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James E. Hocker and Jeffrey B. Basara

reports have been studied, less emphasis has been placed on the parent storm and mode responsible for producing the severe weather. Specific storm-mode climatologies are sparse and have been mainly confined to less numerous mesoscale systems, such as derechos and bow echoes ( Johns 1982 ; Bentley and Mote 1998 ; Burke and Schultz 2004 ; Coniglio and Stensrud 2004 ). Very few climatologies have focused on supercell thunderstorms, and in most cases, supercell studies are limited to the identification

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Matthew R. Kumjian and Alexander V. Ryzhkov

1. Introduction Because of the severity and high-impact nature of supercells, these storms have been intensely studied for several decades. Both the majority of significant tornadoes ( Doswell 2001 ) and about 90% of hail greater than 5 cm in diameter ( Thompson et al. 2003 ) are associated with supercell thunderstorms. Additionally, supercells can cause damaging winds and flooding rains ( Doswell 1994 ; Smith et al. 2001 ). Past observational studies of supercells have mainly emphasized storm

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Eric C. Bruning, W. David Rust, Donald R. MacGorman, Michael I. Biggerstaff, and Terry J. Schuur

1. Thunderstorm charge regions and storm structure This study is concerned with the ability to predict charge regions, associated lighting, and their evolution in time by examining several radar reflectivity cross sections through a supercell. More generally, it tests the expected relationship between precipitation formation and arrangement within the storm as indicated by radar reflectivity and the formation of local cellular maxima in total lightning activity. To facilitate the analysis, it

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Matthew L. Grzych, Bruce D. Lee, and Catherine A. Finley

1. Introduction The association between supercell thunderstorm rear-flank downdrafts (RFDs) and tornadoes has long been recognized ( Markowski 2002a ). More recent research has focused on direct measurements within the RFD by utilizing a mobile mesonet ( Straka et al. 1996 ). The analysis of Markowski et al. (2002 , hereafter MSR2002 ) and Markowski (2002b , hereafter M2002 ) revealed compelling evidence supporting the conclusion that tornado likelihood, intensity, and longevity were

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Matthew J. Bunkers, Jeffrey S. Johnson, Lee J. Czepyha, Jason M. Grzywacz, Brian A. Klimowski, and Mark R. Hjelmfelt

1. Introduction In Bunkers et al. (2006 , hereafter Part I ) it was shown that long-lived supercells (defined as supercells persisting for ≥4 h) are considerably more isolated 1 and discrete than short-lived supercells (defined as supercellswith a lifetime ≤2 h), and they also produce notably more F2–F5 tornadoes than do short-lived supercells. Several regional variations in the long-lived supercell properties were documented across the United States, most prominently between the north

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Matthew J. Bunkers, Mark R. Hjelmfelt, and Paul L. Smith

1. Introduction a. Importance of long-lived supercells Supercell thunderstorms, which were originally defined by Browning (1962 , 1964 ), represent the most organized, most severe, and longest-lived form of isolated, deep moist convection. Their updraft cores can be largely undiluted (i.e., conserved equivalent potential temperature from cloud base), with vertical velocities approaching 50 m s −1 in the strongest storms (e.g., Musil et al. 1986 ; see their Fig. 9). Exemplifying their

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Robert Davies-Jones

1. Introduction In meteorology, the laws governing mass, energy, momentum, angular momentum, and entropy, should be sacrosanct. In supercell simulations, invented forces should be tolerated only to the extent that they do not fundamentally alter the results. The latest supercell simulations with surface drag have such high resolution that they reproduce strong to violent tornadoes. These simulations seek to understand tornadogenesis. Use of a fictitious force that generates spurious horizontal

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Nolan T. Atkins, Eva M. Glidden, and Timothy M. Nicholson

1. Introduction The wall cloud is a lowering of cloud base associated with the updraft of a thunderstorm. The focus of this study concerns wall clouds formed within supercell thunderstorms ( Bluestein 1983 ; Davies-Jones 1986 ; Bluestein 1993 ). Early observational studies suggest that the supercell wall cloud is the visual indicator of a strong updraft core and may exhibit cyclonic rotation. ( Moller 1978 ; Bluestein 1984 ). Recent studies have also revealed the existence of anticyclonic

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Jason Naylor, Matthew S. Gilmore, Richard L. Thompson, Roger Edwards, and Robert B. Wilhelmson

1. Introduction Despite their relatively infrequent occurrence, supercells produce a large fraction of significantly severe convective events ( Doswell 2001 ). For this reason, it is important to be able to distinguish supercells from other modes of convection both observationally and in high-resolution forecast/research models—the latter being the focus of this paper. The formal American Meteorological Society (AMS) definition of a supercell is “an often dangerous convective storm that

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Howard B. Bluestein

attention has been given to how supercells dissipate; most studies have thus far addressed how they form and how they behave when they are mature (see Bluestein 2007 for a summary). In many instances, supercells are transformed into multicellular lines as the evaporatively cooled surface outflow air underneath them (their cold pools) forces new convection along arc-shaped boundaries, marking a gust front (e.g., Weisman and Klemp 1984 ). In other cases, lines of individual supercells merge when

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