Tropical cyclone forecast verification at the National Hurricane Center

For all operationally-designated tropical or subtropical cyclones in the Atlantic and eastern North Pacific basins, the National Hurricane Center (NHC) issues an “official” forecast of the cyclone's center location and maximum 1-min surface wind speed. Forecasts are issued every 6 hours, and contain projections valid 12, 24, 36, 48, 72, 96, and 120 h after the forecast's nominal initial time (0000, 0600, 1200, or 1800 UTC). At the conclusion of the season, forecasts are evaluated by comparing the projected positions and intensities to the corresponding post-storm derived “best track” positions and intensities for each cyclone. Official forecasts of the radial extent of 34, 50, and 64 kt winds are also made, but these forecasts have traditionally not been verified due to the limited availability of ground truth data. In addition, the NHC has recently begun making and verifying probabilistic forecasts of tropical cyclone genesis.

An overview of the NHC forecast verification process will be presented, along with verification results dating back to 1970. Both the performance of the NHC official forecasts and the numerical model guidance will be presented. The value of a multi-model consensus for tropical cyclone track and intensity forecasting will be demonstrated, and the geographic variability of NHC forecast accuracy will also be described.