2004 Pacific hurricane season

A quiet season steered out to sea

Against a long-term average of 16 named storms, 9 hurricanes and 3 major hurricanes, 2004 fell short on the first two measures and only matched the third. The archive tracks 17 systems between May 22 and October 26, five of which never got beyond tropical depression strength, and the season's accumulated cyclone energy comes to 71.1 on the site's measure. The official tally of 12 named storms, 6 hurricanes and 3 major hurricanes, and an energy index of about 71 units, agree with the site's counts.

Forecasters had expected a roughly normal year. Mexico's national weather service and NOAA both assumed neutral conditions in the equatorial Pacific, and NOAA's May outlook called for 13 to 15 named storms and 6 to 8 hurricanes. What developed instead has since been described as a Modoki El Niño, a form in which the warmest water sits farther west than usual and conditions in the eastern Pacific turn less favorable.

The environment explains much of the season's shape. Wind shear was close to normal and waters south of Mexico were slightly warmer than average, but the central part of the eastern Pacific was unusually cool and dry. A strong mid-level ridge stretching from the Atlantic to northern Mexico pushed most storms west into those hostile waters and kept every system of tropical storm strength or greater away from land.

How the season unfolded

Tropical Storm Agatha opened the season on May 22, forming off southwestern Mexico, peaking at 50 kt the next day and falling apart over cooler water by May 24. June then passed without a single tropical cyclone, the first time that had happened since 1969.

July brought the season to life. Two short-lived depressions came and went early in the month, one of them forming in the central Pacific, before Tropical Storm Blas peaked at 55 kt on July 13. Hurricane Celia became the season's first hurricane on July 22, and Hurricane Darby followed within days, reaching 105 kt on July 29 as the first major hurricane in the eastern Pacific since Hurricane Kenna in 2002. Darby weakened quickly over cooler water and shear, and had fallen to a depression by the time it crossed 140°W.

The busiest stretch ran from mid-August to mid-September. Tropical Storm Estelle peaked at 60 kt just after crossing into the central Pacific, while Hurricane Frank, Tropical Storm Georgette and a tropical depression all formed within a few days of each other late in August. Hurricane Howard came next, followed in September by Hurricane Isis and Hurricane Javier. Isis struggled with shear for days, weakened back to a depression, then recovered after a clockwise loop to reach hurricane strength briefly on September 15. Its full track, including the remnant low that drifted toward Hawaii until September 21, is the longest of the season.

October was modest. Tropical Storm Kay lived for less than two days over open water, Tropical Storm Lester formed near the coast of southern Mexico and dissipated just offshore on October 13, and a final tropical depression, Sixteen-E, moved ashore in Sinaloa on October 26 to close the season.

Three major hurricanes

Hurricane Javier was the season's strongest storm. It formed south of the Gulf of Tehuantepec on September 10, became a hurricane on September 12 and then intensified rapidly, reaching 130 kt and 930 hPa at 00:00 UTC on September 14, when satellite images showed a small pinhole eye. Cooler water, strong southwesterly shear and an eyewall replacement cycle wore it down over the following days, and it crossed Baja California as a tropical depression on September 19.

Hurricane Howard was a close second. It became a hurricane on September 1 and intensified rapidly on a northwestward track, peaking at 120 kt and 943 hPa on September 2 before weakening over cooler water. Hurricane Darby, at 105 kt and 957 hPa in late July, was the third major hurricane. The remaining three hurricanes, Celia, Frank and Isis, all peaked at Category 1 strength, and no storm reached Category 5.

Impacts without landfalls

Because no named storm struck land, the season's effects came from swells, outer rainbands and remnant moisture, and no deaths were recorded. The outer bands of Hurricane Howard caused significant flooding on the Baja California peninsula in early September, damaging farmland and at least 393 homes. Its swells reached 18 ft along the Baja California coast and 12 ft in California, where lifeguards made about 1,000 rescues, and its moisture brought light rain to parts of Arizona.

The remnants of Hurricane Darby reached Hawaii from August 2 to 5, where an upper-level trough helped turn their moisture into thunderstorms. The Big Island and Oahu each picked up 2 to 5 in of rain in places, with a local peak of 9.04 in at Kaneohe, flooding streams and closing several roads, and minor stream flooding hit the flank of Haleakalā on Maui. The 3.06 in measured at Honolulu Airport helped make it the city's wettest August since official records began in 1947. Some coffee and macadamia nut trees were damaged.

Hurricane Javier dropped up to 3.14 in of rain at Bacanuchi in Mexico, and three fishermen were reported missing in high surf off the coast. After it weakened, its moisture spread across the Southwest United States and eased a drought that had lasted several years, with up to 7 in at Walnut Creek, Arizona. About 2 in fell in Wyoming, making Javier's remnants the wettest tropical cyclone in the state's reliable record.

Late in the season, Tropical Storm Lester prompted a tropical storm warning along the Guerrero coast and brought 3 to 5 in of rain to parts of Oaxaca and Guerrero, with a 24-hour peak of 106.5 mm on October 12. Mudslides and minor flooding followed, and 42 trees fell in and around Acapulco. Tropical Depression Sixteen-E then made the season's only landfall in Sinaloa, where Culiacán recorded 179.9 mm of rain in 24 hours and a gust of 81 mph at its airport; its remnants later fed heavy thunderstorms over New Mexico, Texas and Oklahoma. None of the sources gives a monetary damage figure for any storm this season.

The central Pacific and the name list

The Central Pacific Hurricane Center in Honolulu had a slightly below-normal season, with three tropical cyclones in its area and no deaths or property damage reported there. Only one formed in the region: Tropical Depression One-C, which developed near 6.8°N on July 5 about 700 miles south-southeast of Johnston Island. It was the farthest south a central Pacific tropical cyclone had formed since two off-season storms in early 1992, and it fell apart within a day despite forecasts of strengthening. Darby arrived as a weakening depression, and Estelle, peaking at 60 kt just west of 140°W, was the only one of tropical storm strength.

Every named storm formed east of 140°W and took its name from the eastern Pacific list last used in 1998. The season used names from Agatha through Lester. None was retired afterward, and the same list returned in 2010.