P60  Evaluation of the WRF model for Frost and Freeze Prediction in Eastern Washington

Ghidey, Tesfamichael, Nicholas Loyd, Gerrit Hoogenboom, AgWeatherNet, Washington State University and Heping Liu, Washington State University

In the eastern Washington tree fruit agricultural area, availability of weather forecasts to predict for damaging spring and fall frost conditions is important in decision making. To address this need, the state-of-the-art next generation mesoscale meteorological model known as the Advanced Research Weather Research and Forecasting (WRF-ARWv3.3.1) was implemented to verify its performance over the state of Washington. A combination of two large scale initial conditions and seven combinations of physics schemes in three nested domain resolutions were used to evaluate the performance of the model for frost and freeze prediction in eastern Washington. WRF was configured with three nested domains of 27, 9 and 3 km horizontal resolutions with the third nested domain covering only the state of Washington. Vertically, 40 sigma levels were used that extended to 50 mb into the free atmosphere as the model top. In this investigation, four freeze weather events were selected, representing spring and fall frost as well as winter arctic outbreak conditions critical for tree fruit industry. Preliminary results showed that the model predicted well over the Columbia basin flat region when it forecasted two days ahead of the freeze day, with the two physics options analyzed showing minimal different in performance.