.gif)
Tropical Storm Norman (2006)
Encyclopedia
Tropical Storm Norman was a weak tropical cyclone
that brought heavy rainfall to southwestern Mexico
in October 2006. The twelfth named storm of the 2006 Pacific hurricane season
, Norman developed on October 9 from a tropical wave
well to the southwest of Mexico. Unfavorable conditions quickly encountered the system, and within two days of forming, Norman dissipated as its remnants turned to the east. Thunderstorms gradually increased again, as it interacted with a disturbance to its east, and on October 15 the cyclone regenerated just off the coast of Mexico. The center became disorganized and quickly dissipated, bringing a large area of moisture which dropped up to 6 inches (150 mm) of rainfall to southwestern Mexico. Rainfall from the storm flooded about 150 houses, of which 20 were destroyed. One person was injured, and initially there were reports of two people missing due to the storm; however, it was not later confirmed.
moved off the coast of Africa on September 21, moving across the Atlantic Ocean
and Caribbean Sea
with little development. On October 1 it entered the eastern Pacific Ocean
, and continuing westward it developed an area of persistent convection
on October 5. Initially the system was disorganized, although gradual development was expected as conditions in the upper-levels of the atmosphere were expected to become more favorable. On October 7 it developed a broad low pressure area
, and by the next day it was located in the eastern portion of a large area of disturbed weather; the western portion of the system later developed into Tropical Storm Olivia. The eastern system developed organized convection near its center, and developed into Tropical Depression Fifteen-E at 0000 UTC
on October 9, about 765 mi (1235 km) southwest of the southern tip of the Baja California Peninsula
.
Upon first becoming a tropical cyclone, the depression was moving north-northwestward, around the western periphery of a weak ridge
; the first forecast advisory by the National Hurricane Center
(NHC) forecast the depression to gradually intensify before weakening and crossing the Baja California Peninsula
. Located over warm water temperatures, the system developed an area of organized, deep convection near the center; with satellite intensity estimates of tropical storm force using the Dvorak technique
, the NHC upgraded the depression to Tropical Storm Norman about 12 hours after it first formed. Strengthening continued, and Norman attained peak winds of 50 mph (85 km/h) early on October 10. At the time, it was officially forecast to strengthen further and continue northeastward. However, some hurricane prediction models anticipated quick weakening and a sharp turn to the southeast. Shortly after peaking in intensity, southwesterly wind shear
increased, which led to a decrease in convection coverage. At the same time, a trough
extending from California
southward caused Norman to stall and turn to the east. The convection rapidly became separated from the center; by late on October 10, the center was located about 115 miles (185 km) from the nearest thunderstorms. By then, it had weakened to tropical depression
status, and early on October 11 Norman degenerated into a remnant low about 530 miles (855 km) southwest of Cabo San Lucas
, Mexico.
The remnants of Norman continued to the east, and later to the east-southeast as it interacted with a tropical disturbance off the coast of Mexico. Initially, re-development of Norman was not expected, as the disturbance was instead given the possibility for further development. On October 13, the NHC noted that the remnants of Norman were merging with the disturbance to its east; during the interaction, convection redeveloped and organized around the remnant low of Norman, and early on October 15 it reformed into a tropical depression, near the coast of southwestern Mexico. With warm waters and favorable upper-level conditions, Norman was predicted to re-attain tropical storm status before moving ashore. However, the center quickly became less-organized, turning northward and northwestward within the larger tropical disturbance. Late on October 15, it is estimated Tropical Depression Norman dissipated 23 miles (37 km) south and offshore of Manzanillo, Colima
, although satellite imagery suggested the center may have dissipated inland.
.png)
When Norman redeveloped into a tropical cyclone, the government of Mexico issued a tropical storm warning
from Lázaro Cárdenas
to Cabo Corrientes
.
The storm brought heavy rainfall to southwestern Mexico, peaking at 6.35 inches (161 mm) in La Villita, Michoacán. Flooding from four days of rainfall caused officials to close schools in and around Acapulco
. The rainfall resulted in downed trees and mudslides. About 150 homes became flooded, resulting in military personnel to assist in evacuating the flooded houses. In total, 20 homes were destroyed, and 20 villages were left without power. A transport vehicle carrying 15 people was swept away by a flooded stream, resulting in one injury; the truck was later rescued by police workers. About 300 hectares (740 acres) of crop fields sustained damage; however, little crop damage was reported, as the storm occurred after harvesting had ended. Across Mexico, the storm affected about 500,000 people, and initially there were two people missing; however, a subsequent report indicated there were no casualties associated with the storm.
Tropical cyclone
A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of water vapor...
that brought heavy rainfall to southwestern Mexico
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...
in October 2006. The twelfth named storm of the 2006 Pacific hurricane season
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...
, Norman developed on October 9 from a tropical wave
Tropical 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...
well to the southwest of Mexico. Unfavorable conditions quickly encountered the system, and within two days of forming, Norman dissipated as its remnants turned to the east. Thunderstorms gradually increased again, as it interacted with a disturbance to its east, and on October 15 the cyclone regenerated just off the coast of Mexico. The center became disorganized and quickly dissipated, bringing a large area of moisture which dropped up to 6 inches (150 mm) of rainfall to southwestern Mexico. Rainfall from the storm flooded about 150 houses, of which 20 were destroyed. One person was injured, and initially there were reports of two people missing due to the storm; however, it was not later confirmed.
Meteorological history
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...
moved off the coast of Africa on September 21, moving across the Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
and Caribbean Sea
Caribbean Sea
The Caribbean Sea is a sea of the Atlantic Ocean located in the tropics of the Western hemisphere. It is bounded by Mexico and Central America to the west and southwest, to the north by the Greater Antilles, and to the east by the Lesser Antilles....
with little development. On October 1 it entered the eastern Pacific Ocean
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...
, and continuing westward it developed an area of persistent convection
Atmospheric convection
Atmospheric convection is the result of a parcel-environment instability, or temperature difference, layer in the atmosphere. Different lapse rates within dry and moist air lead to instability. Mixing of air during the day which expands the height of the planetary boundary layer leads to...
on October 5. Initially the system was disorganized, although gradual development was expected as conditions in the upper-levels of the atmosphere were expected to become more favorable. On October 7 it developed a broad low pressure area
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...
, and by the next day it was located in the eastern portion of a large area of disturbed weather; the western portion of the system later developed into Tropical Storm Olivia. The eastern system developed organized convection near its center, and developed into Tropical Depression Fifteen-E at 0000 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 October 9, about 765 mi (1235 km) southwest of the southern tip of the Baja California Peninsula
Baja California Peninsula
The Baja California peninsula , is a peninsula in northwestern Mexico. Its land mass separates the Pacific Ocean from the Gulf of California. The Peninsula extends from Mexicali, Baja California in the north to Cabo San Lucas, Baja California Sur in the south.The total area of the Baja California...
.
Upon first becoming a tropical cyclone, the depression was moving north-northwestward, around the western periphery of a weak ridge
Ridge (meteorology)
A ridge is an elongated region of relatively high atmospheric pressure, the opposite of a trough....
; the first forecast advisory 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...
(NHC) forecast the depression to gradually intensify before weakening and crossing the Baja California Peninsula
Baja California Peninsula
The Baja California peninsula , is a peninsula in northwestern Mexico. Its land mass separates the Pacific Ocean from the Gulf of California. The Peninsula extends from Mexicali, Baja California in the north to Cabo San Lucas, Baja California Sur in the south.The total area of the Baja California...
. Located over warm water temperatures, the system developed an area of organized, deep convection near the center; with satellite intensity estimates of tropical storm force using the Dvorak technique
Dvorak technique
The Dvorak technique is a widely used system to subjectively estimate tropical cyclone intensity based solely on visible and infrared satellite images. Several agencies issue Dvorak intensity numbers for cyclones of sufficient intensity...
, the NHC upgraded the depression to Tropical Storm Norman about 12 hours after it first formed. Strengthening continued, and Norman attained peak winds of 50 mph (85 km/h) early on October 10. At the time, it was officially forecast to strengthen further and continue northeastward. However, some hurricane prediction models anticipated quick weakening and a sharp turn to the southeast. Shortly after peaking in intensity, southwesterly 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...
increased, which led to a decrease in convection coverage. At the same time, a 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...
extending from California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
southward caused Norman to stall and turn to the east. The convection rapidly became separated from the center; by late on October 10, the center was located about 115 miles (185 km) from the nearest thunderstorms. By then, it had weakened to tropical depression
Tropical cyclone scales
Tropical systems are officially ranked on one of several tropical cyclone scales according to their maximum sustained winds and in what oceanic basin they are located...
status, and early on October 11 Norman degenerated into a remnant low about 530 miles (855 km) southwest of Cabo San Lucas
Cabo San Lucas
Cabo San Lucas , commonly called Cabo, is a city at the southern tip of the Baja California peninsula, in the municipality of Los Cabos in the Mexican state of Baja California Sur. As of the 2010 census, the population was 68,463 people...
, Mexico.
The remnants of Norman continued to the east, and later to the east-southeast as it interacted with a tropical disturbance off the coast of Mexico. Initially, re-development of Norman was not expected, as the disturbance was instead given the possibility for further development. On October 13, the NHC noted that the remnants of Norman were merging with the disturbance to its east; during the interaction, convection redeveloped and organized around the remnant low of Norman, and early on October 15 it reformed into a tropical depression, near the coast of southwestern Mexico. With warm waters and favorable upper-level conditions, Norman was predicted to re-attain tropical storm status before moving ashore. However, the center quickly became less-organized, turning northward and northwestward within the larger tropical disturbance. Late on October 15, it is estimated Tropical Depression Norman dissipated 23 miles (37 km) south and offshore of Manzanillo, Colima
Manzanillo, Colima
The name Manzanillo refers to the city as well as its surrounding municipality in the Mexican state of Colima. The city, located on the Pacific Ocean, contains Mexico's busiest port. Manzanillo was the third port created by the Spanish in the Pacific during the New Spain period...
, although satellite imagery suggested the center may have dissipated inland.
Preparations and impact
Tropical cyclone warnings and watches
Warnings and watches are two levels of alert issued by national weather forecasting bodies to coastal areas threatened by the imminent approach of a tropical cyclone of tropical storm or hurricane intensity. They are notices to the local population and civil authorities to make appropriate...
from Lázaro Cárdenas
Lázaro Cárdenas, Michoacán
Lázaro Cárdenas is a port city that with its surrounding municipality is located in the southern part of the Mexican state of Michoacán. It was formerly known as Los Llanitos, but changed its name as a tribute to Lázaro Cárdenas del Río, a Michoacán-born politician who was president of Mexico from...
to Cabo Corrientes
Cabo Corrientes
Cabo Corrientes is a cape on the Pacific coast of the Mexican state of Jalisco. It marks the southernmost point of the Bahía de Banderas, upon which the port and resort city of Puerto Vallarta stands. The municipality in which the cape lies is also called Cabo Corrientes.Cabo Corrientes is a...
.
The storm brought heavy rainfall to southwestern Mexico, peaking at 6.35 inches (161 mm) in La Villita, Michoacán. Flooding from four days of rainfall caused officials to close schools in and around Acapulco
Acapulco
Acapulco is a city, municipality and major sea port in the state of Guerrero on the Pacific coast of Mexico, southwest from Mexico City. Acapulco is located on a deep, semi-circular bay and has been a port since the early colonial period of Mexico’s history...
. The rainfall resulted in downed trees and mudslides. About 150 homes became flooded, resulting in military personnel to assist in evacuating the flooded houses. In total, 20 homes were destroyed, and 20 villages were left without power. A transport vehicle carrying 15 people was swept away by a flooded stream, resulting in one injury; the truck was later rescued by police workers. About 300 hectares (740 acres) of crop fields sustained damage; however, little crop damage was reported, as the storm occurred after harvesting had ended. Across Mexico, the storm affected about 500,000 people, and initially there were two people missing; however, a subsequent report indicated there were no casualties associated with the storm.
See also
- Other storms of the same name
External links
- The NHC's archive on Tropical Storm Norman.