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 3. Tropical Cyclone watch and warning summary for Hurricane Bonnie.
Date/time
(UTC) | Action | Location |
| 20/0300 | Tropical Storm Watch issued |
Antigua, Barbuda, Anguilla, St. Maarten, Saba and St. Eustatius |
| 20/1500 | Tropical Storm Watch issued |
U.S. and British Virgin Islands |
| 20/2100 | Tropical Storm Warning issued |
U.S. and British Virgin Islands |
| Tropical Storm Watch issued | Puerto Rico |
| 21/0900 | Tropical Storm Watch issued | Turk and Caicos and the
southeastern Bahamas |
| 21/1200 | Tropical Storm Watch discontinued |
Antigua, Barbuda, Anguilla, St. Maarten, Saba and St. Eustatius |
| 21/1500 | Tropical Storm Warnings and a
Hurricane Watch |
Turk and Caicos and southeastern Bahamas |
| Hurricane Watch issued | Central Bahamas |
| Tropical Storm Warning discontinued |
U.S. and British Virgin Islands |
| Tropical Storm Watch discontinued |
Puerto Rico |
| 22/0900 | Hurricane Warning issued | Central Bahamas |
| 22/1500 | Hurricane Watch issued | Northwestern Bahamas |
| 23/0000 | Hurricane Warning discontinued |
Turks and Caicos |
| Hurricane Warning replaced by Tropical Storm Warning |
Southeastern Bahamas |
| 24/0900 | Tropical Storm Warning discontinued |
Southeastern Bahamas |
| 24/2100 | Hurricane Watch issued |
Savannah, Georgia to the North Carolina/Virginia border including the Pamlico and
Albemarle Sounds |
| 25/0900 | Hurricane Warning issued |
from Murrells Inlet, S.C. to the north Carolina Virginia border, including the Palmico
and Albemarle Sounds |
| 25/1200 | Hurricane Watch issued |
from North Carolina/Virginia border to Cape Henlopen, Delaware including the
Chesapeake Bay southward from Windmill point. |
| 25/1500 | Tropical Storm Warning issued |
from Murrels inlet to Cape Romain, S.C. |
| 25/1800 | Hurricane Warning extended northward |
to Chincoteague, VA |
| 25/2100 | Hurricane Warning extended southward |
to Cape Romain, S.C. |
| 26/0600 | Hurricane Warning extended southward |
to Edisto Beach, S.C. |
| 26/1500 | Hurricane Warning and Watches discontinued |
south of Cape Romain |
| 26/2100 | Hurricane 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 |
| 27/0100 | Hurricane warning replaced by Tropical Storm
Warning | south of Murrels Inlet to Cape Romain |
| 27/0900 | Hurricane Warning replaced by
Tropical Storm Warnings | south 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 discontinued | from south of Murrels Inlet |
| 27/1500 | Tropical 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 |
| 27/2100 | Tropical 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 |
| 28/0300 | Tropical Storm Warning discontinued |
south of Cape Lookout, NC |
| 28/0900 | Tropical 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 |
| 28/1500 | Tropical Storm Warning discontinued |
south of NC/VA border including Pamlico and Albemarle Sounds and for Chesapeake and Delaware Bays |
| 28/2100 | Tropical Storm Warning discontinued |
south of Watch Hill including Delaware Bay and Long Island Sound |
| 29/0300 | Tropical Storm Warning discontinued |
remainder of the U.S. East coast |
![[NCEP Logo]](graphics/ncep.gif)
![[1998 Atlantic Hurricane Season]](graphics/smalllogo.gif){kind=small}
