WRF-Model Performance for Wind Power Forecasting in the Coast Ranges of Central California

This study describes the verification of modeled low-level atmospheric conditions in the complex terrain surrounding the Altamont Pass wind farm near Livermore, California, USA. The Weather Research and Forecasting model (WRF) was used to (1) simulate the Coast Range near-surface winds, and (2) simulate low-level flow and available wind power in the Altamont Pass. Standard statistical verifications were performed against low-level wind speed observations at seventeen sites. Available wind power was calculated using equivalent wind speed and was evaluated for six areas within Altamont Pass. The overall results include good model performance for the regional near-surface winds, acceptable to good model performance for the Altamont Pass low-level winds, and good model performance for Altamont Pass capacity factor simulations. More specifically, while modeled hour-to-hour variance was not exact, WRF-modeled wind speeds were close to those observed. Combined with agreement between both modeled and observed wind direction and atmospheric stability, WRF modeled capacity factors were within the range of observed capacity factors in 93 % of the instances. Therefore, WRF modeled winds and derived wind power can be used as a wind power forecasting tool for Altamont Pass and possibly other coastal complex terrain regions.