The 2006 Pacific hurricane season was the first above-average season since 1997 which produced twenty-five tropical cyclones, with nineteen named storms, though most were rather weak and short-lived. There were eleven hurricanes, of which six became major hurricanes. Following the inactivity of the previous seasons, forecasters predicted that season would be only slightly above active. It was also the first time since 2003 in which one cyclone of at least tropical storm intensity made landfall. The season officially began on May 15 in the East Pacific Ocean, and on June 1 in the Central Pacific; they ended on November 30. These dates conventionally delimit the period of each year when most tropical cyclones form in the Pacific basin. However, the formation of tropical cyclones is possible at any time of the year.
Seasonal activity began on May 27, when Tropical Storm Aletta formed off the southwest coast of Mexico. The season became active in July when five named storms developed. These included Hurricane Daniel, which was the second strongest storm of the season, as well as Tropical Storm Emilia. During August, Hurricanes Ioke and John formed, as well as four other storms. The strongest storm of the season was Hurricane Ioke, which reached Category 5 status on the Saffir–Simpson scale in the central Pacific Ocean; Ioke passed near Johnston Atoll and later Wake Island, where it caused heavy damage. The deadliest storm of the season was Hurricane John, which killed six people after striking the Baja California Peninsula, and the costliest storm was Hurricane Lane, which caused $203 million in damage in southwestern Mexico (2006 USD, $324 million 2026 USD). Damage across the basin reached $355.1 million (2006 USD), while 14 people were killed by the various storms.
Seasonal forecast
On May 22, 2006, the National Oceanic and Atmospheric Administration's (NOAA) CPC (CPC) released their forecasts for the 2006 Atlantic and Pacific hurricane seasons. The Pacific season was expected to be hindered by the decades-long cycle that began in 1995, which generally increased wind shear across the basin. NOAA predicted a below-normal level of activity in the Eastern Pacific, with 12–16 named storms, of which 6–8 were expected to become hurricanes, and 1–3 expected to become major hurricanes. The Central Pacific Hurricane Center's area of responsibility was also expected to be below average, with only two to three tropical cyclones expected to form or cross into the area. They expected that neither El Niño nor La Niña would affect conditions significantly.
On May 15, the hurricane season began in the Eastern Pacific basin, which is the area of the northern Pacific Ocean east of 140°W. On June 1, the season began in the Central Pacific warning zone (between 140°W and the International Date Line); however, no storms occurred in the region until July.
Seasonal summary
The accumulated cyclone energy (ACE) index for the 2006 Pacific hurricane season as calculated by Colorado State University using data from the National Hurricane Center was 156.9 units. Broadly speaking, ACE is a measure of the power of a tropical or subtropical storm multiplied by the length of time it existed. Therefore, a storm with a longer duration, such as Hurricane Ioke, which arrived with a total of 32.2250 units and then crossed to the Western Pacific, will have high values of ACE. It is only calculated for full advisories on specific tropical and subtropical systems reaching or exceeding wind speeds of 39 mph (63 km/h).
Overall, there were 19 tropical storms. In addition, 11 hurricanes developed. Furthermore, there were total of six major hurricanes, Category 3 or greater on the Saffir–Simpson hurricane wind scale. The season officially started on May 15 in the East Pacific Ocean, and on June 1 in the Central Pacific; they both ended on November 30. No tropical storms developed in June in the basin, which was unusual compared to the average of two storms forming during the month.
From 1966 to 2008, there have been only three other seasons in which a tropical storm did not form in June, these being 1969, 2004, 2007 seasons. After such an inactive month, the tropics became active in July when five named storms developed, including Hurricane Daniel which was the second strongest storm of the season. During August, Hurricanes Ioke and John formed, as well as four other storms. September was a relatively quiet month with two storms, of which one was Hurricane Lane. By that time, however, El Niño conditions became established across the Pacific, which is known to enhance Pacific hurricane activity. Three storms developed in October, including Hurricane Paul. Tropical activity within the basin in November 2006 was the most active on record, based on the ACE Index. Three tropical cyclones formed, of which two became tropical storms; only one other season on record at the time, 1961, produced two tropical storms in the month of November. In addition, Mexico was struck by four tropical cyclones in 2006, none on the Atlantic coast and all along the Pacific coast. One hit Baja California Peninsula while the others made landfall on the mainland.
An extratropical storm persisted in the extreme northern central Pacific Ocean in late October. It drifted over unusually warm waters up to 3.6 °F (2 °C) above normal, and gradually developed convection near the center. By November 2, QuikSCAT satellite suggested the system attained winds of up to 60 mph (95 km/h) about 900 mi (1,450 km) west of Oregon. The system also developed an eye and an eyewall. The cyclone tracked northeastward as it gradually weakened, and dissipated on November 4. NASA considered the cyclone to be a subtropical storm. However, as it formed outside of the territory of any monitoring organization, it was not named. Operationally, the United States Navy treated the system as a tropical disturbance, numbered 91C.
Systems
Tropical Storm Aletta
The first storm of the year had its genesis from a tropical wave that crossed Central America and entered the East Pacific on May 21. The system interacted with a trough near the Gulf of Tehuantepec, causing thunderstorms to increase. A large low-pressure area formed on May 25 south of Mexico, which organized slowly due to wind shear in the region. Early on May 27, the NHC designated the system as Tropical Depression One-E about 190 mi (305 km) south of Acapulco. The nascent storm moved little, and the wind shear displaced the center west of the convection. Late on May 27, the NHC upgraded the depression to Tropical Storm Aletta. While named tropical cyclones in May are infrequent events, Aletta marked the seventh consecutive year to have a named cyclone form in May. The storm drifted for several days off the southern coast of Mexico. The NHC estimated peak winds of 45 mph (70 km/h) on May 28, as the storm presented an elongated cloud structure. Increased wind shear and dry air caused weakening on May 29, and Aletta weakened into a tropical depression. Drifting westward, the system became a remnant low on May 31, and dissipated soon afterward.
The storm moved toward the Guerrero coast in southwestern Mexico, prompting the Mexican government to issue tropical storm watches between Punta Maldonado and Zihuatanejo. Aletta produced moderate rainfall across Mexico, including a 24-hour rainfall total of 100 mm (3.9 in) in Jacatepec, Oaxaca, on May 30, and 96 mm (3.8 in) in La Calera, Guerrero, on the next day. High winds knocked down trees and caused minor structural damage. In Zihuatanejo, a ship with nine people was rescued after being reported as lost, which may have been a result of high seas generated by Aletta.
Tropical Depression Two-E
On the day after Aletta dissipated, a new area of disturbed weather developed off the southwest Mexican coast, associated with a tropical wave. High shear slowed the development of the system, although the thunderstorms eventually organized around a closed circulation. On June 3, the system developed into Tropical Depression Two-E about 140 mi (240 km) southwest of the Mexican coast. Land interaction and the presence of wind shear prevented much development. Early on June 4, convection weakened significantly, leaving the center partially exposed. Early on June 5, the circulation dissipated, and later that night the remnants moved inland.
Due to uncertainty in whether the depression would attain tropical storm status or not, the government of Mexico issued a tropical storm warning from Punta San Telmo, Michoacán to Acapulco, Guerrero. Prior to affecting the coastline, the Mexican meteorological agency issued a heavy rainfall advisory, also mentioning the potential for flooding and mudslides, for the states of Jalisco, Colima, Michoacán, Guerrero, and Oaxaca. Officials prepared 21 shelters in the region. The depression produced heavy rainfall along the coastline, including a total of 19.1 inches (486 mm) measured in a 48‑hour period in Acapulco. Totals of over 2 inches (50 mm) spread across much of Guerrero and Oaxaca, causing flash flooding and mudslides. The storm partially flooded about 40 houses, and a total of 72 people were forced to leave their homes. In Acapulco, floodwaters washed trash from street corners onto the beaches. Elsewhere in Guerrero, the flooding and mudslides blocked several highways, which stranded dozens of vehicles. The wall of a prison collapsed due to the rainfall. Also in Acapulco, the rainfall downed trees and power lines, causing power outages and sparking a fire when a transformer exploded.
Hurricane Bud
A tropical wave exited the west coast of Africa on June 27, which reached the eastern Pacific on July 7. The system spawned a low-pressure area south of Mexico. Associated convection gradually became better organized, and the system organized into Tropical Depression Three-E early on July 11. Steered by a subtropical ridge over Mexico, the storm tracked west-northwestward for its entirety. Located over warm waters, the depression intensified into Tropical Storm Bud within six hours of its formation. The thunderstorms organized, with good outflow except to the east due to the presence of Tropical Storm Carlotta. On July 12, the NHC upgraded Bud to a hurricane, after an eye developed in the storm's center. Later on July 12, Bud was upgraded to a Category 2 hurricane on the Saffir–Simpson hurricane scale.
Early on July 13, Bud became a Category 3 hurricane, or a major hurricane. At that time, the well-defined eye was enclosed by a ring of deep thunderstorms. That day, the hurricane reached its peak intensity of 125 mph (200 km/h) and a minimum barometric pressure of 953 mbar (28.1 inHg). Bud encountered cooler waters and stable air, and a period of rapid weakening began. The eye became obscured, and core convective cloud tops began to warm, until much of the convection was lost on July 14, impeded by southeasterly wind shear. On July 15, Bud was downgraded to a tropical depression, and the next day it degenerated into a remnant low. The low fully dissipated on July 17 about 750 mi (1,210 km) east-northeast of Hawaii. The remnants of Bud produced light rainfall across Hawaii.
Hurricane Carlotta
A tropical wave exited Africa on June 30 and moved across the Atlantic Ocean without development. On July 9, while crossing Central America into the eastern North Pacific Ocean, thunderstorm activity increased, and the system organized into Tropical Depression Four-E early on July 12 about 290 mi (465 km) south of Zihuatanejo, Guerrero. The large depression moved quickly to the west-northwest to the south of a ridge over northwestern Mexico, and its outer rainbands moved across the coast. Rainfall totals were less than 1 inch (25 mm). The depression intensified into Tropical Storm Carlotta just six hours after forming. By late on July 12, the storm developed banding features, and early on July 13 Carlotta attained hurricane status about 430 mi (690 km) south of the southern tip of the Baja California peninsula.
As Carlotta intensified, the system became more compact, and it reached peak winds of 85 mph (135 km/h) on July 13. An eye formed in the center, and the hurricane was briefly forecast to attain major hurricane status, or a Category 3 on the Saffir–Simpson scale. However, Carlotta weakened due to increased wind shear from Hurricane Bud to its west, and the eye and convection deteriorated. Carlotta briefly weakened to tropical storm status late on July 14, although a decrease in shear allowed it to reintensify into a hurricane. This was short-lived as the center moved into the area of cooler waters, and Carlotta again weakened to tropical storm status. Late on July 15, the circulation became separated from the convection, and Carlotta weakened to tropical depression status on July 16, and the next day generated into a remnant low. The circulation continued generally westward, dissipating on July 20 about 1,500 mi (2,415 km) east of the Hawaiian islands.