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Between 1851 and 1996, North Carolina was hit by 38 hurricanes,
more than any other state but Louisiana. Seven of North Carolina’s
coastal counties have return periods of 10 years or less. A hurricane’s
return period is the inverse annual probability of it occurring.
More simply, it is the average time between two events. The return
periods for each of the coastal counties of North Carolina are shown
in the map below. The return periods for the counties adjacent to
Onlsow Bay (Carteret, Onslow, Pender, New Hanover, and Brunswick)
range from 6.5 (Carteret) to 10.8 (Pender) (Figure 1). So it is
not unreasonable to expect a hurricane once very 6 to 10 years in
the area (Elsner and Kara, 1999).
It
is not unreasonable to expect a hurricane once very 6 to 10
years in southeastern North Carolina. |
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| Figure 1. Map of return period
for hurricane force winds for North Carolina counties adjacent
to Onslow Bay (Modified from Elsner and Kara 1999, p. 298). |
There are a number of climatic oscillations that influence hurricane
development and path. The path of a North Atlantic hurricane is
influenced by the strength and position of the Bermuda High. When
the Bermuda high is weaker and further north, hurricanes tend to
recurve quicker, remaining offshore, and not typically affecting
the eastern coast of the US. The further southward the high pressure
zone shifts, the more hurricanes are directed toward the US or into
the Caribbean (Lutgens and Tarbuck, 2004)). There is also a relationship
between El Nino and hurricane origins and frequency. The warm phase
(El Nino) of the El Nino Southern Oscillation (ENSO) typically result
in fewer Atlantic hurricanes and the cool phase (La Nina) typically
results in more Atlantic hurricanes (Elsner and Kara, 1999).
The
warm phase (El Nino) of the El Nino Southern Oscillation (ENSO)
typically result in fewer Atlantic hurricanes and the cool
phase (La Nina) typically results in more Atlantic hurricanes |
There are a number of environmental impacts of a hurricane landfalling
in North Carolina. Barrier islands, such as those that flank Onslow
Bay, are a very dynamic system being shaped by the daily forces
of ocean currents and waves. When a powerful storm system moves
onshore, they are often drastically reshaped by storm surge or the
large storm waves (Frankenberg, 1995). Another aspect of hurricane
impact is the flooding of inland bodies of water. The year 1999
was particularly disastrous for North Carolina due to large amounts
of rainfall that accompanied hurricanes Dennis and Floyd. Floods
in the Tar River basin caused waters to unprecedented levels that
some estimated to have return intervals of 400 to 500 years (Lecce,
2000). Such natural hazards are part of the southeastern North Carolina
landscape and residents of its coastal communities must be prepared
to evacuate during hurricane season.
Coastal
and river flooding from hurricanes are part of the southeastern
North Carolina landscape and residents of its coastal communities
must be prepared to evacuate during hurricane season. |
Portions of text originally written by Kathleen Sherman-Morris,
Department of Geosciences, Mississippi State University.
References
Elsner, J.B. and A.B. Kara 1999. Hurricanes of the North Atlantic:
Climate and Society. Oxford University Press, New York. 488 pp.
Frankenberg, D. 1995. The Nature of the Outer Banks. University
of North Carolina Press, Chapel Hill, NC. 157 pp.
Lecce, S. 2000. Fallacy of the 500-year Flood: A Cautionary Note
on Flood Frequency Analysis. North Carolina Geographer, Vol. 8,
29-40.
Lutgens, F.K and E.J. Tarbuck 2004. The Atmosphere: An Introduction
to Meteorology. Prentice Hall, Upper Saddle River, NJ. 508 pp.
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