1999 Pacific hurricane season

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, however, this storm was not included into CPHC database.

Systems

Hurricane Adrian

A broad area of low pressure developed into Tropical Depression One at 0600 UTC on June 18, while situated southeast of Acapulco, Guerrero. Moving towards west-northwestward, the depression intensified into Tropical Storm Adrian about 12 hours later. Favorable levels of wind shear and warm sea surface temperatures (SST's) caused the storm to strengthen further. Early on June 20 Adrian intensified into a hurricane, while located about south-southeast of the southern tip of Baja California. About 24 hours later, Adrian reached its peak intensity with winds of and a minimum barometric pressure of .

After reaching peak intensity on June 21, Adrian began weakening due to colder SST's and higher wind shear. Adrian fell to tropical storm status late on June 21, and further weakened to a tropical depression on June 22. Six hours later at 1800 UTC, Adrian degenerated into a swirl of low clouds while situated southwest of the southern tip of Baja California. Heavy rainfall produced from the storm caused minor flooding throughout Mexico. Two fatalities were directly attributed to the floods, while another person was listed as missing. Four other people were killed when they drowned in rough seas produced offshore the Mexican coastline. There is no damage estimate from the heavy rainfall or rough seas associated with the hurricane.

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. 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. By this time, however, the depression was already becoming disorganized and dissipated early on the following day.

According to satellite classifications, it is estimated that Calvin weakened back to a tropical depression at 0600 UTC on July 26. There was a convective burst late on July 26, though the storm did not re-strengthen. Around that time, Calvin turned northwestward in response to a mid-tropospheric trough. The burst in convection did not persist and the depression dissipated by 1200 UTC on July 27, while located well west-southwest of Baja California. A low-cloud swirl remained and subsequently continued on a west-northwesterly course for a few days.

Hurricane Dora

A tropical wave moved off Africa on July 23 and crossed the Atlantic Ocean without development. However, the wave quickly increased in organization after entering the Eastern Pacific Ocean on August 4, and was designated Tropical Depression Seven-E on August 6. The depression strengthened into Tropical Storm Dora later that day. Dora continued to intensify despite upper-level wind shear, and became a hurricane on August 8. Shortly after, the hurricane moved westward into a more favorable environment and began to intensify more quickly, reaching Category 4 strength on August 10. It maintained that intensity for three days as it moved almost due west.

Dora weakened to Category 1 strength as it entered the Central Pacific Hurricane Center's area of responsibility on August 14. However, it briefly restrengthened into a Category 3 as it passed south of Hawaii on August 16. Dora then began weakening for the final time as it passed south of Johnston Atoll on August 18. On August 20, Dora crossed the International Date Line, while weakening to a tropical storm. Due to vertical wind shear, it did not re-strengthen in the western Pacific basin. The storm weakened more, falling to tropical depression intensity early on August 22. Dora dissipated late on the following day, while situated several hundred miles east of Wake Island.

Eugene continued westward, and on August 11, it entered the Central Pacific Hurricane Center's area of responsibility. It continued to weaken and was downgraded to a tropical storm early on August 13. Eugene passed south of the Hawaiian Islands on August 14, with minimal impact noted. Minor surf occurred along the east and southeast shores of the Big Island. Additionally, 24‑hour rainfall totals over windward sections of Maui and the Big Island were near . The storm weakened to a tropical depression by late on August 14. At 0000 UTC on August 16, Eugene dissipated while located about southeast of Johnston Atoll.

Tropical Storm Fernanda

A tropical wave developed into Tropical Depression Ten-E at 0600 UTC on August 17, while located about in south-southwest of Socorro Island, Mexico. The depression intensified gradually due to favorable conditions. At 0000 UTC on August 18, the cyclone was upgraded to Tropical Storm Fernanda while centered about southwest of Socorro Island. The storm continued to slowly strengthened and 1200 UTC on August 19, Fernanda attained its peak intensity with maximum sustained winds of and a minimum barometric pressure of .

Around the time of peak intensity on August 19, Fernanda curved west-southwest track, a motion which persisted for the remainder of its duration. While this track carried the storm over warmer SST's, increasing easterly wind shear caused Fernanda to weaken. By early on August 21, Fernanda weakened to a tropical depression. After weakening slightly further, the storm degenerated into a remnant low cloud swirl at 0000 UTC on August 23. The remnants of Fernanda persisted until finally losing its identity about west-southwest of Socorro Island on August 28. The highest rainfall total reported in Mexico was at Los Cabos, Baja California Sur.

Hurricane Greg

The northern portion of a tropical wave in the Atlantic spawned Tropical Storm Emily, while the southern portion headed westward and crossed Central America between August 31 and September 1. Thereafter, the system emerged into the Pacific Ocean and began to organize. By 1200 UTC on September 5, Tropical Depression Twelve-E developed near Manzanillo, Mexico. Six hours later, the depression strengthened into Tropical Storm Greg. Further intensification occurred, and late on September 6, Greg was upgraded to a hurricane as winds reached . However, Greg weakened to a tropical storm on September 7, while approaching Baja California. At 2100 UTC that day, it made landfall near Cabo San Lucas. The storm then curved westward and weakened over colder SST's, until dissipating on late September 9.

Both Gerg and its predecessor disturbance brought heavy rain to much of Mexico. The highest report was of in Tecomán, Colima. Precipitation from Greg caused flooding in the states of Colima, Michoacán, Sinaloa, Nayarit, and Jalisco. It was most severe along the Los Mezcales River. The flooding killed ten people. In addition, 2,000 people were rendered homeless and 2,000 others were affected in some way. The remnants of Greg produced thunderstorms in California, particularly the San Francisco Bay Area. As a result, there was widespread power outages and isolated damage to houses and vehicles, as well as causing several small wildfires. Overall damage was relatively limited, however.

Hurricane Hilary

A tropical wave moved off the coast of western Africa into the Atlantic Ocean on August 29. It continued to move westward through the tropical waters of the Atlantic into the Caribbean. It still remained a tropical wave as it moved over Central America and began to acquire more convection and organization, from September 10 through September 11. Visible satellite imagery showed low level circulation and more organized deep convection as it became a tropical depression on September 17, while located about south-southeast of the southern tip of the Baja California Peninsula.

Tropical Storm Irwin

The southern portion of the tropical wave that previously spawned Tropical Depression Eleven in the Gulf of Mexico entered the Pacific Ocean in early October. After becoming better organized, the system developed into Tropical Depression Fourteen-E at 1200 UTC on October 8, while situated about south-southwest of Manzanillo, Mexico. The depression initially moved slowly north-northwestward and strengthened into Tropical Storm Irwin about six hours later. After a strong mid-tropospheric ridge developed over northern Mexico, Irwin moved northwestward and remained offshore Mexico.

Early on October 9, the center of the storm passed within about of the coastline between Manzanillo and Cabo Corrientes.

Storm names

The following list of names was used for named storms that formed in the North Pacific Ocean east of 140°W in 1999. This is the same list used for the 1993 season. No names were retired from this list by the World Meteorological Organization following the season, and it was used again for the 2005 season.

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Adrian
Beatriz
Calvin
Dora*
Eugene*
Fernanda
Greg
Hilary

Irwin

For storms that form in the North Pacific between 140°W to the International Date Line, the names come from a series of four rotating lists. Names are used one after the other without regard to year, and when the bottom of one list is reached, the next named storm receives the name at the top of the next list.

Season effects

This is a table of all of the tropical cyclones that formed in the 1999 Pacific hurricane season. It includes their name, duration (within the basin), peak classification and intensities, areas affected, damage, and death totals. Deaths in parentheses are additional and indirect (an example of an indirect death would be a traffic accident), but were still related to that storm. Damage and deaths include totals while the storm was extratropical, a wave, or a low, and all of the damage figures are in 1999 USD.

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References

External links

NHC 1999 Pacific hurricane season archive
HPC 1999 Tropical Cyclone Rainfall pages
Central Pacific Hurricane Center archive