2011 Pacific hurricane season

Season overview

The season was lopsided: the number of named storms was below average, yet the number of hurricanes and major hurricanes was above it. Ten of the 11 tropical storms went on to hurricane strength, Tropical Storm Fernanda being the only exception, and six of those ten reached major hurricane intensity of 96 kt or more. Accumulated cyclone energy came to 120.9 units, a little above the near-normal value of about 113 that NOAA uses for the eastern Pacific.

The Climate Prediction Center had expected a quiet year. Its May outlook gave a 70 percent chance of a below-normal season and called for 9 to 15 named storms, 5 to 8 hurricanes and 1 to 3 major hurricanes, citing increased wind shear, lingering La Niña conditions early in the season and likely ENSO-neutral conditions through the peak months. The named-storm total landed inside that range, but the hurricane and major hurricane totals ran well past the top of it.

The site's counts use US-agency one-minute winds during the tropical stage in the IBTrACS archive. For 2011 they agree with the National Hurricane Center best-track totals quoted in the season article: 13 tropical cyclones, of which 11 became tropical storms, 10 hurricanes and 6 major hurricanes. The two cyclones that never reached tropical storm strength were Tropical Depression Eight-E and Tropical Depression Twelve-E.

How the season unfolded

Activity began on 7 June with Hurricane Adrian, which formed south of Acapulco, paralleled the southwestern Mexican coast and rapidly intensified to 120 kt, an unusually strong start for June. Hurricane Beatriz followed later in the month, strengthening quickly as it approached the coast. July brought the short-lived Hurricane Calvin and then Hurricane Dora, which formed from a tropical wave that had crossed Central America and became the strongest storm of the year. Hurricane Eugene formed on the last day of July and reached Category 4 in early August.

Mid-August produced two storms at once. Tropical Storm Fernanda formed far to the west, about 1,400 nautical miles east-southeast of Hawaii, and crossed into the central Pacific near its 60 kt peak, while Hurricane Greg developed closer to Mexico and peaked at 75 kt before weakening over cooler water. Tropical Depression Eight-E then formed near Zihuatanejo on 31 August and moved inland west of Lázaro Cárdenas within hours.

The first three weeks of September were empty, a lull the season article links to the return of La Niña. Hurricane Hilary broke the pause on 21 September and was followed in early October by a burst from a breakdown of the Intertropical Convergence Zone, which produced Hurricane Irwin and Hurricane Jova almost simultaneously, and then Tropical Depression Twelve-E. Irwin meandered southwest of Mexico for about ten days, turning north, east and back again, which made it the longest-lived storm of the year in the archive. After another quiet month, Hurricane Kenneth closed the season in late November.

Strongest storms

Hurricane Dora was the most intense cyclone of the season. It became a hurricane on 19 July, underwent rapid intensification as an eye cleared out, and peaked at 135 kt with a central pressure of 929 hPa on 21 July, about 175 nautical miles southwest of Manzanillo. Northeasterly shear and cooler water then took it apart quickly: within 24 hours it dropped from 130 kt to a 60 kt tropical storm, and its remnant dissipated off the west coast of the Baja California peninsula on 26 July.

Four other storms reached Category 4. Hurricane Adrian and Hurricane Eugene each peaked at 120 kt, Adrian in June and Eugene on 3 August. Hurricane Hilary, a very small storm with tropical-storm-force winds extending only about 75 nautical miles from its center, went through more than two days of rapid intensification in very warm, low-shear conditions and peaked at 125 kt on 23 September, reaching Category 4 twice. Hurricane Jova, the sixth major hurricane, peaked at 110 kt on 10 October, a figure based on reconnaissance aircraft measurements.

Hurricane Kenneth was the season's latest surprise. A compact storm that stayed over open ocean, it formed about 400 nautical miles south of Acapulco on 19 November and, over sea surface temperatures above 28°C with little wind shear, rapidly intensified to a peak of 125 kt and 940 hPa on 22 November before weakening just as quickly in colder water.

Landfalls and impacts

Hurricane Jova was the season's only hurricane landfall. After weakening from its peak under increasing southwesterly shear, it crossed the Jalisco coast near El Tabaco, about 35 nautical miles northwest of Barra de Navidad, around 06:00 UTC on 12 October with estimated winds of 85 kt, and weakened rapidly over the mountains of western Mexico. The National Hurricane Center counted nine deaths in Mexico, including victims of a mudslide in Cihuatlán and a house collapse in Tomatlán. About 107,000 people lost power, the Mexican Navy evacuated 2,600 people and the port of Manzanillo was closed; the report gives no monetary damage estimate.

Tropical Depression Twelve-E was the deadliest system of the year despite never reaching tropical storm strength. It formed on 12 October south-southeast of Salina Cruz and came ashore near Paredón on the eastern Gulf of Tehuantepec that afternoon. Rain from the depression and the surrounding monsoon-like flow caused severe flooding in southeastern Mexico and Guatemala, where press reports gave totals of up to 12 inches, and the Guatemalan government declared a state of public calamity and attributed 36 direct deaths to the depression. Many more deaths in Central America were tied to the wider rain event rather than to the depression itself.

Hurricane Beatriz brushed the coast in June: its eye passed within 15 nautical miles of shore southeast of Manzanillo at its 80 kt peak, so the National Hurricane Center counts it as a hurricane strike on Mexico. Heavy rain from Guerrero to Jalisco flooded parts of Acapulco, with up to 222.5 mm at Copala. One death was directly attributed to Beatriz, and three people drowned in an indirect accident in Amatillo, in the municipality of Acapulco.

Other storms caused lighter effects. Hurricane Hilary passed close to Acapulco, downing trees, and three fishermen died when their boat sank off the Mexican coast, the only deaths the National Hurricane Center attributes to it. Tropical Depression Eight-E came ashore west of Lázaro Cárdenas on 31 August. Hurricane Adrian, Hurricane Dora and Hurricane Kenneth caused no reported damage or casualties.

Records and names

Hurricane Kenneth set basin records that stood for four years. The National Hurricane Center's report identifies it as the latest-forming major hurricane in the eastern North Pacific in the satellite era and the only major hurricane then on record in November, beating Hurricane Xina, which reached 100 kt on 29 October 1985. Kenneth was also one of only six November hurricanes since record keeping began in 1949. Hurricane Sandra in 2015 later reached major hurricane strength later still, taking both records.

The season used the same list of names as 2005, from Adrian through Kenneth, and no names were retired, so the list returned in 2017. No storms formed in the central Pacific, although Fernanda crossed into that region from the east.