1990 Pacific hurricane season
The 1990 Pacific hurricane season was a very active season which observed 21 named storms within the basin. The season also produced the fourth highest ACE index value on record. The season was officially started on May 15 in the eastern Pacific, and on June 1 in the central Pacific, and lasted until November 30. These dates conventionally delimit the period of each year when most tropical cyclones form in the northeastern Pacific Ocean. However, the formation of tropical cyclones is possible at any time of the year, as illustrated in 1990 by the formation of the season's first named storm, Hurricane Alma, on May 12. At the time, this was the earliest formation of a tropical storm on record in the eastern Pacific.
Overall, the impact of this season was minimal. Tropical Storm Rachel made two landfalls in Mexico and brought rain to the United States. Hurricane Boris brought light showers to California.
Seasonal summary
The 1990 eastern North Pacific hurricane season was active in terms of number of storms that attained at least tropical storm intensity and of Accumulated Cyclone Energy. All of the tropical cyclones of this year developed from westward-moving African tropical waves. The season established several tropical storm records for this basin and was marked by several strong hurricanes. There were 21 named tropical cyclones, seven below the record established by the 1992 Pacific hurricane season two years later, but four more than the long-term average. Sixteen of those named storms, twice the average and four more than the previous record, reached hurricane intensity. Only Cristina, Douglas, Aka, Rachel, and Simon did not reach hurricane strength. Six of those hurricanes reached Category 3 intensity or higher on the Saffir-Simpson Hurricane Scale. Hurricanes Hernan and Trudy were among the strongest ever observed in this area. Alma became the earliest named storm and hurricane in the satellite era in the eastern Pacific Ocean east of the 140th meridian west at the time; a record subsequently eclipsed by Adrian in 2017. The eastern Pacific produced four tropical depressions that did not reach tropical storm status.With the exception of Marie and Polo, these systems developed between 5° and 15°N, east of the longitude of Baja California Peninsula in the climatologically favored area for tropical cyclogenesis in the basin. After their development, most of the tropical cyclones moved on a west to northwest track and dissipated over cool waters without affecting land. Rachel was the only system to make landfall. In addition, one tropical storm formed in the Central Pacific and eventually crossed the International Dateline before dissipating.
The Accumulated Cyclone Energy index for the 1990 Pacific hurricane season as calculated by Colorado State University using data from the National Hurricane Center was 249.5 units, the fourth highest ACE on record for a Pacific hurricane season.
Systems
Hurricane Alma
A tropical wave emerged from Africa on April 29. It then moved across the Atlantic, crossed northern South America, and entered the Pacific Ocean on May 9. Convection started to increase with the wave just to the south of Panama. The wave moved westward and continued to become better organized over the next few days. On May 12, the wave had become organized enough and was designated Tropical Depression One-E.Tropical Depression One-E moved slowly to the northwest while strengthening slowly due to easterly vertical wind shear. The depression was upgraded to Tropical Storm Alma on May 14. The storm quickly strengthened once the vertical wind shear relaxed and was near hurricane force by the morning of May 15. Hurricane Alma reached its peak intensity early on May 16 with maximum sustained winds of. The hurricane entered an area of southwesterly wind shear caused by an upper-level ridge of high pressure. The increasing vertical wind shear and cooler water caused Alma to weaken to a tropical storm. On May 17, the storm continued to weaken and became a depression. The next day, the system dissipated as a tropical cyclone well west of mainland Mexico.
Hurricane Boris
A tropical wave came off the northwest coast of Africa on May 20. The wave did not significantly develop as it moved west across the Atlantic Ocean and Caribbean Sea. Once it crossed Central America into the eastern Pacific Ocean, cloudiness increased considerably with the system on May 31. It became well-enough organized to be upgraded to Tropical Depression Two-E on June 2. After becoming a depression, the system moved to the west-northwestward. Upper-level easterly vertical wind shear limited the amount of the initial strengthening. However, an increase in convective banding led to its upgrade to Tropical Storm Boris on June 4, southwest of Manzanillo. Further strengthening occurred due to an anticyclone aloft fostered additional development, and by June 5, Boris became a hurricane. The hurricane began to move to the north-northwest in response to a trough off of the West Coast of the United States. Strengthening continued, and the storm reached its peak strength with winds of and a minimum central pressure of. The hurricane's cloud pattern became elongated along a southwest–northeast axis on June 6 due to an increased amount of vertical wind shear. Boris was downgraded to a tropical storm later in the day on June 6. The deep convection of the tropical storm decreased, as Boris moved over cooler waters. It was downgraded to a tropical depression on June 7 due to these factors. The depression dissipated as a tropical cyclone on June 8 as the system quickly lost its tropical characteristics. A small circulation remained in the cloud field offshore the northwest coast of Baja California for a few more days.The winds in the eyewall of Boris ripped off the sails of the Azure Dream sailboat. Outer rainbands from the storm produced moderate rain in several Mexican states. In Mexico, rainfall peaked at near San Lucas, Michoacán. The remnants of Boris also brought sporadic rainfall over the western United States, with precipitation being reported in Arizona, California, Colorado, Nevada and Wyoming. The remnants of Boris were responsible for causing the wettest June in San Diego since records began in 1850; however, not even of rain fell at that location. Rainfall from the remnant system in the United States peaked at over the Santa Rita Mountains. No other direct damages or casualties were reported from Boris.
Tropical Storm Cristina
A tropical wave emerged into the Atlantic Ocean off the coast of Africa on May 28. The wave moved across Central America into the northeastern Pacific Ocean, where convection organized with the system on June 6. The system became well-enough organized to be upgraded to Tropical Depression Three-E on June 8, while south of the southern tip of Baja California. The depression continued to strengthen, and was upgraded to Tropical Storm Cristina on June 9.Cristina initially had well-established upper-level outflow. It failed to reach hurricane status, peaking with maximum sustained winds of due to movement of its associated upper-level anticyclone to the north over Mexico which caused Cristina to be exposed to easterly vertical wind shear. Cristina moved generally northwestward, which eventually placed the storm in cooler waters, and caused the deep convection of the system to dissipate. On June 14, Cristina diminished to a tropical depression. Cristina moved west-northwestward with the low-level flow. The depression dissipated as a tropical cyclone on June 16, after a lack of deep convection for 48 hours.
Tropical Storm Douglas
A tropical wave moved off the northwest coast of Africa on June 5. It continued westward across the tropical North Atlantic and Caribbean Sea without significant development. The wave entered the northeastern Pacific Ocean on June 16, where it generated an area of increased cloudiness. Organization of thunderstorm activity increased late on June 18 and early on June 19. Tropical Depression Four-E formed on June 19, when it was south of Acapulco after evidence of low-level circulation for the past 24 hours. The depression moved in a west-northwest direction, due to a subtropical ridge north of the depression. Satellite analysis indicated that the depression had reached tropical storm force strength, and it was upgraded to Tropical Storm Douglas on June 19, while southwest of Acapulco. Douglas reached peak strength of on June 21A tropical storm warning was issued on June 21, from Punta Tejupan to Cabo Corrientes before being discontinued on June 22. Tropical Storm Douglas brushed the western coast of Mexico. The center of circulation approached within of the coast of Mexico on June 22. Douglas then began to weaken because of interaction with the mountainous terrain of Mexico. The system continued to weaken despite warm water temperatures and favorable upper-level conditions. Douglas dissipated early on June 24, while south-southeast off the southern tip of Baja California Sur. The highest rainfall report from Mexico from Douglas totaled at La Huerta. No deaths or damage were reported.
Hurricane Elida
A tropical wave came off the coast of Africa into the eastern Atlantic Ocean on June 10 and 11. The system moved across the Atlantic and entered into the northeastern Pacific Ocean. The wave became a significant tropical system, with cyclonic turning in the lower and middle layers of the system's cloudiness on June 25. The center of circulation was located south of Acapulco, Mexico. The system exhibited sufficient organization to be considered Tropical Depression Five-E on June 26. The depression quickly strengthened and became Tropical Storm Elida later that day. The track of Elida was west-northwestward to northwestward from June 27 through June 28. Some rainbands moved over the mountainous region of southwestern Mexico, but no flooding, damage, or casualties were reported as a result. Elida continued strengthening and it was upgraded to a hurricane early on June 28 passing directly over Socorro Island later in the day, right as Elida reached peak strength of, dropping of rain on the island. Some windows broke also as a result, and minor structural damage was reported as a result on the island.A high-pressure area to the north forced Elida to move more westward on June 29. Convection began to decrease in the hurricane as it moved into cooler waters, and it weakened to a tropical storm later in the day. It then weakened to a tropical depression on July 1, and dissipated on July 2.