The Record-Setting 2018 Eastern North Pacific Hurricane Season

The extremely active 2018 eastern North Pacific (ENP) hurricane season set records for number of hurricane days, major hurricane days, and accumulated cyclone energy (ACE). The Western Development Region (116°W-180°) was especially active, shattering its prior record for ACE set in 2015. In addition, Hawaii was impacted by Hurricane Lane in August and Tropical Storm Olivia in September. Despite above-normal sea surface temperatures (SSTs) and below-normal vertical wind shear in 2018, large-scale conditions were generally less conducive for tropical cyclone (TC) formation than in 2015. However, the strong subtropical ridge in August and September of 2018 enhanced westward steering flow, thereby keeping TCs over hurricane-favorable conditions and preventing recurvature toward lower SSTs and higher vertical wind shear. The 2018 ENP hurricane season highlights that El Niño conditions are not necessary for extremely high ENP TC activity.