An Analysis of Atlantic Tropical Cyclone Forecast Errors, 1970–1979

Abstract Official Atlantic tropical cyclone track forecasts issued by the National Hurricane Center over the decade of the 1970's are examined in this study. The purpose is to isolate any significant biases, trends or other statistical properties of the forecast errors. In this analysis, we consider (i) storms Initially located in the easterlies and (ii) storms initially in the westerlies. Latitude 24.5°N approximately delimits the two zones. The mean forecast error (MFE) on group (i) storms is shown to be substantially less than group (ii). However, it also is shown that “skill,” defined as the ability to improve on a forecast based only on climatology and persistence, is greater for storms embedded in the westerlies. An examination of the year-to-year variation in MFE, after these errors have been adjusted according to attendant year-to-year variation in average storm latitude and translational speed, fails to disclose any upward or downward trend in the ability to forecast tropical cyclone motion over ...