Tropical cyclones of the eastern North Pacific Ocean, 1949-2006

The eastern North Pacific basin produces more tropical cyclones (TCs) per square km than any other basin. While the NHC database begins in 1949, reliable basin-wide records started in 1971 and this study examines a 37-year climatology of the area, including a contrast to the activity to the Atlantic basin. The long-term averages for the number of tropical storms, hurricanes and major hurricanes in the eastern Pacific are 15, 8 and 4, respectively. The peak number of TCs observed was 24 in 1992, and a minimum of 8 was noted in 1977. Overall TC activity in the basin shows a bimodal distribution, with a notable minimum in activity observed from the third dekad of July through the second dekad of August. Reasons for this mid-season minimum will be discussed at the talk. This distribution is much different than the prominent single peak in activity observed in the Atlantic basin during September.

Although most eastern Pacific TCs avoid land, mainland Mexico has averaged a little more than one hurricane strike per year since reliable landfall records began 1949. Four hurricane strikes were noted in 1996, the maximum of any year in the database. Hurricane impacts in Mexico also show a bi-model distribution, though the risk of a major hurricane strike is much higher in October than any other month of the year. On average, a major hurricane strikes Mexico about every 7 years.

This work is part of a long-term project to reanalyze TC statistics in the eastern Pacific basin and produce a track book, similar to the ones that have been produced for Atlantic tropical storms and hurricanes.