Hurricane Fred (2009)
Encyclopedia
Hurricane Fred was one of the easternmost forming major hurricanes in the North Atlantic basin on record. Forming out of a strong tropical wave
on September 7 near the Cape Verde Islands, Fred gradually organized within an area of moderate wind shear
. The following day, decreasing shear allowed the storm to intensify and develop well-organized convective
banding features
. Later on September 8, Fred attained hurricane intensity and underwent rapid intensification
overnight, attaining its peak intensity as a strong Category 3 hurricane with winds of 120 mph (195 km/h) and a barometric pressure of 958 mbar (hPa; 28.29 inHg). Shortly after reaching this intensity, the hurricane began to weaken as wind shear increased and dry air hampered convective development.
Throughout September 10, Fred maintained Category 2 status before weakening to a Category 1 hurricane. Continued weakening took place on September 11 as convection became fully disorganized. Later that day, Fred weakened to a tropical storm and by September 12, no convection remained around the center of the former hurricane, leaving an exposed low-level circulation. The storm degenerated into a remnant-low later that day, corresponding with the final advisory from the National Hurricane Center
(NHC). The remnants of Fred persisted for nearly a full week, traveling west-northwest across the Atlantic basin. The remnants finally dissipated on September 19. Prior to becoming a tropical depression, the precursor to Fred produced moderate to heavy rainfall in the southern Cape Verde Islands, leading to two flight cancellations and several delays.
that moved off the west coast of Africa on September 6. Environmental conditions ahead of the system favored development and the system was forecast to slowly develop into a tropical cyclone
. The following day, the wave tracked south of the Cape Verde Islands; however, it was close enough to bring showers and gusty winds to the southern islands. By this time, the National Hurricane Center anticipated the system to organize into a tropical depression within 24 hours. While passing near Cape Verde, a broad area of low pressure
developed within the tropical wave. Following further development, the NHC declared that the low strengthened into a tropical depression, the seventh of the 2009 season, and issued their first advisory on it. Upon being classified a tropical depression, the system was located roughly 160 mi (260 km) south of the southernmost Cape Verde Islands.
Upon being classified a tropical depression, the NHC noted that the center of circulation was difficult to locate and the mid-level circulation was displaced from the low-level circulation. The cyclone tracked slightly north of due west in response to a small ridge
to the north. Moderate wind shear
initially displaced convective activity
to the west. Several hours after being classified, the NHC upgraded the depression to Tropical Storm Fred; this was the first use of the name Fred in the Atlantic basin after it replaced Fabian
which was retired in 2003
. This followed the development of convective banding features
along the periphery of the storm and strong shower and thunderstorm activity forming over the center of Fred. The system continued to organize, with the banding features becoming well-defined within hours and strong outflow
developing around the storm.
By the afternoon of September 8, an eye
began to develop within a central dense overcast. Later that day, Fred intensified into a Category 1 hurricane with winds estimated at 75 mph (120 km/h). By the morning of September 9, satellite imagery depicted that Fred had undergone rapid intensification
and attained Category 2 status. This resulted from the formation of a 12 mi (19 km) wide eye due to low wind shear and high sea surface temperature
s. This intensification continued for several more hours, ending with Fred attaining its peak intensity as a strong Category 3 hurricane with winds of 120 mph (195 km/h) and a barometric pressure of 958 mbar (hPa; 28.29 inHg), making it the second strongest storm of the season.
Hours after attaining its peak intensity, Fred began to weaken as clouds began to fill the eye. By this time, the hurricane was beginning to turn toward the northwest as a subtropical
ridge to the north weakened. Continued weakening took place as dry air started to erode convection along the southern edge of the system and the eye was no longer present on satellite imagery and wind shear also increased. Convection gradually became elongated in response to the shear and outflow was mostly restricted to the northeast region of the hurricane. By September 10, the mid-level circulation center was displaced from the low-level circulation center. On September 11, the convective pattern of Fred had no organized shape to it and the NHC downgraded the hurricane to a tropical storm. Unrelenting shear and dry air finally took their toll on September 12. By that time, no deep convection was associated with the main circulation of Fred, leaving the center fully exposed. The storm degenerated into a remnant-low later that day, corresponding with the final advisory from the National Hurricane Center.
On September 13, despite being in an extremely hostile environment with very high wind shear, convection redeveloped near the center of Fred, and regeneration into a tropical cyclone was seen as a possibility. Two days later, the NHC noted that environmental conditions could become marginally favorable for redevelopment of the system. On September 16, the circulation of Fred became less defined and only intermittent convection persisted around the system. By September 17, the remnant circulation became increasingly disorganized and the system dissipated later that day without regenerating into a tropical cyclone. However, several hours later, a new area of low pressure formed in association with the remnants of Fred roughly 525 mi (845 km) south of Bermuda
. The remnant low finally dissipated on September 19 roughly 520 mi (835 km) southwest of Bermuda
.
and east of 35°W
. This storm was Hurricane Frances in 1980
. Frances attained major hurricane status farther south and east than Fred; however, Fred was the strongest of the two, peaking with estimated winds of 120 mph (195 km/h) and a minimum pressure of 958 mbar (hPa; 28.29 inHg). Just over a year later, this record was broken by Hurricane Julia
which attained winds of 140 mph (220 km/h), along with a pressure of 948 mbar (hPa; 27.99 inHg), at 17.7°N and 32.2°W, becoming the easternmost forming Category 4 on record. In one of the NHC's discussions on Hurricane Fred, it was mentioned that due to the unusual location of a storm of its intensity, it would likely have gone unnoticed prior to the advent of satellite imagery in the 1960s.
Several hours before being declared a tropical depression, the precursor to Fred produced moderate rainfall and gusty winds across the southern Cape Verde Islands. In the city of Praia
, Cape Verde
, only a trace of rain, less than 0.1 in (2.5 mm) fell on September 7 and sustained winds reached 25 mph (35 km/h). The increased winds and heavy rains led to the cancellation of two flights and several others were delayed.
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...
on September 7 near the Cape Verde Islands, Fred gradually organized within an area of moderate 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...
. The following day, decreasing shear allowed the storm to intensify and develop well-organized convective
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...
banding features
Rainband
A rainband is a cloud and precipitation structure associated with an area of rainfall which is significantly elongated. Rainbands can be stratiform or convective, and are generated by differences in temperature. When noted on weather radar imagery, this precipitation elongation is referred to as...
. Later on September 8, Fred attained hurricane intensity and underwent rapid intensification
Rapid deepening
Rapid deepening, also known as rapid intensification, is a meteorological condition that occurs when the minimum sea-level atmospheric pressure of a tropical cyclone decreases drastically in a short period of time. The National Weather Service describes rapid deepening as a decrease of...
overnight, attaining its peak intensity as a strong Category 3 hurricane with winds of 120 mph (195 km/h) and a barometric pressure of 958 mbar (hPa; 28.29 inHg). Shortly after reaching this intensity, the hurricane began to weaken as wind shear increased and dry air hampered convective development.
Throughout September 10, Fred maintained Category 2 status before weakening to a Category 1 hurricane. Continued weakening took place on September 11 as convection became fully disorganized. Later that day, Fred weakened to a tropical storm and by September 12, no convection remained around the center of the former hurricane, leaving an exposed low-level circulation. The storm degenerated into a remnant-low later that day, corresponding with the final advisory from 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). The remnants of Fred persisted for nearly a full week, traveling west-northwest across the Atlantic basin. The remnants finally dissipated on September 19. Prior to becoming a tropical depression, the precursor to Fred produced moderate to heavy rainfall in the southern Cape Verde Islands, leading to two flight cancellations and several delays.
Meteorological history
Hurricane Fred originated from a strong 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 west coast of Africa on September 6. Environmental conditions ahead of the system favored development and the system was forecast to slowly develop into a 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...
. The following day, the wave tracked south of the Cape Verde Islands; however, it was close enough to bring showers and gusty winds to the southern islands. By this time, the National Hurricane Center anticipated the system to organize into a tropical depression within 24 hours. While passing near Cape Verde, a broad 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...
developed within the tropical wave. Following further development, the NHC declared that the low strengthened into a tropical depression, the seventh of the 2009 season, and issued their first advisory on it. Upon being classified a tropical depression, the system was located roughly 160 mi (260 km) south of the southernmost Cape Verde Islands.
Upon being classified a tropical depression, the NHC noted that the center of circulation was difficult to locate and the mid-level circulation was displaced from the low-level circulation. The cyclone tracked slightly north of due west in response to a small ridge
Ridge (meteorology)
A ridge is an elongated region of relatively high atmospheric pressure, the opposite of a trough....
to the north. Moderate 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...
initially displaced convective activity
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 the west. Several hours after being classified, the NHC upgraded the depression to Tropical Storm Fred; this was the first use of the name Fred in the Atlantic basin after it replaced Fabian
Hurricane Fabian
Hurricane Fabian was a powerful Cape Verde-type hurricane that hit Bermuda in early September during the 2003 Atlantic hurricane season. Fabian, the sixth named storm, fourth hurricane, and first major hurricane of the season, developed from a tropical wave in the tropical Atlantic Ocean on August 25...
which was retired in 2003
2003 Atlantic hurricane season
The 2003 Atlantic hurricane season was an active Atlantic hurricane season with tropical activity before and after the official bounds of the season – the first such occurrence in 50 years. The season produced 21 tropical cyclones, of which 16 developed into named storms; seven...
. This followed the development of convective banding features
Rainband
A rainband is a cloud and precipitation structure associated with an area of rainfall which is significantly elongated. Rainbands can be stratiform or convective, and are generated by differences in temperature. When noted on weather radar imagery, this precipitation elongation is referred to as...
along the periphery of the storm and strong shower and thunderstorm activity forming over the center of Fred. The system continued to organize, with the banding features becoming well-defined within hours and strong outflow
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...
developing around the storm.
By the afternoon of September 8, an eye
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...
began to develop within a central dense overcast. Later that day, Fred intensified into a Category 1 hurricane with winds estimated at 75 mph (120 km/h). By the morning of September 9, satellite imagery depicted that Fred had undergone rapid intensification
Rapid deepening
Rapid deepening, also known as rapid intensification, is a meteorological condition that occurs when the minimum sea-level atmospheric pressure of a tropical cyclone decreases drastically in a short period of time. The National Weather Service describes rapid deepening as a decrease of...
and attained Category 2 status. This resulted from the formation of a 12 mi (19 km) wide eye due to low wind shear and high 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. This intensification continued for several more hours, ending with Fred attaining its peak intensity as a strong Category 3 hurricane with winds of 120 mph (195 km/h) and a barometric pressure of 958 mbar (hPa; 28.29 inHg), making it the second strongest storm of the season.
Hours after attaining its peak intensity, Fred began to weaken as clouds began to fill the eye. By this time, the hurricane was beginning to turn toward the northwest as a 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...
ridge to the north weakened. Continued weakening took place as dry air started to erode convection along the southern edge of the system and the eye was no longer present on satellite imagery and wind shear also increased. Convection gradually became elongated in response to the shear and outflow was mostly restricted to the northeast region of the hurricane. By September 10, the mid-level circulation center was displaced from the low-level circulation center. On September 11, the convective pattern of Fred had no organized shape to it and the NHC downgraded the hurricane to a tropical storm. Unrelenting shear and dry air finally took their toll on September 12. By that time, no deep convection was associated with the main circulation of Fred, leaving the center fully exposed. The storm degenerated into a remnant-low later that day, corresponding with the final advisory from the National Hurricane Center.
On September 13, despite being in an extremely hostile environment with very high wind shear, convection redeveloped near the center of Fred, and regeneration into a tropical cyclone was seen as a possibility. Two days later, the NHC noted that environmental conditions could become marginally favorable for redevelopment of the system. On September 16, the circulation of Fred became less defined and only intermittent convection persisted around the system. By September 17, the remnant circulation became increasingly disorganized and the system dissipated later that day without regenerating into a tropical cyclone. However, several hours later, a new area of low pressure formed in association with the remnants of Fred roughly 525 mi (845 km) south of Bermuda
Bermuda
Bermuda is a British overseas territory in the North Atlantic Ocean. Located off the east coast of the United States, its nearest landmass is Cape Hatteras, North Carolina, about to the west-northwest. It is about south of Halifax, Nova Scotia, Canada, and northeast of Miami, Florida...
. The remnant low finally dissipated on September 19 roughly 520 mi (835 km) southwest of Bermuda
Bermuda
Bermuda is a British overseas territory in the North Atlantic Ocean. Located off the east coast of the United States, its nearest landmass is Cape Hatteras, North Carolina, about to the west-northwest. It is about south of Halifax, Nova Scotia, Canada, and northeast of Miami, Florida...
.
Historical perspective and impact
In the past 158 years that the Atlantic hurricane basin has been thoroughly studied, there was only one other storm prior to Hurricane Fred, to attain Category 3 intensity south of 30°N30th parallel north
The 30th parallel north is a circle of latitude that is 30 degrees north of the Earth's equatorial plane. It stands one-third of the way between the equator and the North Pole and crosses Africa, Asia, the Pacific Ocean, North America and the Atlantic Ocean....
and east of 35°W
35th meridian west
The meridian 35° west of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, Greenland, the Atlantic Ocean, South America, the Southern Ocean, and Antarctica to the South Pole....
. This storm was Hurricane Frances in 1980
1980 Atlantic hurricane season
The 1980 Atlantic hurricane season officially began on June 1, 1980, and lasted until November 30, 1980. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin. The season was fairly active, with eleven storms forming, of which nine reached...
. Frances attained major hurricane status farther south and east than Fred; however, Fred was the strongest of the two, peaking with estimated winds of 120 mph (195 km/h) and a minimum pressure of 958 mbar (hPa; 28.29 inHg). Just over a year later, this record was broken by Hurricane Julia
Hurricane Julia (2010)
Hurricane Julia was the easternmost Category 4 hurricane recorded in the Atlantic basin since reliable satellite observations became available. The twelfth tropical cyclone, fifth hurricane and fourth major hurricane of the 2010 Atlantic hurricane season, Julia rapidly developed on...
which attained winds of 140 mph (220 km/h), along with a pressure of 948 mbar (hPa; 27.99 inHg), at 17.7°N and 32.2°W, becoming the easternmost forming Category 4 on record. In one of the NHC's discussions on Hurricane Fred, it was mentioned that due to the unusual location of a storm of its intensity, it would likely have gone unnoticed prior to the advent of satellite imagery in the 1960s.
Several hours before being declared a tropical depression, the precursor to Fred produced moderate rainfall and gusty winds across the southern Cape Verde Islands. In the city of Praia
Praia
Praia , is the capital and largest city of Cape Verde, an island nation in the Atlantic Ocean west of Senegal. It lies on the southern coast of Santiago island in the Sotavento Islands group. It is the island's ferry port and is home to one of the nation’s four international airports...
, Cape Verde
Cape Verde
The Republic of Cape Verde is an island country, spanning an archipelago of 10 islands located in the central Atlantic Ocean, 570 kilometres off the coast of Western Africa...
, only a trace of rain, less than 0.1 in (2.5 mm) fell on September 7 and sustained winds reached 25 mph (35 km/h). The increased winds and heavy rains led to the cancellation of two flights and several others were delayed.
See also
- List of tropical cyclones
- 2009 Atlantic hurricane season2009 Atlantic hurricane seasonThe 2009 Atlantic hurricane season was a below-average year, unlike the 2009 Pacific hurricane season, which was above average, both due to a moderate El Niño. During this year, nine tropical storms formed, the fewest since the 1997 season.An average season has ten tropical storms, six hurricanes...
- Timeline of the 2009 Atlantic hurricane seasonTimeline of the 2009 Atlantic hurricane seasonThe 2009 Atlantic hurricane season was a below-average year in which nine tropical storms formed, the fewest since 1997.An average season has eleven tropical storms, six hurricanes and two major hurricanes. Although Tropical Depression One formed on May 28, 2009, the season officially began on...
- 2009 Georgia floods
- Hurricane Frances (1980)