Evaluation of high resolution model QPF performance in the complex terrain of the Great Basin as part of the DTC Winter Forecast Experiment

The National Weather Service (NWS) Weather Forecast Office (WFO) in Salt Lake City, Utah, participated in the Developmental Testbed Center Winter Forecasting Experiment (DWFE), held during the 2005 winter season. This experiment involved running two configurations of the Weather Research and Forecasting (WRF) model at 5-km resolution out to 48 hours and over large (CONUS) domains. To evaluate high-resolution model performance in complex terrain of the Great Basin, WRF model output from the NCAR ARW and FSL NMM 5-km versions were viewed at the Salt Lake City WFO using the FX-Net display software. WRF performance was evaluated in an operational WFO setting, with emphasis on evaluating model precipitation patterns and intensities in areas of complex terrain. WRF output was also compared to Eta/NAM and GFS data during real-time and post-mortem settings.

Overall, the WRF models examined proved to be useful as forecasting tools in the complex terrain of Utah. Model strengths recognized during this evaluation included the depiction of orographic precipitation, lake-effect snowfall, and the ability to capture heavy snow bands along the Wasatch Front. However, weaknesses that were observed include the tendency to over follow the boundary conditions of the Eta, and to over forecast moist convection. This study examines WRF model performance in two Wasatch Front banded snow events that occurred on 7 and 15 February 2005, and a lake effect snow storm of the Great Salt Lake on 30 March 2005.