[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT45 KNHC 052051
TCDAT5

Hurricane Dorian Discussion Number  50
NWS National Hurricane Center Miami FL       AL052019
500 PM EDT Thu Sep 05 2019

During the last 12 h, Dorian appears to have started the expected
slow weakening trend.  Air Force Reserve Hurricane Hunter data show
that the central pressure inside the 35-45 n mi wide eye is slowly
rising, and satellite imagery indicates that the eye is becoming
less well defined.  The current Hurricane Hunter aircraft has
reported maximum SFMR surface wind estimates of 88 kt, along with
700 mb flight-level winds of 91 kt. Based on these data, the initial
intensity is reduced to 90 kt.

The hurricane is continuing its expected northeastward turn, and the
initial motion is now 035/9.  The mid-latitude westerlies should
steer Dorian generally northeastward at an increasing forward speed,
with the eye passing near of over portions of the North Carolina
coast 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 60 h.  As was the case in
the previous advisory, the track guidance remains tightly clustered,
and the new forecast track is changed little from the previous
one.

Due to increasing shear, Dorian is forecast to slowly weaken as it
moves near and along the South and North Carolina coasts.
Extratropical transition should begin around 36-48 h and be complete
by 60 h, although Dorian is forecast to maintain hurricane-force
winds through the transition.  After transition is complete, the
extratropical low should weaken over the far north Atlantic and be
absorbed into a larger low pressure area by 120 h.

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.  It also
appears that Dorian will affect portion of eastern Canada as a
hurricane-force extratropical low.

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 is occurring, and will continue to become more
widespread across the eastern Carolinas and far southeast Virginia
through 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  05/2100Z 33.1N  78.5W   90 KT 105 MPH
 12H  06/0600Z 34.2N  77.2W   90 KT 105 MPH
 24H  06/1800Z 36.0N  74.4W   85 KT 100 MPH
 36H  07/0600Z 38.5N  70.4W   80 KT  90 MPH
 48H  07/1800Z 42.0N  65.9W   75 KT  85 MPH
 72H  08/1800Z 50.0N  57.5W   65 KT  75 MPH...POST-TROP/EXTRATROP
 96H  09/1800Z 56.0N  45.5W   50 KT  60 MPH...POST-TROP/EXTRATROP
120H  10/1800Z...DISSIPATED

$$
Forecaster Beven
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