ZCZC MIATCDAT5 ALL
TTAA00 KNHC DDHHMM

Tropical Storm Dorian Discussion Number  11
NWS National Hurricane Center Miami FL       AL052019
1100 PM AST Mon Aug 26 2019

An Air Force Reserve Unit Hurricane Hunter aircraft has been
investigating Dorian this evening.  Data from the plane indicate
that the storm is not quite as strong as previously estimated, and
based on flight-level winds and SFMR-observed surface winds the
intensity is set at 45 kt.  Fixes from the aircraft show that the
center of the cyclone moved just south of the southern coast of
Barbados within the last couple of hours, and tropical-storm-force
winds were reported over that island.  There is fairly well-defined
upper-level outflow over the eastern semicircle of the circulation.
Although some dry mid-level air is likely to continue to affect
Dorian while it moves over the northeastern Caribbean, the dynamical
guidance indicates that the shear will not become very strong.
Therefore it is still expected that the cyclone will become a
hurricane in a couple of days.  Some disruption of the system will
likely occur when the center moves near eastern Hispaniola.  The
official intensity forecast is on the high end of the model guidance
and is subject to considerable uncertainty, particularly from days 3
to 5.

Dorian continues to move west-northwestward, or 290/11 kt, while
being steered by the flow on the south side of the subtropical
ridge.  In a day or two, the tropical cyclone is expected to turn
northwestward due to a weakness in the ridge.  The ridge is
expected to build somewhat later in the forecast period, which
should cause Dorian to turn slightly to the left.  The ECMWF model
is near the northern side of the guidance suite and the UKMET is
near the southern side.  The GFS model continues to practically
dissipate the system so it was unable to generate a forecast
track.  The official track forecast was shifted a bit to the north,
but lies south of the latest dynamical model consensus.  It is
advisable that one not focus on small changes in the forecast track
due to uncertainties.

Key Messages:

1. Dorian is expected to bring tropical storm conditions to portions
of the Lesser Antilles through Tuesday morning, where tropical storm
watches and warnings are in effect.  Rainfall of 3 to 8 inches is
expected from Martinique to St.  Vincent, including Barbados, with
isolated totals as high as 10 inches possible.

2. Tropical storm conditions are possible in Puerto Rico on
Wednesday, where a tropical storm watch has been issued. Rainfall
of 2 to 4 inches with maximum totals of 6 inches are possible
across Puerto Rico and St. Croix.

3. Watches will likely be issued for portions of Hispaniola early
Tuesday, as the threat of wind and rain impacts continues to
increase.

4. While uncertainty is high, wind and rain impacts are possible in
the Bahamas and Florida later this week and this weekend.  Residents
in these areas should monitor the progress of Dorian and ensure that
they have their hurricane plan in place.


FORECAST POSITIONS AND MAX WINDS

INIT  27/0300Z 13.2N  59.7W   45 KT  50 MPH
 12H  27/1200Z 14.0N  61.3W   50 KT  60 MPH
 24H  28/0000Z 15.2N  63.5W   55 KT  65 MPH
 36H  28/1200Z 16.5N  65.5W   60 KT  70 MPH
 48H  29/0000Z 17.9N  67.6W   65 KT  75 MPH
 72H  30/0000Z 21.0N  71.0W   50 KT  60 MPH
 96H  31/0000Z 24.0N  74.8W   55 KT  65 MPH
120H  01/0000Z 26.5N  79.0W   60 KT  70 MPH

$$
Forecaster Pasch

NNNN