Trapp 2020 ). Qualitatively, these criteria follow the findings of Atkins et al. (2004) , which describe tornadic MVs as being “longer-lived and stronger at low levels” and deepening rapidly prior to tornadogenesis. In applying the above criteria, 42 unique MVs ( within 39
anticyclonic tornadoes. a. Tornadogenesis and evolution of the parent supercell and other supercells Although there was a brief tornado reported at 2255–2256 UTC ( Fig. 8 ), the most intense and longest lived of all the tornadoes on 31 May 2013 produced by the El Reno supercell (marked with an A in Fig. 12 ) began at 2304 UTC to the west-southwest of our deployment spot; the tornado moved initially to the southeast. The entire genesis phase of this tornado was documented by volume scans ( Table 1 ; Fig
anticyclonic tornadoes. a. Tornadogenesis and evolution of the parent supercell and other supercells Although there was a brief tornado reported at 2255–2256 UTC ( Fig. 8 ), the most intense and longest lived of all the tornadoes on 31 May 2013 produced by the El Reno supercell (marked with an A in Fig. 12 ) began at 2304 UTC to the west-southwest of our deployment spot; the tornado moved initially to the southeast. The entire genesis phase of this tornado was documented by volume scans ( Table 1 ; Fig
horizontal grid spacing is far too coarse for resolving tornadoes, Potvin and Flora (2015) showed that idealized Δ x = 3 km simulations could capture low-level mesocyclone tracks reasonably well. Their finding is encouraging, given that (i) mesocyclones are a necessary precursor for tornadogenesis in supercell thunderstorms ( Markowski and Richardson 2010 ); and that (ii) supercells spawn the majority of deadly U.S. tornadoes ( Schoen and Ashley 2011 ). Although only ∼25% of all mesocyclones detected
horizontal grid spacing is far too coarse for resolving tornadoes, Potvin and Flora (2015) showed that idealized Δ x = 3 km simulations could capture low-level mesocyclone tracks reasonably well. Their finding is encouraging, given that (i) mesocyclones are a necessary precursor for tornadogenesis in supercell thunderstorms ( Markowski and Richardson 2010 ); and that (ii) supercells spawn the majority of deadly U.S. tornadoes ( Schoen and Ashley 2011 ). Although only ∼25% of all mesocyclones detected
weather production. For example, flow channeling was indicated as the contributor to localized enhancements in storm-relative helicity (SRH) and instability that were associated with rapidly intensifying supercells and tornadogenesis (e.g., LaPenta et al. 2005 ; Bosart et al. 2006 ; Schneider 2009 ; Tang et al. 2016 ; LeBel et al. 2021 ). Model simulations have further underscored the importance of these terrain-induced environmental variations on supercell evolution. Markowski and Dotzek (2011
weather production. For example, flow channeling was indicated as the contributor to localized enhancements in storm-relative helicity (SRH) and instability that were associated with rapidly intensifying supercells and tornadogenesis (e.g., LaPenta et al. 2005 ; Bosart et al. 2006 ; Schneider 2009 ; Tang et al. 2016 ; LeBel et al. 2021 ). Model simulations have further underscored the importance of these terrain-induced environmental variations on supercell evolution. Markowski and Dotzek (2011
many respects (due to the radar’s sampling characteristics), the integration of information from a variety of other sensors (e.g., near-storm environment, satellites, lightning, etc.) may provide important missing pieces to the puzzle, thereby distinguishing, with more skill, between significant and insignificant vortices (and thus reducing the FAR to a respectable low number). Our understanding of tornadogenesis within thunderstorms is still limited. An extensive tornado field project ( Rasmussen
many respects (due to the radar’s sampling characteristics), the integration of information from a variety of other sensors (e.g., near-storm environment, satellites, lightning, etc.) may provide important missing pieces to the puzzle, thereby distinguishing, with more skill, between significant and insignificant vortices (and thus reducing the FAR to a respectable low number). Our understanding of tornadogenesis within thunderstorms is still limited. An extensive tornado field project ( Rasmussen
