Interannual variability of near-coastal Eastern Pacific tropical cyclones

Interannual fluctuations of tropical storms affecting the west coast of North America are modulated by the ENSO cycle and by Pacific decadal variability, particularly during the early months of the tropical storm season. More tropical storms affect the Pacific coast in May-July during La Niña years (when equatorial Pacific Ocean temperature is anomalously cold) than during El Niño years. The difference between La Niña and El Niño years was especially pronounced during the mid-20th Century epoch when cold equatorial ocean temperatures were enhanced, associated with Pacific decadal variability. The results potentially provide a basis for probabilistic seasonal prediction of the propensity for landfalling tropical storms on the west coast of Mexico.