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Tropical Storm Don Discussion Number   4
NWS National Hurricane Center Miami FL       AL052017
1100 AM AST Tue Jul 18 2017

Reports from an Air Force Reserve reconnaissance aircraft
indicate that the tropical storm has weakened this morning.  The
highest flight-level and SFMR observations support an intensity of
30-35 kt and the data also show that the circulation has become
less defined and in fact it may lack a closed surface circulation.
Advisories are being maintained for now pending another
reconnaissance aircraft mission later today.

Increasing westerly shear and dry mid-level air are likely to
continue to weaken the tropical cyclone as it moves through the
Windward Islands and the eastern Caribbean during the next day or
so.  The NHC forecast calls for Don to weaken to a tropical
depression in about 24 hours and degenerate into a an open wave
within 36 hours.  This could occur much sooner than indicated below.

The track forecast reasoning remains unchanged.  Don should continue
to move quickly westward within the strong trade wind flow until
dissipation occurs.  The NHC track forecast is similar to the
previous advisory and is near the model consensus.

FORECAST POSITIONS AND MAX WINDS

INIT  18/1500Z 11.5N  58.0W   35 KT  40 MPH
 12H  19/0000Z 11.7N  60.9W   35 KT  40 MPH
 24H  19/1200Z 12.0N  65.0W   30 KT  35 MPH
 36H  20/0000Z...DISSIPATED

$$
Forecaster Brown

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