2017 Pacific hurricane season

Many storms, modest energy

NOAA counts an average eastern and central Pacific season as about 15 tropical storms, 7 hurricanes and 3 major hurricanes, so 2017 ran above normal on storm numbers. The site's archive records 18 tropical storms, 9 hurricanes and 4 major hurricanes, with accumulated cyclone energy, a measure combining strength and duration, of 100.7. That total is close to average and well below the extremely active seasons of 2014, 2015 and 2016, because many of the year's storms were weak and short-lived: half of the tropical storms never became hurricanes, and several held tropical storm winds for only a day or two.

Forecasters had expected roughly this much activity. In late May, NOAA gave an 80 percent chance of a near- or above-normal season with 14 to 20 named storms, 6 to 11 hurricanes and 3 to 7 major hurricanes, while Mexico's Servicio Meteorológico Nacional predicted 16 named storms, 10 hurricanes and 6 major hurricanes. The National Hurricane Center's own best track gives the same 18, 9 and 4 as the site's archive. The site counts storms from US-agency one-minute winds during the tropical stage, and both tallies land on the same totals this year.

Activity was concentrated in the eastern part of the basin. No tropical cyclone formed in the central Pacific, west of 140°W, for the first time since 2012, although Hurricane Fernanda and Tropical Storm Greg both drifted across that line late in their lives.

An early start, a crowded July and a slow fade

The season began before its official 15 May opening. Tropical Storm Adrian formed south of the El Salvador and Guatemala border on 9 May and briefly reached 40 kt before wind shear tore its thunderstorms away from the center. Late May and June then brought three storms close to southern Mexico: Tropical Storm Beatriz and Tropical Storm Calvin both came ashore in Oaxaca within two weeks of each other, and Hurricane Dora became the season's first hurricane on 26 June, peaking at 90 kt before cooler water broke it down near Socorro Island.

July was the heart of the season. Hurricanes Eugene, Fernanda, Hilary and Irwin all formed that month, alongside Tropical Storm Greg and a short-lived tropical depression, and the month's accumulated cyclone energy was the fifth highest on record for July. By 24 July, Greg, Irwin and Hilary were strung out across the eastern Pacific at the same time. Irwin, the longest-lived storm in the archive, weakened as outflow from the strengthening Hilary to its east began to disrupt it, and the nearby storm pulled Irwin through a small loop before it turned north into cold water.

August was much quieter, with only three storms. Tropical Storm Jova grew from the remnants of Atlantic Hurricane Franklin after that storm crossed Mexico, Hurricane Kenneth became the third major hurricane far out at sea, and Tropical Storm Lidia formed at the end of the month south of Baja California. September added Otis, Max, Norma and Pilar, several of them tied to Atlantic systems: Otis grew from the mid-level remains of Hurricane Katia, and Max from the same tropical wave that spawned Hurricane Jose. After Tropical Storm Ramon lasted barely a day in early October, Tropical Storm Selma closed the season on 28 October.

Fernanda and the rapid intensifiers

Hurricane Fernanda was the season's strongest storm, peaking at 125 kt, Category 4, with a central pressure of 948 hPa at 00:00 UTC on 15 July, far south-southwest of Baja California. Its rise was remarkable: with light wind shear and sea surface temperatures of 28 to 29°C, it strengthened by 90 kt in 54 hours, from a newly named tropical storm to its peak. Fernanda held Category 4 strength through an eyewall replacement cycle until early on 17 July, then weakened slowly over cooler water and crossed into the central Pacific as a tropical storm, dissipating well east of Hawaii on 23 July.

Three other storms reached major hurricane strength, all over open ocean. Hurricane Kenneth went through 36 hours of rapid intensification to peak at 115 kt, Category 4, on 21 August. Hurricane Eugene climbed from 35 kt to 100 kt, Category 3, in 42 hours on 8 and 9 July. Hurricane Otis was the oddest of the group: after drifting for days as a weak, largely unnoticed system, it rapidly intensified to 100 kt on 18 September and then collapsed just as fast, back to a 40 kt tropical storm within 24 hours. The National Hurricane Center rated Otis's peak as more uncertain than usual because of its small size and the wide spread of satellite estimates. Hurricane Hilary, at 95 kt on 26 July, fell just short of major hurricane strength.

Floods in Mexico and a rare landfall in El Salvador

Tropical Storm Beatriz came ashore about 20 nautical miles west of Puerto Ángel, Oaxaca, around 00:00 UTC on 2 June. Its rains set off hundreds of mudslides in Oaxaca's mountains, and the National Hurricane Center counted six direct deaths, four women and two children killed in mudslides. Local reports put damage in Oaxaca at about 3.2 billion pesos, roughly US$172 million in 2017 dollars. Tropical Storm Calvin followed on 13 June, landing near Paja Blanca at 40 kt and dropping 14.90 inches of rain on Salina Cruz; no deaths were reported, and Oaxaca officials estimated at least 70 million pesos, about US$3.9 million in 2017 dollars, in additional road damage from its rains.

Tropical Storm Lidia was a large storm that passed very close to Cabo San Lucas at the end of August, made landfall near Punta Marquez at 50 kt on 1 September and crossed the coast again near Punta Abreojos the next day. Up to 18.9 inches of rain fell at Sierra Laguna in Baja California Sur, where some 3,000 people went to shelters. The National Hurricane Center recorded five direct deaths and two indirect deaths from electrocution.

Hurricane Max was the season's only landfalling hurricane. It strengthened quickly as it approached Mexico and struck the eastern coast of Guerrero, about 40 nautical miles east-southeast of Acapulco, at 80 kt around 18:00 UTC on 14 September, with hurricane warnings issued only six hours before landfall. More than 1,500 homes in Guerrero were damaged by water or wind; media reports, not confirmed by the Mexican government, described one drowning death, and damage was estimated at around US$13 million in 2017 dollars.

Other storms were felt at a distance. Rain from Hurricane Dora's outer bands flooded homes in Chilpancingo, Tixtla and Ayutla de los Libres in Guerrero, and swells from Hurricane Eugene produced dangerous rip currents in southern California, where lifeguards in Los Angeles County made about 600 rescues on 10 July. Tropical Storm Selma, the last storm of the year, made landfall near Playa El Pimental, El Salvador, at 35 kt on 28 October; the National Hurricane Center reported downed trees and mudslides there but no casualties.

Records and a new kind of advisory

Tropical Storm Adrian became the earliest named storm on record in the eastern Pacific when it formed on 9 May, a mark that stood until Tropical Storm Andres in 2021. At the other end of the season, Tropical Storm Selma was only the second eastern Pacific storm to reach tropical storm strength east of 90°W, after Alma in 2008, and the only tropical storm on record to make landfall in El Salvador.

Before the season, the National Hurricane Center began issuing advisories on disturbances that were not yet tropical cyclones but were likely to become one and bring tropical storm or hurricane conditions to land within 48 hours, so that watches and warnings could go up in time. The first such Potential Tropical Cyclone in the eastern Pacific, Fourteen-E, became Tropical Storm Lidia on 30 August. The names came from the same list used in 2011, and none was retired after the season.