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Tropical Storm Aletta (2006)
Encyclopedia
Tropical Storm Aletta was the first tropical cyclone of the 2006 Pacific hurricane season
. Aletta developed from an area of disturbed weather located south-southwest of the Mexican
port of Acapulco, Guerrero. It gradually gained organized convection and was classified as a tropical depression early on May 27, and became a tropical storm later that morning, the first of 2006 in the Western Hemisphere
. Aletta strengthened to a tropical storm with 45 mph (75 km/h) sustained winds, while moving towards the Guerrero
coast in southwestern Mexico. The storm became stationary, though it later turned to the west and weakened on May 29. Aletta continued to weaken until it dissipated on May 31. The storm dropped moderate rainfall along the Mexican coast, and generated winds that downed trees and caused minor damage.
crossed Central America
and entered the East Pacific
. The wave drifted westward, and after several days began to interact with a low-level trough
near the Gulf of Tehuantepec
, and as a result deep convection increased. By May 25, a large area of low pressure
formed several hundred miles south of Acapulco, Mexico. Wind shear
inhibited development initially, though conditions became slightly more favorable after a number of days, and at 0600 UTC
on May 27, a tropical depression formed about 190 mi (305 km) south of Acapulco.
Moving very little, the depression was disorganized due to continued shear, leaving the center of circulation west of the convective activity. By later in the morning hours of May 27, the system began to show overall signs of organization, primarily related to a burst of convection in the eastern semicircle. At the same time, the center of circulation either reformed or began to move farther north, possibly north-northeast. Embedded within the steering currents of a ridge
, most forecasts anticipated the storm would drift northward for several days, though some computer models
predicted the storm would eventually move inland near Acapulco. At 1800 UTC on May 27, the depression organized into a tropical storm, and as such was named Aletta by the National Hurricane Center
.
With continued forecasting difficulty, a burst of new convection formed east of the center early on May 28, as the storm began meandering southward. At 0600 UTC, Aletta attained peak winds of 45 mph (72.4 km/h) while nearly stationary in forward movement. Later in the afternoon, the storm's center was obscured, thus subjecting the exact location to speculation. In addition, the circulation fluctuated in organization with the alternating intensity of the wind shear, and at the time maintained elongated cloud patterns, rather than the typical circulatory shape. As the storm drifted to the west and executed a small cyclonic loop by early on May 29, increased shear and dry air became entrained in the system, causing it to weaken to a tropical depression at 1800 UTC. Little convection remained afterward, and the storm struggled for several days, becoming a remnant low by May 31. The low dissipated shortly thereafter.
. By 1800 UTC on May 29, the advisory was discontinued after a series of modifications and extensions.
Aletta produced moderate rainfall across Mexico, including a 24-hour rainfall total of 100.2 mm (3.94 inches) in Jacatepec, Oaxaca on May 30, and 96.0 mm (3.78 inches) in La Calera, Guerrero, 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. However, there were no reports of fatalities associated with Aletta.
2006 Pacific hurricane season
The 2006 Pacific hurricane season was the most active Pacific hurricane season since 2000 producing 19 tropical storms or hurricanes. Eighteen developed within the National Hurricane Center area of warning responsibility, which is east of 140ºW, and one storm formed between 140ºW and the...
. Aletta developed from an area of disturbed weather located south-southwest of the Mexican
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
port of Acapulco, Guerrero. It gradually gained organized convection and was classified as a tropical depression early on May 27, and became a tropical storm later that morning, the first of 2006 in the Western Hemisphere
Western Hemisphere
The Western Hemisphere or western hemisphere is mainly used as a geographical term for the half of the Earth that lies west of the Prime Meridian and east of the Antimeridian , the other half being called the Eastern Hemisphere.In this sense, the western hemisphere consists of the western portions...
. Aletta strengthened to a tropical storm with 45 mph (75 km/h) sustained winds, while moving towards the Guerrero
Guerrero
Guerrero officially Estado Libre y Soberano de Guerrero is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 81 municipalities and its capital city is Chilpancingo....
coast in southwestern Mexico. The storm became stationary, though it later turned to the west and weakened on May 29. Aletta continued to weaken until it dissipated on May 31. The storm dropped moderate rainfall along the Mexican coast, and generated winds that downed trees and caused minor damage.
Meteorological history
On May 21, 2006, a tropical waveTropical wave
Tropical waves, easterly waves, or tropical easterly waves, also known as African easterly waves in the Atlantic region, are a type of atmospheric trough, an elongated area of relatively low air pressure, oriented north to south, which move from east to west across the tropics causing areas of...
crossed Central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
and entered the East Pacific
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
. The wave drifted westward, and after several days began to interact with a low-level trough
Trough (meteorology)
A trough is an elongated region of relatively low atmospheric pressure, often associated with fronts.Unlike fronts, there is not a universal symbol for a trough on a weather chart. The weather charts in some countries or regions mark troughs by a line. In the United States, a trough may be marked...
near the Gulf of Tehuantepec
Gulf of Tehuantepec
Gulf of Tehuantepec is a large body of water on the Pacific coast of the Isthmus of Tehuantepec, southeastern Mexico, at . Most of the hurricanes that form in the Eastern Pacific organize in or near this body of water...
, and as a result deep convection increased. By May 25, a large area of low pressure
Low pressure area
A low-pressure area, or "low", is a region where the atmospheric pressure at sea level is below that of surrounding locations. Low-pressure systems form under areas of wind divergence which occur in upper levels of the troposphere. The formation process of a low-pressure area is known as...
formed several hundred miles south of Acapulco, Mexico. Wind shear
Wind shear
Wind shear, sometimes referred to as windshear or wind gradient, is a difference in wind speed and direction over a relatively short distance in the atmosphere...
inhibited development initially, though conditions became slightly more favorable after a number of days, and at 0600 UTC
Coordinated Universal Time
Coordinated Universal Time is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose...
on May 27, a tropical depression formed about 190 mi (305 km) south of Acapulco.
Moving very little, the depression was disorganized due to continued shear, leaving the center of circulation west of the convective activity. By later in the morning hours of May 27, the system began to show overall signs of organization, primarily related to a burst of convection in the eastern semicircle. At the same time, the center of circulation either reformed or began to move farther north, possibly north-northeast. Embedded within the steering currents of a ridge
High pressure area
A high-pressure area is a region where the atmospheric pressure at the surface of the planet is greater than its surrounding environment. Winds within high-pressure areas flow outward due to the higher density air near their center and friction with land...
, most forecasts anticipated the storm would drift northward for several days, though some computer models
Tropical cyclone forecasting
Tropical cyclone forecasting is the science and art of forecasting where a tropical cyclone's center, and its effects, are expected to be at some point in the future. There are several elements to tropical cyclone forecasting: track forecasting, intensity forecasting, rainfall forecasting, storm...
predicted the storm would eventually move inland near Acapulco. At 1800 UTC on May 27, the depression organized into a tropical storm, and as such was named Aletta by the National Hurricane Center
National Hurricane Center
The National Hurricane Center , located at Florida International University in Miami, Florida, is the division of the National Weather Service responsible for tracking and predicting weather systems within the tropics between the Prime Meridian and the 140th meridian west poleward to the 30th...
.
With continued forecasting difficulty, a burst of new convection formed east of the center early on May 28, as the storm began meandering southward. At 0600 UTC, Aletta attained peak winds of 45 mph (72.4 km/h) while nearly stationary in forward movement. Later in the afternoon, the storm's center was obscured, thus subjecting the exact location to speculation. In addition, the circulation fluctuated in organization with the alternating intensity of the wind shear, and at the time maintained elongated cloud patterns, rather than the typical circulatory shape. As the storm drifted to the west and executed a small cyclonic loop by early on May 29, increased shear and dry air became entrained in the system, causing it to weaken to a tropical depression at 1800 UTC. Little convection remained afterward, and the storm struggled for several days, becoming a remnant low by May 31. The low dissipated shortly thereafter.
Preparations and impact
When the storm began to move towards the coast, the Mexican government issued tropical storm watches between Punta Maldonado and ZihuatanejoZihuatanejo
Zihuatanejo or Ixtapa-Zihuatanejo, is the fourth-largest city in the Mexican state of Guerrero. Politically the city belongs to the municipality of Zihuatanejo de Azueta in the western part of Guerrero, but both are commonly referred to as Zihuatanejo...
. By 1800 UTC on May 29, the advisory was discontinued after a series of modifications and extensions.
Aletta produced moderate rainfall across Mexico, including a 24-hour rainfall total of 100.2 mm (3.94 inches) in Jacatepec, Oaxaca on May 30, and 96.0 mm (3.78 inches) in La Calera, Guerrero, the next day. High winds knocked down trees and caused minor structural damage. In Zihuatanejo
Zihuatanejo
Zihuatanejo or Ixtapa-Zihuatanejo, is the fourth-largest city in the Mexican state of Guerrero. Politically the city belongs to the municipality of Zihuatanejo de Azueta in the western part of Guerrero, but both are commonly referred to as 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. However, there were no reports of fatalities associated with Aletta.
See also
- List of Pacific hurricanes
- Other tropical cyclones named Aletta
- Timeline of the 2006 Pacific hurricane seasonTimeline of the 2006 Pacific hurricane seasonThe 2006 Pacific hurricane season was the most active since the 2000 season, producing produced 21 tropical depressions; 19 of which became tropical storms or hurricanes...
- List of storms in the 2006 Pacific hurricane season