2007 Pacific hurricane season

A season held back by wind shear

The archive tracks 16 systems between May 27 and October 23. Twelve reached tropical-storm strength, four became hurricanes and only Flossie reached major-hurricane intensity. No storm reached Category 5. The season's accumulated cyclone energy on the site comes to 53.5, a low figure for a basin that regularly produces several intense hurricanes a year.

Official summaries count 11 named storms, 4 hurricanes and 1 major hurricane, well short of the 1971 to 2006 averages of about 15, 9 and 4. The extra tropical storm in the site's count is Lingling, a system carrying a western Pacific designation that the archive records at tropical-storm strength in mid-October within this basin, so it falls outside the eastern and central Pacific named-storm tally. Colorado State University's energy figure of 51.6 units, based on National Hurricane Center advisories, sits close to the site's value and was at the time the second-lowest since reliable records began in 1971.

Forecasters had expected a quiet year. In May, NOAA predicted 11 to 16 named storms for the eastern Pacific, citing neutral or La Niña conditions and a long-running lull in activity since 1995, while the Central Pacific Hurricane Center expected only two or three cyclones to form in or enter its region. The main reason activity fell even lower was wind shear that ran well above average across the basin for much of the season.

How the season unfolded

The season began briskly. Tropical Storm Alvin formed on May 27 and Tropical Storm Barbara two days later, making 2007 only the third year on record with more than one tropical storm in May. The momentum stopped there: June produced just a short-lived depression, Three-E, and 2007 became one of only four years without a tropical storm in that month.

July brought two more depressions that never strengthened, followed by Hurricane Cosme, which became the season's first hurricane on July 16 far out at sea before cooler water weakened it. Tropical Storm Dalila and the brief Tropical Storm Erick followed later in the month. By then the season ranked among the quietest on record for its date, and it slipped further behind as the year went on.

August contained the season's one burst of real strength. Flossie formed on August 8 and became a Category 4 hurricane within three days, and at the end of the month Tropical Storm Gil and Henriette developed almost together off the Mexican coast. September added Hurricane Ivo, another brief depression and Tropical Storm Juliette, which became the tenth tropical storm of the eastern Pacific season about a month later than average.

October closed the year with Lingling's short spell at tropical-storm strength far to the west and then Tropical Storm Kiko, the longest-lived system in the archive. Kiko formed on October 15 inside a broad gyre, drifted south and then east-northeast toward Mexico, and finally turned northwest to reach 60 kt about 150 nautical miles west-southwest of Manzanillo before weakening. Its end on October 23 marked the last tropical-stage observation of the season.

Flossie and the season's other hurricanes

Hurricane Flossie was the strongest storm by a wide margin. It formed on August 8 about 1,700 nautical miles east-southeast of the Big Island, became a hurricane on August 10 once an eye appeared, and reached Category 4 just before crossing 140°W into the central Pacific. Its peak of 120 kt and 949 hPa came at 00:00 UTC on August 12, and it held Category 4 strength for about two days before rising shear began to take it apart on August 14.

Flossie's track was forecast well, but its strength was not. The National Hurricane Center judged the environment less favorable than it proved to be, and several of its three- to five-day intensity forecasts were too low by 70 kt or more.

No other storm came close. Hurricane Henriette peaked at 75 kt south-southeast of Cabo San Lucas on September 4, Hurricane Ivo reached 70 kt well southwest of Baja California on September 20, and Cosme was a hurricane only briefly at 65 kt. The strongest tropical storm was Kiko at 60 kt.

Landfalls in Mexico and near misses in Hawaii

Tropical Storm Barbara made the season's first landfall at about 13:00 UTC on June 2, roughly 20 nautical miles northwest of the Mexico-Guatemala border, with winds of 45 kt. Structural damage was mostly limited to roofs and trees, and a river flood washed out a bridge in coastal Guatemala, but the National Hurricane Center reported more than $50 million (US dollars, 2007) in crop damage in southeastern Mexico.

Hurricane Henriette was the season's deadliest storm. While its center ran just offshore from Oaxaca and Guerrero at the end of August, it dropped 5 to 9 inches of rain on the coast, and mudslides near Acapulco killed six people. It then made landfall near San José del Cabo at about 21:00 UTC on September 4 with winds near 70 kt, crossed the Gulf of California and came ashore a final time near Guaymas early on September 6 at about 60 kt. The National Hurricane Center counted at least nine direct deaths in Mexico, with four more people missing at sea, and media reports put damage in Sonora at about $25 million (US dollar equivalent, 2007).

Two storms brought Hawaii anxious days without serious harm. Cosme passed about 160 nautical miles south of South Point as a depression on July 21, and its outer showers dropped up to 6.94 inches of rain at Hakalau on the Big Island without significant flooding. Flossie prompted a hurricane watch and then a tropical storm warning for the Big Island on August 13; by the time its center passed about 90 nautical miles south of South Point early on August 15 it had weakened, but it still brought tropical-storm-force winds to South Point and surf estimated near 20 feet on southeast-facing shores. No casualties or significant damage were reported.

Hurricane Ivo prompted a brief tropical storm watch for southern Baja California before it weakened offshore, bringing heavy rain to Baja California Sur without reported damage. Tropical Storm Kiko triggered advisories along southwestern Mexico before a ridge steered its center parallel to the coast, and the National Hurricane Center received no reports of damage or casualties from it.

Names and the central Pacific

Alvin was used for the first time in 2007, replacing Adolph on the list otherwise last used in 2001. The eastern Pacific list ran only as far as Kiko, no names were retired afterward, and the same list returned in 2013. No named storms formed in the central Pacific; Cosme and Flossie were the only cyclones to cross into that region, fewer than the typical four or five.

A curious footnote came from the Big Island's lava coast. During the night of August 13, as Flossie's large swells pounded the Big Island's southeast shore, a 44-acre lava bench at East Lae'apuki collapsed into the sea. The US Geological Survey considered the surf, a magnitude 5.4 earthquake at about the same time, or both as possible causes.