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Tropical Storm Dorothy (1970)
Encyclopedia
Tropical Storm Dorothy was the deadliest tropical cyclone
of the 1970 Atlantic hurricane season
. The fourth named storm and fifth tropical storm or hurricane of the season, Dorothy developed on August 17 from a tropical wave
to the east of the Lesser Antilles
. It tracked west-northwestward throughout its entire duration, and despite forecasts of attaining hurricane status, Dorothy reached peak winds of 70 mph (110 km/) – slightly below hurricane status. The storm struck Martinique
on August 20, and subsequently began a gradual weakening trend in the Caribbean Sea. On August 23, Dorothy dissipated south of Hispaniola
.
Most significantly affected by the storm was Martinique, which received 26.8 in
(680 mm
) of rainfall in a 24 hour period. The rainfall caused flooding and mudslides, resulting in about $34 million in damage (1970 USD); 186 homes were destroyed, and 700 people were left homeless. The flooding killed up to 50 people on the island. Elsewhere in the Lesser Antilles, the storm killed one person on Dominica
from heavy rainfall, and in Guadeloupe
heavy damage to the banana crop was reported.
that moved off the coast of Africa on August 13. It tracked generally westward, developing into a tropical depression on August 17 about 1375 mi
(2210 km
) east of Tobago
in the Lesser Antilles
. Two days later, it strengthened into Tropical Storm Dorothy, while located about 500 mi (800 km) east of the Lesser Antilles, with its intensity confirmed by the Hurricane Hunters
.
With light vertical wind shear
and warm water temperatures, the National Hurricane Center
(NHC) remarked on August 19 that "hurricane status would probably be attained this afternoon or tonight." Its track was expected to continue generally west-northwestward, influenced by a ridge
near the Bahamas, and within 60 hours Dorothy was forecast to be north or over Puerto Rico. However, a subsequent Hurricane Hunters flight reported a more westerly motion, which would bring its track through the central Lesser Antilles. Tropical Storm Dorothy gradually intensified, reaching peak winds of 70 mph (110 km/h) on August 20 just east-northeast of Barbados
. Hurricane Hunters confirmed the intensity, though the flight also reported a weakness of low-level inflow
. Despite maintaining winds of just below hurricane-force, there was no evidence of an eyewall
on radars as the storm approached the Lesser Antilles. Late on August 20, the storm moved across Martinique
into the Caribbean Sea, during which its low-level circulation became disorganized.
As Tropical Storm Dorothy moved further into the Caribbean Sea, it began a gradual weakening trend initiated by a persistent tropical upper tropospheric trough
, as well as the presence of strong wind shear and a lack of inflow. Hurricane Hunter flights late on August 21 and early on August 22 failed to locate a closed low-level circulation, and as a result the storm was downgraded to a tropical depression. After another flight into the system could not detect a circulation, the NHC discontinued advisories on Dorothy to the south of Hispaniola late on August 22. Around the same time, thunderstorms increased in association with the cyclone, and forecasters remarked the potential for re-intensification over the western Caribbean Sea. However, the storm became more disorganized, and on August 23 Dorothy degenerated into a tropical wave.
and storm warning were issued for the Leeward Islands
from Dominica
northward. As its westward track became more apparent, the watches and warnings were extended southward to include Martinique
and Saint Lucia
. On Martinique, authorities released a statement that warned the public for the potential for strong winds, heavy rainfall, and rough waves. Also on the island, officials converted schools and government buildings into shelters for people in low-lying areas. As a result of the storm, the Martinique Aimé Césaire International Airport
in Le Lamentin
was closed.
The storm dropped heavy rainfall while crossing the Lesser Antilles. In Martinique, the highest 24 hour total was 26.8 inches (680 mm) in Fourniols, which was twice the average rainfall for August. Additionally, the capital city of Fort-de-France reported 13.4 in (341 mm). There, the rainfall broke all records for durations up to 24 hours; about 1 inch (26 mm) fell in 5 minutes, and in one hour a station reported 6.02 inches (153 mm). The rainfall caused flooding and mudslides, as well as rivers exceeding their banks; several bridges collapsed during the storm, and many homes were washed away. During the passage of the storm, sustained winds on the island reached 67 mph (108 km/h), with gusts reaching 99 mph (160 km/h) in Caravelle
. Throughout the country, the storm destroyed 186 homes and left 700 people homeless. The passage of Dorothy left heavy crop damage on the island, totaling 32 million francs (1970 FRF
, $5.8 million 1970 USD); a total of 3.75 mi² (9.72 km²) of banana crop was destroyed, and 2.16 mi² (5.6 km²) of sugar cane was destroyed. Damage on the island totaled 190 million francs (1970 FRF, $34 million 1970 USD).
Tropical Storm Dorothy caused several deaths on Martinique, although the exact death toll is unknown. The National Hurricane Center reported 50 deaths, although the post event report provided by the French meteorological agency reported 44 people dead or missing. Most of the deaths were in Saint-Joseph
, where 20 people drowned in the Riviere l'Or. Floodwater rescues had been made difficult due to washed out roads and poor communications after the storm. In addition to the deaths, several people were injured. After the passage of the storm, Martinique was temporarily left isolated, when communications were downed with other nearby islands. The French Red Cross
distributed 500 blankets and one ton of condensed milk; the agency also sought international assistance.
Elsewhere in the Lesser Antilles, the storm caused flooding and mudslides in Dominica. There, the storm caused one death, when flooding heavy rainfall washed out a bridge. Also, all of the capital city of Roseau lost power and water service due to the storm. In neighboring Guadeloupe, the storm left much of the banana crop destroyed. Later, after it entered the Caribbean Sea, small craft warnings were issued for the Leeward Islands, the Virgin Islands, and Puerto Rico. In its review of the storm, the National Hurricane Center did not mention any damage in the Greater Antilles.
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...
of the 1970 Atlantic hurricane season
1970 Atlantic hurricane season
The 1970 Atlantic hurricane season officially began on June 1, 1970, and lasted until November 30, 1970. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin...
. The fourth named storm and fifth tropical storm or hurricane of the season, Dorothy developed on August 17 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...
to the east of the Lesser Antilles
Lesser Antilles
The Lesser Antilles are a long, partly volcanic island arc in the Western Hemisphere. Most of its islands form the eastern boundary of the Caribbean Sea with the Atlantic Ocean, with the remainder located in the southern Caribbean just north of South America...
. It tracked west-northwestward throughout its entire duration, and despite forecasts of attaining hurricane status, Dorothy reached peak winds of 70 mph (110 km/) – slightly below hurricane status. The storm struck Martinique
Martinique
Martinique is an island in the eastern Caribbean Sea, with a land area of . Like Guadeloupe, it is an overseas region of France, consisting of a single overseas department. To the northwest lies Dominica, to the south St Lucia, and to the southeast Barbados...
on August 20, and subsequently began a gradual weakening trend in the Caribbean Sea. On August 23, Dorothy dissipated south of Hispaniola
Hispaniola
Hispaniola is a major island in the Caribbean, containing the two sovereign states of the Dominican Republic and Haiti. The island is located between the islands of Cuba to the west and Puerto Rico to the east, within the hurricane belt...
.
Most significantly affected by the storm was Martinique, which received 26.8 in
Inch
An inch is the name of a unit of length in a number of different systems, including Imperial units, and United States customary units. There are 36 inches in a yard and 12 inches in a foot...
(680 mm
Millimetre
The millimetre is a unit of length in the metric system, equal to one thousandth of a metre, which is the SI base unit of length....
) of rainfall in a 24 hour period. The rainfall caused flooding and mudslides, resulting in about $34 million in damage (1970 USD); 186 homes were destroyed, and 700 people were left homeless. The flooding killed up to 50 people on the island. Elsewhere in the Lesser Antilles, the storm killed one person on Dominica
Dominica
Dominica , officially the Commonwealth of Dominica, is an island nation in the Lesser Antilles region of the Caribbean Sea, south-southeast of Guadeloupe and northwest of Martinique. Its size is and the highest point in the country is Morne Diablotins, which has an elevation of . The Commonwealth...
from heavy rainfall, and in Guadeloupe
Guadeloupe
Guadeloupe is an archipelago located in the Leeward Islands, in the Lesser Antilles, with a land area of 1,628 square kilometres and a population of 400,000. It is the first overseas region of France, consisting of a single overseas department. As with the other overseas departments, Guadeloupe...
heavy damage to the banana crop was reported.
Meteorological history
The origins of Tropical Storm Dorothy were from 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...
that moved off the coast of Africa on August 13. It tracked generally westward, developing into a tropical depression on August 17 about 1375 mi
Mile
A mile is a unit of length, most commonly 5,280 feet . The mile of 5,280 feet is sometimes called the statute mile or land mile to distinguish it from the nautical mile...
(2210 km
Kilometre
The kilometre is a unit of length in the metric system, equal to one thousand metres and is therefore exactly equal to the distance travelled by light in free space in of a second...
) east of Tobago
Tobago
Tobago is the smaller of the two main islands that make up the Republic of Trinidad and Tobago. It is located in the southern Caribbean, northeast of the island of Trinidad and southeast of Grenada. The island lies outside the hurricane belt...
in the Lesser Antilles
Lesser Antilles
The Lesser Antilles are a long, partly volcanic island arc in the Western Hemisphere. Most of its islands form the eastern boundary of the Caribbean Sea with the Atlantic Ocean, with the remainder located in the southern Caribbean just north of South America...
. Two days later, it strengthened into Tropical Storm Dorothy, while located about 500 mi (800 km) east of the Lesser Antilles, with its intensity confirmed by the Hurricane Hunters
Hurricane Hunters
The Hurricane Hunters are aircraft that fly into tropical cyclones in the North Atlantic Ocean and Northeastern Pacific Ocean for the specific purpose of directly measuring weather data in and around those storms. In the United States, the Air Force, Navy, and NOAA units have all participated in...
.
With light vertical 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...
and warm water temperatures, 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) remarked on August 19 that "hurricane status would probably be attained this afternoon or tonight." Its track was expected to continue generally west-northwestward, influenced by a ridge
Ridge (meteorology)
A ridge is an elongated region of relatively high atmospheric pressure, the opposite of a trough....
near the Bahamas, and within 60 hours Dorothy was forecast to be north or over Puerto Rico. However, a subsequent Hurricane Hunters flight reported a more westerly motion, which would bring its track through the central Lesser Antilles. Tropical Storm Dorothy gradually intensified, reaching peak winds of 70 mph (110 km/h) on August 20 just east-northeast of Barbados
Barbados
Barbados is an island country in the Lesser Antilles. It is in length and as much as in width, amounting to . It is situated in the western area of the North Atlantic and 100 kilometres east of the Windward Islands and the Caribbean Sea; therein, it is about east of the islands of Saint...
. Hurricane Hunters confirmed the intensity, though the flight also reported a weakness of low-level inflow
Outflow (meteorology)
Outflow, in meteorology, is air that flows outwards from a storm system. It is associated with ridging, or anticyclonic flow. In the low levels of the troposphere, outflow radiates from thunderstorms in the form of a wedge of rain-cooled air, which is visible as a thin rope-like cloud on weather...
. Despite maintaining winds of just below hurricane-force, there was no evidence of 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...
on radars as the storm approached the Lesser Antilles. Late on August 20, the storm moved across Martinique
Martinique
Martinique is an island in the eastern Caribbean Sea, with a land area of . Like Guadeloupe, it is an overseas region of France, consisting of a single overseas department. To the northwest lies Dominica, to the south St Lucia, and to the southeast Barbados...
into the Caribbean Sea, during which its low-level circulation became disorganized.
As Tropical Storm Dorothy moved further into the Caribbean Sea, it began a gradual weakening trend initiated by a persistent tropical upper tropospheric trough
Tropical Upper Tropospheric Trough
A tropical upper tropospheric trough , also known as the mid-oceanic trough, is a trough situated in upper-level tropics. Its formation is usually caused by the intrusion of energy and wind from the mid-latitudes into the tropics. It can also develop from the inverted trough adjacent to an upper...
, as well as the presence of strong wind shear and a lack of inflow. Hurricane Hunter flights late on August 21 and early on August 22 failed to locate a closed low-level circulation, and as a result the storm was downgraded to a tropical depression. After another flight into the system could not detect a circulation, the NHC discontinued advisories on Dorothy to the south of Hispaniola late on August 22. Around the same time, thunderstorms increased in association with the cyclone, and forecasters remarked the potential for re-intensification over the western Caribbean Sea. However, the storm became more disorganized, and on August 23 Dorothy degenerated into a tropical wave.
Preparations and impact
After the first tropical cyclone advisory was issued on Tropical Storm Dorothy, a hurricane watchTropical 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...
and storm warning were issued for the Leeward Islands
Leeward Islands
The Leeward Islands are a group of islands in the West Indies. They are the northern islands of the Lesser Antilles chain. As a group they start east of Puerto Rico and reach southward to Dominica. They are situated where the northeastern Caribbean Sea meets the western Atlantic Ocean...
from Dominica
Dominica
Dominica , officially the Commonwealth of Dominica, is an island nation in the Lesser Antilles region of the Caribbean Sea, south-southeast of Guadeloupe and northwest of Martinique. Its size is and the highest point in the country is Morne Diablotins, which has an elevation of . The Commonwealth...
northward. As its westward track became more apparent, the watches and warnings were extended southward to include Martinique
Martinique
Martinique is an island in the eastern Caribbean Sea, with a land area of . Like Guadeloupe, it is an overseas region of France, consisting of a single overseas department. To the northwest lies Dominica, to the south St Lucia, and to the southeast Barbados...
and Saint Lucia
Saint Lucia
Saint Lucia is an island country in the eastern Caribbean Sea on the boundary with the Atlantic Ocean. Part of the Lesser Antilles, it is located north/northeast of the island of Saint Vincent, northwest of Barbados and south of Martinique. It covers a land area of 620 km2 and has an...
. On Martinique, authorities released a statement that warned the public for the potential for strong winds, heavy rainfall, and rough waves. Also on the island, officials converted schools and government buildings into shelters for people in low-lying areas. As a result of the storm, the Martinique Aimé Césaire International Airport
Martinique Aimé Césaire International Airport
Martinique Aimé Césaire International Airport is the international airport of Martinique in the French West Indies. Located in Le Lamentin, a suburb of the capital Fort-de-France, it was opened in 1950 and renamed in 2007 after author and politician Aimé Césaire.- Passenger airlines :- Charter :-...
in Le Lamentin
Le Lamentin
Le Lamentin is a town and the second-largest commune in the French overseas department of Martinique.It is located in the center of the island of Martinique, and is part of the metropolitan area of Fort-de-France, the largest conurbation in Martinique. In the 1999 census, Le Lamentin had a...
was closed.
The storm dropped heavy rainfall while crossing the Lesser Antilles. In Martinique, the highest 24 hour total was 26.8 inches (680 mm) in Fourniols, which was twice the average rainfall for August. Additionally, the capital city of Fort-de-France reported 13.4 in (341 mm). There, the rainfall broke all records for durations up to 24 hours; about 1 inch (26 mm) fell in 5 minutes, and in one hour a station reported 6.02 inches (153 mm). The rainfall caused flooding and mudslides, as well as rivers exceeding their banks; several bridges collapsed during the storm, and many homes were washed away. During the passage of the storm, sustained winds on the island reached 67 mph (108 km/h), with gusts reaching 99 mph (160 km/h) in Caravelle
Caravelle
Caravelle may be a reference to:* Caravelle, the French marketing name for the typeface Folio* Sud Aviation Caravelle, the short/medium-range jet airliner, produced by Sud Aviation...
. Throughout the country, the storm destroyed 186 homes and left 700 people homeless. The passage of Dorothy left heavy crop damage on the island, totaling 32 million francs (1970 FRF
French franc
The franc was a currency of France. Along with the Spanish peseta, it was also a de facto currency used in Andorra . Between 1360 and 1641, it was the name of coins worth 1 livre tournois and it remained in common parlance as a term for this amount of money...
, $5.8 million 1970 USD); a total of 3.75 mi² (9.72 km²) of banana crop was destroyed, and 2.16 mi² (5.6 km²) of sugar cane was destroyed. Damage on the island totaled 190 million francs (1970 FRF, $34 million 1970 USD).
Tropical Storm Dorothy caused several deaths on Martinique, although the exact death toll is unknown. The National Hurricane Center reported 50 deaths, although the post event report provided by the French meteorological agency reported 44 people dead or missing. Most of the deaths were in Saint-Joseph
Saint-Joseph, Martinique
Saint-Joseph is a commune in the Arrondissement of Fort-de-France on Martinique.-References:*...
, where 20 people drowned in the Riviere l'Or. Floodwater rescues had been made difficult due to washed out roads and poor communications after the storm. In addition to the deaths, several people were injured. After the passage of the storm, Martinique was temporarily left isolated, when communications were downed with other nearby islands. The French Red Cross
International Red Cross and Red Crescent Movement
The International Red Cross and Red Crescent Movement is an international humanitarian movement with approximately 97 million volunteers, members and staff worldwide which was founded to protect human life and health, to ensure respect for all human beings, and to prevent and alleviate human...
distributed 500 blankets and one ton of condensed milk; the agency also sought international assistance.
Elsewhere in the Lesser Antilles, the storm caused flooding and mudslides in Dominica. There, the storm caused one death, when flooding heavy rainfall washed out a bridge. Also, all of the capital city of Roseau lost power and water service due to the storm. In neighboring Guadeloupe, the storm left much of the banana crop destroyed. Later, after it entered the Caribbean Sea, small craft warnings were issued for the Leeward Islands, the Virgin Islands, and Puerto Rico. In its review of the storm, the National Hurricane Center did not mention any damage in the Greater Antilles.
See also
- Other tropical cyclones named Dorothy