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Katherine L. Horgan, David M. Schultz, John E. Hales Jr., Stephen F. Corfidi, and Robert H. Johns

by Rochette and Moore (1996) , Rochette et al. (1999) , and Moore et al. (1998 , 2003 ) focused on elevated convective storms that produce heavy rainfall, finding they were associated with elevated instability. Sometimes elevated convection produces severe weather in the form of large hail, strong winds, and/or tornadoes (e.g., Branick et al. 1988 ; Colman 1990b ; Schmidt and Cotton 1989 ; Bernardet and Cotton 1998 ; Banacos and Schultz 2005 ). Grant (1995) examined 11 cases of

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Harold E. Brooks, Charles A. Doswell III, Xiaoling Zhang, A. M. Alexander Chernokulsky, Eigo Tochimoto, Barry Hanstrum, Ernani de Lima Nascimento, David M. L. Sills, Bogdan Antonescu, and Brad Barrett

1. Introduction There are many variations in the definition of what constitutes a severe convective storm. From a physical perspective, a convective storm is one driven by buoyancy. Buoyancy is determined by differences in air density leading to a vertical pressure gradient that is unbalanced by gravity, leading in turn to the development of vertical acceleration ( Doswell and Markowski 2004 ). Note that buoyancy can be either negative or positive, so the vertical acceleration due to buoyancy

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Lawrence D. Carey and Kurt M. Buffalo

1. Introduction Although the overwhelming majority (i.e., about 90%) of ground flashes lower net negative charge across the contiguous United States (CONUS; Orville and Huffines 2001 ), a few severe storms can generate positive cloud-to-ground (+CG) flash rates, densities, and percentages comparable to those typically observed for negative cloud-to-ground (−CG) flashes in active thunderstorms (e.g., MacGorman and Burgess 1994 ; Stolzenburg 1994 ; Carey and Rutledge 1998 ; Lang and Rutledge

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Thea N. Sandmæl, Cameron R. Homeyer, Kristopher M. Bedka, Jason M. Apke, John R. Mecikalski, and Konstantin Khlopenkov

1. Introduction Severe and tornadic storms have been extensively studied using ground-based weather radar and satellite observations during the past four decades. A common goal of past research efforts has been enabling improvements in tornado prediction, which can save lives. Substantial efforts are almost always underway to improve tornado warnings, including ongoing projects like Warn-on-Forecast and the Probability of Severe (ProbSevere) model ( Stensrud et al. 2009 ; Cintineo et al. 2018

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Steven V. Vasiloff and Kenneth W. Howard

1. Introduction During the past 10 yr, the frequency of damaging winds from downbursts occurring in the Phoenix, Arizona, metropolitan area and surrounding suburbs has markedly increased, presumably due to population growth and better reporting ( SPC 2007 ). Within the southwestern U.S. Sonoran Desert, downbursts from severe storms frequently produce strong outflows that entrain dust and reduce visibility to dangerous levels, particularly hazardous to traffic along the Interstate Highway System

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Richard Dworak, Kristopher Bedka, Jason Brunner, and Wayne Feltz

) improve forecaster understanding of OT detection output relative to commonly available radar products, 2) assess OT detection product accuracy, and 3) demonstrate the utility of an OT detection product for diagnosing hazardous convective storms over the continental United States. The volume of data used in this study far exceeds that from previous work, which had primarily relied on a limited sample size of case studies, or in the case of Bedka (2011) , a relatively small severe weather event

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Kelly A. Lombardo and Brian A. Colle

1. Introduction The investigation of severe convective weather over the northeastern United States (hereafter referred to as Northeast) has received less attention than that in the central United States. This is likely because of the fewer number of severe weather events over the Northeast as compared to the central Great Plains and Midwest ( Brooks et al. 2003 ; Doswell et al. 2005 ). The Northeast can experience severe warm season (May–August) storms, which can pose a large threat to life

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Fabian Senf, Felix Dietzsch, Anja Hünerbein, and Hartwig Deneke

used the time of the first lightning stroke and maximum volume of reflectivity values above 35 dB Z for synchronization of storm tracks for lightning-producing and nonlightning storms, respectively. Satellite-observed anvil expansion rates provide, in addition to cloud-top cooling rates, information about cloud growth processes. They have been related to further development of convective systems and severe-weather phenomena ( Adler and Fenn 1979a ; McAnelly and Cotton 1989 ; Machado et al. 1998

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Robert H. Johns and Charles A. Doswell III

588 WEATHER AND FORECASTING VOLUME7Severe Local Storms Forecastlng* ROBERT H. JOHNSNational Severe Storms Forecast Center, Kansas City, Missouri CHARLES A. DOSWELL IllNational Severe Storms Laboratory, Norman, Oklahoma(Manuscript received l 1 May 1992, in final form 13 August 1992)ABSTRACT Knowledge of severe local storms has been increasing rapidly in recent years

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Howard B. Bluestein and Jeffrey C. Snyder

1. Introduction Forecasting severe local storms and especially the type, location, and time of severe weather events associated with them is still a challenge, despite many years of progress in numerical weather prediction and in detection technology (e.g., Lilly 1990 ; Johns and Doswell 1992 ; Droegemeier 1997 ; Trapp et al. 2005 ; Weisman et al. 2008 ; Clark et al. 2010 ; Coniglio et al. 2010 ; Kain et al. 2013 ). Major challenges include defining the large-scale forcing and

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