A hurricane (from a Caribbean Indian word for “big wind” or “storm god”) is, technically, a tropical cyclone — a huge, rotating low-pressure system — with organized convection (i.e., thunderstorms) and sustained surface winds of 74 miles per hour or more.
A tropical cyclone with winds of less than 39 mph is known as a tropical depression. A cyclone with winds of greater than 39 mph is known as a tropical storm and is typically assigned a name by the National Ocean and Atmospheric Administration.
Hurricanes are essentially the same sort of storm as a typhoon (found in the Northwest Pacific) and a tropical cyclone (Southwest Pacific and Southeast Indian Ocean). The only difference is in the location.
Hurricane season in the Atlantic Ocean runs from June 1 to Nov. 30. Most hurricanes that affect Southeastern North Carolina strike in late August or September, although Hurricane Hazel, a Category 4 hurricane that demolished most of the Brunswick County coast, came ashore near Calabash on Oct. 15, 1954.
Most hurricanes that affect coastal North Carolina are either Category 1 (sustained winds 74-95 mph, storm surge 4-5 feet above normal) or Category 2 (winds 96-110 mph, surge 6-8 feet above normal) on the Saffir-Simpson scale.
No Category 5 storms (winds 155 mph or more; surge more than 18 feet above normal) have struck the state in modern times. Hazel, a Category 4 storm, reached sustained winds of 140 mph at Oak Island, and its storm surge of 18 feet was worsened by the fact that it struck at the exact time of the highest lunar tide of the year in 1954. Hurricane Fran, in 1956, was a Category 3 hurricane, reached gusts of up to 126 mph at Wrightsville Beach.
Hurricanes unleash intense and prolonged rain showers — as much as 12 inches in a matter of hours over parts of Brunswick and Pender counties in the case of Fran. Hurricane Floyd, a Category 2 hurricane, caused relatively minor damage on the coast, but dumped an unusually high amount of rain (19.06 inches in Wilmington alone), causing severe flooding in Pender, Duplin and Onslow counties.
Tornadoes are often reported; four were spotted in the Wilmington area during Floyd.
For reasons scientists still do not understand, hurricanes tend to come in clusters, followed by years or decades of relative inactivity. In the 1950s, North Carolina was nicknamed “Hurricane Alley,” and the Cape Fear area was hit by Hazel (1954), Diane (1955). Helene (1958) and Donna (1960). After Donna, the area saw relatively few hurricanes until Bertha (1996), Fran (1996), Bonnie (1998) and Floyd (1999).
The greatest threat from hurricanes lies in coastal flooding from the storm surge. Residents of low-lying areas should be ready to evacuate. Further inland, power lines will likely be downed, posing a threat on highways; large numbers of branches will fall, blocking streets and roads, while roofs and mobile homes may be damaged. More severe property damage is rare, although a gust from Fran toppled the steeple of First Baptist Church, 411 Market St., Wilmington [Map this].
The greatest danger to human life during a hurricane is from drowning, usually when cars are swept off roads by floodwaters in low-lying areas. Some 52 deaths across North Carolina were attributed to Hurricane Floyd alone.
Residents who do not evacuate during hurricanes should stay indoors, or seek shelter in an evacuation center for the duration of the storm and should monitor radio reports for bulletins.
Date posted: April 1, 2009