Quantifying tropical cyclone track forecast uncertainty using an ensemble of dynamical models

Tropical cyclone (TC) track forecasts from regional and global numerical weather prediction models have become increasingly more important in recent years as guidance to TC forecasters at both the National Hurricane Center (NHC) and the Joint Typhoon Warning Center. Forecasters at NHC routinely utilize the TC track forecasts from the GFDL model, the Navy Operational Global Atmospheric Prediction System, and the UK Meteorological Office global model. The TC track forecast performance out to five days for these models, the European Centre for Medium-Range Weather Forecasts global model, and various ensembles derived utilizing these models is evaluated for the 1995-99 Atlantic hurricane seasons. In particular, the uncertainty in the TC track forecasts, as measured by the standard deviation and 95th percentile of forecast position error, is determined for the individual models and for their various ensembles. The relationships between forecast uncertainty and ensemble spread and composition are explored so that forecasters might assign a priori some level of confidence to their TC track forecasts based on the available guidance.