The Record-Breaking 2015 North Central Pacific Hurricane Season

The 2015 North Central Pacific (180-140°W) hurricane season was one for the record books. The season witnessed a total of eight named storm formations, shattering the old record of four formations set in 1982. In addition, more named storms, hurricanes and major (Cat. 3-5) hurricanes passed through the North Central Pacific than any other year on record (reliable records date back about 40 years). Accumulated Cyclone Energy (ACE) generated during 2015 exceeded 125 units, breaking the old record of 107 units set in 1994.

The large-scale features responsible for generating such an active North Central Pacific will be discussed in detail during this presentation. A strong El Niño helped to drive a more favorable dynamic and thermodynamic environment, through an increase in sea surface temperatures (SSTs), an increase in mid-level moisture and a decrease in vertical wind shear. In addition, a strongly positive phase of the Pacific Meridional Mode helped to further increase SST anomalies and reduce vertical wind shear in the subtropical North Central Pacific, amplifying the already favorable conditions generated by El Niño.