Exploring the Sensitivity of Convective Storm Characteristics, Dynamics, and Evolution to Grid Spacing in Convection-allowing NAM Simulations

In support of the Next Generation Global Prediction System (NGGPS) project, two severe weather cases (28 April 2014 and 6 May 2015) are simulated using the NAM 1.33-km fire-weather nest and 4-km CONUS nest, each producing 5-min output.  On 28 April 2014, convection along and ahead of a cold front traversing Mississippi was responsible for over 450 severe weather reports (153 of which were tornado reports). On 6 May 2015, convection initiated by a dryline resulted in nearly 200 severe weather reports (65 of which were tornado reports) in the central Great Plains region. Comparisons are made between the simulations and observations to explore how convection evolves differently on the two model grids.  The analysis focuses on the models’ representations of both the environment and storm attributes, such as the cold pools of the storms, storm motion, and mesocyclones.