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Robert Davies-Jones

1. Introduction Vorticity dynamics is fundamental to understanding tornadogenesis (see reviews by Davies-Jones et al. 2001 , hereafter DJ+01 ; Davies-Jones 2015a ). Dutton (1986) showed theoretically that the vorticity of a parcel in inviscid, isentropic flow decomposes into barotropic and baroclinic parts. By using propagators, Epifanio and Durran (2002) and Davies-Jones (2006 , 2015b) extended this work to include vorticity arising from frictional torques, planetary vorticity, and

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Paul Markowski
,
Yvette Richardson
,
James Marquis
,
Joshua Wurman
,
Karen Kosiba
,
Paul Robinson
,
David Dowell
,
Erik Rasmussen
, and
Robert Davies-Jones

. 3. Unedited logarithmic radar reflectivity factor (dB Z ) observed by the KCYS WSR-88D (0.5° elevation angle) and DOW7 radars (1° elevation angle) at (a) 2107:04, (b) 2116:14, (c) 2125:23, (d) 2132:26, (e) 2140:06, and (f) 2148:07 UTC (“ t − X min” indicates X min prior to tornadogenesis). The DOW7 reflectivity is uncalibrated. Fig . 4. Large-scale depiction of the track of the Goshen County storm on 5 Jun 2009 as evidenced by the 40-, 50-, and 60-dB Z isopleths of logarithmic reflectivity

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James W. Wilson

270 MONTHLY WEATHER REVIEW VOLUME 114Tornadogenesis by Nonprecipitation Induced Wind Shear Lines JAMES W. WILSONNational Center for Atmospheric Research,* Boulder, Colorado 80307(Manuscript received 31 May 1985, in final form 17 September 1985) Five tornadoes occurred within a 40 rain period on 18 May 1984 in eastern Colorado. The evolution of thesetornadoes was documented by

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Paul Markowski
,
Yvette Richardson
,
James Marquis
,
Robert Davies-Jones
,
Joshua Wurman
,
Karen Kosiba
,
Paul Robinson
,
Erik Rasmussen
, and
David Dowell

1. Introduction One focus of our ongoing research is the relative role of environmental vorticity versus storm-generated vorticity in tornadogenesis and maintenance. In supercell environments, which are characterized by relatively large vertical shear of the horizontal wind, the horizontal vorticity is typically on the order of 10 −2 s −1 in the lower troposphere. In contrast, vorticity can be generated internally within a storm by horizontal buoyancy gradients (i.e., baroclinity). The

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Robert Davies-Jones

supercell simulations and thus assess the merits of various tornado theories. A subsequent paper will report and lightly test a methodology for computing partial vorticities of a parcel along its forward trajectory. The method requires the parcel’s initial vorticity and, along its path, its velocity-gradient matrix and the torques acting on it. This information can be obtained from the output of a simulation. Although still not providing conclusive evidence in favor of a single tornadogenesis theory

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R. J. Trapp

1. Introduction The Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX; Rasmussen et al. 1994 ) was conducted during the spring of 1994 and 1995 in the southern Great Plains of the United States. The objectives of this validation experiment were driven by a set of hypotheses (see Rasmussen 1995 ) that concerned (i) the initiation of tornadic storms; (ii) low-level mesocyclogenesis, tornadogenesis, and the role(s) of mesoscale and stormscale boundaries in

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Edward A. Brandes

MAY 1984 EDWARD A. BRANDES 1033Relationships Between Radar-Derived Thermodynamic Variables and Tornadogenesis EDWARD A. BRANDESNOAA/ERL, National Severe Storms Laboratory, Norman, OK 73069(Manuscript received 23 October 1983, in final form 3 February 1984)ABSTRACT A methodology for obtaining pressure perturbations and buoyancy in

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Leslie R. Lemon
and
Charles A. Doswell III

potential modularing role in tornadogenesis by solenoidal generation of vorticity, in analogy with the extratropicalcyclone, to which the transformed mesocyclone bears a striking resemblance.1. Introduction The Wrnado vortex is one of the atmosphere'smost intense concentrations of vorticity. For atypical violent tornado with a maximum tangentialspeed of 100 m s-~ at a radius of 100 m, the verticalcomponent of vorticity is 2 s-~. The means by whichsuch vorticity is developed within a thunderstormare

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Matthew S. Van Den Broeke
,
Jerry M. Straka
, and
Erik N. Rasmussen

southwest from the storm and often marked by young developing cells, indicates the leading edge of RFD-associated outflow. Brandes (1981) examined supercell structural evolution through the tornado life cycle. His Fig. 10 (shown here as Fig. 1d ) shows a region of dry upper-level air intruding on the southwest side of the storm at the pretornado time, under which a rear-flank downdraft develops near the time of tornadogenesis. The swirling component of the low-level flow is at maximum during the

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James S. Goodnight
,
Devin A. Chehak
, and
Robert J. Trapp

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

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