Hurricane Kenna - Meteorological History

Meteorological History

The origin of Hurricane Kenna can be traced to a tropical wave moving westward through the Caribbean Sea on October 16, possibly the same wave that passed near Barbados two days earlier. The wave entered the eastern Pacific Ocean on October 19, and a tropical disturbance along the wave axis gradually became better organized. Conditions favored continued development, and Dvorak classifications began late on October 20. Early on October 22, the system developed into Tropical Depression Fourteen-E while located about 375 mi (605 km) south of Manzanillo, Colima. Initially the depression was disorganized, with little inner convective structure and sporadic deep convection. Computer models predicted an increase in wind shear by 60 hours; as such the National Hurricane Center forecast the depression to strengthen to a peak strength of 45 mph (70 km/h) before weakening.

The depression quickly became better organized with a great increase in convection near the center, and six hours after forming it strengthened into Tropical Storm Kenna. Upper-level outflow and banding features improved in organization, as well. With warm water temperatures of over 29 °C (84 °F) and updated model forecasts anticipating light amounts of vertical wind shear, forecasters predicted Kenna to slowly intensify to reach winds of 85 mph (135 km/h) within 72 hours of October 22. The storm moved to the west-northwest around the periphery of a mid-level high-pressure system, and initially failed to strengthen further with much of its convection being associated with outer rainbands. On October 23, the outer rainbands dissipated and convection became more concentrated near the center, which coincided with a steady increase in strength. Late on October 23, Kenna intensified into a hurricane while located about 380 mi (615 km) southwest of Manzanillo.

Shortly after becoming a hurricane, Kenna began to rapidly intensify with a 17 mi (27 km) wide eye located within its well-defined central dense overcast. Early on October 24 Kenna became a major hurricane, and in a 24 hour period the hurricane more than doubled its windspeed from 70 mph (115 km/h) winds to 145 mph (235 km/h). After turning to the north and northeast in response to the flow ahead of a large mid to upper-level trough, Kenna attained peak winds of 165 mph (265 km/h) early on October 25 while located about 255 mi (410 km) southwest of Puerto Vallarta, the third Category 5 hurricane of the season. A Reconnaissance Aircraft flight into the hurricane while it was near peak intensity recorded a pressure of 913 mbar (hPa), the third lowest recorded pressure for a Pacific hurricane.

Quickly after peaking, wind shear from the approaching trough weakened the hurricane, and by six hours after reaching peak intensity, the winds in Hurricane Kenna dropped to 150 mph (240 km/h) after the eye nearly dissipated. Despite a 27 mbar increase in pressure in 12 hours, convective activity increased prior to Kenna making landfall. On October 25 Hurricane Kenna struck near San Blas in the state of Nayarit with estimated winds of 140 mph (225 km/h). The hurricane rapidly weakened over the mountainous terrain of western Mexico, and the circulation dissipated on October 26 over the Sierra Madre Occidental mountains. The remnants continued northeastward into the Gulf of Mexico and southeastern United States.