[Tropical] Tropical Cyclone Discussion

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WTNT45 KNHC 051455
TCDAT5

Hurricane Dorian Discussion Number  49
NWS National Hurricane Center Miami FL       AL052019
1100 AM EDT Thu Sep 05 2019

The latest NOAA Doppler radar data, along with Air Force Reserve and
NOAA Hurricane Hunter reports, indicate that Dorian has an well-
defined eye with a diameter of about 40 n mi, with the northwestern
edge of the eyewall not far from the South Carolina coast.  The
Hurricane Hunter data indicate that the flight-level and SFMR
surface winds have decreased some since 12 h ago, accompanied by a
rise in the central pressure.  Based on this, the initial intensity
is decreased to a possibly generous 95 kt.  The central pressure of
958 mb is based partly on data from NOAA buoy 41004, which is
currently inside the eye.

Dorian has nudged eastward during the past several hours and the
initial motion is now 020/7.  The hurricane is now moving into the
mid-latitude westerlies, and during the next several hours it is
expected to turn northeastward with an increase in forward speed.
This should bring the eye near or over the coasts of eastern South
Carolina and southeastern North Carolina during the next 12-24 h.
After that, Dorian is forecast to move quickly across the northwest
Atlantic and be near or over the Canadian Maritimes/Atlantic
provinces by 72 h.  The track guidance remains tightly clustered,
and the new forecast track is changed little from the previous
forecast.

Dorian is forecast to slowly weaken as it moves along the South and
North Carolina coasts.  Extratropical transition should begin
around 48 h and be complete by 72 h, although Dorian is forecast
to maintain hurricane-force winds through the transition.  After
72 h, the extratropical low should weaken over the far north
Atlantic.

The center of Dorian is expected to move very near or over the
coastline of the Carolinas and the southern Mid-Atlantic states.
Residents of these areas should already be prepared for damaging
winds, life-threatening storm surges, and flooding rains.

Key Messages:

1. Life-threatening storm surge and dangerous winds are expected
along portions the coasts of 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 more widespread across the eastern
Carolinas and far southeast Virginia today into tonight. There is a
high risk of flash flooding over these areas, where significant,
life-threatening, flash flooding is expected.

FORECAST POSITIONS AND MAX WINDS

INIT  05/1500Z 32.5N  79.1W   95 KT 110 MPH
 12H  06/0000Z 33.5N  78.0W   90 KT 105 MPH
 24H  06/1200Z 35.1N  75.8W   85 KT 100 MPH
 36H  07/0000Z 37.2N  72.4W   80 KT  90 MPH
 48H  07/1200Z 40.1N  68.0W   80 KT  90 MPH
 72H  08/1200Z 48.0N  59.5W   65 KT  75 MPH...POST-TROP/EXTRATROP
 96H  09/1200Z 54.5N  48.5W   50 KT  60 MPH...POST-TROP/EXTRATROP
120H  10/1200Z 59.5N  32.0W   40 KT  45 MPH...POST-TROP/EXTRATROP

$$
Forecaster Beven
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