Hurricane Dennis (1999)
|Category 2 hurricane (SSHS)|
|Hurricane Dennis on August 30|
|Formed||August 24, 1999|
|Dissipated||September 7, 1999|
|Highest winds||1-minute sustained:
105 mph (165 km/h)
|Lowest pressure||962 mbar (hPa); 28.41 inHg|
|Damage||$157 million (1999 USD)|
|Areas affected||Bahamas, North Carolina, Virginia, Maryland, Pennsylvania|
|Part of the 1999 Atlantic hurricane season|
Hurricane Dennis was a North Atlantic hurricane that affected The Bahamas and parts of the Mid-Atlantic and Northeast during the 1999 Atlantic hurricane season. The fifth tropical cyclone, fourth tropical storm, and third hurricane of the season, Dennis originated from a tropical wave that passed north of the Leeward Islands in mid-to-late August. Moving west-northwest, the wave organized into a tropical depression on August 24. Tracking just north of Grand Turk that same day, the depression was upgrade to a tropical storm just several hours later. Positioned on the eastern end of an elongated trough, Dennis was embedded within an area of high wind shear. However, despite this, the storm strengthened into a hurricane on August 26, and then further into Category 2 hurricane status on August 28. Moving in an erractic motion off the North Carolina coastline, Dennis became entangled within a cold front that caused dry air to impact the circulation, thus weakening the storm to a tropical storm. On August 30, Dennis made landfall along the Outerbanks of North Carolina, resulting in tropical storm-force sustained winds and hurricane-force gusts in the area. Rapidly weakening, Dennis weakened into a tropical depression over the central portion of North Carolina, and was absorbed within a larger extratropical low on September 8, while located over Canada.
Meteorological history 
A tropical wave moved off the African coast on August 17. The wave continued west-northwestward, not organizing until August 21 when an increase in convection occurred. A low-level circulation slowly developed as it passed north of the Lesser Antilles, and on August 24 it was upgraded to Tropical Depression Five while located around 220 mi (350 km) east of Grand Turk Island. It moved to the west-northwest, and later on the 24th it strengthened into Tropical Storm Dennis.
Located at the eastern end of an elongated trough, Dennis was affected by westerly shear. Despite the unfavorable conditions, the storm intensified, and reached hurricane status on August 26 over the Bahamas. Due to the trough, Dennis moved very erratically, varying between a fast forward speed to a near drift in its developmental stages. After passing through the Bahamas, the shear decreased, and Dennis was able to reach Category 2 strength on the 28th.
A mid-latitude trough brought Dennis north and northeastward, causing it to parallel the Florida through North Carolina coastlines. While east of Florida on August 28, Dennis peaked at 105 mph (170 km/h) winds, though the wind field never resembled a classical tightly wound hurricane. The eye wall was around 35 miles (56 km) wide, and at some occasions reconnaissance aircraft did not even report an eye. This may be because some upper level shear remained. Dennis weakened as it continued northeastward, but still brought hurricane force winds to the North Carolina coast on August 30.
Hurricane Dennis became involved with a cold front, which caused vertical shear and cool, dry air to impact the circulation. A ridge of high pressure to its north caused Dennis to stall, leading to the cyclone's weakening to a tropical storm on September 1 as a result of the unfavorable conditions. On the 1st and 2nd, with disorganized convection and a large wind field, Dennis resembled a subtropical cyclone or even an extra-tropical storm, but it retained its warm core as it drifted southward over warmer waters. Dennis restrengthened as it turned to the west-northwest, and made landfall near Harkers Island, North Carolina on September 5 while just below hurricane strength. The storm rapidly weakened over land, and turned northward through Virginia. It became extra-tropical on September 7, and was absorbed by a larger extra-tropical low the following day, while located over Canada.
The erratic motion of Hurricane Dennis resulted in several tropical storm watches and warnings, as well as hurricane watches and warning to be issued. Alerts from this hurricane were issued starting on August 24, at which time a tropical storm warning was put it place for the southeast Bahamas and Turks and Caicos Islands, simultaneously, a tropical storm watch was also issued for the central Bahamas. Less than 24 hours, the tropical storm watch was upgraded to a tropical storm warning, while there was also an additional hurricane watch. All watches and warnings within the Bahamas were discontinued by late August 28.
Watches and warnings in the United States started on August 27 with a hurricane watch being issued from Sebastian Inlet, Florida to Fernandina Beach, Florida. A tropical storm warning was also issued for much of the same area several hours later. As Hurricane Dennis began turning northward, the threat of it strike Florida lessened, which resulted in discontinuations of the watches and warnings.
Dennis left $157 million (1999 USD) in damage and four deaths in North Carolina, Virginia and the northeastern United States. The heavy rain from Dennis staged a catastrophic flood disaster wrought by Hurricane Floyd about two weeks later.
Dennis brought tropical storm and hurricane force winds to the Bahamas. In Grand Bahama, a weather station reported winds of 40 mph (64 km/h) while other areas reported winds between 70-75 mph. A 976 mbar reading and storm tides 1–3 feet above normal occurred as the center of the storm moved across Abaco Island on August 28. The only official rainfall total from the Bahamas was 4.4 inches (110 mm) at Eleuthera and Abaco. Dennis caused moderate damage across the Bahamas. On Abaco Island, the rain caused heavy flooding and storm surge washed out roads. Dennis also caused considerable damage to trees and boats. However, there were no reports of deaths or injuries and damage totals from the Bahamas are unavailable.
Southeastern United States 
When Dennis was offshore the storm brought winds up to 35 mph (56 km/h) with gusts reaching to 40 mph (64 km/h) to Jacksonville, Florida. In St. Augustine, a weather station reported a 35 mph (56 km/h) gust. Rainfall from Dennis was minimal, amounting to only 0.11 inches (2.8 mm) at Jacksonville International Airport. Dennis also brought storm tides between 6–8 feet in some areas and there was only minor beach erosion. The strong rip currents brought by Dennis caused one fatality.
In South Carolina, numerous weather stations reported winds between 40-55 mph and gusts reaching hurricane force. Rainfall up to 1.2 inches (30 mm) fell in some areas while buoys offshore reported tides 2 feet (0.61 m) 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 
Dennis brought tropical storm force winds with gusts up to hurricane force to the North Carolina coast. In Oregon Inlet, there were 60 mph (97 km/h) winds, while Cape Hatteras and Wrightsville Beach reported gusts between 90-100 mph. A weather station reported 90 mph (140 km/h) wind gusts and a barometric pressure reading of 977 mbar. When Dennis made landfall on September 4, it brought tropical storm force winds to much of eastern North Carolina. 45 mph (72 km/h) winds were reported in Cherry Point, North Carolina. Storm tides 3–5 feet above normal were reported along the North Carolina coast. Because Dennis was a slow moving storm, it produced heavy rains across eastern North Carolina. The highest rainfall total was 19.13 inches (486 mm) in Ocracoke, while rainfall between 3-10 inches was reported elsewhere. The rain was beneficial as it broke a prolonged dry spell, but it also staged the catastrophic flood disaster caused by Hurricane Floyd a month later. The heavy rains caused significant flooding that left $60 million dollars (1999 USD) in structural damage and $37 million dollars (1999 USD) in agricultural damage — totaling $97 million (1999 USD). In addition, Dennis caused two indirect deaths when two cars collided during the storm. The heavy rains knocked down power lines near Wilmington, North Carolina, leaving 56,000 residents without electricity.
Virginia and Mid-Atlantic 
The remnants of Dennis tracked across Maryland between September 4 and September 6, producing heavy rainfall in central portions of the state and tidal flooding along the western shoreline of the Chesapeake Bay. Rainfall totals include 5.59 inches (142 mm) at Clarksburg, 4.50 inches (114 mm) at Glenmont, and 4.41 inches (112 mm) at Gaithersburg. Winds in the state gusted to 35 miles per hour (56 km/h), causing downed tree limbs and scattered power outages. Associated lightning in Allegany County struck two main power poles. The incident forced the closer of Interstate 68 and left 4,700 customers without power. Tides generally ran 2 to 3 feet (0.61 to 0.91 m) above normal along the coast; coastal flooding was reported at several locations. Two days of heavy rain swelled Jones Falls Creek, which swept away a 13 year old boy. After an hour, he was rescued from a pile of debris and treated for hypothermia. Street flooding of up to 2 feet (0.61 m) in depth was reported. In Baltimore, persistent winds pushed water over a seawall at Inner Harbor.
Periods of heavy rain, street flooding, wind gusts of up to 35 miles per hour (56 km/h), and tidal flooding along the Potomac River were also reported in Washington, D.C.. The Washington Reagan National Airport recorded 2.31 inches (59 mm) of rain. The winds resulted in isolated power outages throughout the district. To protect the Washington Harbor, officials erected a flood wall along the Potomac River. The storm also dropped light rainfall in parts of Delaware.
Rainfall in Pennsylvania reached 7.29 inches (185 mm) at Lewisburg. Elsewhere, in Lycoming County, 4 to 8 inches (100 to 200 mm) of precipitation was reported. The heavy rainfall triggered flash flooding that was compared to that of Hurricane Agnes in 1972. In Montgomery, 30 houses were damaged and 80 residents were evacuated. Also struck severely by the flooding was Union County. Several hundred homes and businesses were affected, and throughout the county, numerous vehicles were damaged. Elsewhere, trailers were swept away by the flood waters. Campers along the banks of various creeks were forced to higher ground. An entire neighborhood in Swatara Township evacuated when flood waters reached depths of 8 feet (2.4 m). Across the region, basements and roads were flooded. In addition, mudslides closed two highways north of Liverpool.
A narrow band of rainfall produce precipitation rates of over 2 inches (51 mm) per hour in some areas across southeastern New York, which resulted in significant street flooding. The heaviest precipitation fell on the higher terrain of southeast Orange County and northwest Rockland County. On some roads, flood waters accumulated to 3 feet (0.91 m) deep; this led to stalled vehicles. Several basements were flooded in the region. In New York City, a period of hot weather, followed by heavy rainfall from the remnants of Dennis, contributed to the formation of a swarm of disease-carrying mosquitoes. A strong high pressure system developed over eastern Canada and New England. Combined with swells from Hurricane Dennis, beach erosion, rouge surf, and minor tidal flooding battered the coast of New Jersey. Tides ranged as high as 7 feet (2.1 m) along the coast, and street flooding was reported onshore. As a result of the rouge surf, swimming restrictions were set. The beach at Cape Map Point lost approximately 1 foot (0.30 m) of sand to the erosion. Moderate rainfall extended into New England, where in excess of 3 inches (76 mm) of precipitation was recorded.
See also 
|Wikimedia Commons has media related to: Hurricane Dennis (1999)|
- Other storms of the same name
- List of Florida hurricanes
- List of North Carolina hurricanes
- List of New Jersey hurricanes
- Beven II, John L; National Hurricane Center (January 11, 2000). "Hurricane Dennis (1999)" (Preliminary Report). United States National Oceanic and Atmospheric Administration's National Weather Service. Retrieved 3 May 2010.
- Hurricane City.com
- CNN Report from Florida
- CNN report from Georgia and South Carolina
- National Climatic Data Center (2009). "Heavy Rain Event Report for Maryland". United States National Oceanic and Atmospheric Administration's National Weather Service. Retrieved 2009-01-15.
- National Climatic Data Center (2009). "Heavy Rain Event Report for the District of Columbia". United States National Oceanic and Atmospheric Administration's National Weather Service. Retrieved 2009-01-15.
- Roth, David M; Hydrometeorological Prediction Center (2012). "Tropical Cyclone Rainfall for the New England United States". Tropical Cyclone Rainfall Point Maxima. United States National Oceanic and Atmospheric Administration's National Weather Service. Retrieved June 23, 2012.
- Roth, David M; Weather Prediction Center (2012). "Tropical Cyclone Rainfall in the Mid-Atlantic United States". Tropical Cyclone Rainfall Point Maxima. United States National Oceanic and Atmospheric Administration's National Weather Service. Retrieved June 23, 2012.
- National Climatic Data Center (2009). "Flash Flood Event Report for Pennsylvania". United States National Oceanic and Atmospheric Administration's National Weather Service. Retrieved 2009-01-15.
- National Climatic Data Center (2009). "Flash Flood Event Report for Pennsylvania (2)". United States National Oceanic and Atmospheric Administration's National Weather Service. Retrieved 2009-01-15.
- National Climatic Data Center (2009). "Flash Flood Event Report for Pennsylvania (3)". United States National Oceanic and Atmospheric Administration's National Weather Service. Retrieved 2009-01-15.
- "Flash Flood Event Report for Pennsylvania (4)". National Climatic Data Center. 2009. Retrieved 2009-01-15.
- National Climatic Data Center (2009). "Flash Flood Event Report for Pennsylvania (5)". United States National Oceanic and Atmospheric Administration's National Weather Service. Retrieved 2009-01-15.
- National Climatic Data Center (2009). "Flash Flood Event Report for New York". United States National Oceanic and Atmospheric Administration's National Weather Service. Retrieved 2009-01-14.
- Staff Writer (September 20, 1999). "Barkers at pleasure beach side shows". BBC News. Retrieved 2009-01-15.
- National Climatic Data Center (2009). "Coastal Flooding/Erosion Event Report for New Jersey". United States National Oceanic and Atmospheric Administration's National Weather Service. Retrieved 2009-01-15.