Statistical verification of Numerical Weather Prediction (NWP) for rainfall estimation in the East Coast Region

Abstract

Intense hydrological event such as floods are increasing lately especially in Peninsular Malaysia. Therefore, it is important to forecast the intense rainfall as part of flood preparedness and mitigation measures. In this study, Numerical Weather Prediction (NWP) model precipitation outputs using Weather Research and Forecasting (WRF) with horizontal resolution of 3 km have been validated against observed rainfall data measurements for its performance measurement. Forecasted rainfall event data of three (3) states in the East Coast Region; Kelantan, Terengganu and Pahang were evaluated and compared with the observed rainfall data before statistically verifying their accuracy using False Alarm Ratio (FAR) and Probability of Detection (POD). The results indicate a very promising potential of the models in producing quantitative precipitation forecast (QPF) for flood forecasting purpose in Kelantan, Terengganu and Pahang. Since these three states, which are located in the East Coast region of Peninsular Malaysia experienced annual flood event, accurate forecast rainfall data can be used to improve forecast information for flood indicator.