Hurricane Sergio (2006)

Infobox Hurricane
Name=Hurricane Sergio
Type=hurricane
Year=2006
Basin=EPac
Image location=Hurricane Sergio 15 nov 2006 1725Z.jpg


Formed=November 13, 2006
Dissipated=November 20, 2006
1-min winds=95
Pressure=965
Da

Inflated=
Fatalities=None
Areas=Guerrero, Mexico
Hurricane season=2006 Pacific hurricane season

Hurricane Sergio was the strongest Pacific hurricane in the month of November on record. The nineteenth named storm and eleventh hurricane of the 2006 Pacific hurricane season, Sergio developed from a tropical wave on November 13 about 460 miles (740 km) south of Manzanillo, Mexico, and steadily intensified as it tracked southeastward. It reached peak winds of 110 mph (175 km/h) on November 15, and subsequently began to weaken due to increased wind shear as it turned to the north. Sergio later turned to the west, remaining well off the coast of Mexico, and dissipated on November 20 about 320 miles (515 km) west-northwest of it originally formed.

Sergio produced light rainfall along the coast of Mexico, though its effects were minimal. The formation of Sergio marked the 2006 season as the busiest in 12 years and the first season in which more than one tropical storm formed in November. Sergio, in addition to being the strongest hurricane after November 1, was also the longest-lived Pacific tropical cyclone in November, lasting a total of seven days.

Meteorological history

A tropical wave crossed Central America and entered the eastern Pacific Ocean on November 7. An area of convection along the wave tracked westward to the south of Central America and Mexico, and became more concentrated on November 12 while located about 400 miles (645 km) south of Acapulco. Later that day, Dvorak classification began on the disturbance, and the convection continued to organize.cite web|author=Richard Pasch and David Roberts|year=2006|title=Hurricane Sergio Tropical Cyclone Report|publisher=National Hurricane Center|accessdate=2007-02-13|url=http://www.nhc.noaa.gov/pdf/TCR-EP212006_Sergio.pdf] Early on November 13, the National Hurricane Center indicated the possibility of the system developing into a tropical depression.cite web|author=Franklin|year=2006|title=November 13 Tropical Weather Outlook|publisher=NHC|accessdate=2007-02-13|url=ftp://ftp.met.fsu.edu/pub/weather/tropical/Outlook-P/2006111317.ABPZ20] Thunderstorm activity briefly decreased,cite web|author=Brown & Pasch|year=2006|title=November 13 Tropical Weather Outlook (2)|publisher=NHC|accessdate=2007-02-13|url=ftp://ftp.met.fsu.edu/pub/weather/tropical/Outlook-P/2006111323.ABPZ20] though late on November 13 the system acquired enough circulation and organized convection for it to be designated Tropical Depression Twenty-One-E while located about 460 miles (740 km) south of Manzanillo, Mexico. Operationally, the depression was not upgraded until eleven hours later.

Initially, the tropical depression tracked to the northwest, and was forecast to peak as a 50 mph (80 km/h) tropical storm while continuing on a northwest motion. Located within an area of weak wind shear, deep convection increased near the center, and banding features became more pronounced.cite web|author=Pasch & Brown|year=2006|title=Tropical Depression Twenty-One-E Special Discussion One|publisher=NHC|accessdate=2007-02-13|url=http://www.nhc.noaa.gov/archive/2006/ep21/ep212006.discus.001.shtml?] Anticyclonic flow aloft and a moist troposphere allowed the depression to intensity into Tropical Storm Sergio on November 14. Shortly after becoming a tropical storm, Sergio turned to the southeast, believed to be due to the flow associated with a mid- to upper-level trough to its northeast. It steadily intensified, and Sergio attained hurricane status on November 15 while located about 420 miles (675 km) southwest of Acapulco. With a small, distinct eye located in the center of the deep convection, Sergio rapidly intensified to attain peak winds of 110 mph (175 km/h) about 6 hours after becoming a hurricane.

Upon reaching peak strength, forecasters at the National Hurricane Center predicted Hurricane Sergio to intensify further to reach winds of 120 mph (195 km/h).cite web|author=Avila|year=2006|title=Hurricane Sergio Discussion Nine|publisher=NHC|accessdate=2007-02-13|url=http://www.nhc.noaa.gov/archive/2006/ep21/ep212006.discus.009.shtml?] Shortly after peaking, the hurricane turned to the north and gradually weakened as wind shear from an upper-level trough to its northwest increased. By early on November 17, the low-cloud circulation became partially exposed on the west side of the deep convection, and it is estimated that Sergio weakened to a tropical storm later that day. A ridge to its north and northeast turned the storm to the northwest and later to the west as Sergio gradually weakened. Deep convection reformed near the center on November 18, resulting in a slight increase in winds, though vertical shear quickly weakened it again. Later that day, the storm made its closest approach to land, about 225 miles (360 km) southwest of Michoacán.cite web|author=Servicio Meteorológico Nacional|year=2006|title=Resumen del Huracan "Sergio" del Océano Pacífic|accessdate=2007-02-13|language=Spanish|url=http://smn.cna.gob.mx/ciclones/tempo2006/pacifico/sergio/sergio.pdf] Early on November 20 it degenerated into a tropical depression, and later that day Sergio dissipated about 360 miles (580 km) southwest of Manzanillo, Mexico, or about 320 miles (515 km) west-northwest of where it originally formed. The remnants of Sergio continued westward for about a day before the minimal amount of convection diminished.cite web|author=Franklin|year=2006|title=November 21 Tropical Weather Outlook|publisher=NHC|accessdate=2007-02-13|url=ftp://ftp.met.fsu.edu/pub/weather/tropical/Outlook-P/2006112204.ABPZ20]

Impact, naming, and records

No tropical cyclone warnings or watches were issued in relation to Sergio. Several advisories indicated a slight threat to coastal regions of Mexico, with the National Hurricane Center giving a 29% probability for tropical storm force winds affecting Barra de Navidad in Jalisco.cite web|author=Avila|year=2006|title=Hurricane Sergio Wind Speed Probabilities Fifteen|publisher=NHC|accessdate=2007-02-13|url=http://www.nhc.noaa.gov/archive/2006/ep21/ep212006.wndprb.012.shtml] From November 16 and 17, the outer rainbands of the hurricane dropped light precipitation along the Mexican coastline, peaking at 1.97 inches (50 mm) at Tierra Colorada in Guerrero.

When Sergio became a tropical storm on November 14, the 2006 season had the most tropical storms in the eastern Pacific Ocean since 1994. Additionally, it was also the first season since 1961 that more than one tropical storm formed in the basin in November, with Tropical Storm Rosa becoming a tropical storm about five days prior to Sergio.cite web|author=Hurricane Research Division|year=2007|title=Hurricane Data for Pacific Hurricanes 1949-2006|publisher=NOAA|accessdate=2007-02-13|url=http://www.nhc.noaa.gov/tracks1949to2006_epa.txt]

Sergio was the first hurricane in the Eastern Pacific during the month of November since Hurricane Octave in 2001, which formed in late October. Sergio was also the first to form and attain hurricane status in the basin in November since Hurricane Rick in 1997. Sergio was the strongest Pacific hurricane after November 1 on record, surpassing the previous record set by Hurricane Nora in 1991 with winds of 105 mph (170 km/h) and a pressure of 970 mbar. Sergio was also the longest lasting-lived November tropical cyclone in the eastern Pacific Ocean on record, lasting seven days; the previous record was six days by Nora in 1991.

External links

* [http://www.nhc.noaa.gov/archive/2006/SERGIO.shtml? The NHC's archive] on Hurricane Sergio.

ee also

* List of Pacific hurricanes

References