Tropical Storm Anita (2010)
Encyclopedia
Tropical Storm Anita was the second tropical cyclone in the Southern Atlantic Ocean on record, following Cyclone Catarina
in March 2004. Originating from an extratropical cyclone
over southern Brazil
, this system quickly moved offshore, entering a region favoring subtropical development. Above-average sea surface temperature
s allowed for sufficient convective development
to take place for the storm to be declared a subtropical cyclone by March 8. Gradual organization followed while the storm maintained winds of 65 km/h (40 mph). The system remained roughly 100 to 150 km (62.1 to 93.2 mi) off the coast of Brazil as it drifted in a general eastward direction. Early on March 10, the National Oceanic and Atmospheric Administration
declared that the storm had transitioned into a tropical cyclone, marking the first fully tropical system in the region since a storm in February 2006. Shortly thereafter, the cyclone attained its peak intensity with winds of 75 km/h (45 mph) and a barometric pressure of 1000 mbar (hPa). The system gradually lost its tropical characteristics and by March 12, the cyclone transitioned into an extratropical system. Around this time, six Brazilian Meteorological services announced that the cyclone would be designated as Tropical Cyclone Anita.
Although a small cyclone, the outer fringes of the storm brought gusty winds to parts of costal Brazil, estimated up to 50 km/h (31.1 mph) in some places. Heavy rain was also reported in areas further inland, including the city of Porto Alegre
. However, the precursor to the cyclone caused more substantial damage. Torrential rainfall and severe weather damaged numerous homes in Rio Grande do Sul. Several tornado
es also touched down between March 5 and 7. Despite the damage, there were no reports of fatalities in relation to the cyclone.
(HPC), based in the United States
, on March 5 over southern Brazil
. The system was noted as having the possibility of becoming subtropical
as it moved over above average waters. The next day, the Brazilian meteorological service began issuing summaries on the system as an extratropical cyclone
just off the coast of Uruguay
. This system quickly tracked northward, moving over southern Brazilian state of Rio Grande do Sul
the following day, before moving over the cool waters of the Southern Atlantic Ocean
. Sea surface temperature
s in the region were above average; however, slightly cooler than late February. On March 8, the United States Naval Research Laboratory
classified the system as an area of interest, designating it as 90Q.
Later on March 8, the National Hurricane Center
, based in Miami, Florida
, classified the system as Low 90SL. By this time, the cyclone was estimated to have winds between 65 and 100 km/h (40 and 65 mph) and featured a strong, onshore flow. Deep convection
developed around the center of circulation
in response to favorable atmospheric conditions. Additionally, satellites monitoring the storm determined that the cyclone was developing a warm core, a feature of tropical cyclone
s and was being enhanced by a trough
to the west. By March 9, the Brazilian Meteorological service classified the low as a subtropical cyclone, the first such storm since an unnamed cyclone in January 2009.
Cells of deep convection persisted around the system throughout the day, indicating that it was acquiring more tropical characteristics. Sustained winds at this time were estimated at 65 km/h (40 mph), equivalent to a minimal tropical storm. It was stated by the HPC that if wind shear
in the region subsided, there was a possibility of the cyclone becoming fully tropical. Radar
imagery from nearby meteorological stations indicated that the storm could be developing an eyewall
as it drifted offshore. A scatterometer image later on March 9 confirmed that the system had developed a closed, low-level circulation. In response to this data, the Brazilian Meteorological service stated that the subtropical system had transitioned into a tropical cyclone.
By March 10, the cyclone began moving away from the Brazilian coastline and continued to become better defined. During the morning hours, the National Oceanic and Atmospheric Administration
officially classified the cyclone as being tropical through the Dvorak technique
. Later that day, the system attained its peak intensity with winds of 75 km/h (45 mph) and a barometric pressure of 1000 mbar (hPa). On March 12, the Brazilian Meteorological service announced that the system would be classified with the name Anita, after Anita Garibaldi
, a historic figure of the states of Rio Grande do Sul
and Santa Catarina
, both affected by the storm.
produced by the system were estimated at 3 to 5 m (9.8 to 16.4 ft).
Brazilian meteorologists stated that the formation of this storm and its transition into a tropical cyclone could be regarded as "historic". Tropical cyclone formation in the Atlantic Ocean south of the equator
is extremely rare, with only eight other documented cyclones forming in this region in history. Although a minor system, it marked the first time that a tropical or subtropical system formed in consecutive years, following a subtropical storm in January 2009. Upon being declared subtropical by the HPC on March 8, the tropical cyclone became the first system in the southern Atlantic to be identified using the new suffix; SL, for the region. On March 12, the system was designated as Anita.
Cyclone Catarina
Cyclone Catarina is one of several informal names for a South Atlantic tropical cyclone that hit southeastern Brazil in late March 2004. The storm developed out of a stationary cold-core upper-level trough on March 12...
in March 2004. Originating from an extratropical cyclone
Extratropical cyclone
Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and...
over southern Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
, this system quickly moved offshore, entering a region favoring subtropical development. Above-average sea surface temperature
Sea surface temperature
Sea surface temperature is the water temperature close to the oceans surface. The exact meaning of surface varies according to the measurement method used, but it is between and below the sea surface. Air masses in the Earth's atmosphere are highly modified by sea surface temperatures within a...
s allowed for sufficient convective development
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...
to take place for the storm to be declared a subtropical cyclone by March 8. Gradual organization followed while the storm maintained winds of 65 km/h (40 mph). The system remained roughly 100 to 150 km (62.1 to 93.2 mi) off the coast of Brazil as it drifted in a general eastward direction. Early on March 10, the National Oceanic and Atmospheric Administration
National Oceanic and Atmospheric Administration
The National Oceanic and Atmospheric Administration , pronounced , like "noah", is a scientific agency within the United States Department of Commerce focused on the conditions of the oceans and the atmosphere...
declared that the storm had transitioned into a tropical cyclone, marking the first fully tropical system in the region since a storm in February 2006. Shortly thereafter, the cyclone attained its peak intensity with winds of 75 km/h (45 mph) and a barometric pressure of 1000 mbar (hPa). The system gradually lost its tropical characteristics and by March 12, the cyclone transitioned into an extratropical system. Around this time, six Brazilian Meteorological services announced that the cyclone would be designated as Tropical Cyclone Anita.
Although a small cyclone, the outer fringes of the storm brought gusty winds to parts of costal Brazil, estimated up to 50 km/h (31.1 mph) in some places. Heavy rain was also reported in areas further inland, including the city of Porto Alegre
Porto Alegre
Porto Alegre is the tenth most populous municipality in Brazil, with 1,409,939 inhabitants, and the centre of Brazil's fourth largest metropolitan area . It is also the capital city of the southernmost Brazilian state of Rio Grande do Sul. The city is the southernmost capital city of a Brazilian...
. However, the precursor to the cyclone caused more substantial damage. Torrential rainfall and severe weather damaged numerous homes in Rio Grande do Sul. Several tornado
Tornado
A tornado is a violent, dangerous, rotating column of air that is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. They are often referred to as a twister or a cyclone, although the word cyclone is used in meteorology in a wider...
es also touched down between March 5 and 7. Despite the damage, there were no reports of fatalities in relation to the cyclone.
Meteorological history
The tropical cyclone was first identified by the Hydrometeorological Prediction CenterHydrometeorological Prediction Center
The Hydrometeorological Prediction Center is one of nine service centers under the umbrella of the National Centers for Environmental Prediction , a part of the National Weather Service, which in turn is part of the National Oceanic and Atmospheric Administration of the U.S. government...
(HPC), based in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, on March 5 over southern Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
. The system was noted as having the possibility of becoming subtropical
Subtropical cyclone
A subtropical cyclone is a weather system that has some characteristics of a tropical and an extratropical cyclone. As early as the 1950s, meteorologists were unclear whether they should be characterized as tropical or extratropical cyclones. They were officially recognized by the National...
as it moved over above average waters. The next day, the Brazilian meteorological service began issuing summaries on the system as an extratropical cyclone
Extratropical cyclone
Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and...
just off the coast of Uruguay
Uruguay
Uruguay ,officially the Oriental Republic of Uruguay,sometimes the Eastern Republic of Uruguay; ) is a country in the southeastern part of South America. It is home to some 3.5 million people, of whom 1.8 million live in the capital Montevideo and its metropolitan area...
. This system quickly tracked northward, moving over southern Brazilian state of Rio Grande do Sul
Rio Grande do Sul
Rio Grande do Sul is the southernmost state in Brazil, and the state with the fifth highest Human Development Index in the country. In this state is located the southernmost city in the country, Chuí, on the border with Uruguay. In the region of Bento Gonçalves and Caxias do Sul, the largest wine...
the following day, before moving over the cool waters of the Southern 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...
. Sea surface temperature
Sea surface temperature
Sea surface temperature is the water temperature close to the oceans surface. The exact meaning of surface varies according to the measurement method used, but it is between and below the sea surface. Air masses in the Earth's atmosphere are highly modified by sea surface temperatures within a...
s in the region were above average; however, slightly cooler than late February. On March 8, the United States Naval Research Laboratory
United States Naval Research Laboratory
The United States Naval Research Laboratory is the corporate research laboratory for the United States Navy and the United States Marine Corps and conducts a program of scientific research and development. NRL opened in 1923 at the instigation of Thomas Edison...
classified the system as an area of interest, designating it as 90Q.
Later on March 8, 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...
, based in Miami, Florida
Miami, Florida
Miami is a city located on the Atlantic coast in southeastern Florida and the county seat of Miami-Dade County, the most populous county in Florida and the eighth-most populous county in the United States with a population of 2,500,625...
, classified the system as Low 90SL. By this time, the cyclone was estimated to have winds between 65 and 100 km/h (40 and 65 mph) and featured a strong, onshore flow. Deep 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...
developed around the center of circulation
Eye (cyclone)
The eye is a region of mostly calm weather found at the center of strong tropical cyclones. The eye of a storm is a roughly circular area and typically 30–65 km in diameter. It is surrounded by the eyewall, a ring of towering thunderstorms where the second most severe weather of a cyclone...
in response to favorable atmospheric conditions. Additionally, satellites monitoring the storm determined that the cyclone was developing a warm core, a feature of tropical cyclone
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...
s and was being enhanced by 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...
to the west. By March 9, the Brazilian Meteorological service classified the low as a subtropical cyclone, the first such storm since an unnamed cyclone in January 2009.
Cells of deep convection persisted around the system throughout the day, indicating that it was acquiring more tropical characteristics. Sustained winds at this time were estimated at 65 km/h (40 mph), equivalent to a minimal tropical storm. It was stated by the HPC that if 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...
in the region subsided, there was a possibility of the cyclone becoming fully tropical. Radar
Weather radar
Weather radar, also called weather surveillance radar and Doppler weather radar, is a type of radar used to locate precipitation, calculate its motion, estimate its type . Modern weather radars are mostly pulse-Doppler radars, capable of detecting the motion of rain droplets in addition to the...
imagery from nearby meteorological stations indicated that the storm could be developing an eyewall
Eye (cyclone)
The eye is a region of mostly calm weather found at the center of strong tropical cyclones. The eye of a storm is a roughly circular area and typically 30–65 km in diameter. It is surrounded by the eyewall, a ring of towering thunderstorms where the second most severe weather of a cyclone...
as it drifted offshore. A scatterometer image later on March 9 confirmed that the system had developed a closed, low-level circulation. In response to this data, the Brazilian Meteorological service stated that the subtropical system had transitioned into a tropical cyclone.
By March 10, the cyclone began moving away from the Brazilian coastline and continued to become better defined. During the morning hours, the National Oceanic and Atmospheric Administration
National Oceanic and Atmospheric Administration
The National Oceanic and Atmospheric Administration , pronounced , like "noah", is a scientific agency within the United States Department of Commerce focused on the conditions of the oceans and the atmosphere...
officially classified the cyclone as being tropical through 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...
. Later that day, the system attained its peak intensity with winds of 75 km/h (45 mph) and a barometric pressure of 1000 mbar (hPa). On March 12, the Brazilian Meteorological service announced that the system would be classified with the name Anita, after Anita Garibaldi
Anita Garibaldi
Ana Maria de Jesus Ribeiro di Garibaldi, best known as Anita Garibaldi, was the Brazilian wife and comrade-in-arms of Italian revolutionary Giuseppe Garibaldi...
, a historic figure of the states of Rio Grande do Sul
Rio Grande do Sul
Rio Grande do Sul is the southernmost state in Brazil, and the state with the fifth highest Human Development Index in the country. In this state is located the southernmost city in the country, Chuí, on the border with Uruguay. In the region of Bento Gonçalves and Caxias do Sul, the largest wine...
and Santa Catarina
Santa Catarina (state)
Santa Catarina is a state in southern Brazil with one of the highest standards of living in Latin America. Its capital is Florianópolis, which mostly lies on the Santa Catarina Island. Neighbouring states are Rio Grande do Sul to the south and Paraná to the north. It is bounded on the east by...
, both affected by the storm.
Impact, classification, and records
In Rio Grande do Sul, officials warned residents of the possibility of heavy rains and strong winds, gusting up to 150 km/h (90 mph) at times. Boaters were advised not to venture out into the storm as swellsSwell (ocean)
A swell, in the context of an ocean, sea or lake, is a series surface gravity waves that is not generated by the local wind. Swell waves often have a long wavelength but this varies with the size of the water body, e.g. rarely more than 150 m in the Mediterranean, and from event to event, with...
produced by the system were estimated at 3 to 5 m (9.8 to 16.4 ft).
Brazilian meteorologists stated that the formation of this storm and its transition into a tropical cyclone could be regarded as "historic". Tropical cyclone formation in the Atlantic Ocean south of the equator
Equator
An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....
is extremely rare, with only eight other documented cyclones forming in this region in history. Although a minor system, it marked the first time that a tropical or subtropical system formed in consecutive years, following a subtropical storm in January 2009. Upon being declared subtropical by the HPC on March 8, the tropical cyclone became the first system in the southern Atlantic to be identified using the new suffix; SL, for the region. On March 12, the system was designated as Anita.
See also
- Cyclone CatarinaCyclone CatarinaCyclone Catarina is one of several informal names for a South Atlantic tropical cyclone that hit southeastern Brazil in late March 2004. The storm developed out of a stationary cold-core upper-level trough on March 12...
- Subtropical Storm AraniSubtropical Storm AraniSubtropical Cyclone Arani was a subtropical cyclone that existed in March 2011 in the South Atlantic. Arani was the ninth recorded storm in South Atlantic history, fourth subtropical cyclone, third named storm, and first officially named subtropical storm....
- 2009–10 Southern Hemisphere tropical cyclone season (disambiguation)
- 2010 Atlantic hurricane season2010 Atlantic hurricane seasonThe 2010 Atlantic hurricane season was the third most active Atlantic hurricane season on record, tying with the 1887 Atlantic hurricane season, 1995 Atlantic hurricane season and the 2011 Atlantic hurricane season. It had the most number of named storms since the 2005 season and also ties with the...
- South Atlantic tropical cycloneSouth Atlantic tropical cycloneSouth Atlantic tropical cyclones are unusual weather events that occur in the southern hemisphere. Strong wind shear and a lack of weather disturbances favorable for tropical cyclone development make any hurricane-strength cyclones extremely rare...
- List of tropical cyclones