Preliminary Report
Hurricane Bonnie
19 - 31 August 1998

1998 PRELIMINARY REPORTS

Tropical Storm Alex (TS)
Hurricane Bonnie (3)
Tropical Storm Charley (TS)
Hurricane Danielle (2)
Hurricane Earl (2)
Tropical Storm Frances (TS)
Hurricane Georges (4)
Tropical Storm Hermine (TS)
Hurricane Ivan (1)
Hurricane Jeanne (2)
Hurricane Karl (2)
Hurricane Lisa (1)
Hurricane Mitch (5)
Hurricane Nicole (1)

Bonnie was the third hurricane to directly hit the coast of North Carolina during the past three years.

 

a. Synoptic History

The origin of Bonnie was a large and vigorous tropical wave that moved over Dakar, Senegal on 14 August. The wave was depicted on visible satellite imagery by a large cyclonic low- to mid-level circulation void of deep convection. The wave caused a 24-h surface pressure change of -3.5 and -4.0 mb at Dakar and Sal respectively. There was a well established 700 mb easterly jet which peaked at 58 mph just before the wave axis crossed Dakar, followed by a well marked wind-shift from the surface to the middle troposphere. The overall circulation exited Africa basically just north of Dakar where the ocean was relatively cool. However, a strong high pressure ridge steered the whole system on a west-southwest track over increasingly warmer waters and convection began to develop. Initially, there were several centers of rotation within a much larger circulation and it was not until 1200 UTC 19 August that the system began to consolidate and a tropical depression formed. Although the central area of the tropical depression was poorly organized, the winds to the north of the circulation were nearing tropical storm strength. This was indicated by ship observations and high resolution low-cloud wind vectors provided in real time by the University of Wisconsin. The depression was then upgraded to Tropical Storm Bonnie based on these winds and satellite intensity estimates at 1200 UTC 20 August. Bonnie moved on a general west to west-northwest track around the circulation of the Azores-Bermuda High toward the northern Leeward Islands.

The first reconnaissance plane reached Bonnie late on the 20th and measured a minimum pressure of 1004 mb and winds of 70 mph at 1500 feet to the northeast of the center. Bonnie skirted the Leeward Islands and most of the associated weather remained to the north over the open Atlantic. During that period, Bonnie's circulation was very asymmetric.

Under a favorable upper-level wind environment, Bonnie gradually strengthened and became a hurricane at 0600 UTC 22 August when it was located about 200 nautical miles north of the eastern tip of Hispaniola. At that time, the hurricane hunters found a nearly complete eyewall and flight-level peak winds of 87 mph. Bonnie moved on a general west-northwest heading and reached maximum winds of 115 mph and a minimum pressure of 954 mb about 150 nautical miles east of San Salvador in the Bahamas.

The ridge to the north of Bonnie temporarily weakened and the steering currents collapsed. The hurricane then drifted northward for a period of 18 to 24 hours. Thereafter, the subtropical ridge reintensified, forcing Bonnie to move northwestward and then northward toward the coast of North Carolina while the hurricane maintained winds of 115 mph.

After a slight weakening, the eye of Bonnie passed just east of Cape Fear around 2130 UTC 26 August and then made landfall near Wilmington as a border line Category 2/3 hurricane on the Saffir/Simpson Hurricane Scale (SSHS) around 0330 UTC 27 August.

The hurricane slowed down and weakened while moving over eastern North Carolina. It was then downgraded to tropical storm status based on surface observations and WSR88-D winds. Bonnie turned northeastward over water ahead of a middle-level trough and rapidly regained hurricane strength as indicated by aircraft reconnaissance data. Thereafter, the hurricane moved on a general northeast to east track and became extratropical near 1800 UTC 30 August, about 240 nautical miles south southeast of New Foundland.

b. Meteorological Statistics

The maximum winds measured were 133 mph at the 700-mb level at 0113 UTC 25 August and then again at 1659 UTC 26 August. These measurements were taken during the AF963 and the NOAA 43 reconnaissance missions, respectively. Table 2 displays selected surface observations during Bonnie, primarily over the area where the hurricane made landfall. There were several important and useful observations relayed to the NHC and to the local NWS forecast offices from amateur observing reports. These include reports of peak winds of 120 mph at 0138 UTC near NC State Port and 115 mph at Wrightsville Beach at 1951 UTC 27 August.

1. Storm Surge Data

Storm tides of 5 to 8 feet above normal were reported mainly in eastern beaches of Brunswick County NC, while a storm surge of 6 feet was reported at Pasquotank and Camdem counties in the Albemarle Sound.

2. Rainfall Data

3. Tornadoes

A tornado was reported in the town of Edenton NC in Chowan County.

c. Casualty and Damage Statistics

There were 3 deaths attributed to Bonnie; 1 in North Carolina, 1 in Delaware and 1 in Maine.

Three people died as a consequence of Bonnie. A 12-year old girl was killed when a large tree fell on her home in Currituck County, NC. Another person was caught in rip currents and drowned in Rehoboth Beach, Delaware. The third person died in Cape Cod in a rowboat accident when choppy seas overturned the boat. The last one may have been indirectly related to Bonnie.

There are numerous reports of many trees down, roof and structural damage and widespread power outages primarily in eastern North Carolina and Virginia where a federal disaster was declared for several counties. The area hardest hit appears to have been Hampton Roads, Virginia, where the damage could reach well into the hundreds of millions of dollars.

The Property Claim Services Division of the American Insurance Services Group reports that Bonnie caused an estimated $360 Million in insured property damage to the United States. This estimate includes $240 Million in North Carolina, $95 Million in Georgia, and $25 Million in South Carolina. A conservative ratio between total damage and insured property damage, compared to past landfalling hurricanes, is two to one. Therefore, the total U.S. damage estimate is $720 Million.