000
WTNT45 KNHC 032049
TCDAT5

Hurricane Dorian Discussion Number  42
NWS National Hurricane Center Miami FL       AL052019
500 PM EDT Tue Sep 03 2019

Dorian has finally begun a more definitive northwestward motion this
afternoon.  The satellite presentation of the hurricane is slightly
better in one-minute GOES 16 imagery with the large eye becoming a
little more apparent.  The eye has also become better defined in NWS
Doppler radar from Melbourne, Florida. Reconnaissance aircraft data
continue to show an expansion of the tropical-storm and 50-kt wind
radii, and it is likely that the area of hurricane-force winds
will also increase somewhat during the next 24-36 hours. The initial
intensity remains 95 kt, and is a blend of the earlier
reconnaissance data and the latest satellite estimates.  Dorian will
be moving northwestward over untapped waters east of the Florida
peninsula, which may lead to some structural re-organization, but
little overall change in intensity is expected during the next
couple of days.  After that time, a gradual decrease in the peak
wind speed and an increase in storm size are predicted while the
vertical shear increases and the storm moves farther north.  An
approaching mid-latitude trough and front will begin interacting
with the hurricane on Saturday and Dorian is forecast to become a
powerful extratropical low by 120 hours.

Dorian is now moving northwestward or 325/5 kt.  The deep-layer
trough along the east coast of the United States is expected to
amplify on Wednesday, which should cause Dorian to move at a
slightly faster north-northwestward motion tonight and Wednesday.
After that time, Dorian should turn northward, and then north-
northeastward ahead of a shortwave trough moving into the eastern
United States.  Once Dorian is offshore of eastern North Carolina,
it should accelerate northeastward within the mid-latitude
westerlies. The track envelope has edged closer to the coasts of
South Carolina and North Carolina and the NHC track has been
adjusted in that direction.  A track that close to the coast, even
if landfall does not occur, is likely to bring dangerous winds,
life-threatening storm surge, and flooding rains across the eastern
portions of the Carolinas.

Key Messages:

1. Life-threatening storm surge and dangerous winds are expected
along portions of the Florida east coast and the coasts of Georgia,
South Carolina, and North Carolina, regardless of the exact track of
Dorian's center. Water levels could rise well in advance of the
arrival of strong winds. Residents in these areas should follow
advice given by local emergency officials.

2. The risk of wind and rain impacts along portions of the Virginia
coast and the southern Chesapeake Bay are increasing. Residents in
these areas should continue to monitor the progress of Dorian.

3. The flash flood threat will increase tonight along the Florida
east coast and then spread up the southeast and mid-Atlantic
coast during the middle and latter part of the week.

FORECAST POSITIONS AND MAX WINDS

INIT  03/2100Z 27.7N  78.7W   95 KT 110 MPH
 12H  04/0600Z 28.7N  79.4W   95 KT 110 MPH
 24H  04/1800Z 30.0N  80.0W   95 KT 110 MPH
 36H  05/0600Z 31.4N  80.0W   95 KT 110 MPH
 48H  05/1800Z 32.6N  79.2W   90 KT 105 MPH
 72H  06/1800Z 36.1N  74.0W   80 KT  90 MPH
 96H  07/1800Z 42.0N  65.0W   75 KT  85 MPH
120H  08/1800Z 50.0N  55.0W   60 KT  70 MPH...POST-TROP/EXTRATROP

$
Forecaster Brown