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Zhixiao Zhang, Adam Varble, Zhe Feng, Joseph Hardin, and Edward Zipser

errors in their representation within models. Relatively coarse resolution climate models largely fail to capture precipitation associated with MCSs because cumulus parameterization schemes do not consider mesoscale processes within MCSs (e.g., Bukovsky and Karoly 2009 ; Kooperman et al. 2015 ; Lin et al. 2017 ; Feng et al. 2019 ). Regional convection permitting models (CPMs; grid spacing < 4 km) like the High Resolution Rapid Refresh (HRRR; Benjamin et al. 2016 ) can better predict MCS cloud

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Jeremiah O. Piersante, Russ. S. Schumacher, and Kristen L. Rasmussen

upscale toward the east ( Rasmussen and Houze 2011 , 2016 ; Rasmussen et al. 2014 ). This “back-building” phenomenon leads to persistent convection and is unique to subtropical South America ( Rasmussen et al. 2014 ). Previous studies describe the relative depth and role of the SALLJ in convective initiation and contribution to regional rainfall ( Marengo et al. 2002 , 2004 ; Salio et al. 2002 , 2007 ; Nascimento et al. 2016 ), but use LLJ identification criteria originally designed for North

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Jeremiah O. Piersante, Kristen L. Rasmussen, Russ S. Schumacher, Angela K. Rowe, and Lynn A. McMurdie

-season rainfall in SSA ( Nesbitt et al. 2006 ; Rasmussen et al. 2016 ). MCSs are also responsible for the regional maximum in high impact weather such as significant hail (≥2.5-cm diameter), flooding, damaging straight-line winds, and tornadoes that are detrimental to society and the economy of the La Plata basin where agriculture thrives ( Rasmussen and Houze 2011 ; Matsudo and Salio 2011 ; Cecil and Blankenship 2012 ; Rasmussen et al. 2014 ; Bruick et al. 2019 ). A typical pattern for the initiation of

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Russ S. Schumacher, Deanna A. Hence, Stephen W. Nesbitt, Robert J. Trapp, Karen A. Kosiba, Joshua Wurman, Paola Salio, Martin Rugna, Adam C. Varble, and Nathan R. Kelly

subtropical South America is the South American low-level jet (e.g., Vera et al. 2006 ; Salio et al. 2007 ; Montini et al. 2019 ). During RELAMPAGO, a sounding site at Villa de María del Río Seco (hereinafter Villa de María), located approximately 175 km north of Córdoba ( Fig. 1a ), collected daily soundings at 0900 UTC, along with other times during IOPs, to monitor the SALLJ and its potential effects on convection. The objective criteria for identifying low-level jets first introduced by Bonner

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Adam C. Varble, Stephen W. Nesbitt, Paola Salio, Joseph C. Hardin, Nitin Bharadwaj, Paloma Borque, Paul J. DeMott, Zhe Feng, Thomas C. J. Hill, James N. Marquis, Alyssa Matthews, Fan Mei, Rusen Öktem, Vagner Castro, Lexie Goldberger, Alexis Hunzinger, Kevin R. Barry, Sonia M. Kreidenweis, Greg M. McFarquhar, Lynn A. McMurdie, Mikhail Pekour, Heath Powers, David M. Romps, Celeste Saulo, Beat Schmid, Jason M. Tomlinson, Susan C. van den Heever, Alla Zelenyuk, Zhixiao Zhang, and Edward J. Zipser

used global numerical weather prediction and regional convection-allowing model guidance that was run every 6–12 h by SMN, the University of Illinois, and Colorado State University (CSU). When deep convection was forecasted, AMF1 radiosonde launch frequency was increased from 4- to 3-hourly between 0900 and 2100 LT. Additional sondes were also occasionally launched from the Villa Dolores site. In addition, Geostationary Operational Environmental Satellite-16 ( GOES-16 ) mesoscale domain sectors

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Sujan Pal, Francina Dominguez, María Eugenia Dillon, Javier Alvarez, Carlos Marcelo Garcia, Stephen W. Nesbitt, and David Gochis

environments; 2) characterize thermodynamic and microphysical properties of clouds and precipitation, convective outflow, lightning, and hail events; and 3) observe hydrometeorological interactions with convective systems ( Nesbitt 2016 ). The occurrence of convective events in this region is linked to the strengthening of topographically guided South American low-level jet (SALLJ), which brings moist air poleward, and strong convection is formed at the exit region controlled primarily by diabatic effects

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Hernán Bechis, Paola Salio, and Juan José Ruiz

regions of the world ( Schaefer 1986 ) like India ( Weston 1972 ; Akter and Tsuboki 2017 ), eastern China ( Golden 1980 ; Qin and Chen 2017 ), central West Africa ( Hamilton et al. 1945 ), Australia ( Arnup and Reeder 2007 ), and Canada ( Taylor et al. 2011 ). In each of these regions, drylines have their own characteristics and development mechanisms, which are strongly linked to local orography and regional synoptic climatology. Dryline climatologies (i.e., the study of their frequency, spatial

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Stephen W. Nesbitt, Paola V. Salio, Eldo Ávila, Phillip Bitzer, Lawrence Carey, V. Chandrasekar, Wiebke Deierling, Francina Dominguez, Maria Eugenia Dillon, C. Marcelo Garcia, David Gochis, Steven Goodman, Deanna A. Hence, Karen A. Kosiba, Matthew R. Kumjian, Timothy Lang, Lorena Medina Luna, James Marquis, Robert Marshall, Lynn A. McMurdie, Ernani de Lima Nascimento, Kristen L. Rasmussen, Rita Roberts, Angela K. Rowe, Juan José Ruiz, Eliah F.M.T. São Sabbas, A. Celeste Saulo, Russ S. Schumacher, Yanina Garcia Skabar, Luiz Augusto Toledo Machado, Robert J. Trapp, Adam C. Varble, James Wilson, Joshua Wurman, Edward J. Zipser, Ivan Arias, Hernán Bechis, and Maxwell A. Grover

The United States is infamous for its hazardous convective storms that produce high-impact weather (HIW), including tornadoes, hail, strong winds, lightning, heavy precipitation, and flooding, and cause significant loss of life and property. The hazardous storms are also important components of the regional climate over much of the eastern two-thirds of the United States. Past field campaigns, observational studies, and model experiments have produced knowledge that is the foundation of current

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Robert J. Trapp, Karen A. Kosiba, James N. Marquis, Matthew R. Kumjian, Stephen W. Nesbitt, Joshua Wurman, Paola Salio, Maxwell A. Grover, Paul Robinson, and Deanna A. Hence

-time, 48-h CAM forecasts were generated by three participating institutions, using regional configurations of the Weather Research and Forecasting (WRF) Model (e.g., Skamarock et al. 2008 ). Additionally, a 96-h forecast was generated using the Model for Prediction Across Scales (MPAS) ( Skamarock et al. 2012 ), in a 15–3 km configuration, such that the computational mesh for the entirety of the South American continent had 3-km gridpoint spacing. It is noteworthy that the simulated reflectivity

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James N. Marquis, Adam C. Varble, Paul Robinson, T. Connor Nelson, and Katja Friedrich

1. Introduction Correctly representing moist convective processes is critical to accurately predicting regional and global weather and climate, and accompanying operational forecasting of near- and long-term hydrology and severe weather. Numerical simulations rely on a mix of cumulus, turbulence, microphysics, and planetary boundary layer parameterization schemes to represent the generation of shallow and deep moist updrafts and precipitation (e.g., Tiedtke 1989 ; Kain and Fritsch 1990

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