Hurricane Danielle (2004)
Encyclopedia
Hurricane Danielle was the first of several Cape Verde-type hurricane
to form during the 2004 Atlantic hurricane season
. Danielle was the fourth named storm
and third hurricane of the season. Danielle formed on August 13, 2004 in the far eastern Atlantic Ocean
and remained over the central Atlantic, peaking as a strong Category 2 hurricane on August 16 before weakening over cooler waters; becoming a remnant low
on August 21 and dissipating on August 24. Danielle never approached land, although it briefly threatened the Azores
as it made the northerly turn. As a result, there was no impact caused by the storm.
over Africa
. As the wave emerged into the Atlantic, it quickly became more organized due to favorable conditions, including low wind shear
. The circulation consolidated and spawned Tropical Depression Four on the morning of August 13 south-southeast of the Cape Verde
islands. The system was over somewhat cooler water at first with sea surface temperatures around 79°F (26°C); however, the low shear environment allowed the depression to continue to organize. Late that evening, the system strengthened into Tropical Storm Danielle.
As Danielle tracked westward into the open Atlantic early on August 14, the storm encountered warmer water southwest of Cape Verde and began to gradually intensify, becoming a moderate tropical storm with 50 mph (85 km/h) winds that morning. At that point, a bout of rapid intensification
began to take place, and the storm was upgraded to Hurricane Danielle that evening as an eye
began to form. Over a 24 hour period ending in the morning of August 15, the pressure
fell from 1004 to 978 mbar
and the winds increased to 90 mph (145 km/h), making it a high-end Category 1 hurricane on the Saffir-Simpson hurricane scale
.
Danielle levelled off somewhat in intensity after that round of rapid intensification, only gradually strengthening afterward due to structural changes in the storm related to the small wind field relative to the size of the eye. Nonetheless, Danielle became a Category 2 hurricane on the afternoon of August 15 as it approached the subtropical ridge
which blocked the continued westward movement. Beginning late on August 15, at about 35°W, Danielle began to recurve to the northwest and eventually north while continuing to gradually strengthen. Early on August 16, the recurvature became more pronounced, and Danielle turned abruptly northward in the central Atlantic Ocean
as an upper-level trough
opened up a large break in the ridge. That movement took it along the eastern side of the subtropical ridge, preventing Danielle from moving any farther west and becoming any threat to North America
or the Caribbean
. While moving northwest, Danielle strengthened a bit more, reaching its peak intensity of 110 mph (175 km/h), just under Category 3 intensity, on the afternoon of August 16.
The northward movement also sent Danielle into somewhat increased shear, which allowed it to begin to weaken. However, the weakening was gradual at first as the waters remained fairly warm. The abrupt northerly turn meant that, for a while on August 17, the Azores
were threatened by Danielle in the long-range forecast, as a weakened tropical storm or extratropical cyclone. Danielle weakened to a Category 1 hurricane on the evening of August 17 as shear continued to increase. Danielle began to turn to the northeast early on August 18, and at that point, the weakening trend accelerated. Some of the deep convection was being removed from the system due to wind shear, and that morning, Danielle weakened to a tropical storm. The rapid weakening trend continued that afternoon, and Danielle weakened to a low-end tropical storm with 45 mph (75 km/h) winds late that evening. However, the intensity levelled off early on August 19 and Danielle remained a tropical storm for the next couple days over moderately warm water of around 78°F (just under 26°C) while south-southwest of the Azores.
Intermittent deep convection continued to fire up, keeping the storm afloat for the next day and turning it away from the Azores. Danielle also changed direction and meandered slightly to the northwest, away from the Azores, due to very weak steering currents. After holding on as a minimal tropical storm, Danielle finally lost its deep convection due to high upper-level vertical shear and was downgraded to a tropical depression on the afternoon of August 20. The depression turned once again to the north, and continued to lose organization over cooler water. It degenerated into a remnant low on the afternoon of August 21 as the convection was completely sheared away from the center of Danielle. The remnant low remained in the open ocean, remaining devoid of any deep convection, until August 24 when it dissipated west-southwest of the Azores.
in the 2000 Atlantic hurricane season
.
Cape Verde-type hurricane
A Cape Verde-type hurricane is an Atlantic hurricane that develops near the Cape Verde islands, off the west coast of Africa. The average hurricane season has about two Cape Verde-type hurricanes, which are usually the largest and most intense storms of the season because they often have plenty of...
to form during the 2004 Atlantic hurricane season
2004 Atlantic hurricane season
The 2004 Atlantic hurricane season officially began on June 1, 2004, and lasted until November 30, 2004. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin...
. Danielle was the fourth named 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...
and third hurricane of the season. Danielle formed on August 13, 2004 in the far eastern 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 remained over the central Atlantic, peaking as a strong Category 2 hurricane on August 16 before weakening over cooler waters; becoming a remnant low
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...
on August 21 and dissipating on August 24. Danielle never approached land, although it briefly threatened the Azores
Azores
The Archipelago of the Azores is composed of nine volcanic islands situated in the middle of the North Atlantic Ocean, and is located about west from Lisbon and about east from the east coast of North America. The islands, and their economic exclusion zone, form the Autonomous Region of the...
as it made the northerly turn. As a result, there was no impact caused by the storm.
Meteorological history
Hurricane Danielle began as a vigorous 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...
over Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
. As the wave emerged into the Atlantic, it quickly became more organized due to favorable conditions, including low 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 circulation consolidated and spawned Tropical Depression Four on the morning of August 13 south-southeast of the 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...
islands. The system was over somewhat cooler water at first with sea surface temperatures around 79°F (26°C); however, the low shear environment allowed the depression to continue to organize. Late that evening, the system strengthened into Tropical Storm Danielle.
As Danielle tracked westward into the open Atlantic early on August 14, the storm encountered warmer water southwest of Cape Verde and began to gradually intensify, becoming a moderate tropical storm with 50 mph (85 km/h) winds that morning. At that point, a bout of 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...
began to take place, and the storm was upgraded to Hurricane Danielle that evening as 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 form. Over a 24 hour period ending in the morning of August 15, the pressure
Atmospheric pressure
Atmospheric pressure is the force per unit area exerted into a surface by the weight of air above that surface in the atmosphere of Earth . In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point...
fell from 1004 to 978 mbar
Bar (unit)
The bar is a unit of pressure equal to 100 kilopascals, and roughly equal to the atmospheric pressure on Earth at sea level. Other units derived from the bar are the megabar , kilobar , decibar , centibar , and millibar...
and the winds increased to 90 mph (145 km/h), making it a high-end Category 1 hurricane on the Saffir-Simpson hurricane scale
Saffir-Simpson Hurricane Scale
The Saffir–Simpson Hurricane Scale , or the Saffir–Simpson Hurricane Wind Scale , classifies hurricanes — Western Hemisphere tropical cyclones that exceed the intensities of tropical depressions and tropical storms — into five categories distinguished by the intensities of their sustained winds...
.
Danielle levelled off somewhat in intensity after that round of rapid intensification, only gradually strengthening afterward due to structural changes in the storm related to the small wind field relative to the size of the eye. Nonetheless, Danielle became a Category 2 hurricane on the afternoon of August 15 as it approached the subtropical ridge
Subtropical ridge
The subtropical ridge is a significant belt of high pressure situated around the latitudes of 30°N in the Northern Hemisphere and 30°S in the Southern Hemisphere. It is characterized by mostly calm winds, which acts to reduce air quality under its axis by causing fog overnight, and haze during...
which blocked the continued westward movement. Beginning late on August 15, at about 35°W, Danielle began to recurve to the northwest and eventually north while continuing to gradually strengthen. Early on August 16, the recurvature became more pronounced, and Danielle turned abruptly northward in the central 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...
as an upper-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...
opened up a large break in the ridge. That movement took it along the eastern side of the subtropical ridge, preventing Danielle from moving any farther west and becoming any threat to North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
or the Caribbean
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...
. While moving northwest, Danielle strengthened a bit more, reaching its peak intensity of 110 mph (175 km/h), just under Category 3 intensity, on the afternoon of August 16.
The northward movement also sent Danielle into somewhat increased shear, which allowed it to begin to weaken. However, the weakening was gradual at first as the waters remained fairly warm. The abrupt northerly turn meant that, for a while on August 17, the Azores
Azores
The Archipelago of the Azores is composed of nine volcanic islands situated in the middle of the North Atlantic Ocean, and is located about west from Lisbon and about east from the east coast of North America. The islands, and their economic exclusion zone, form the Autonomous Region of the...
were threatened by Danielle in the long-range forecast, as a weakened tropical storm or extratropical cyclone. Danielle weakened to a Category 1 hurricane on the evening of August 17 as shear continued to increase. Danielle began to turn to the northeast early on August 18, and at that point, the weakening trend accelerated. Some of the deep convection was being removed from the system due to wind shear, and that morning, Danielle weakened to a tropical storm. The rapid weakening trend continued that afternoon, and Danielle weakened to a low-end tropical storm with 45 mph (75 km/h) winds late that evening. However, the intensity levelled off early on August 19 and Danielle remained a tropical storm for the next couple days over moderately warm water of around 78°F (just under 26°C) while south-southwest of the Azores.
Intermittent deep convection continued to fire up, keeping the storm afloat for the next day and turning it away from the Azores. Danielle also changed direction and meandered slightly to the northwest, away from the Azores, due to very weak steering currents. After holding on as a minimal tropical storm, Danielle finally lost its deep convection due to high upper-level vertical shear and was downgraded to a tropical depression on the afternoon of August 20. The depression turned once again to the north, and continued to lose organization over cooler water. It degenerated into a remnant low on the afternoon of August 21 as the convection was completely sheared away from the center of Danielle. The remnant low remained in the open ocean, remaining devoid of any deep convection, until August 24 when it dissipated west-southwest of the Azores.
Impact, naming, and records
Hurricane Danielle did not have any impact on land and no damage or fatalities were reported. No ships were reported to have come into contact with Danielle. When Danielle became a tropical storm at 24.8°W, it was the farthest east that a storm had received a name since Hurricane AlbertoHurricane Alberto (2000)
Hurricane Alberto was an Atlantic Cape Verde-type hurricane that formed on August 3, 2000 and became extratropical on August 23. Alberto was the first named storm, first hurricane, and first major hurricane of the 2000 Atlantic hurricane season....
in the 2000 Atlantic hurricane season
2000 Atlantic hurricane season
The 2000 Atlantic hurricane season was the first season without a tropical cyclone in July since 1987. The season officially began on June 1, 2000, and lasted until November 30, 2000. The June through November dates conventionally delimit the period of each year when most tropical cyclones form in...
.
External links
- NHC's Tropical Cyclone Report on Hurricane Danielle