2001 Pacific hurricane season

A near-average year in both Pacific basins

The archive tracks 19 systems between May 25 and November 3, and the season's accumulated cyclone energy comes to 90.6 on the site's measure. No storm reached Category 5. In the eastern Pacific the number of named storms was about average, while the hurricane and major hurricane totals ran slightly below the long-term norm. The central Pacific saw four tropical cyclones, close to its long-term average of 4.5, but the Central Pacific Hurricane Center described all of them as weak, and none threatened Hawaii.

The broad climate backdrop was quiet. The run of neutral or La Niña conditions that had held since 1998 continued, a pattern that tends to hold eastern Pacific activity in check. Many of the season's storms grew from tropical waves that had crossed the Atlantic from Africa, and several of those same waves had already spawned Atlantic systems: Flossie, Gil, Juliette, Kiko and Manuel all trace back to disturbances that produced Atlantic storms first.

Headline counts vary slightly by source because they measure different things. The National Hurricane Center's summaries and Wikipedia list 15 named storms. The site counts 16 tropical storms because it uses the one-minute winds in the archived best track, where the central Pacific system Tropical Depression Two-C reaches 35 knots; the Central Pacific Hurricane Center's own report kept that system at 30 knots, below tropical storm strength, and it never received a name. The hurricane and major hurricane totals, 8 and 2, agree across sources.

How the season unfolded

The season started early and fast. Adolph became a tropical depression south of the Gulf of Tehuantepec on May 25 and was a Category 4 hurricane four days later. June brought only Tropical Storm Barbara, which formed far out to sea, weakened as it crossed 140°W and became the first tropical storm on record to reach the central Pacific in June before its remnant passed north of Hawaii.

July added three storms. Tropical Storm Cosme and Tropical Storm Erick were short-lived and hampered by shear and cool water, while Hurricane Dalila tracked west-northwest parallel to the Mexican coast, came within about 100 nautical miles of land between Acapulco and Manzanillo, and reached hurricane strength for only a few hours on July 24. August produced just one named storm, Hurricane Flossie, which rapidly strengthened southwest of Baja California, looped briefly while interacting with an upper-level low and peaked at 90 knots on August 29.

September was the busiest month. Hurricane Gil and Tropical Storm Henriette formed on the same day, September 4, several hundred nautical miles apart, then Tropical Storm Ivo hugged the southwest Mexican coast from September 10. Hurricane Juliette and Hurricane Kiko both formed on September 21; Kiko briefly reached hurricane strength before stable air and shear broke it down. Two short-lived central Pacific depressions, One-C and Two-C, also formed southeast of Hawaii that month.

October kept the season going with Tropical Storm Lorena, which briefly threatened southwestern Mexico, and Tropical Storm Manuel, which formed on the Pacific side from the remnants of Atlantic Hurricane Iris after Iris struck Belize. Because Iris had dissipated before its moisture reached the Pacific, the new system took a Pacific name rather than keeping the Atlantic one. Hurricane Narda peaked at 75 knots far out to sea and crossed into the central Pacific on October 23, and Hurricane Octave, the last storm, reached 75 knots before shear wore it down to a swirl of low clouds on November 3.

Adolph and Juliette at the top

Hurricane Adolph was the season's strongest storm by the site's measure and the first to reach its peak. After drifting unusually east-northeast as a depression, it became a hurricane on May 27 and intensified dramatically, gaining 50 knots in 30 hours to reach 125 knots and 940 hPa on May 29 about 145 nautical miles off Acapulco at its closest. No other Category 4 hurricane had been recorded in the northeast Pacific in May. Forecast models did not anticipate the rapid strengthening, and some official intensity forecasts during the burst were as much as 55 knots too low at 72 hours.

Hurricane Juliette matched Adolph's 125-knot peak on September 25 and went further on pressure. Reconnaissance aircraft measured 923 hPa that day, the lowest pressure of the season and, when the National Hurricane Center wrote its report, the second-lowest sea-level pressure ever measured in the northeast Pacific, behind only Hurricane Ava's 915 hPa in June 1973. Juliette rapidly intensified from a hurricane to 115 knots with a pinhole eye within a day, went through several eyewall replacement cycles, and stayed a tropical cyclone for 282 hours, the longest of the season.

Below those two, Hurricane Flossie peaked at 90 knots and Hurricane Gil at 85 knots, both Category 2. Gil is remembered less for its winds than for its encounter with Henriette: as Henriette passed to its north on September 7 and 8, the two storms began to rotate around each other, and Gil's outflow and shear sapped both before Gil absorbed Henriette's remnant circulation on September 9. The National Hurricane Center called such mergers uncommon in its area, the previous documented eastern Pacific case being Norbert's absorption of Tropical Depression Eighteen-E in September 1990.

Juliette's landfall and other impacts

Juliette was the season's only landfalling storm. It tracked parallel to mainland Mexico 100 to 200 nautical miles offshore, then turned north and passed just west of Cabo San Lucas on September 28 with winds near 80 knots; an automatic station at Cabo San Lucas recorded 76 knots sustained with a gust to 94 knots. The weakening storm moved inland near San Carlos on the west coast of Baja California on September 30 at about 35 knots, then crossed into the Gulf of California as a depression. Rainfall reached 6.59 inches at Empalme in Sonora and 8.16 inches at San Felipe in northern Baja California.

The National Hurricane Center attributed two deaths to Juliette: a fisherman near Acapulco whose boat capsized in high seas on September 24 and a US tourist who drowned while surfing off Baja California on September 27. Cabo San Lucas was cut off for several days, and flooding drove more than 38,000 people from their homes in coastal Sonora. Wider tallies compiled later give 13 deaths in Mexico from Chiapas to Baja California and damage of more than US$400 million in 2001 dollars, with the worst effects in Sonora. Thunderstorms from the remnants reached southern California, where they brought down trees and power lines in the Coachella Valley.

Flossie never threatened land as a tropical cyclone, but its remnant moisture helped set off thunderstorms over southern California on September 2 and 3. Lightning killed two people in the San Diego and San Bernardino Mountains, whom the National Hurricane Center did not count as deaths directly caused by the storm, and flash flooding in San Diego and Riverside counties added to damage estimated at $35,000 in 2001 dollars. Dalila's rains caused flash flooding on the Chiapas coast that damaged dozens of homes, and lightning there killed two people. Adolph, Dalila, Ivo and Lorena all prompted watches or warnings along Mexico's Pacific coast, but no damage or casualties were reported from the other storms.

Adolph's retirement and a first Ivo

The 2001 season was the last to use the name Adolph. After the season had begun, the name was retired for political reasons following controversy over its use, and Alvin replaced it from 2007. The same decision withdrew Israel, which had been chosen to replace the earlier retired name Ismael; Ivo took its place before Israel was ever used, so 2001 brought the first storm named Ivo. No storms were named in the central Pacific in 2001, although Barbara and Narda both crossed into it from the east.