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Tropical Depression Three Discussion Number 6
NWS National Hurricane Center Miami FL AL032018
1100 PM EDT Sat Jul 07 2018
The depression is gradually becoming better organized. Geostationary
satellite and microwave images indicate that the center is located
on the northern side of a convective burst and to the east of a
broken curved band. The initial intensity is held at 30 kt, in
agreement with the Dvorak classification from SAB and ADT values
from CIMSS at the University of Wisconsin. This estimate also uses
data from NOAA buoy 41002 located about 60 n mi south-southeast of
the center. An Air Force reconnaissance aircraft is scheduled to
investigate the system overnight, and it should provide a better
estimate of the cyclone's intensity.
Satellite fixes suggest that the depression has now stalled, as
forecast. The cyclone is caught in very weak steering currents
between two mid-level ridges and a mid- to upper-level trough to its
north. A very slow southeastward motion is expected during the next
couple of days as ridging builds to the north of the system.
Thereafter, a sharp northeastward turn with an abrupt increase in
forward speed is predicted when a deep-layer trough approaches the
cyclone. The NHC track forecast is adjusted a little to the south
of the previous one in the short term based on the latest guidance.
The depression is presently over the warm waters of the Gulf Stream
Current and it will remain over these warm SSTs during the next few
days. In addition, light to moderate wind shear and perhaps some
baroclinic forcing from the approaching trough should allow the
cyclone to steadily strengthen during the next few days. The NHC
intensity forecast is slightly higher than the previous one, and
near the middle of the guidance envelope. Extratropical transition
is forecast to occur in a little more than 4 days when the system is
expected to cross the north wall of the Gulf Stream current and move
over very cold waters.
Although the depression is expected to remain offshore of the North
Carolina coastline, the tight pressure gradient between the
depression and high pressure over the northeastern U.S. is expected
to produce gale-force winds over Pamlico and Albemarle Sounds.
See products issued by the National Weather Service forecast offices
for more details.
FORECAST POSITIONS AND MAX WINDS
INIT 08/0300Z 32.9N 75.1W 30 KT 35 MPH
12H 08/1200Z 32.8N 74.9W 40 KT 45 MPH
24H 09/0000Z 32.6N 74.6W 45 KT 50 MPH
36H 09/1200Z 32.4N 74.3W 50 KT 60 MPH
48H 10/0000Z 32.3N 73.9W 55 KT 65 MPH
72H 11/0000Z 34.5N 71.0W 70 KT 80 MPH
96H 12/0000Z 41.0N 63.0W 70 KT 80 MPH
120H 13/0000Z 49.0N 53.0W 55 KT 65 MPH...POST-TROP/EXTRATROP