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Tropical Storm Dorian Discussion Number   5
NWS National Hurricane Center Miami FL       AL052019
1100 AM AST Sun Aug 25 2019

The convective organization of Dorian has improved a little since
the last advisory, as a more persistent area of central convection
has formed along with increased, but ragged, outer banding.
However, the various satellite intensity estimates remain clustered
around 35 kt, and that remains the initial intensity.

A combination of 1-minute GOES-16 visible imagery and microwave
satellite data have helped pinpoint the center, and the initial
motion is 280/12.  The subtropical ridge to the north of the
cyclone should steer it generally westward to west-northwestward
for the next 3-4 days, with a more northwestward motion possible
thereafter as Dorian approaches an upper-level low pressure area
forecast to be over the north-central Caribbean.  The model
guidance continues the previous trend of being south of and a bit
faster than the previous runs, and as a result the new forecast
track is again shifted a little to the south.  The new forecast
lies between the previous forecast and the various consensus
models.  However, it is south of the forecasts of the HWRF, the
UKMET, and the UKMET Ensemble mean.  Additional adjustments to the
track may be required on the next advisory if the current model
trends continue.

While vertical wind shear is decreasing over Dorian, the cyclone
still appears to be ingesting dry air based on the ragged convective
pattern.  Some dry air entrainment is expected to continue for the
next few days, and based on this the new intensity forecast again
calls for gradual strengthening through 72 h.  This part of the
intensity forecast is in best agreement with the SHIPS model, and it
lies near the upper edge of the intensity guidance.  The intensity
forecast becomes low confidence after 72 h due to uncertainties in
the amount of shear and land that Dorian will encounter.  The new
forecast calls for some weakening due to shear before Dorian moves
over Hispaniola, followed by weakening to a depression due to
passage over the island.  However, the large range of possibilities
includes both Dorian going north of Hispaniola and remaining a
hurricane and the small cyclone dissipating completely over
Hispaniola.

Key Messages:

1. A Tropical Storm Warning has been issued for Barbados, and a
Tropical Storm Watch is in effect for St. Lucia, St. Vincent, and
the Grenadines. Additional watches and warnings for other portions
of the Lesser Antilles could be required later today.

2. It is too soon to determine the specific timing or magnitude of
impacts in Puerto Rico, the Virgin Islands, or Hispaniola, but
interests in those areas should monitor the progress of Dorian.

FORECAST POSITIONS AND MAX WINDS

INIT  25/1500Z 11.2N  52.9W   35 KT  40 MPH
 12H  26/0000Z 11.5N  54.6W   40 KT  45 MPH
 24H  26/1200Z 12.0N  56.9W   45 KT  50 MPH
 36H  27/0000Z 12.7N  59.1W   50 KT  60 MPH
 48H  27/1200Z 13.5N  61.2W   55 KT  65 MPH
 72H  28/1200Z 15.6N  65.3W   65 KT  75 MPH
 96H  29/1200Z 17.5N  69.0W   60 KT  70 MPH
120H  30/1200Z 20.0N  72.0W   25 KT  30 MPH

$$
Forecaster Beven

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