Verification of NDFD gridded forecasts over complex terrain

This paper will describe some of the major issues in verification of gridded forecasts over the mountainous terrain of the western United States. These issues include: verification at grid points vs. observation locations; sensitivity to synoptic condition and climatic regime; and sensitivity to the quality of the verifying analysis. Objective analysis grids derived by the ARPS Data Assimilation System (ADAS) will be used to verify experimental forecast grids issued by National Weather Service forecasters using the Interactive Forecast Preparation System (IFPS). The ADAS grids of surface temperature, wind, and relative humidity used in this study reflect an adjustment of the Rapid Update Cycle gridded fields by approximately 2500 local observations provided by MesoWest (www.met.utah.edu/mesowest).