2006 Pacific hurricane season

The first busy season in almost a decade

After several quiet years, 2006 was the first above-average Pacific hurricane season since 1997. The archive tracks 25 systems between May 27 and November 20, with an accumulated cyclone energy of 208 on the site's measure. Hurricane Ioke was the strongest, the lowest in pressure and the longest lived, and Hurricane Bud was the first to reach hurricane strength, on July 11.

Official tallies agree with the site's headline counts of 19 tropical storms, 11 hurricanes and 6 major hurricanes once the central Pacific is included; the eastern Pacific alone, east of 140°W, produced 18, 10 and 5, with Ioke making up the difference. Energy totals differ more. Colorado State University put the season at 156.9 units from National Hurricane Center advisories, and counted Ioke only up to its crossing of the International Date Line. The site follows US-agency one-minute winds through each storm's whole tropical life in the calendar year, so Ioke's long run as a typhoon in the western Pacific adds to its figure.

Forecasters had not expected this. In May, NOAA predicted a below-normal eastern Pacific season of 12 to 16 named storms, citing a decades-long pattern of higher wind shear that had begun in 1995, and expected neither El Niño nor La Niña to matter much. Instead a weak El Niño developed in September, warming the ocean near the Date Line. The Central Pacific Hurricane Center linked that warmth to the fact that four of the five central Pacific systems formed within its own region and to a cluster of depressions there from mid-September to mid-October.

A slow start, a crowded summer and a lively November

Tropical Storm Aletta opened the season on May 27, drifting for several days off the coast of Guerrero, and Tropical Depression Two-E followed in early June, dropping nearly 11 inches of rain on Acapulco. No tropical storm formed in June, something that had happened in only a handful of years since 1966.

July changed the pace. Five named storms formed, beginning with Bud and Hurricane Carlotta a day apart on July 11 and 12, then Hurricane Daniel, Tropical Storm Emilia and Tropical Storm Fabio. August was busier still. Tropical Storm Gilma and Hurricane Hector were followed within days by Ioke south of Hawaii and Hurricane Ileana off Mexico, and the month ended with Hurricane John and Hurricane Kristy forming almost together.

September was quieter, with Hurricane Lane, the brief Tropical Storm Miriam and two central Pacific depressions that never reached storm strength. October brought Tropical Storm Norman and Tropical Storm Olivia from the same tropical wave, a third central Pacific depression and Hurricane Paul. November then became the most active on record for the basin by accumulated cyclone energy: Tropical Storm Rosa was the first November tropical storm since 2000, and Hurricane Sergio made 2006 only the second year, after 1961, with two tropical storms that month. Sergio's end on November 20 closed the season.

Ioke and a year of major hurricanes

Hurricane Ioke formed from the Intertropical Convergence Zone about 675 nautical miles south of Honolulu on August 20, in warm water and almost no wind shear. It went from a depression to 115 kt in 48 hours, weakened to Category 2 as shear rose while it passed about 30 miles south of Johnston Island on August 22, then strengthened again to 140 kt on August 25. It held Category 5 strength as it crossed the Date Line on August 27 and became a super typhoon, heading toward Wake Island.

Ioke set a string of central Pacific marks. It was the first named storm to form there since 2002, the first Category 5 hurricane on record to originate there, and the lowest in estimated pressure for the region, at 915 hPa as it reached the Date Line. It stayed at Category 4 or stronger for 198 consecutive hours, a record at the time for any tropical cyclone worldwide. The site's lowest pressure of 900 hPa at the same moment comes from its merged track, which combines estimates from more than one agency. Ioke's tropical life ran until September 6, the longest of the season.

Five other storms reached major-hurricane strength. Hurricane Daniel peaked at 130 kt on July 22 and developed an annular structure, a nearly symmetrical eyewall with little convection outside it, which helped it hold its strength for longer than most hurricanes. Hurricane John reached 115 kt on August 30, Hurricane Bud and Hurricane Lane each peaked at 110 kt, and Hurricane Ileana at 105 kt. Hurricane Hector and Hurricane Sergio both topped out at 95 kt, just short of major status.

Mexico takes the brunt

Hurricane John ran parallel to the coast of southwestern Mexico, its eye coming within about 50 nautical miles of the shore between Manzanillo and Lázaro Cárdenas on August 31, before making landfall at Cabo del Este in southern Baja California at about 02:00 UTC on September 2 with winds near 95 kt. It then moved up the peninsula past La Paz. Press reports compiled by the National Hurricane Center put the toll at five deaths, all in Baja California, with hundreds of homes destroyed or damaged around La Paz and Mulegé; Wikipedia gives damage in Mexico of 663 million pesos, about US$60.8 million in 2006 dollars. Its remnant moisture flooded parts of Ciudad Juárez and El Paso.

Hurricane Lane was the season's strongest landfall. After skirting the coast from Acapulco northward and brushing the Islas Marías, it came ashore in Sinaloa about 15 nautical miles southeast of El Dorado at 19:15 UTC on September 16 as a Category 3 hurricane with 110 kt winds. The National Hurricane Center reported four direct deaths from floods and mudslides and heavy losses to farmland, roads and a bridge between Culiacán and Mazatlán. Wikipedia puts damage at 2.2 billion pesos, about US$203 million in 2006 dollars, making Lane the costliest storm of the season.

Hurricane Paul weakened under strong shear before passing about 40 nautical miles south of Cabo San Lucas, and it made landfall in Sinaloa as a tropical depression early on October 26. High surf in southern Baja California killed two people and flooding in Navolato killed two more, four direct deaths in all; media reports said 5,000 homes in Sinaloa were damaged. Wikipedia gives Paul's damage as more than 35 million pesos, about US$3.2 million in 2006 dollars.

Other storms caused lesser harm. Tropical Storm Emilia passed close to the southern tip of Baja California, where minor flooding and wave damage closed several marinas for about two days, and Tropical Storm Norman brought heavy rain to southwestern Mexico without reported damage or casualties in the National Hurricane Center's account. Hawaii felt the remnants of Daniel, which dropped two to five inches of rain on windward areas of the Big Island and Maui, and later of Tropical Depression Four-C, which helped fuel flooding on the Big Island on October 17.

Johnston and Wake islands

Ioke's two island encounters were the season's most unusual impacts. On Johnston Island, normally uninhabited, a survey crew of 12 sheltered in a concrete building and estimated peak winds of 95 to 115 kt; the storm washed away part of a sea wall and a road and stripped the tops from about 15 percent of the palm trees, but no one was hurt. Wake Island was fully evacuated for the first time since 1967, and on August 31 Ioke passed close by with winds near 155 mph, tearing off roofs and causing about US$88 million in damage in 2006 dollars. Its extratropical remnants later drove surge and beach erosion along the coast of Alaska.

Names

The eastern Pacific list, last used in 2000, ran through Sergio, and none of its names was retired. Ioke was the only named storm to form in the central Pacific, and the World Meteorological Organization retired its name in 2007, replacing it with Iopa.