Search Results

You are looking at 1 - 9 of 9 items for :

  • RELAMPAGO-CACTI: High Impact Weather in Subtropical South America x
  • Refine by Access: All Content x
Clear All
Jake P. Mulholland, Stephen W. Nesbitt, Robert J. Trapp, and John M. Peters

semislip with the surface exchange coefficient for momentum ( C D ) based on Fairall et al. (2003) at low-to-mid wind speeds, and Donelan et al. (2004) at higher wind speeds (the default option in CM1), while the (constant) surface exchange coefficient for enthalpy ( C E ) was based on the specified land-use index. The top boundary condition was rigid and free slip. A Rayleigh damping layer (coefficient = 3.33 × 10 −3 s −1 ) was applied above 15 km to minimize the artifacts of the rigid top

Restricted access
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

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

the U.S. operational National Weather Service radiosonde network (horizontal spacing ~300 km). Studies using data from these and other sources have illustrated significant environmental variability surrounding focal areas of CI owing to: intersections between air masses (e.g., Wilson and Mueller 1993 ; Kingsmill 1995 ; Ziegler and Rasmussen 1998 ; Markowski et al. 2006 ; Arnott et al. 2006 ; Buban et al. 2007 ; Wakimoto and Murphey 2009 ), complex terrain (e.g., Banta and Schaaf 1987

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

develop broad stratiform regions beyond the mature phase ( Romatschke and Houze 2010 ; Rasmussen and Houze 2011 , 2016 ; Rasmussen et al. 2016 ). This convection life cycle was examined for a case in SSA using available satellite observations and a WRF model simulation that confirmed this life cycle evolution ( Rasmussen and Houze 2016 ), which aligns well with that of other global convective hotspots featuring frequent upscale growth into MCSs over both land and ocean regions ( Houze 2004

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

, and land use). Flash flood prediction at a subdaily scale remains a challenge in poorly gauged and remote basins, especially in mountainous regions ( Reed et al. 2007 ; Norbiato et al. 2008 ; Band et al. 2012 ; Tao and Barros 2013 ). The headwaters of the Carcarañá River are prone to flash flooding events. The most devastating recorded flood event occurred in March of 1919, as several towns were flooded causing economic losses in farmlands, and damages in civil infrastructure such as bridges

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

between ENSO phases. The TRMM PR rainfall algorithm is known to underestimate precipitation produced by deep convection over land ( Iguchi et al. 2009 ; Rasmussen et al. 2013 ). Therefore, rainfall was instead estimated with the Z – R relationship used by Rasmussen et al. (2013) , Z = aR b , where Z is the radar reflectivity factor (mm 6 m −3 ) and R is the corrected rain rate (mm h −1 ). The parameters a and b are constants based on rain type. The values used to calculate rainfall in

Full access
Hernán Bechis, Paola Salio, and Juan José Ruiz

distribution, relation to diurnal and seasonal cycles, and associated synoptic conditions) have also been studied over different regions using different datasets and detection criteria. Usually, a conservative moisture variable is utilized to identify the dryline—either specific humidity or mixing ratio—although some works use near-surface dewpoint temperature. In addition, conditions over the temperature field are often included to eliminate surface fronts, and on occasions, a wind shift across the

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

( Morrison 2017 ); thus, initial updraft width could be one factor governing CI. Numerical representation of updraft size and vertical mass flux is sensitive to the model grid resolution (e.g., Bryan et al. 2003 ; Varble et al. 2014 ; Varble et al. 2020 ; Hirt et al. 2020 ), as well as other physical parameterizations, limiting what can be ascertained about updraft-environment interactions using convection-allowing mesoscale models. A more complete understanding of CI requires synchronized

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

-to-bowing MCS transition has been documented before in the USA by Moller et al. (1990) , Conway et al. (1996) , Finley et al. (2001) , Klimowski et al. (2004) , among others, although not explicitly orographic supercell-to-bowing MCS transitions. Finley et al. (2001) used a numerical modeling approach to analyze a supercell-to-bowing MCS transition, determining that just prior to UCG, the low-level cold pool deepened and intensified, which resulted in a strong low-level horizontal pressure gradient

Free access