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T. Connor Nelson, James Marquis, Adam Varble, and Katja Friedrich

environments supporting it with adequate spatial and temporal resolution, as well as an incomplete understanding of environment–cloud interactions supporting growing congestus (e.g., Crook 1996 ; Weckwerth and Parsons 2006 ; Houston and Niyogi 2007 ; Lock and Houston 2014 ; Rousseau-Rizzi et al. 2017 ; Weckwerth et al. 2019 ). For CI to occur, the atmosphere requires three fundamental ingredients: static instability, moisture, and a triggering mechanism (e.g., surface airmass boundaries, orographic

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

feedbacks, and cold pool interactions ( Stensrud and Fritsch 1993 ; Stensrud 1996 ; Laing and Fritsch 2000 ; Coniglio et al. 2010 ; Trier et al. 2011 ; Peters and Schumacher 2015 ; Yang et al. 2017 ; Chasteen et al. 2019 ). Likewise, Rasmussen and Houze (2016) suggest that long MCS lifetimes in SSA are regulated by the slow-moving nature of midlevel troughs approaching the Andes from the west; however, their investigation was limited to the austral summer despite a comparable severe weather and

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

months were included to highlight how precipitation forecast skill is lowest during the warm season; the change in error with season is discussed throughout the paper. All members were run via the Advanced Research version of the Weather and Forecasting (WRF) Model ( Skamarock et al. 2008 ) version 3.7.1 with RRTMG radiation ( Iacono et al. 2008 ), Noah land surface ( Tewari et al. 2004 ), 43 vertical levels, a 90-s time step, and GFS initial/lateral boundary conditions (except for one that uses GEFS

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Hernán Bechis, Paola Salio, and Juan José Ruiz

. Bechtold , T. Mauritsen , and G. Balsamo , 2013 : Why is it so difficult to represent stably stratified conditions in numerical weather prediction (NWP) models? J. Adv. Model. Earth Syst. , 5 , 117 – 133 , . 10.1002/jame.20013 Saulo , C. , L. Ferreira , J. Nogués-Paegle , M. Seluchi , and J. Ruiz , 2010 : Land–atmosphere interactions during a northwestern Argentina low event . Mon. Wea. Rev. , 138 , 2481 – 2498 ,

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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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Zachary S. Bruick, Kristen L. Rasmussen, Angela K. Rowe, and Lynn A. McMurdie

during La Niña ( Allen et al. 2015 ). In Southeast Asia, El Niño causes higher surface pressure over the ocean, leading to onshore flow and increased precipitation over land ( Yoshida et al. 2007 ). During El Niño farther south, colder ocean waters surrounding Indonesia suppress convection, which leads to enhanced drought conditions during summer ( Hendon 2003 ). Recent research has examined how ENSO affects rainfall in tropical regions of South America, such as the Amazon rain forest in northern

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Jake P. Mulholland, Stephen W. Nesbitt, and Robert J. Trapp

, regardless of external influences, such as fronts or LLJs (also see Peters and Schumacher 2016 ). Low-level lifting associated with the interaction between ambient low-level vertical wind shear and convective cold pools has been invoked as one idea for long-lived squall lines ( Rotunno et al. 1988 ), although other authors have stressed the importance of upper-level vertical wind shear on squall-line intensity (e.g., Coniglio et al. 2006 ). The leading edge of cold pools (hereafter “gust fronts” or

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