A climatology of the characteristics of tropical cyclones in the Northeast Pacific during the period 1966-1980
Allard, Richard Arthur
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The Northeast Tropical Pacific (NETROPAC) ranks second only to the Northwest Tropical Pacific in terms of annual tropical cyclone occurrence. Prior to the introduction of the weather satellite in the 1960's, cyclone frequencies had been grossly underestimated. During the past decade, the decline in ship reports has made the satellite the primary tool for estimates of NETROPAC cyclone location and intensity. In this study, NETROPAC cyclone tracks are constructed for the period 1966-1980. The majority of storms form between 10.0 and 30.0 N latitude with a mean direction toward 300 with a speed of 12 kt. The results indicate that three tropical cyclones per year can be expected in the area bounded by 15.0-17.5Â°N and 105.0-115.0Â°W. Most of the NETROPAC experiences at least one cyclone between 10.0 and 25.0 N per 2.5 by 2.5 degree latitude-longitude grid square. Research indicates that the poleward position of the intertropical convergence zone, weak vertical wind shear between 850 and 200 mb, and a sea-surface temperature of 26.5 C or greater are necessary for tropical cyclone development. Recurving NETROPAC cyclones and those which make landfall upon the west coast of Mexico are studied. The resulting damage patterns are also investigated.