Convective Simulations Using A WRF Microphysics Ensemble

Severe local storms and their associated risks of heavy rain, damaging winds, hail and tornadoes cause billions of dollars in property damage each year along with injury and loss of life. Accurately representing these extreme convective events through numerical weather prediction is important in helping society prepare for these extreme events. Recent advancements in computing power have led to widespread use in convection permitting models and ensemble practices, which are run at a grid scale (Δx < 4 km) able to explicitly resolve such local storms. Previous studies suggest that the simulated convective properties of convection-permitting simulations for case studies are dramatically affected by the microphysics scheme. However, these microphysics studies have largely been limited to studies with a limited number of cases/events and the performance of various configurations of Weather Research and Forecasting (WRF) are not understood for longer periods such as seasons or years. This study performs detailed evaluations of a 9-member microphysics WRF ensemble for a data-set containing numerous convective cases from 2010-2013. Convective events are analyzed over multiple seasons rather than just a test case, setting it apart from other studies. The objectives analyze several smaller regions of interest from the continental United States: The Southern and Northern Great Plains, the Gulf Coast, the Midwest, and the Northeast. A nested methodology for the domain is utilized, consisting of two-domains with the inner nest (4 km grid spacing) centered over the regions of interest. To analyze the results, simulated reflectivity and satellite products; such as, cloud fraction and cloud top temperatures are assessed against NSSL Q2/3 products and NOAA Geostationary Operational Environmental Satellite (GOES) observations.