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Preliminary Report
Hurricane Bonnie
19-30 August 1998

Lixion A. Avila
National Hurricane Center
24 October 1998

Tropical Storm Alex
Hurricane Bonnie
Tropical Storm Charley
Hurricane Danielle
Hurricane Earl
Tropical Storm Frances
Hurricane Georges
Tropical Storm Hermine
Hurricane Ivan
Hurricane Jeanne
Hurricane Karl
Hurricane Lisa
Hurricane Mitch
Hurricane Nicole

[1998 Atlantic Hurricane Season]

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 50 knots 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 61 knots 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 n mi north of the eastern tip of Hispaniola. At that time, the hurricane hunters found a nearly complete eyewall and flight-level peak winds of 76 knots. Bonnie moved on a general west-northwest heading and reached maximum winds of 100 knots and a minimum pressure of 954 mb about 150 n mi 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 100 knots.

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 n mi south southeast of New Foundland.

Bonnie's track is shown in Fig. 1 (50K GIF). Table 1 is a listing, at six-hourly intervals, of the best-track position, estimated minimum central pressure and maximum 1-minute surface wind speed.

b. Meteorological Statistics

The best track pressure and wind curves as a function of time are shown in Figs. 2 (25K GIF) and 3 (20K GIF) and are primarily based on data from numerous reconnaissance flights into the hurricane. The best track also incorporates WSR-88D data, surface observations and GPS sondes in the eyewall of the hurricane. The routine satellite intensity estimates from the Tropical Analysis and Forecast Branch (TAFB), the Satellite Analysis Branch (SAB) and the Air Force Weather Agency, (AFGWC in figures) were also included. The Hurricane Bonnie event was characterized by a high density of observations. During Bonnie, the NOAA high altitude jet and P-3 deployed a very large number of sondes over a large portion of the Atlantic as a part of a major synoptic flow experiment. These observations were primarily used to initialize the numerical models.

The maximum winds measured were 116 knots 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 104 knots at 0138 UTC near NC State Port and 100 knots at Wrightsville Beach at 1951 UTC 27 August. Rainfall totals of about 8 to 11 inches were recorded in portions of eastern NC.

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.

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

c. Casualty and Damage Statistics

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.

d. Forecast and Warning Critique

Figure 4 (26K GIF) shows a sequence of numerical guidance forecast track for 1800 UTC on 22, 23 and 24 August. Note that on the 22nd, most of the models suggested that Bonnie was going to remain out to sea. Thereafter, during the 23rd and 24th, there was a significant change in the model forecasts and some of them turned the hurricane toward the west while others kept it out to sea. At that point, the forecast became very difficult and highly uncertain. Consequently, watches and warnings were required for a large portion of the southeast U.S. coast (Table 3). In spite of the model's scatter, the official forecast tracks remained basically unchanged and in the middle of the model forecast ensemble. Apparently, during the earlier runs, the models weakened the ridge to the north of the hurricane too soon and forecast a premature recurvature.

Table 4 lists track forecast error statistics. The official forecast errors for Bonnie were in general very close to the most recent 10-year average. There was only a small improvement in the 48 and 72 hour forecast if compared to the average.

With the exception of a few 72-h forecast errors at the beginning of Bonnie's life, the NHC intensity forecasts for Bonnie were smaller than the past 10-year average errors.

Table 1. Best track, Hurricane Bonnie, 19- 30 August, 1998
Position Pressure
Wind Speed
Lat. (°N)Lon. (°W)
19/120014.748.1100925tropical depression
120017.357.3100735tropical storm
23/000023.4 71.096290"
25/000026.9 73.2963100"
27/000034.0 77.796395"
180035.476.698060tropical storm
180037.373.299160tropical storm
29/000038.3 71.499345"
060043.041.0  absorbed by a front
24/000024.871.8954100minimum pressure
27/040034.477.796495Landfall near Wilmington NC

Table 2. Hurricane Bonnie selected surface observations, August 1998.
Maximum surface wind speed
(kts) a
gust (kts)
(storm total)
U.S.Virgin Islands
St. Thomas Airport1006.121/1128233321/0851   0.29
Puerto Rico
Ceiba1006.821/1121243321/0156   0.51
Carolina        1.10
Grand Turk Island        3.50
South Carolina
Charleston International Airport1007.026/18562533 26/2034   
Charleston City Office  2539 26/1230   
Myrtle Beach (MYR)  3852 26/1715   
North Carolina
Wilmington969.927/00534964 26/1827  9.04
Kure Beach   7726/1630    
Florence Air.   3444 26/2150   
Elizabeth City995.728/0030516328/0333   1.42
Ocracoke990.527/1815 6627/1457   6.60
Oregon Inlet989.1  5427/2015    
Emerald Isle976.9  62     
Newport985.127/1030 5227/0553   9.51
Greenville   6327/0915   8.20
Morehead City        10.70
Cherry Point  416127/0114   10.93
Jacksonville   6227/1133  11.00
Frisco  496927/1109    
New Hanover       7-9 
Tide Gage on Masonboro Isl.       9.1 
Wrightsville Beach       7- 7.3 
Cape Henry  709028/0300    
Chesapeake Light Stn. Brookley Field  68 8128/0350   
Currituck County EOC   81 28/0400   
Oceana NAS999.0 3854 28/0357   
Langley AFB1005.0 4658 27/2355   
Norfolk Airport (ORF)1000.428/00244056 28/0141  6.77
Porthmouth1000.028/0105 5528/0222   2.44
Norfolk NAS1002.0 364827/2315   4.91
Sewells Point      6.0 
Coastal Pasquotank      6.0  
Chowan County      5-6  
New Jersey/Delaware
Delaware Light Buoy1005.228/1800324028/1700    
Reedy Point        6.28 
Cape May       6.05 
Atlantic City       4.97 
Sandy Hook       5.64 
Georges Bank Buoy990.229/16003545 29/1700    
CMAN Stations
Frying Pan Shoals (FPSN7)964.026/163076f 9026/2130   
Cape Lookout (CLKN7)994.227/13004875 27/1211   
Diamond Shoals (DSLN7)996.827/22006879 27/2034   
Duck NC (DUCN7)993.528/01004555 27/2000   
Cheasepeake Lt. (CHLV7)995.728/060072f 8628/0532   
41002998.726/030042f57 26/0426   
41004990.526/13003849 26/1600   
44004994.329/060036f46 29/0131   
44137998.230/000050 30/0300    
44144990.830/030047 30/0300    

a Standard NWS ASOS and C-MAN maveraging period is 2 min; buoys are 8 min unless otherwise indicated.

b Date/time is for sustained wind when both sustained and gust are listed.

c Storm surge is water height above normal astronomical tide level.

d Storm tide is water height above NGVD.

e Estimated.

f 10 min average wind.

Table 3. Tropical Cyclone watch and warning summary for Hurricane Bonnie.
20/0300Tropical Storm Watch issued Antigua, Barbuda, Anguilla, St. Maarten, Saba and St. Eustatius
20/1500Tropical Storm Watch issued U.S. and British Virgin Islands
20/2100Tropical Storm Warning issued U.S. and British Virgin Islands
Tropical Storm Watch issuedPuerto Rico
21/0900Tropical Storm Watch issuedTurk and Caicos and the southeastern Bahamas
21/1200Tropical Storm Watch discontinued Antigua, Barbuda, Anguilla, St. Maarten, Saba and St. Eustatius
21/1500Tropical Storm Warnings and a Hurricane Watch Turk and Caicos and southeastern Bahamas
Hurricane Watch issuedCentral Bahamas
Tropical Storm Warning discontinued U.S. and British Virgin Islands
Tropical Storm Watch discontinued Puerto Rico
22/0900Hurricane Warning issuedCentral Bahamas
22/1500Hurricane Watch issuedNorthwestern Bahamas
23/0000Hurricane Warning discontinued Turks and Caicos
Hurricane Warning replaced by Tropical Storm Warning Southeastern Bahamas
24/0900Tropical Storm Warning discontinued Southeastern Bahamas
24/2100Hurricane Watch issued Savannah, Georgia to the North Carolina/Virginia border including the Pamlico and Albemarle Sounds
25/0900Hurricane Warning issued from Murrells Inlet, S.C. to the north Carolina Virginia border, including the Palmico and Albemarle Sounds
25/1200Hurricane Watch issued from North Carolina/Virginia border to Cape Henlopen, Delaware including the Chesapeake Bay southward from Windmill point.
25/1500Tropical Storm Warning issued from Murrels inlet to Cape Romain, S.C.
25/1800Hurricane Warning extended northward to Chincoteague, VA
25/2100Hurricane Warning extended southward to Cape Romain, S.C.
26/0600Hurricane Warning extended southward to Edisto Beach, S.C.
26/1500Hurricane Warning and Watches discontinued south of Cape Romain
26/2100Hurricane Warnings and Watches revised. Tropical Storm Warning and Hurricane Watch issued from North Carolina/Virginia border to Chincoteague, Virginia and for the Chesapeake Bay from Smith Point southward
Tropical Storm Warning issued from Chincoteague, Virginia to Cape Henlopen, Delaware
27/0100Hurricane warning replaced by Tropical Storm Warningsouth of Murrels Inlet to Cape Romain
27/0900Hurricane Warning replaced by Tropical Storm Warningssouth of Little River Inlet, NC to Murrels Inlet, SC
Tropical Storm Watch issued from north of Cape Henlopen to Sandy Hook, NJ including Delaware Bay
Tropical Storm Warning discontinuedfrom south of Murrels Inlet
27/1500Tropical Storm Warning issued from new River Inlet, NC to Cape Henlopen, DE including Palmico and Albemarle Sounds and Chesapeake Bay southward from Smith Point
Tropical Storm Watch issued Chesapeake bay from Smith Point to Drum Point and for the Potomac River from Cobb Point to Smith Point
27/2100Tropical Storm Warnings extended northward from New River Inlet NC to Watch Hill, RI including Palmico and Albemarle Sounds, Chesapeake Bay southward from Smith Point and Delaware Bay
Tropical Storm Watch issued from east of Watch Hill, RI to Plymouth, MA
28/0300Tropical Storm Warning discontinued south of Cape Lookout, NC
28/0900Tropical Storm Warning issued from Watch Hill to Plymouth
Tropical Storm Warning discontinued south of Ocracoke, NC and for the Chesapeake Bay and Potomac River north of Smith Point
28/1500Tropical Storm Warning discontinued south of NC/VA border including Pamlico and Albemarle Sounds and for Chesapeake and Delaware Bays
28/2100Tropical Storm Warning discontinued south of Watch Hill including Delaware Bay and Long Island Sound
29/0300Tropical Storm Warning discontinued remainder of the U.S. East coast

* Tropical Cyclone watches and warnings are issued by respectively countries in coordination with the National Hurricane Center.

Table 4. Preliminary forecast evaluation of Hurricane Bonnie. Heterogeneous sample. (Errors in nautical miles for tropical storm and hurricane stages with number of forecasts in parenthesis)
Forecast TechniquePeriod (hours)
CLIP60 (41)127 (40)196 (38)258 (36)318 (32)
GFDI47 (39) 86 (38)136 (37)203 (36)397 (32)
GFDL*43 (34) 79 (34)116 (33)180 (33)348 (31)
LBAR44 (41) 89 (40)137 (38)213 (36)393 (32)
AVNI46 (41) 89 (40)140 (37)214 (37)468 (30)
BAMD40 (41) 66 (40) 87 (38)137 (36)183 (32)
BAMM40 (41) 81 (40)112 (38)142 (36)242 (32)
BAMS69 (41)124 (40)162 (38)194 (36)327 (32)
NGPI42 (34) 78 (33)117 (31)157 (29)226 (25)
UKMI46 (40) 78 (39)117 (31)143 (35)214 (31)
NHC OFFICIAL45 (41) 86 (39)129 (37)172 (36)232 (32)
NHC OFFICIAL (1988-1997)47 (1838)88 (1633)127 (1449)165 (1284)248 (1006)

Jack Beven

Last updated May 1, 1999