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Aaron Johnson and Xuguang Wang

Johnson et al. (2015) , Johnson and Wang (2017) , Johnson et al. (2017) , and Wang and Wang (2017) . The ensemble mean analysis on the 1-km domain is used to initialize the deterministic forecasts evaluated in this study. The forecast model is version 3.8 of the WRF ARW. All forecasts use the WSM6 ( Hong and Lim 2006 ) microphysics scheme, Noah ( Ek et al. 2003 ) land surface model, and Dudhia (1993) shortwave and RRTM ( Mlawer et al. 1997 ) longwave radiation schemes. Forecasts that use a

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Aaron Johnson, Xuguang Wang, Kevin R. Haghi, and David B. Parsons

source of initial and lateral boundary condition perturbations. All members use Noah land surface scheme ( Ek et al. 2003 ) and RRTMG radiation ( Mlawer et al. 1997 ). In this study, assimilation of surface and upper-air observations from the operational National Centers for Environmental Prediction (NCEP) data stream on the 12-km domain is conducted every 3 h from 0300 UTC 10 July through 0000 UTC 11 July. NEXRAD observations, together with the North American Mesoscale Forecast System (NAM) model

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Stanley B. Trier, James W. Wilson, David A. Ahijevych, and Ryan A. Sobash

, 2002 ) PBL scheme, the Rapid Radiative Transfer Model for global climate models (RRTMG; Mlawer et al. 1997 ; Iacono et al. 2008 ) longwave and shortwave radiation schemes, and the Noah land surface model ( Chen and Dudhia 2001 ). Figure 8 compares vertical profiles of adjusted diagnosed from observations with corresponding area-averaged from the model ensemble. Since an important criterion used for triangle selection is the absence of significant precipitation within the triangle at the time

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Samuel K. Degelia, Xuguang Wang, and David J. Stensrud

al. 2007 ), although hail and wind are the most common threats ( Reif and Bluestein 2017 ). Past studies have shown that numerical weather prediction (NWP) models that employ convective parameterizations often underpredict nocturnal convective events in the High Plains of the United States ( Davis et al. 2006 ). Although various deficiencies have been resolved through the use of convection-resolving models ( Weisman et al. 2008 ), many of the mechanisms that initiate convection at night remain

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Samuel K. Degelia, Xuguang Wang, David J. Stensrud, and Aaron Johnson

both supercells and an MCS in WRF. The Lin scheme has also been shown to perform well for other convective modes (e.g., Nasrollahi et al. 2012 ). Additional sensitivity studies were conducted using various microphysical and PBL parameterization schemes; all schemes produced CI at similar locations and times. The Noah land surface model ( Ek et al. 2003 ), Rapid Radiative Transfer Model for general circulation models (longwave radiation; Iacono et al. 2008 ), Goddard shortwave radiation ( Tao et

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John M. Peters, Erik R. Nielsen, Matthew D. Parker, Stacey M. Hitchcock, and Russ S. Schumacher

IV (ST4) analyzed precipitation ( Fig. 8b ) in the CSUWRF and DSRAP simulations, and approximately 50–100 km northeastward of the stage IV precipitation in the DSNAM. Finally, we analyzed a 10-member ensemble of forecasts with similar configurations to the CSUWRF (e.g., 4-km horizontal grid spacing, Morrison two-moment microphysics, Noah land surface model, see Table 1 ), but with a different member of the Global Ensemble Forecast System (GEFS/R; Hamill et al. 2013 ) used as ICs and LBCs to

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David J. Bodine and Kristen L. Rasmussen

-dimensional community mesoscale model developed by the National Center for Atmospheric Research with many user-contributed physics parameterizations. The platform supports many options for microphysics, land surface, cumulus and shallow convection, planetary boundary layer, surface layer, and radiation parameterizations. The WRF Model has been used extensively to model weather and climate phenomena, thus these parameterizations have been reasonably well tested. For this study, the following parameterizations were

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Manda B. Chasteen, Steven E. Koch, and David B. Parsons

developed near the terminus of the LLJ and triggered both gravity waves and bores, which initiated subsequent convection. During the morning, this elevated convection evolved into a surface-based MCS. Trier et al. (2011) examined this case using a WRF-ARW simulation and found that mesoscale processes were important for conditioning the inflow environment of the MCS and that the system lacked a well-defined cold pool until midmorning, which suggests that it had been maintained via elevated convergence

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Matthew D. Parker, Brett S. Borchardt, Rachel L. Miller, and Conrad L. Ziegler

soundings are shown in Fig. 3 . The observed PECAN soundings were passed through a simple vertical smoother (the same procedure used by Parker 2014 ) to remove noise before plotting. Fig . 3. CAPE, CIN, and required lifting depth (Δ z LFC ) as a function of a parcel’s original level. CIN and Δ z LFC are only plotted for parcels with CAPE > 0 J kg −1 . All data from the 0300 UTC 26 Jun 2015 PECAN observation are plotted in blue. All data from the 0430 UTC 26 Jun 2015 PECAN observation are plotted in

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Dylan W. Reif and Howard B. Bluestein

−1 , then it takes just over 2.5 h to travel 100 km. The Rossby radius of deformation is used to identify objectively what may be considered “pristine” convection (convection that is not influenced by other neighboring convective storms). For this study, CI events that occurred within 100 km and within 3 h of the main event are counted as the same event. Fig . 1. The area of concern (outlined in the dashed gray box). The locations of NWS sounding stations used are denoted by the gray dots. Night

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