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1996 PRELIMINARY
REPORTS |
a. Synoptic HistoryEdouard originated from a tropical wave that was already
well-marked by a spiral-shaped mass of convective clouds while moving
across western Africa on 17-18 August. The wave crossed the west coast
of Africa early on the 19th, accompanied by a 52-mph mid-tropospheric
jet seen in rawinsonde data. Observations from Dakar and nearby stations
showed thunderstorms and squalls, along with 24-hour surface pressure
falls on the order of 3 to 4 mb as the wave passed. Soon after entering
the eastern tropical Atlantic, ship reports showed the presence of a large
surface circulation. It is estimated that a tropical depression formed
around 1800 UTC on 19 August, centered about 300 nautical miles southeast
of the Cape Verde Islands. This was the first in a series of four tropical
cyclones that would form over the eastern Atlantic from waves that moved
off the west coast of Africa during a two-week span in late August and
early September of 1996. Three of these systems (Edouard, Fran,
and Hortense)
eventually became category three (or stronger) hurricanes. Initially, it appeared that the westward-moving tropical
cyclone would soon take a northwestward turn in response to a weakness
in the subtropical ridge over the eastern Atlantic. However, the subtropical
ridge remained strong enough to the north of the system to keep it on
a generally westward track into the central tropical Atlantic. Higher-level
winds favored intensification of the cyclone, as an upper-tropospheric
anticyclone became well established over the area. The system became Tropical
Storm Edouard early on 22 August, and strengthened into a hurricane around
1200 UTC the following day, when a banding-type eye was noted in satellite
pictures. When the hurricane neared 45W longitude on the 24th, a deep-layer
cyclone to the east of Bermuda began to create a weakness in the subtropical
ridge. In response to this, Edouard's direction of motion changed from
westward to west-northwestward. Meanwhile, intensification continued,
and Edouard's winds strengthened to 115 mph on the 24th and to 144 mph
on the 25th, making it a category four hurricane. The latter wind speed
was the maximum intensity, and a similar wind speed is estimated on the
26th and also around 0000 UTC on the 28th. From the 26th to the 28th,
some fluctuations in intensity were noted, apparently as the result of
eyewall replacement cycles and occasional doses of stronger vertical shear
over the area. Nonetheless, Edouard maintained 132 mph or greater winds
throughout the above period. The final deepening episode in Edouard was
observed late on 29-30 August. During that event, three concentric
eyewalls were indicated by aerial reconnaissance observations. Overall,
Edouard remained a powerful, 115-mph or stronger hurricane for a very
long time - from 24 August until early on 1 September. Edouard moved relentlessly towards the west-northwest, at
around 14 mph, until the 29th of August. This track kept the hurricane
well to the northeast and north of the islands of the northeastern Caribbean
Sea. On the 29th, a mid-tropospheric trough became established near the
U.S. east coast, creating a more northward steering component for Edouard.
Slowing its forward speed slightly, the hurricane turned northwestward,
and then northward, while gradually weakening. The cyclone passed about
midway between Cape Hatteras and Bermuda on 1 September, and then started
moving slightly east of north. Late on the 1st, the hurricane wobbled
toward the north, in the general direction of southeastern New England.
However, early on the 2nd, Edouard veered sharply toward the northeast,
and the center of the hurricane passed about 75 nautical miles southeast
of Nantucket island around 0900 UTC, the closest point of approach to
the United States. Maximum winds had diminished to near 81 mph by that
time. Edouard weakened to a tropical storm near 0000 UTC on the
3rd, and became extratropical shortly thereafter. The storm's motion became
east-northeastward, keeping the center south of Nova Scotia, and, later,
well offshore of Newfoundland. Edouard's remnant low was drawn around
and into the circulation of a larger extratropical cyclone on the 6th,
and was absorbed by this bigger system by 0000 UTC 7 September. b. Meteorological StatisticsMost of the aircraft reconnaissance flights into Edouard
were accomplished by the "Hurricane Hunters" of the U.S. Air Force Reserves.
The Hurricane Hunters flew 15 missions, and made 66 center fixes. NOAA
aircraft provided four additional fixes. The highest wind speed reported
was 161 mph (at 700 mb) at 0003 UTC 28 August. Lowest central pressure
reported was 934 mb at 1727 UTC 30 August. However, the highest wind reported
by aircraft around that time was 154 mph. Subjective and objective Dvorak
intensity estimates indicate that Edouard was stronger on 25-26 August,
and also at 0000 UTC 28 August, than it was at the time of the minimum
aircraft-reported pressure. At the latter time, the hurricane appeared
considerably less well-organized on satellite images than on the earlier
days. Since Edouard crossed over the New York shipping channels,
there was a large number of encounters by vessels at sea with this hurricane. The hurricane came close enough to New England to produce
sustained winds of tropical storm force at Nantucket Island and the Cape
Cod area. Wind gusts to hurricane force were reported at Nantucket. Table
3 lists selected surface observations from Massachusetts, New Hampshire
and Maine. In addition, there were unofficial reports of wind gusts to
90 mph at Nantucket, 80 mph at Martha's Vineyard, and 77 mph on Cape Cod. Large swells, minor beach erosion, and some coastal flooding,
presumably minor as well, occurred along the coast from North Carolina
northward through Maine. c. Casualty and Damage StatisticsThere were 2 deaths attributed to Edouard; 2 in New Jersey.
Maximum Intensity For Hurricane Edouard
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