Forecasting Tropical Cyclone Motion over the Northeastem Pacific Ocean by an Analog Scheme

Abstract

The Navy's EPANALOG (Northeastern Pacifi.c Analog Tropical Cyclone Tracker) f~recast prog~am is introduced. EP ANALOG selects analog tropical cyclones from a 25-year northeastern Pa~fi.c Ocean history. The selected analog tracks, statistically adjusted for position, vector motio~, an? date ~erences between them and the recent history of the tropical cyclone being forecast, are composited mto a smgle forecast track. Verifications of EPANALOG forecasts to 96 h, as initiated from best-track positions, are shown for randomly selected historical cases with a Monte Carlo simulation of initial position inaccuracies, as well as for forecasts generated from 1973 operational cyclone positions. The latter are intercompared with a homogeneous set of objective persistence and MOHATT forecasts as well as subjective OFFICIAL forecasts for. the 24, 48, and 72 h intervals. The 1973 EPANALOG accuracy is shown to generally excel that of the existent techniques for all forecast intervals tested.