[Tropical] Tropical Cyclone Discussion

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WTNT45 KNHC 050255
TCDAT5

Hurricane Dorian Discussion Number  47
NWS National Hurricane Center Miami FL       AL052019
1100 PM EDT Wed Sep 04 2019

Satellite imagery indicated that the cloud pattern associated with
Dorian was a little better organized with a clear eye surrounded
by a ring of very deep convection. This trend was confirmed with
data from both NOAA and Air Force reconnaissance planes, which
measured a minimum central pressure of 955 mb. SFMR and flight-level
winds support an initial intensity of 100 kt. In fact, Dvorak
numbers also call for 100 kt.

Dorian could maintain this intensity for about 12 hours or so,
but guidance is showing shear increasing, and that should result
in gradual weakening. The intensity forecast is basically the same
as the previous advisory, keeping Dorian at the border of category 2
or 3 intensity as it moves near the southeast coast of the United
States. This forecast is consistent with the intensity models, which
unanimously gradually weaken the cyclone. On the other hand, the
wind field is expected to gradually expand during the next several
days until the cyclone becomes extratropical near Atlantic Canada.

Aircraft fixes yield a northward motion or 010 degrees at 6 kt.
Dorian is already recurving as it is becoming steered by the south-
southwesterly flow ahead of an eastward-moving mid-level trough. The
track guidance is tightly clustered, and the NHC forecast follows
very closely the multi-model consensus. No significant change to
the previous track forecast was necessary. The forecast motion
should bring the core of Dorian near the coast of South Carolina
during the next 6 to 12 hours and over the Outer Banks of North
Carolina between 24 and 36 hours.

Since the NHC track prediction continues to take Dorian dangerously
close to the southeast U.S. coast, all interests from Georgia
to the Carolinas should remain vigilant to the possibility of
experiencing destructive winds, flooding rains, and life-
threatening storm surges from this hurricane.

Key Messages:

1. Life-threatening storm surge and dangerous winds are expected
along portions the coasts of Georgia, South Carolina, and North
Carolina, and portions of southeast Virginia and the southern
Chesapeake Bay, 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. Flash flooding will become increasingly likely across coastal
Georgia into the eastern Carolinas overnight. On Thursday, there is
a high risk of flash flooding over coastal sections of the
Carolinas, where significant, life-threatening, flash flooding is
expected.


FORECAST POSITIONS AND MAX WINDS

INIT  05/0300Z 31.3N  79.6W  100 KT 115 MPH
 12H  05/1200Z 32.2N  79.4W  100 KT 115 MPH
 24H  06/0000Z 33.6N  78.1W   90 KT 105 MPH
 36H  06/1200Z 35.2N  75.9W   85 KT 100 MPH...OVER NC OUTER BANKS
 48H  07/0000Z 37.5N  72.2W   80 KT  90 MPH
 72H  08/0000Z 45.0N  62.8W   65 KT  75 MPH
 96H  09/0000Z 53.5N  52.5W   50 KT  60 MPH...POST-TROP/EXTRATROP
120H  10/0000Z 58.0N  38.5W   40 KT  45 MPH...POST-TROP/EXTRATROP

$$
Forecaster Avila
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