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Hurricane Dennis was the fourth named storm and the third hurricane of the 1999 Atlantic hurricane season. Dennis developed east of Grand Turk, tracked northwest, becoming a hurricane as it did so. Dennis then looped offshore North Carolina, before ultimately hitting as a tropical storm. Dennis brought hurricane-force winds to coastal North Carolina, as it meandered offshore. Dennis's heavy rainfall also set the stage for the destructive flood brought by Hurricane Floyd later in the season.

Dennis caused $157,000,000 (1999 USD) in damage and 4 direct deaths.

Dennis offshore North Carolina
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Formation August 24, 1999
Dissipation September 7, 1999
Highest winds 105 mph
Lowest pressure 962 mbar
Deaths 4 direct, 2 indirect
Damages $157,000,000 (1999 USD)
Areas affected Bahamas, North Carolina, Virginia, Maryland, Pennsylvania

Meteorological History

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A tropical wave moved off the coast of Africa on August 17. The wave moved west-northwest across the Atlantic Ocean, and it did not begin to organize until August 21 when an increase in convection occured within the wave. A low-level circulation gradually developed as the wave passed north of the Lesser Antilles. On August 24, the wave was upgraded to Tropical Depression Five while located 220 miles east of Grand Turk. After forming, the depression moved west-northwest, becoming Tropical Storm Dennis later on August 24. Located at the eastern end of an elongated trough, westerly wind shear affected Dennis. Despite the unfavorable conditions, Dennis continued to intensify, and on August 26, Dennis became a hurricane while over the Bahamas. Because of the trough's influence, Dennis moved very eratically, varying in a fast foward speed to a near drifting motion during its developmental stages. After Dennis passed through the Bahamas, the shear decreased, and on August 28, Dennis became a Category 2 hurricane. A mid-latitude trough brought Dennis northeastward after this, causing it to parallel the coastlines of Florida to North Carolina. While located east of Florida on August 28, Dennis reached its peak of 105 mph as a Category 2 hurricane, although the wind field within the hurricane never resembled a classic tightly wound hurricane.

Dennis's eyewall was 35 miles wide, and on some occasions Reconnaissance Aircraft did not even report an eye within the hurricane. This may be due to the fact that some upper-level wind shear remained. As Dennis continued northeastward, it weakened, but brought hurricane-force winds to coastal North Carolina on August 30. Dennis interacted with a cold front, which causing cool, dry air and strong vertical wind shear to impact Dennis. A ridge of high pressure to its north caused Dennis to stall offshore, and this led to Dennis weakening to a tropical storm on September 1, because of upwelling. On September 1 and 2, with disorganized convection and an asymmetric wind field, Dennis resembled a subtropical cyclone or even an extratropical cyclone. Nevertheless, as Dennis moved southward over the warm waters of the Gulf Stream, it maintained its warm-core. As Dennis turned to the west-northwest, it re-strengthened, and it made landfall near Harkers Island, North Carolina on September 5 as a 70 mph tropical storm. After landfall, Dennis rapidly weakened, and then turned northward through Virginia. On September 7, Dennis became extratropical, and was absorbed by another extratropical cyclone on September 8 over Canada.

Impact

Dennis caused about $157,000,000 (1999 USD) in damage throughout its path. It caused four deaths as well, all direct. It also caused 2 indirect deaths. Dennis produced heavy rainfall along the Mid-Atlantic states and the northeastern United States, which broke a dry spell, but unfortunately set the stage for the destructive flood wrought by Hurricane Floyd later on in the season.

Bahamas

Dennis produced tropical storm-force winds and hurricane-force winds in the Bahamas. In Grand Bahama, a weather station reported sustained winds of up to 40 mph, while other stations across the Bahamas reported 70-75 mph sustained winds. A pressure reading of 976 mb as well as storm tides of 1-3 feet above normal occured as Dennis's center of circulation moved across Abaco Island on August 28. The only official rainfall total reported in the Bahamas was 4.4 inches at Eleuthera and Abaco. Dennis caused moderate damage across the Bahamas. On Abaco Island, Dennis's heavy rainfall as well as storm surge caused heavy flooding and also washed out roads. Dennis also caused considerable damage to trees and boats. There were no reports of deaths or injuries, and damage estimates in the Bahamas are unavailable.

Southeastern United States

While Dennis was offshore, it brought winds of up to 35 mph, with gusts to 40 mph in Jacksonville, Florida. In St. Augustine, a weather station reported a wind gust of 35 mph. Dennis only produced minimal rainfall, amounting to only 0.11 inches at Jacksonville International Airport. Dennis produced storm surge between 6-8 feet in some areas, and there was some minor beach erosion, and finally, rip currents produced by Dennis killed one person in Florida.

In Georgia, wind gusts of 35 mph occured, and only a trace of rain occured.

In South Carolina, numerous weather stations reported sustained winds between 40-55 mph, with gusts up to hurricane-force. Rainfall up to 1.2 inches fell in some areas of the state, while offshore buoys repoted tides 2 feet above normal. Minor to moderate beach erosion was reported from Charleston to Colleton County. Damage in South Carolina was limited to downed trees and scattered power outages.

North Carolina

In North Carolina, where Dennis made its eventual landfall, it produced gusts up to hurricane-force to coastal North Carolina on August 30. In Oregon Inlet, sustained winds of 60 mph occured, while Cape Hatteras and Wrightsville Beach reported gusts of 90-100 mph. A weather station reported wind gusts of up to 90 mph and a pressure reading of 977 mb. When Dennis made landfall on September 4, it produced tropical storm-force winds to much of eastern North Carolina. 45 mph sustained winds were reported in Cherry Point. Storm tides of 3-5 feet above normal were reported along the coast of North Carolina as Dennis came ashore. Because Dennis was a slow-moving storm, it produced heavy rainfall in eastern North Carolina. The highest rainfall report from Dennis was 19.13 inches at Ocracoke, with rainfall amounts of 3-10 inches reported elsewhere. The rainfall was beneficial, since it broke a prolonged dry spell, but it also set the stage for the catastrophic flood disaster brought by Hurricane Floyd later on. Dennis's heavy rainfall caused significant flooding with damage that amounted to $60,000,000 (1999 USD) in structural damage, and $37,000,000 (1999 USD) in agricultural damage, with total damage being $97,000,000 (1999 USD).

In addition, the hurricane caused two indirect deaths when two cars collided during the storm. The hurricane knocked down power lines near Wilmington, leaving 56,000 residents without power.

Virginia

Winds of up to 50 mph with gusts up to 75 mph occured at Langley Air Force Base, and tides were reported to be 2-4 feet above normal. 1-3 inches of rain fell across much of southeastern Virginia, and an F2 tornado spawned by Dennis touched down in Hampton, damaging several buildings and injuring fifteen people, six of them seriously. Damage from the tornado was $7,000,000 (1999 USD). The tropical storm-force produced by Dennis also knocked out power to 22,500 residents across southeastern Virginia. In all, damage amounted to $97,000,000 (1999 USD) in Virginia from Dennis.

Lack of Retirement

Because damage was not extreme, the name Dennis was not retired by the World Meteorological Organization in the Spring of 2000. It was, however, retired during the 2005 Atlantic hurricane season, and was replaced with Don for the 2011 Atlantic hurricane season.

See Also

1999 Atlantic hurricane season

References

http://en.wikipedia.org/wiki/Hurricane_Dennis_%281999%29

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