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Hurricane Danny (2003)
Encyclopedia
Hurricane Danny was the fourth tropical storm and second hurricane of the 2003 Atlantic hurricane season
. Forming from a tropical wave
at a high latitude on July 16, Danny initially was not expected to strengthen past minimal storm intensity. However, as the storm followed a large loop-like path over the north Atlantic Ocean, it reached hurricane intensity on July 19 at an unusually high latitude and in an area of higher than normal pressures. After maintaining its strength for 24 hours, the convection quickly diminished as the storm moved over cooler water temperatures, and Danny degenerated to a remnant area of low pressure. The system turned to the southwest and west, and it dissipated on July 27, about 630 miles (1,015 km) east of where the storm originally formed. Danny did not affect land and resulted in no injuries or fatalities.
moved off the coast of Africa on July 9. Due to cooler waters the wave weakened as it tracked northwestward, and by the next day it was devoid of deep convection. On July 13, deep convection developed near a mid-level circulation along the wave axis, and the convection slowly organized and increased over the following days. Dvorak classifications
began late on July 15, and based on satellite imagery and ship reports of a closed surface circulation, the system developed into Tropical Depression Five on July 16 about 630 miles (1,015 km) east of Bermuda
.
The depression quickly developed outer banding features as the convection organized, and the system strengthened into Tropical Storm Danny early on July 17. The storm moved steadily northwestward around the edge of the Bermuda-Azores High pressure area
in the central Atlantic Ocean, and as it moved around its periphery its motion turned to the northeast on July 18. Despite being at a high latitude, Danny continued to strengthen over unusually warm water temperatures. Based on the formation of a 17 mile (27 km) wide eye
, it is estimated the storm attained hurricane status late on July 18 while located 525 miles (850 km) south of St. John's, Newfoundland and Labrador
. Due to the storm forming at a high latitude, Danny was embedded within a higher than average surrounding pressure field, and as a result the minimum central pressure was an unusually high 1000 mbar
.
Despite moving over cooler waters and into an area of higher vertical wind shear
, Danny maintained minimal hurricane status for 24 hours until late on July 19 when it weakened to a tropical storm. Continuing around the northern periphery of the Bermuda-Azores high, Danny turned to the east and east-southeast into an area of cooler waters, resulting in rapid weakening. The storm deteriorated into a tropical depression on July 20, and on July 21 Danny degenerated into a remnant area of low pressure. The low turned southward and southwestward into an area of warmer water temperatures, and after executing a small loop on July 24 the system developed deep convection over the center. However, large quantities of dry air prevented re-development of the storm. On July 27, the remnant low dissipated about 1,240 miles (2,000 km) east of Bermuda
, or about 630 miles (1,015 km) east of where Danny first developed.
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The tropical depression that would become Danny was not originally forecast to strengthen into a tropical storm, yet it defied forecasts to become a tropical storm and hurricane. A narrow region of unusually high sea-surface temperatures (27 °C – 27.5 °C, 80.6 °F – 81.5 °F) was responsible for the intensification at a relatively high latitude. The NHC was accurate in predicting Danny's movement clockwise around the subtropical ridge.
Later in the forecast period as Danny was weakening, the NHC also discussed the possibility of Danny reintensifying as it moved south into a region of warmer sea-surface temperatures and less vertical wind shear. However, such a possibility was not considered likely due to the expectation that Danny would be too weak to regenerate by that point.
. However, a high pressure system forced the system to turn northward well to the east of the island. The hurricane entered the Canadian Hurricane Centre
's response zone, although tropical storm winds were not reported in Canadian waters. The Canadian Hurricane Centre issued a gale warning for the southern half of the southeastern Grand Banks
, though it was cancelled after gale force winds were no longer expected. Only one ship reported tropical storm force winds in association with Hurricane Danny; a ship on July 20 recorded a west wind of 45 mph (72 km/h) while located 105 miles (170 km) south of the center. Because Danny stayed well out to sea, no warnings or watches were issued.
When Danny became a tropical storm on July 17, it was the third earliest that a hurricane season produced its fourth tropical storm (it has since dropped to fourth). Danny became a hurricane at 39.2° N, the furthest north that a tropical cyclone has intensified into a hurricane before the month of August.
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...
. Forming 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...
at a high latitude on July 16, Danny initially was not expected to strengthen past minimal storm intensity. However, as the storm followed a large loop-like path over the north Atlantic Ocean, it reached hurricane intensity on July 19 at an unusually high latitude and in an area of higher than normal pressures. After maintaining its strength for 24 hours, the convection quickly diminished as the storm moved over cooler water temperatures, and Danny degenerated to a remnant area of low pressure. The system turned to the southwest and west, and it dissipated on July 27, about 630 miles (1,015 km) east of where the storm originally formed. Danny did not affect land and resulted in no injuries or fatalities.
Meteorological history
A large and well-organized 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 July 9. Due to cooler waters the wave weakened as it tracked northwestward, and by the next day it was devoid of deep convection. On July 13, deep convection developed near a mid-level circulation along the wave axis, and the convection slowly organized and increased over the following days. Dvorak classifications
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...
began late on July 15, and based on satellite imagery and ship reports of a closed surface circulation, the system developed into Tropical Depression Five on July 16 about 630 miles (1,015 km) east 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 depression quickly developed outer banding features as the convection organized, and the system strengthened into Tropical Storm Danny early on July 17. The storm moved steadily northwestward around the edge of the Bermuda-Azores High pressure area
High pressure area
A high-pressure area is a region where the atmospheric pressure at the surface of the planet is greater than its surrounding environment. Winds within high-pressure areas flow outward due to the higher density air near their center and friction with land...
in the central Atlantic Ocean, and as it moved around its periphery its motion turned to the northeast on July 18. Despite being at a high latitude, Danny continued to strengthen over unusually warm water temperatures. Based on the formation of a 17 mile (27 km) wide 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...
, it is estimated the storm attained hurricane status late on July 18 while located 525 miles (850 km) south of St. John's, Newfoundland and Labrador
St. John's, Newfoundland and Labrador
St. John's is the capital and largest city in Newfoundland and Labrador, and is the oldest English-founded city in North America. It is located on the eastern tip of the Avalon Peninsula on the island of Newfoundland. With a population of 192,326 as of July 1, 2010, the St...
. Due to the storm forming at a high latitude, Danny was embedded within a higher than average surrounding pressure field, and as a result the minimum central pressure was an unusually high 1000 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...
.
Despite moving over cooler waters and into an area of higher 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...
, Danny maintained minimal hurricane status for 24 hours until late on July 19 when it weakened to a tropical storm. Continuing around the northern periphery of the Bermuda-Azores high, Danny turned to the east and east-southeast into an area of cooler waters, resulting in rapid weakening. The storm deteriorated into a tropical depression on July 20, and on July 21 Danny degenerated into a remnant area of low pressure. The low turned southward and southwestward into an area of warmer water temperatures, and after executing a small loop on July 24 the system developed deep convection over the center. However, large quantities of dry air prevented re-development of the storm. On July 27, the remnant low dissipated about 1,240 miles (2,000 km) east 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...
, or about 630 miles (1,015 km) east of where Danny first developed.
Predictions
Later in the forecast period as Danny was weakening, the NHC also discussed the possibility of Danny reintensifying as it moved south into a region of warmer sea-surface temperatures and less vertical wind shear. However, such a possibility was not considered likely due to the expectation that Danny would be too weak to regenerate by that point.
Impact and records
Hurricane Danny did not affect any land areas and there were no reports of damage or fatalities. Early in its life, Danny moved in a direction towards BermudaBermuda
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...
. However, a high pressure system forced the system to turn northward well to the east of the island. The hurricane entered the Canadian Hurricane Centre
Canadian Hurricane Centre
The Canadian Hurricane Centre is a division of the Meteorological Service of Canada, an agency of Canada's Department of the Environment, which exists to advise Canadians on the threat of tropical cyclones such as hurricanes and tropical storms...
's response zone, although tropical storm winds were not reported in Canadian waters. The Canadian Hurricane Centre issued a gale warning for the southern half of the southeastern Grand Banks
Grand Banks
The Grand Banks of Newfoundland are a group of underwater plateaus southeast of Newfoundland on the North American continental shelf. These areas are relatively shallow, ranging from in depth. The cold Labrador Current mixes with the warm waters of the Gulf Stream here.The mixing of these waters...
, though it was cancelled after gale force winds were no longer expected. Only one ship reported tropical storm force winds in association with Hurricane Danny; a ship on July 20 recorded a west wind of 45 mph (72 km/h) while located 105 miles (170 km) south of the center. Because Danny stayed well out to sea, no warnings or watches were issued.
When Danny became a tropical storm on July 17, it was the third earliest that a hurricane season produced its fourth tropical storm (it has since dropped to fourth). Danny became a hurricane at 39.2° N, the furthest north that a tropical cyclone has intensified into a hurricane before the month of August.