Performance Analysis of the HURRAN Tropical Cyclone Forecast System

Abstract

The HURRAN (hurricane analog) technique, a fully computerized objective forecast aid making use of past tracks in forecasting hurricane motion, was developed prior to the 1969 hurricane season. Encouraging operational results during the 1969 and 1970 hurricane seasons suggested further evaluation of the technique. To this end, HURRAN computations were made for approximately 1,000 forecast situations. Results are stratified according to initial direction and speed of movement of the sample storms and the number of analogs selected. The utility of the technique is discussed, and the importance of position accuracy at forecast time is demonstrated. Initial indications of the value of the technique are substantiated.