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S. Lim
,
S. Allabakash
,
B. Jang
, and
V. Chandrasekar

al. 2006 ; Byko et al. 2009 ). The DRC typically occurs prior to the development of the hook echo. The DRC signatures can be used to detect tornadogenesis. DRCs may or may not be associated with tornadic storms. Rasmussen et al. (2006) performed the preliminary study on DRCs in which they described the characteristics of DRC in convective storms. They also discussed the frequency of occurrence of DRCs prior to tornadic supercell storms. Subsequently, Kennedy et al. (2007) presented a

Open access
Vincent T. Wood
,
Robert P. Davies-Jones
, and
Alan Shapiro

-in fields utilizing a histogram and a linear regression model. Figure 9 presents KOUN WSR-88D scans of ground-relative base Doppler velocity ( V r ), base reflectivity ( Z ) of and base spectrum width ( σ υ ) of the violent El Reno tornado as collected with superresolution (0.5° azimuthal interval and 250-m range increment) at the 0.97° launch angle at 2311:04 UTC 31 May 2013. Tornadogenesis, tornado evolution, photogrammetric and polarimetric analyses, and aerial damage survey in the El Reno tornadic

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Robert P. Davies-Jones
and
Vincent T. Wood

detection of increasing convergence beneath a mesocyclone aloft ( Burgess 2004 ). The solutions roughly model tornadogenesis without a dynamic pipe effect ( Trapp and Davies-Jones 1997 ). In contrast, tornadoes that form with a dynamic pipe effect descend from aloft and develop more slowly, allowing the issuance of warnings with long lead times based on TVS detection. We perform experiments with different values of the constant eddy viscosity and the uniform convergence ( section 3 ) to obtain tornadoes

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Rachael N. Cross
,
David J. Bodine
,
Robert D. Palmer
,
Casey Griffin
,
Boonleng Cheong
,
Sebastian Torres
,
Caleb Fulton
,
Javier Lujan
, and
Takashi Maruyama

with leaves, one with wood boards, and one with metal sheets. Raindrops are randomly populated in the SimRadar domain at the onset of a simulation, while debris are initialized at the bottom of the domain. However, not all debris are lofted above 89 m AGL. To illustrate this, the debris count with height is plotted at the end of the tornadogenesis case ( Fig. 1 ). Regardless of debris type, only a fraction of debris are lofted to the lowest height of the radar beam. Specifically, only 19.74% of

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Daniel P. Betten
,
Michael I. Biggerstaff
, and
Louis J. Wicker

mesocyclogenesis . J. Atmos. Sci. , 56 , 2045 – 2069 , doi: 10.1175/1520-0469(1999)056<2045:ANSOCM>2.0.CO;2 . Biggerstaff , M. I. , and Coauthors , 2005 : The Shared Mobile Atmospheric Research and Teaching radar: A collaboration to enhance research and teaching . Bull. Amer. Meteor. Soc. , 86 , 1263 – 1274 , doi: 10.1175/BAMS-86-9-1263 . Brandes , E. A. , 1978 : Mesocyclone evolution and tornadogenesis: Some observations . Mon. Wea. Rev. , 106 , 995 – 1011 , doi: 10

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Matthew B. Wilson
and
Matthew S. Van Den Broeke

the progression of supercell and tornado life cycles. Palmer et al. (2011) observed a cyclic pattern of Z DR arc evolution in a violently tornadic supercell during the 10 May 2010 tornado outbreak in Oklahoma, with the Z DR arc extending back toward the hook echo leading up to tornadogenesis and weakening around tornado demise and occlusion, only to strengthen again as a new mesocyclone became established and produced another tornado. Kumjian et al. (2010) documented a similar pattern of

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Nathan A. Dahl
,
Alan Shapiro
,
Corey K. Potvin
,
Adam Theisen
,
Joshua G. Gebauer
,
Alexander D. Schenkman
, and
Ming Xue

-use tables. The simulation includes a period of cyclical tornadogenesis ( Fig. 1 ; see also Fig. 9d of Schenkman et al. 2014 ), which is selected for analysis here. Fig . 1. “True” horizontal winds (vectors) and vertical winds (color fill) at 3 km above radar level, valid at the analysis time, within the provisional domain for the ARPS simulation. Hatched regions denote areas where the radar reflectivity is less than 5 dB Z . Occluded and developing tornado locations are denoted by “T1” and “T2

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David C. Dowell
and
Alan Shapiro

variational concept. J. Climate Appl. Meteor. , 22 , 1227 – 1241 . 10.1175/1520-0450(1983)022<1227:TDWFAF>2.0.CO;2 Dowell, D. C. , and Bluestein H. B. , 1997 : The Arcadia, Oklahoma, storm of 17 May 1981: Analysis of a supercell during tornadogenesis. Mon. Wea. Rev. , 125 , 2562 – 2582 . 10.1175/1520-0493(1997)125<2562:TAOSOM>2.0.CO;2 Dowell, D. C. , and Bluestein H. B. , 2002 : The 8 June 1995 McLean, Texas storm. Part I: Observations of cyclic tornadogenesis. Mon. Wea. Rev. , 130

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Bradley Isom
,
Robert Palmer
,
Redmond Kelley
,
John Meier
,
David Bodine
,
Mark Yeary
,
Boon-Leng Cheong
,
Yan Zhang
,
Tian-You Yu
, and
Michael I. Biggerstaff

-temporal-resolution data, though the observed phenomena evolved on a relatively slow temporal scale. In future deployments, the AIR will focus on meteorological phenomena that evolve at faster temporal scales, such as tornadogenesis. During tornadogenesis, the low-level wind field may change in 15 s or less ( Bluestein et al. 1999 ). Bluestein et al. (2010) observed rapid changes in relative power and velocity associated with the formation of a cyclonic vortex signature. Because the AIR collects data over a 20

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Robert Davies-Jones
,
Vincent T. Wood
, and
Erik N. Rasmussen

velocity. In contrast to Δ V and azimuthal shear, Davies-Jones and Wood (2006) found that the circulation of a Doppler velocity signature Γ D provides a fairly good estimate of the actual value for the vortex, and is relatively insensitive to range, beamwidth, and stage of vortex evolution. Rapid contraction of a rotation signature with large circulation provides indication of imminent tornadogenesis to a weather forecaster ( Kuster et al. 2015 ). Circulation Γ ob is an important parameter for

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