Forecasting wave height probabilities with numerical weather prediction models

Operational weather forecasts now allow two week probabilistic forecasts of wave height. This paper discusses methods for generating such forecasts from numerical model output from the European Centre for Medium Range Weather Forecasting Ensemble Prediction System. The ECMWF system produces Monte Carlo style forecasts of wave statistics out to a lead time of 10 days. This ensemble of forecasts is designed to reflect uncertainty in current global weather conditions. In this paper a method for post-processing the ensemble forecasts of wave statistics is described and demonstrated using the significant wave height forecasts for four locations of interest to the offshore industry. The post-processing results in ensemble forecasts which have improved reliability, and which are better predictors of the expected error in the forecast.