Performance of the WRF-ARW in the Complex Terrain of Salt Lake City

The Army Research Laboratory has an interest in high spatial and temporal resolution weather products with an emphasis on the boundary layer in complex terrain. In order to study and investigate small-scale weather processes, the advanced research Weather Research and Forecasting model (WRF-ARW) was run over a variety of locations. One of the more intriguing model areas of study was over the Salt Lake City area where a nested version of the model was run for a 24-h period mainly during the cold season. Approximately 40 model runs were completed and results of the temperature, dew point, wind speed, and wind direction were examined over the forecast period. One of the main objectives of these 2-km model runs was to study the interaction of the Lake Breeze, valley breeze, and downslope winds off the local terrain. Results show that the WRF-ARW had a bias to overforecast the downslope winds from the east as well as the valley winds but underforecast the lake breeze. The most accurate wind speeds were noted at 1200 UTC, but the model underforecasted wind speeds during the afternoon hours. This paper will investigate possible causes for these errors and how they are related in the Salt Lake area.