Statistical guidance for the prediction of eastern North Pacific tropical cyclone motion. Part I

This report documents the derivation, application and operational utility of an analog and simulated analog model for the prediction of tropical cyclone motion over the Eastern North Pacific tropical cyclone basin. These two models, together with an additional statistical synoptic model (to be reported on separately), form the nucleus of a recently activated statistical prediction guidance package for use by the National Weather Service (NWS) Eastern Pacific Hurricane Center located at the Weather Service Forecast Office (WSFO), San Francisco, California. A similar statistical guidance package has been used on Atlantic tropical cyclones for a number of years. Testing of the two models on 1976 operational data shows that both perform well on nonrecurving storms. However, the analog model shows an excessive left-of-track bias on recurving storms. The simulated analog model shows a similar but less severe bias. The report also includes recommended procedures on initializing the models as well as a discussion on the operational utility of probability ellipses. Finally, the study concludes with a description of the communications and computer resources which are needed to run the package in its present configuration. Charles J. Neumann and Preston W. Leftwich. "August 1977." Includes bibliographical references (pages 31-32). 1977 NWS (National Weather Service) WR (Western Region) Library Public Domain 1931