Surface-based Wind and Pressure Fields in Hurricane
Fran over North Carolina
Joel W. Cline
NOAA/National Weather Service Raleigh North Carolina
Introduction -
Hurricane Fran made landfall near Bald Head Island on the coast of North Carolina
around 0030 UTC on September 6, 1996. Fran became the first Saffir-Simpson scale
Category 3 hurricane to directly hit the state since Hurricane Donna in 1960
(Barnes, 1995). Fran struck only 7 weeks after Category 2 Hurricane Bertha hit
North Carolina on July 12, 1996. Not since 1955 had two or more hurricanes directly
impacted the state in the same season.
The effects of Fran were extensive and noticed well inland over North Carolina.
Winds gusting to hurricane force occurred north of Raleigh, some 230 km from the
point of landfall. Surface-based wind and pressure fields clearly revealed the
path of the most economically destructive natural disaster ever recorded for the
state. The hurricane caused an estimated $2.3 billion in damages.
Data Collection and Instrumentation -
Surface-based wind, pressure and rainfall measurements were collected over eastern North
Carolina during the night of September 5th and morning of the 6th. The data base thus
far is comprised of almost 250 observations. The recording locations ranged from National
Weather Service offices, television stations and their networks of observations, state
agricultural networks, Federal Aviation Administration and military installations, buoys,
ships, National Oceanic and Atmospheric Administration reconnaissance aircraft, river rain
gauges, city and county: marinas, airports, water and sewer plants, golf courses, amateur
radio operators, and reports from the general public.
These readings from a wide variety of observational platforms have not been standardized.
However, some observations were eliminated and considered to be erroneous based on the time
of occurrence, calibration, exposure of the instruments, damaged sensors, communication
problems and power outages.
Furthermore, the wind reports were not standardized to 10-m height level in conformance
with the recommendations of the World Meteorological Organization, and the time averaging
periods for the wind data varied considerably for the different types of observing equipment.
Therefore, graphs (Figures 1 and 2) representing the data will be presented instead of a
table of the observations.
Wind Observations -
The Cape Verde type hurricane made landfall with an estimated minimum pressure of 954
mb at 0030 UTC September 6. The estimated sustained winds were 52 m/s (100 kts), with
gusts to 55 m/s (106 kts) and 56 m/s (108 kts) as reported near Figure Eight Island
(east of Wilmington) and Frying Pan Shoals Light, respectively. Flight-level winds
obtained from an unprecedented overland reconnaissance flight were 55 m/s (107 kts)
at landfall 76 km to the northeast of the center. Winds of 58 m/s (113 kts) were
recorded at flight level near 3,050 m (10,000 feet) at 2314 UTC on September 5, 96 km
east of the center (Mayfield, 1996).
Figure 1
Figure 1 shows the envelope of wind gusts in meters/second and the best track of Fran.
Winds gusted to 35 m/s (69 kts ) at Raleigh-Durham International Airport with sustained
winds of 31 m/s (60 kts). Seymour-Johnson Air Force Base at Goldsboro recorded a wind gust of
36 m/s (70 kt). Winds gusted to 47 m/s (91 kts) in New Bern, and 41 m/s (80 kts) at Duke
Marine Research Laboratory in Beaufort. Efland, to the west of Durham, reported a peak wind
of 39 m/s (75 kts).
Pressure Observations -
The pressure (in mb), as shown in Figure 2, had risen from 954 mb at time of landfall
to 976.6 mb at the Raleigh-Durham airport at approximately 0700 UTC. This represented
a steady rise of nearly 3.5 mb/hr. The rise is nearly double the actual filling rate
(~2 mb/hr) of 11 hurricanes described by Malkin (1959), but less than that for Hazel
(1954, 11 mb/hr) and Camille (1969, 8 mb/hr) (as indicated in Powell et al. 1991).
Figure 2
Impacts -
Widespread destruction occurred well inland over the state. A polar orbiting satellite
image shown in Figure 3 illustrates this point. With the track of Fran overlaid, the
infrared image shows the sources of light (cities) of eastern North Carolina. The
image was a composite of the night before and night after Fran. Depicted in red are
cities which had power outages during Fran since they were evident on the night before
but not the night after Fran. The damage and stronger winds occurred mainly to the right
of the storm center track. The power outages and wind gust envelopes decreased rapidly
with increasing distance from the coast as Fran filled and decreased in sustained wind
speed. Outages along the Outer Banks were attributed to saltwater entering electrical
equipment associated with the strong winds.
Figure 3
Acknowledgments -
Comments on previous versions of this paper by Steve Harned and Kermit Keeter of the
NWS Raleigh Office and Gary Carter of SSD Eastern Region of the NWS were greatly
appreciated. Graphical assistance was provided by Woody Vondracek of the Raleigh
News and Observer newspaper.
References -
Barnes, J., 1995: North Carolina’s Hurricane History. University of North Carolina press, Chapel Hill & London, pp. 120 -132.
Mayfield, M. 1996: Preliminary Report on Hurricane Fran. NOAA/National Hurricane Center, Miami, FL, 13 pp.
Malkin, W., 1959: Filling and intensity changes in hurricanes overland. NHRP Rep. No. 34, U.S.Dept. Commerce, 18 pp. [Available from: NOAA/HRD, 4301 Rickenbacker Cswy, Miami, FL 33149].
Powell, M. D., P.D. Dodge, and M.L. Black, 1991: The landfall of Hurricane Hugo in the Carolinas: Surface wind distribution. Wea. Forecasting, 6, 379-399.
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