The 1984 Pacific hurricane season featured numerous tropical cyclones, several of which were impactful to land. It was a busy hurricane season with 21 named storms, 13 hurricanes, and 7 major hurricanes, the latter of which are Category 3 or stronger cyclones on the Saffir–Simpson scale. The season also had an above-normal accumulated cyclone energy (ACE) rating of 193.7, despite the presence of a La Niña event, which typically results in less activity, and had the second-most storms for a La Niña year on record, largely due to average sea surface temperatures across the Eastern Pacific. Seasonal activity began on May 17 and ended on November 8. This lies within the confines of a traditional hurricane season which begins on May 15 in the East Pacific and June 1 in the Central Pacific, and ends on November 30 in both basins. These dates conventionally delimit the period during each year when most tropical cyclones form.
The drought-stricken Hawaiian Islands received beneficial rainfall from Hurricane Douglas in July and Tropical Storm Kenna in August. The remnants of hurricanes Iselle, Marie, Norbert, and Odile all contributed to enhanced precipitation across the Southwestern United States during the season, including snowfall in higher elevations; flash flooding killed one person in Texas. Hurricane Lowell attracted widespread coverage for damaging the Blue Falcon and forcing the rescue of its 23 crewmembers. In September, torrential rains from Hurricane Odile in Southern Mexico severely damaged crops, inflicted water damage to about 900 homes, and left thousands of residents displaced or without normal services. The storm killed at least 21 people. Multiple hurricanes contributed to rough surf along the California coastline, resulting in one death and hundreds of water rescues.
Systems
Tropical Storm Alma
On May 13, an area of disturbed weather within the Intertropical Convergence Zone (ITCZ) crossed Panama and Colombia into the East Pacific. Strong westerly wind shear inhibited this disturbance initially, but atmospheric conditions improved over subsequent days, allowing it to become the season's first tropical depression around 18:00 UTC on May 17. The system increased rapidly in size as developing high pressure to its north brought it over very warm ocean waters. The depression intensified into Tropical Storm Alma by 18:00 UTC on May 18, attaining peak winds of 60 mph (97 km/h) the next day. After fluctuating in intensity for a few days, Alma weakened to a tropical depression and dissipated after 18:00 UTC on May 21.
Hurricane Boris
A tropical depression developed south of the Gulf of Tehuantepec around 18:00 UTC on May 28. It intensified into Tropical Storm Boris over the next six hours, and further development allowed it to become the season's first hurricane by 12:00 UTC on May 30. After reaching peak winds of 75 mph (121 km/h), Boris weakened and began to move erratically as upper-level troughing progressed over western Mexico. The storm conducted a counter-clockwise loop over numerous days, finally tracking west again as ridging redeveloped to its north. The system, which had persisted as a tropical depression during that time, regained tropical storm intensity on June 13 before crossing into cooler waters. Boris dissipated after 00:00 UTC on June 18 to the southwest of the Baja California Peninsula.
Hurricane Cristina
A weak cold-core low drifted westward across the southern Gulf of Mexico, acting as the impetus for a tropical depression that formed south of Mexico around 06:00 UTC on June 17. The depression intensified into Tropical Storm Cristina within six hours and further organized into a hurricane around 18:00 UTC on June 19. The next day, it attained Category 2 strength with winds of 105 mph (169 km/h). High pressure over Oklahoma, and upper-level troughing over southern California, both retrograded west as Cristina developed. This caused the storm to track in stair-step fashion throughout its duration. The cyclone weakened to a tropical storm on August 21, but it regained hurricane strength two days later before feeling the effects of an upper-level trough off Baja California. Cristina weakened rapidly, dissipating after 00:00 UTC on June 26.
Hurricane Douglas
An area of disturbed weather formed east of Clipperton Island on June 23, organizing into a tropical depression around 00:00 UTC on June 25. The newly developed system moved west-northwest and intensified over warm waters, becoming Tropical Storm Douglas by 18:00 UTC on June 25 and strengthening into a hurricane about 48 hours later. In a 24-hour period ending at 00:00 UTC on June 29, the cyclone's winds increased from 85 to 145 mph (137 to 233 km/h), equivalent to Category 4 intensity. At its peak, Douglas displayed a well-defined eye on satellite imagery. After persisting as an intense hurricane for several days, it encountered waters cooler than 77 °F (25 °C) on July 2 and began to weaken. Douglas crossed into the Central Pacific as a tropical depression the following day, where it ultimately dissipated after 18:00 UTC on July 6. The remnants of the cyclone crossed Maui and the Big Island on July 8–9, where it produced rainfall accumulations up to 2 in (51 mm) over the parched slopes of those islands.
Hurricane Elida
A tropical disturbance formed south of Salina Cruz, Oaxaca, on June 26 and was upgraded to a tropical depression around 00:00 UTC on June 28. By 12:00 UTC the next day, the system intensified into Tropical Storm Elida. Like Douglas before it, Elida entered a period of rapid intensification and became a Category 4 hurricane, peaking with winds of 130 mph (210 km/h). The cyclone fluctuated in intensity before starting a more definitive weakening trend after July 3. Around this time, the steering regime around Elida collapsed, causing the system to backtrack toward the east within low-level flow imparted by Tropical Storm Fausto to the north and Hurricane Genevieve to the east. Tracking over cold waters, the system dissipated after 18:00 UTC on July 8.
Hurricane Fausto
An area of disturbed weather crossed Guatemala into the East Pacific on July 1. It passed over extremely warm waters and rapidly organized accordingly, becoming a tropical depression around 12:00 UTC on July 3 and a tropical storm, Fausto, six hours later. The newly formed cyclone moved northwest, guided by two potent upper-level troughs to its north. Fausto became a hurricane around 18:00 UTC on July 4 and further developed into a Category 2 storm with winds of 110 mph (180 km/h) at 00:00 UTC on July 6. After maintaining hurricane strength until July 8, Fausto entered progressively cooler waters and began to weaken. Ridging became established north of the storm, which curved west and dissipated after 00:00 UTC on July 10.
Hurricane Genevieve
To the southeast of Hurricane Fausto, a new area of disturbed weather formed south of the Gulf of Tehuantepec on July 6. The system coalesced into a tropical depression by 06:00 UTC on July 7; within twelve hours, it became Tropical Storm Genevieve. The system moved northwest parallel to the Mexico coastline, and warm waters facilitated its continued development. Genevieve became a hurricane at 18:00 UTC on July 8 and a major hurricane, with peak winds of 115 mph (185 km/h), 48 hours later. Its forward trajectory soon brought the cyclone over colder waters, and the cyclone began to weaken. It curved north and made landfall about 90 mi (140 km) northwest of Cabo San Lucas, Baja California Sur, at 09:00 UTC on July 14, possessing 35 mph (56 km/h) winds by that point. Genevieve transitioned into an extratropical cyclone three hours later before dissipating.
Tropical Storm Hernan
A tropical depression formed well south of Baja California Sur at 12:00 UTC on July 27. The cyclone moved west-northwest and then west, becoming Tropical Storm Hernan by 00:00 UTC on July 28. Unlike previous storms before it, Hernan encountered a less conducive environment of cool waters and wind shear. It reached peak winds of 50 mph (80 km/h) on July 29, thus ending a string of East Pacific hurricanes. Hernan slowly succumbed to hostile conditions and dissipated after 00:00 UTC on August 1.
Hurricane Iselle
A tropical disturbance drifted into the Gulf of Tehuantepec on August 3 and organized into a tropical depression around 18:00 UTC that day. A potent upper-level trough dug southward into the coastal waters of California, creating a steering pattern that shunted the system northwest. The depression intensified into a tropical storm 24 hours after formation, a hurricane by 06:00 UTC on August 6, and a major hurricane around 12:00 UTC on August 8. Six hours later, Iselle became a Category 4 cyclone with winds of 130 mph (210 km/h). The system soon encountered ocean waters of 72–75 °F (22–24 °C) and weakened to the west of Baja California, dissipating after 12:00 UTC on August 12.
As the cyclone passed offshore, small craft warnings were enacted along the Mexico coastline. Some street flooding was reported in Acapulco, Guerrero. Farther north in western Texas, moisture from Iselle collided with cooler air from the north, causing thunderstorms and heavy rainfall. Up to 1.75 in (44 mm) fell in El Paso. Flash flood watches had been hoisted across several counties, and minor street flooding was reported in both El Paso and Juarez. Some mountain roads were impassable. A girl was killed when her normally dry home in a creekbed was overwhelmed by a flood. One person was also injured by lightning. At beaches in Orange County, California, waves up to 13 ft (4.0 m) necessitated numerous lifeguard rescues. Some 385 rescues occurred in Newport Beach, while an additional 50 people were saved at San Clemente; rescues more than tripled the average at Huntington Beach.
Tropical Storm Julio
At 00:00 UTC on August 15, a new tropical depression formed south of Acapulco. High pressure, extending across Mexico from the Gulf of Mexico, directed the system west-northwest. It strengthened into Tropical Storm Julio eighteen hours later and soon peaked with winds of 65 mph (105 km/h). An expansive upper-level outflow setup was disrupted by an increase in wind shear, which caused Julio to weaken despite warm ocean waters. The center dissipated about halfway between Socorro Island and Cabo Corrientes, Jalisco, after 12:00 UTC on August 20.
Hurricane Keli
In mid-August, an area of disturbed weather persisted within the ITCZ across several days. It definitively organized into Tropical Depression One-C around 18:00 UTC on August 16, becoming Tropical Storm Keli six hours later. The storm moved well to the south of the Hawaiian Islands, but it intensified rapidly on a course toward Johnston Atoll. Keli became a hurricane around 06:00 UTC on August 8 and a major hurricane, with peak winds of 115 mph (185 km/h), when a reconnaissance aircraft intercepted it about 48 hours later. A nearby upper-level trough began to shear Keli, directing its convection to the north; low-level flow, meanwhile, forced the storm's actual center westward. The system passed about 70 mi (110 km) southwest of Johnston Atoll, where an evacuation had been ordered. About 1 in (25 mm) of rainfall and wind gusts to 39 mph (63 km/h) were recorded there. The system dissipated after 00:00 UTC on August 22.
Tropical Storm Kenna
An area of disturbed weather crossed Panama on August 7. It moved on a persistent westerly course under ridging that extended from California to the Hawaiian Islands. The system organized into a tropical depression over the far western reaches of the East Pacific basin around 18:00 UTC on August 16. Six hours later, it strengthened into Tropical Storm Kenna. On August 18, the cyclone crossed into the Central Pacific, attaining maximum winds of 60 mph (97 km/h) as estimated by a reconnaissance aircraft despite a generally disheveled presentation on satellite imagery. Gradual weakening occurred thereafter, and Kenna degenerated to a remnant low after 18:00 UTC on August 21. The remnants of the cyclone curved northwest and moved across the Big Island of Hawaii, producing rainfall accumulations of 6–8 in (150–200 mm) across its windward districts. These rains were beneficial during an ongoing drought.
Tropical Storm Lala
An area of vigorous thunderstorm activity developed within the ITCZ over the open East Pacific on August 21. It moved west-northwest and acquired a well-defined circulation, thus becoming a tropical depression around 18:00 UTC on August 23. The system crossed into the Central Pacific early on August 26. Four days later, a reconnaissance aircraft intercepted the cyclone for the first time, finding winds of 50 mph (80 km/h) and supporting the system's upgrade to Tropical Storm Lala. Lala tracked to the south of the Hawaiian Islands and Johnston Atoll, dissipating after 18:00 UTC on September 2.
Hurricane Lowell
A tropical wave entered the Gulf of Tehuantepec on August 22. The system moved rapidly westward amid a favorable combination of low wind shear and warm ocean waters. It became a tropical depression around 06:00 UTC on August 26, coalesced into Tropical Storm Lowell twelve hours later, and intensified into a hurricane by 18:00 UTC on August 27. The next day, Lowell acquired peak winds of 85 mph (137 km/h). It later encountered cooler waters, which caused the cyclone to dissipate after 06:00 UTC on August 30. As a hurricane, Lowell clipped the 350 ft (110 m) freighter Blue Falcon, cracking its bow and forcing the rescue of 23 crewmembers.