Event Summary
     National Weather Service, Raleigh NC

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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