The 1999 Pacific hurricane season was one of the least active Pacific hurricane seasons on record. The season officially began on May 15 in the Eastern Pacific, and on June 1 in the Central Pacific; in both basins, it ended on November 30. These dates conventionally delimit the period during which most tropical cyclones form in the northeastern Pacific Ocean. The first tropical cyclone of the season, Hurricane Adrian, developed on June 18, while the final storm of the season, Tropical Storm Irwin, dissipated on October 11. No storms developed in the Central Pacific during the season. However, two storms from the Eastern Pacific, Dora and Eugene, entered the basin, with the former entering as a hurricane and becoming the second farthest travelling Pacific hurricane on record.
The season produced fourteen tropical cyclones and nine named storms, which was well below the average of sixteen named storms per season; this was largely due to a strong La Niña taking over much of the Pacific. However, the total of six hurricanes and two major hurricanes during the season was near the averages of eight and three, respectively. Although it remained offshore, Hurricane Adrian caused 6 deaths from flooding and rough surf in Mexico. The deadliest tropical cyclone, Hurricane Greg, killed 10 people from flooding in Mexico.
Seasonal summary
The 1999 Pacific hurricane season officially started on May 15, 1999 in the eastern Pacific, and on June 1, 1999, in the central Pacific, and lasted until November 30, 1999. These dates conventionally delimit the period of each year when most tropical cyclones form in the northeastern Pacific Ocean. The 1999 Pacific hurricane season was well below average, due to the strong La Niña that was occurring at the time, which causes wind shear to be increased and water temperatures to decrease, resulting in conditions less conductive for tropical cyclones in the East Pacific. There were 14 cyclones in total, including 5 unnamed tropical depressions. Of these, 9 became a tropical storm, while 6 reached hurricane status. Further, 2 of these became major hurricanes, which is Category 3 intensity or higher on the Saffir-Simpson hurricane scale.
Tropical cyclogenesis began with Hurricane Adrian, which developed on June 18. Although it remained offshore, Adrian brought rough surf and flooding to Mexico, which resulted in 6 fatalities. The storm peaked as a Category 2 before dissipating on June 22. No other tropical cyclones formed in June. Activity halted until July 9, when Hurricane Beatriz developed. Though it peaked as a Category 3 hurricane before dissipating on July 17, the storm caused no damage on land because it remained well offshore. The next system, a short-lived Tropical Depression Three-E, did not result in impact as a tropical cyclone, though the precursor brought heavy rainfall and gusty winds to Central America. Tropical Depression Four-E, was the first of three cyclones to cross into the Central Pacific Hurricane Center's area of responsibility, which is between 140°W and the International Date Line. Two other short-lived system in July, Tropical Storm Calvin and Tropical Depression Six-E, caused no damage.
In August, Hurricane Dora, the strongest storm of the 1999 Pacific hurricane season, produced gusty winds and large waves on Johnston Atoll and the island of Hawaii, though minimal damage was left in its wake. After crossing the International Date Line on August 20, Dora became the first tropical cyclones to exist in all three basins of the North Pacific – Eastern, Central, and Western – since Hurricane John in 1994. Hurricane Eugene also existed in the Eastern and Central Pacific, but dissipated on August 15 while south of the main Hawaiian Islands, well before reaching the International Date Line. Nonetheless, it produced up to of rainfall on the Big Island of Hawaii. In the remainder of August, there was a series of short-lived tropical cyclones that did not effect land, including Tropical Depression Nine-E, Tropical Storm Fernanda, and Tropical Depression Eleven-E.
During the month of September, the deadliest tropical cyclone of the season, Hurricane Greg, was spawned near the Pacific coast of Mexico. Greg which killed 10 people when it made landfall on southern Baja California. The hurricane and its precursor produced heavy rainfall across much of Mexico, with the highest total reaching . The heavy rains damaged or destroyed more than 2,000 homes. The remnant moisture from the system, combined with an area of low pressure, resulted in strong thunderstorms across California, which led to numerous power outages, damage to homes and vehicles, and started many wildfires. The other in the month of September was Hurricane Hilary, a storm that approached Baja California, but dissipated offshore on September 21, resulting in no impact. The final system, Tropical Storm Irwin, produced scattered areas of heavy rainfall over Mexico in October, but caused no significant flooding. It dissipated on October 11, over a month and a half before the official end of the season on November 30.
In addition to the systems observed by the CPHC and NHC, a tropical depression formed east of the International Dateline on August 19, and quickly exited CPHC's area of responsibility; however, this storm was not included into CPHC database.
Systems
Hurricane Adrian
In mid-June, a broad cyclonic area of cloudiness persisted to the south of the Gulf of Tehuantepec. A low-level circulation and banding features became more prominent on June 16, and further development was aided by the presence of a tropical wave that first departed the western coastline of Africa on June 5. As extremely deep convection festered within a band west of the disturbance's center, it is estimated the first tropical depression of the season formed around 06:00 UTC on June 18, located about 260 mi (420 km) southeast of Acapulco, Mexico. The newly-formed cyclone tracked west-northwest parallel to the coastline, steered by a strong area of high pressure to its north and east. Moderate easterly wind shear that had been affecting the developing system began to relax almost immediately after formation, allowing upper-level outflow to expand in most directions and the depression to intensify into Tropical Storm Adrian. A small central dense overcast materialized early on June 19, followed shortly thereafter by hints of an eye-like feature. Thus, in accordance with increasing satellite intensity estimates, Adrian was upgraded to the season's first hurricane by 00:00 UTC on June 20 while located about 485 mi (780 km) south-southeast of the southern tip of the Baja California Peninsula. The storm further organized to attain its peak as a Category 2 hurricane with winds of 100 mph (160 km/h) as the aforementioned eye-like feature became readily apparent in satellite imagery. Following peak intensity, Adrian's cloud pattern became less symmetric, its eye became obscured, and its convection warmed as southeasterly wind shear increased and the storm passed over ocean temperatures near 77 °F (25 °C). The storm slowed as it passed near Socorro Island, all the while the continued unfavorable regime weakened Adrian and stripped it of its all convection. The system was reduced to an exposed swirl of clouds over the open East Pacific by late on June 22.
In preparation for the cyclone, the port of Acapulco was closed to all vessels. The government of Michoacán organized shelters to house up to 5,000 people, while surrounding states were placed on alert. Along the southern coastline of Chiapas, four people were swept away and drowned by a large wave, while farther inland in northwestern Durango, two men died and a five-year-old girl went missing after attempting to cross a river in a pick-up truck. Along the central coastline of Michoacán, a powerful hailstorm demolished many homes and left around 2,000 people homeless. A 1.2 mi (2 km) stretch of coastal road was ruined in the city of Tecomán. The outer bands of the hurricane produced heavy rainfall peaking at 15.75 in (400 mm) in the municipality of Coyutla; minor flooding was reported across Coahuila and Colima. Two highway bridges and a railway bridge were damaged by flooding near the Guatemala border. Passing very near Socorro Island on June 21, Adrian produced peak winds of 45 mph (72 km/h) there, potentially damaging weather monitoring equipment.
Hurricane Beatriz
A tropical wave developed into by 0600 UTC on July 9, while situated roughly south of Lázaro Cárdenas, Mexico. At this time, the depression was in an environment of strong upper-tropospheric outflow, resulting in gradual intensification. The depression was upgraded to Tropical Storm Beatriz at 1200 UTC on July 9. Steady strengthened continued and about 48 hours later, Beatriz became a Category 1 while situated roughly south-southwest of Cabo San Lucas. Moving westward around the southern periphery of a ridge to the north, it continued to intensify. A well-defined eye became visible on satellite imagery early on July 12. Microwave imagery a few hours later revealed that Beatriz was likely undergoing an eyewall replacement cycle and was complete by 1700 UTC.
Further intensification occurred, and Beatriz became the first major hurricane of the season at 1800 UTC on July 12. At 0600 UTC the following day, the hurricane attained its peak intensity with winds of and a minimum barometric pressure of while situated roughly southwest of Cabo San Lucas. Curving towards the west-northwest, Beatriz began to encounter an area of cooler sea surface temperatures, which led to gradual weakening. The hurricane weakened to a tropical storm at 0000 UTC on July 16, and further to a tropical depression by 1800 UTC that day. At 0600 UTC on July 17, Beatriz degenerated into a swirl of clouds.
Tropical Depression Three-E
A tropical wave moved across the Atlantic and Caribbean in early July. While crossing Central America on July 11 and July 12, the system produced gusty winds and heavy rainfall, especially in Honduras, Nicaragua, and Mexico, where precipitation reached in Coyutla, Veracruz. By July 13, the wave and associated low pressure area emerged into the Pacific Ocean. The system organized further and developed into Tropical Depression Three-E at 1200 UTC on July 14, while located about west-southwest of Manzanillo, Mexico. It initially headed west-northwestward until July 15, when it curved west-southwestward. The depression failed to strengthen further and dissipated at 1800 UTC on July 15, while located about southwest of Cabo San Lucas, Mexico.
Tropical Depression Four-E
On July 15, a tropical wave entered the eastern Pacific Ocean. Over the following days, slow organization occurred, and it is estimated that the system became developed into Tropical Depression Four-E at 0000 UTC on July 23. Later that day, the depression reached its peak intensity with maximum sustained winds of and a minimum barometric pressure of , having failed to reach tropical storm status. While moving westward, the depression entered the Central Pacific Hurricane Center's area of responsibility on July 24. By this time, however, the depression was already becoming disorganized and dissipated early on the following day.
Tropical Storm Calvin
A tropical wave crossed the Atlantic Ocean and Caribbean Sea between early and mid-July. Later in the month, the wave acquired a low-level circulation. Thus, Tropical Depression Five-E developed at 0600 UTC on July 25, while situated about south-southwest of Cabo San Lucas. Due to further organization on satellite imagery, the depression was upgraded to Tropical Storm Calvin six hours later. However, wind shear exposed the low-level circulation and halted intensification. Calvin continued west-northwestward as a sheared cyclone.