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Tropical Storm Dorian Discussion Number  15
NWS National Hurricane Center Miami FL       AL052019
1100 PM AST Tue Aug 27 2019

Reports from an Air Force Hurricane Hunter aircraft indicate that
Dorian is yet to strengthen, and the initial intensity remains near
45 kt.  The storm's cloud pattern remains rather ragged-looking
with no clear convective banding features.  Since the storm has
strong upper-level outflow over the western semicircle of the
circulation and vertical shear should remain low for the next day or
two, strengthening is still forecast before Dorian reaches Puerto
Rico on Wednesday.  Some weakening is likely by 24 hours due to the
interaction of the circulation with Puerto Rico.  The intensity
forecast in 3-5 days remains problematic because of a significant
spread in the model guidance and some run-to-run inconsistencies.
The official intensity forecast has been increased in comparison to
the previous ones.  However, it is now near the low end of the
numerical guidance suite.

Dorian has turned toward the northwest, and the initial motion
estimate is 310/11 kt.  Over the next couple of days, the cyclone
will be headed toward a weakness in the subtropical ridge.  In 3-4
days, the global models show the ridge rebuilding somewhat over the
western Atlantic.  This scenario should cause Dorian to turn toward
the left later in the forecast period.  The official forecast has
been shifted to the north of the previous one.  This is in close
agreement with the ECMWF model track, but south and southwest of
the latest simple and corrected consensus predictions.


Key Messages:

1. Tropical storm conditions are expected in the U.S. and British
Virgin Islands and Puerto Rico on Wednesday, and are possible in
portions of the Dominican Republic Wednesday night and Thursday.
Hurricane conditions are possible in Puerto Rico on Wednesday.

2. Heavy rainfall over portions of Puerto Rico and the Dominican
Republic could produce flash flooding during the next few days.
Heavy rains are expected to occur over portions of the Bahamas and
Florida later this week and into early next week.

3. The threat of tropical storm or hurricane conditions, along with
storm surge, in the Bahamas and along portions of the Florida east
coast have increased. Residents in these areas should monitor the
progress of Dorian and ensure that they have their hurricane plan in
place.

4. Uncertainty in the intensity forecast later this week remains
higher than usual due a large spread in model guidance.
storm.


FORECAST POSITIONS AND MAX WINDS

INIT  28/0300Z 16.0N  63.0W   45 KT  50 MPH
 12H  28/1200Z 17.0N  64.5W   55 KT  65 MPH
 24H  29/0000Z 18.5N  66.5W   45 KT  50 MPH...INLAND
 36H  29/1200Z 20.3N  68.1W   50 KT  60 MPH
 48H  30/0000Z 22.1N  69.6W   55 KT  65 MPH
 72H  31/0000Z 25.3N  72.7W   65 KT  75 MPH
 96H  01/0000Z 27.4N  76.8W   70 KT  80 MPH
120H  02/0000Z 28.8N  81.0W   65 KT  75 MPH...INLAND

$$
Forecaster Pasch

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