Evaluation of Real-Time Finescale UAS Forecast Guidance on Winds and Turbulence Obtained Using WRF LES over a Sub-Alpine Desert Valley

A nested version of WRF model was run down to 100 m grid spacing (LES-mode) in realtime to support UAS mission planning during the International Society for Atmospheric Research using Remotely-piloted Aircraft (ISARRA) Lower Atmospheric Process Studies at Elevation - a Remotely-piloted Aircraft Team Experiment (LAPSE-RATE) which took place in the San Luis Valley of Colorado on 14-20 July 2018. This period was characterized by strong diurnal cycle of mountain initiated convection during the day and shallow drainage flows at night under the large-scale flow regime known as the North American Monsoon. The simulations were initialized and driven at lateral boundaries using the NCEP High Resolution Rapid Refresh. This study focuses on evaluating model performance with respect to simulating finescale variations in the evolution of nocturnal boundary layer flows and their transition to up-valley flows using data collected by multiple observing systems stationed throughout the valley including ASOS station data, flux towers, two Doppler lidars, NSSL soundings, University of Nebraska-Lincoln mobile mesonet and a number of Unmanned Aerial Systems (UAS). Analyses generated using EnKF to assimilate UAS data are used to develop a gridded truth field that is, in turn, used to evaluate the realtime forecasts.