a. Synoptic History
A tropical wave moved off the African coast
on 6 August. Satellite imagery indicated that it quickly displayed evidence of
a circulation as it moved toward the west. The post-analysis "best
track" (Fig. 1 [94K GIF]) shows that the
Tropical Depression Seven about 400 n mi
west-southwest of the Cape Verde Islands at 0000 UTC 8 August
when loosely organized deep convection increased. Best track position,
central pressure and maximum one-minute sustained wind speed are listed
for every six hours in Table 1.
The depression strengthened into
Felix later on the 8th and followed a west-northwestward track at 15-20 knots for the next three days.
Based on satellite intensity estimates, Felix
reached hurricane strength at 0000 UTC 11
August while centered about 500 n mi east-northeast of the Leeward Islands. Reports from
reconnaissance aircraft indicated rapid strengthening from the time
of the first eye penetration near 1200 UTC
on the 11th through the 12th. Maximum sustained surface winds of
120 knots are estimated
to have occurred near 1800 UTC 12 August. A well-defined
eye was visible in satellite imagery at this time.
Felix moved northwestward on 12 August, and then turned more
toward the north and started to weaken on 13 August. Two factors
likely contributed to the weakening: 1) Felix went through a
cycle, and 2) wind shear increased over the
system when Felix's upper-level anticyclone didn't remain centered
over the lower-level cyclonic circulation. Aircraft data on the
13th when Felix was centered 300 to 400 n mi south-southeast of
Bermuda indicated a large wind field with several wind maxima and
no tight center.
These characteristics would persist for much of the remainder of the storm's life.
Felix's northward turn was due to a large deep-layer trough
over the western Atlantic. The trough split as Felix approached,
with one part moving northeastward and filling and the other moving
southward to the southwest of the hurricane. The resulting
steering pattern allowed Felix to resume a general northwestward
motion by 15 August, with this motion persisting into the next day.
This track took the storm center within 65 n mi of Bermuda and
toward the North Carolina coast.
The split in the trough resulted in increased ridging over the
western Atlantic that appeared to be strong enough to drive Felix
into the eastern United States. However, a small weakness remained
between 70 and 75°W as indicated by
reconnaissance data on the 16th. Felix turned northward into the
weakness and almost stalled late on the 16th. It then moved slowly
northeastward on 17 August. A second westerly trough failed to
pick up the storm on 18-19 August, and Felix performed an
anticyclonic loop offshore as the trough bypassed the
The hurricane accelerated northward on 20 August and
northeastward on 21 August in response to a third trough.
During 17-19 August, Felix had a 50-70 n mi wide eye on
aircraft radar and rather weak convection in satellite imagery.
Despite this, the storm maintained 65-70 knot sustained
winds and a central pressure near 970 mb. It is possible that this structure
was due to cooler, drier air entering the circulation at low and
mid levels. Felix dropped below hurricane strength on 20 August as
it moved over colder water and shearing again increased.
Felix became extratropical
about 300 n mi east-northeast of Newfoundland on 22 August. The extratropical
cyclone was tracked
across the North Atlantic between Scotland and Iceland and then toward Norway.
On a historical note, the threat of Hurricane Felix postponed
Bermuda's scheduled vote for independence. Ironically, the first
inhabitants at Bermuda were survivors of a hurricane-caused
shipwreck on the island in 1609. Their stories helped inspire
Shakespeare's writing of The Tempest.
b. Meteorological Statistics
Figures 2 and 3 (71K GIF) show the
curves of minimum central pressure and maximum one-minute wind speed,
respectively, versus time, along with the observations on which they are based.
The satellite estimates were provided by the
Synoptic Analysis Branch
(SAB), the NHC's Tropical Analysis and Forecast Branch
(TAFB, formerly TSAF as in figures) and the
Air Force Global Weather Central (AFGWC).
U.S. Air Force Reserve aircraft
provided a total of 70 operational center fixes on Felix. The 24
missions and approximately 280 flying hours of reconnaissance on this hurricane
are both records for an Atlantic tropical cyclone. The maximum winds of
143 knots from a flight-level of 700 mb were measured at
1254 UTC 12 August. The minimum central pressure reported by
aircraft was 930 mb at 2328 UTC 12 August, and it is likely that
the pressure was somewhat lower during the previous 10 hours when
there were no aircraft measurements. In addition to the
Air Force Reserve reconnaissance,
flew a research mission on 16 August.
During most of the 15th and 16th, the minimum central pressure
hovered between 965 and 970 mb, which would normally be consistent
with 85-100 knot surface winds. However, maximum flight-level
winds reported by reconnaissance aircraft were only 65 to 75 knots
at 850 and 700 mb. This would suggest a minimal hurricane at most.
The rawinsonde at Bermuda indicated 55 knot surface winds with
80 knots at 400 feet. Because a large component of these winds
were probably brought to the surface in strong convective bands, the
maximum sustained surface winds are estimated at 70-75 knots
during this time.
Numerous ship reports were received in the vicinity of Felix
and were helpful in defining the extent of tropical storm force
winds. Table 2 lists 81 ship reports of at least
tropical storm force winds in association with the cyclone.
Bermuda reported a minimum pressure of 988.1 mb and maximum
sustained winds of 55 knots with gusts to
70 knots at 0000 UTC 15
August as the center of Felix passed about 65 n mi to the south-
southwest. No sustained tropical storm force winds were reported
by U.S. land stations. Wind gusts to 37 knots were
reported from the NWS office at Buxton, North Carolina at 2058 UTC 16 August and
at 0102 UTC 17 August while the hurricane was centered about 125 n mi to the east.
The eye of Felix passed over NOAA buoy 41001
located at 34.7°N 72.6°W, about 150 n mi east of Cape Hatteras, near
1600 UTC 16 August. The buoy reported a 970.4 mb pressure at this time with
light winds. A 10-minute average wind of 53 knots and gusts to
66 knots were reported earlier by the buoy near 1200 UTC.
Rain bands associated with Hurricane Felix remained offshore of the U.S. coast.
Although the strong winds and heavy rains did not directly
affect the United States, large swells generated by Felix produced
dangerous surf conditions including some coastal flooding and rip
currents from northeastern Florida to New England. Isolated areas
of severe beach erosion occurred along the New Jersey coast, but
the most significant beach erosion occurred on the Outer Banks of
North Carolina. Highway 12 on the Outer Banks was flooded with
sand and ocean overwash at times of high tides. Beach nourishment
occurred in some coastal areas of North Carolina to the southwest
of the Outer Banks.
c. Casualty and Damage Statistics
A total of 8 deaths were confirmed in association with Felix,
3 off the North Carolina coast and 5 off the New Jersey coast. All
of these fatalities were a result of drowning.
Although there was considerable beach erosion, little
significant property damage occurred.
d. Forecast and Warning Critique
During the time when Felix was a tropical storm or hurricane,
the mean official track forecast errors were 38 (54 cases), 75 (52
cases), 112 (50 cases), 147 (48 cases) and 227 (44 cases) n mi at
12, 24, 36, 48 and 72 hours, respectively. Although these errors
were lower than the long-term averages from the previous ten years,
there were some large individual errors including five over 500 n
mi at 72 hours. Three of these large errors occurred while Felix
was between Bermuda and North Carolina and were primarily a result
of not correctly anticipating the decrease in forward speed on 13-
15 August. The other two cases occurred while Felix was beginning
the anticyclonic loop well off the U.S. coast and resulted from not
correctly anticipating the beginning and amount of the acceleration
toward the northeast. On average, the official forecast errors
were similar to the track prediction model errors. The GFDI, BAMM
and BAMD 72-hour mean forecast errors were only slightly lower than
the official forecast errors.
Some large 72 hour intensity forecast errors (35 to 45 knots)
occurred. The intensity forecasts did not correctly indicate the
rapid strengthening on the 11th and 12th, nor the weakening
thereafter. Other relatively large underforecasts (35 to 40 knots)
resulted from incorrectly forecasting Felix to weaken along a track
that moved the hurricane inland.
Table 3 lists the coastal watches and warnings
issued during Felix. Although Felix never made landfall in the United States,
some of the official forecasts and several of the track prediction
models indicated this possibility. If Felix had continued on the
northwestward track onto the mid-Atlantic coast, considerable
damage and loss of life were possible. Given the NHC track
forecasts, time required for evacuations from coastal areas and
barrier islands, and the limitations in track forecasting, the
watches and warnings were deemed necessary and were well-
coordinated with appropriate NWS offices and the U.S. Navy.
Some information in this report was provided by NWS offices in
the watch and warning areas. Position estimates during the extratropical
stage were provided by the
Hydrological Prediction Center.
Table 3. Watch and warning summary, Hurricane Felix.
|13/1500||Tropical Storm Warning
||Edisto Beach, SC to Cape Henlopen, DE including Albemarle and Pamlico Sounds
and Chesapeake Bay south of Windmill Point|
|Hurricane Warning replaced with a
Tropical Storm Warning
||North of Little River Inlet, SC to Chincoteague, VA including Albemarle and Pamlico Sounds and
Lower Chesapeake Bay from Windmill Point southward|
|15/2100||Tropical Storm Warning
||North of Chincoteague, VA to Manasquan Inlet, NJ including Chesapeake Bay north of
Windmill Point and Delaware Bay|
|16/0600||Tropical Storm Warning discontinued
|16/1200||Hurricane Watch discontinued
||Little River Inlet, SC southward to Edisto Beach, SC|
|16/1500||Hurricane Warning discontinued
||South of New River Inlet, NC|
|17/0300||Tropical Storm Warning replaced with a
Tropical Storm Watch
||Chesapeake Bay north of Patuxent River|
||Tropical Storm Warning replaced
with a Tropical Storm Watch
||North of Cape Henlopen, DE to Manasquan Inlet, NJ including Chesapeake Bay from Patuxent River
to Windmill Point...and Delaware Bay|
|Tropical Storm Watch discontinued
||Chesapeake Bay north of Patuxent River|
||Hurricane Warning replaced with a
Tropical Storm Warning and Hurricane Watch
||Cape Lookout, NC to Chincoteague, VA including Albemarle and Pamlico Sounds|
|Hurricane Warning replaced with a
||Chesapeake Bay from Windmill Point southward|
|Tropical Storm Watch discontinued
||Chesapeake Bay from Patuxent River to Windmill Point|
|Hurricane Warning discontinued
||South of Cape Lookout, NC|
|18/0000||Hurricane Watch discontinued
||Chesapeake Bay south of Windmill Point|
||All Tropical Storm Warnings discontinued|| |
||All Hurricane and Tropical Storm Watches discontinued
||along U.S. mid-Atlantic coast|
|19/1030||Tropical Storm Watch
|20/1800||Tropical Storm Watch discontinued