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Brian J. Carroll, Belay B. Demoz, David D. Turner, and Ruben Delgado

Rapid Refresh (RAP) The Rapid Refresh (RAP) analysis was evaluated against measurements for its ability to produce observed moisture distribution and transport features. RAP is an hourly updated data assimilation and modeling system run operationally at the National Centers for Environmental Prediction (NCEP). RAP is run at 13 km horizontal grid spacing over North America. RAP output is archived hourly. The operational version during PECAN, and used in this study, was RAPv2. A comprehensive

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Thomas R. Parish

operational 12-km horizontal resolution North American Mesoscale Forecast System (NAM). Here the focus is on summertime months of June and July for a 2-yr period 2008–09 to provide a composite gridded output set with which to compare the PECAN observations. To focus on the LLJ environment, model output was selected to include only those days for which a southerly LLJ was present. Bonner (1968) lists three criteria by which the intensity of the jet is categorized that have guided the selection process

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Joshua G. Gebauer, Alan Shapiro, Evgeni Fedorovich, and Petra Klein

, NWP models used by the PECAN forecasters, such as the North American Mesoscale Forecast System (NAM), Rapid Refresh (RAP), High-Resolution Rapid Refresh (HRRR), and Colorado State 4-km WRF, had strong signals for no-boundary CI on the corresponding nights. Although these models did struggle with predicting convection on 5 July, they nevertheless produced some signal of CI in the correct location. One particular numerical model that showed skill at forecasting these CI events was the RAP model

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

featured an outer domain with a 15-km grid spacing, an inner domain with a 3-km grid spacing ( Fig. 8a ), a one-way feedback from the outer domain to the inner domain, and was run from 0000 UTC 24 June to 1200 UTC 25 June 2015 with lateral boundaries updated every hour. The third WRF simulation was configured with the North American Mesoscale Forecast System (NAM) analysis at 0000 UTC 24 June 2015 as ICs, and the subsequent 6-hourly NAM analyses as LBCs [this simulation is hereafter referred to as the

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Tammy M. Weckwerth and Ulrike Romatschke

precipitation. This paper uses radar-derived quantitative precipitation estimates (QPEs) to illustrate where and when the precipitation during PECAN occurred and uses North American Regional Reanalysis (NARR) composites to assess why the PECAN precipitation patterns and timing occurred. It has been known for more than a century that the diurnal pattern of summertime precipitation in the U.S. Great Plains has a strong nocturnal maximum (e.g., Kincer 1916 ; Bleeker and Andre 1951 ; Wallace 1975

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

denied from the assimilation on both the outer and inner domain. Table 4. List of experiments. The cycling description that follows describes the ALL experiment. On the outer domain, conventional data are assimilated at 3-h intervals from 0000 to 2100 UTC 25 June. While the assimilation interval is 3 h, only observations from a 1-h time window (±30 min centered on the analysis time) are assimilated on the outer domain. The conventional data are provided by the North American Mesoscale Forecast

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

. Rev. , 141 , 3735 – 3756 , https://doi.org/10.1175/MWR-D-12-00343.1 . 10.1175/MWR-D-12-00343.1 Adams-Selin , R. D. , S. C. van den Heever , and R. H. Johnson , 2013 : Impact of graupel parameterization schemes on idealized bow echo simulations . Mon. Wea. Rev. , 141 , 1241 – 1262 , https://doi.org/10.1175/MWR-D-12-00064.1 . 10.1175/MWR-D-12-00064.1 Benjamin , S. G. , and Coauthors , 2016 : A North American hourly assimilation and model forecast cycle: The Rapid Refresh . Mon

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J. W. Wilson, S. B. Trier, D. W. Reif, R. D. Roberts, and T. M. Weckwerth

Research Program. The National Center for Atmospheric Research is sponsored by the National Science Foundation. The third author was supported by Grant AGS-1560945. REFERENCES Bellamy , J. C. , 1949 : Objective calculations of divergence, vertical velocity and vorticity . Bull. Amer. Meteor. Soc. , 30 , 45 – 49 . 10.1175/1520-0477-30.2.45 Benjamin , S. G. , and Coauthors , 2016 : A North American hourly assimilation and model forecast cycle: The Rapid Refresh . Mon. Wea. Rev. , 144 , 1669

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Dana Mueller, Bart Geerts, Zhien Wang, Min Deng, and Coltin Grasmick

Interferometer (AERI), and a surface weather station. We also use reflectivity and radial velocity data from the KLNX (North Platte, Nebraska), KOAX (Omaha, Nebraska), and KUEX (Hastings, Nebraska) WSR-88Ds, as well as some operational surface and upper-air data. Fig . 1. Google Earth terrain map of eastern Nebraska. The 20 Jun 2015 UWKA flight track is shown in black, and WSR-88Ds in green. Area 1 represents legs 1–12 and area 2 represents legs 13–18. 4. UKWA-observed structure and evolution a. Cold pool

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David J. Bodine and Kristen L. Rasmussen

1. Introduction Mesoscale convective systems (MCSs; Houze 2004 ) are a substantial contributor to precipitation and severe weather hazards in the United States and globally. In the Great Plains region, MCSs contribute 30%–70% of warm season precipitation with the highest contribution during the summer months ( Fritsch et al. 1986 ). In other regions (e.g., South America), MCSs are also very large contributors to warm season precipitation ( Rasmussen et al. 2016 ). In addition to contributing

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