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Hurricane Dorian Discussion Number  35
NWS National Hurricane Center Miami FL       AL052019
1100 PM EDT Sun Sep 01 2019

Dorian remains an incredibly powerful hurricane and it is currently
making landfall on the eastern end of Grand Bahama Island.
Satellite images show an symmetrical cyclone with a circular 10 n mi
diameter eye and intense eyewall convection with lots of lightning
being detected.  Doppler radar data from Miami and the Bahamas show
that Dorian has developed concentric eyewalls, and this feature is
also noted by a double wind maximum that is evident in data from the
Air Force Hurricane Hunters.  The initial intensity of Dorian is set
at 155 kt based mostly on the SFMR winds from the aircraft.  The
aircraft data also indicated that the radii of tropical-storm-force
winds are a little larger than they were earlier today.

Dorian is still moving slowly westward at about 5 kt. The ridge to
the north of Dorian is gradually weakening and shifting eastward in
response to a mid- to upper-level trough that is moving across the
eastern U.S.  This change in the steering pattern should cause
Dorian to slow down even more and perhaps stall, before it turns to
the northwest late Monday or early Tuesday.  This expected slow
motion will likely be devastating to the Great Abaco and Grand
Bahama Islands since it would prolong the catastrophic winds, storm
surge, and rainfall over those areas.  The timing of the northwest
or north turn is very critical in determining how close Dorian will
get to the Florida peninsula on Tuesday and Wednesday.  In general,
the track models have changed little from the previous cycle, and
the NHC forecast continues to show the core of Dorian very near, but
offshore, of the Florida peninsula on Tuesday and Wednesday.  The
hurricane is then expected to track near the Georgia and Carolina
coasts late this week.  This forecast is in best agreement with the
various consensus models, which typically have the lowest errors. It
is once again emphasized that although the official track forecast
does not show landfall, users should not focus on the exact track.
A small deviation to the left of the track could bring the intense
core of the hurricane and its dangerous winds closer to or onto the
Florida coast.

Category 5 hurricanes like Dorian usually don't hold that intensity
for very long, and it is expected that Dorian will weaken slowly
during the next few days.  However, the observed eyewall replacement
cycle will likely cause fluctuations in strength, both up and down,
while the system is near Florida.  The models show an increase in
shear when Dorian tracks near Georgia and the Carolinas, which
should cause more notable weakening.  This forecast is near the
high end of the latest model guidance.

Based on this forecast, the hurricane watch has been extended
northward to the Florida-Georgia line.


Key Messages:

1. A prolonged period of catastrophic winds and storm surge will
affect the Abaco Islands and Grand Bahama Island for several more
hours.  Everyone there should take immediate shelter and not venture
into the eye.

2. Life-threatening storm surges and dangerous hurricane-force winds
are expected along portions of the Florida east coast through
mid-week, and storm surge and hurricane warnings are in effect. Only
a slight deviation to the left of the official forecast would bring
the core of Dorian near or over the Florida east coast.  Residents
should listen to advice given by local emergency officials.

3. There is an increasing likelihood of strong winds and dangerous
storm surge along the coasts of Georgia, South Carolina, and North
Carolina later this week. Residents in these areas should continue
to monitor the progress of Dorian and listen to advice given by
local emergency officials.

4. Heavy rains, capable of producing life-threatening flash floods,
are expected over northern portions of the Bahamas and coastal
sections of the southeast and lower mid-Atlantic regions of the
United States through late this week.


FORECAST POSITIONS AND MAX WINDS

INIT  02/0300Z 26.6N  77.9W  155 KT 180 MPH
 12H  02/1200Z 26.8N  78.5W  145 KT 165 MPH
 24H  03/0000Z 26.9N  79.0W  135 KT 155 MPH
 36H  03/1200Z 27.3N  79.3W  125 KT 145 MPH
 48H  04/0000Z 28.2N  79.8W  120 KT 140 MPH
 72H  05/0000Z 30.6N  80.2W  105 KT 120 MPH
 96H  06/0000Z 33.5N  77.7W   85 KT 100 MPH
120H  07/0000Z 37.5N  71.8W   75 KT  85 MPH

$$
Forecaster Cangialosi

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