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Hurricane Maria Discussion Number  22
NWS National Hurricane Center Miami FL       AL152017
1100 AM AST Thu Sep 21 2017

Maria is maintaining a large, 40 nm wide eye, and overall, the
hurricane's satellite presentation has not changed since the
previous advisory.  An Air Force Reserve Hurricane Hunter aircraft
investigating the system has not measured flight-level winds as
high as last evening's mission, and the central pressure has
remained relatively steady.  Although there were higher SFMR winds
measured, especially to the northeast of the center, the flight
meteorologist reported that the instrument appears to be running
5-10 kt too high.  Therefore, the initial intensity is held at 100
kt.

Maria appears to be moving over the remnant cold wake leftover from
Hurricane Irma, but it should begin to move over an area of higher
oceanic heat content during the next 24 hours or so.  Therefore,
some strengthening is still forecast, although it is not especially
aggressive given what the latest intensity guidance is showing.
Gradual weakening is likely from 48 hours onward due to some
increase in southwesterly shear, as well as lower oceanic heat
content over the western Atlantic.  Still, Maria is expected to
remain a hurricane for the next 5 days.

The initial motion is northwestward, or 310/8 kt.  Maria will be
moving between a mid-level high centered south of Bermuda and a
broad trough extending from Tropical Storm Jose southwestward into
the northern Gulf of Mexico.  As a result, Maria is expected to
turn gradually north-northwestward to north-northeastward by the
end of the forecast period, keeping it over the waters of the
western Atlantic after moving by the Turks and Caicos Islands and
the southeastern Bahamas.  The track models continue to be tightly
clustered, and the updated NHC track forecast lies right along the
previous forecast, down the middle of the guidance envelope.

KEY MESSAGES:

1. Flash flood emergencies continue in portions of Puerto Rico due
to persistent heavy rainfall from Maria's trailing rainbands.
Catastrophic flooding is occurring on the island, especially in
areas of mountainous terrain, and everyone in Puerto Rico should
continue to follow advice from local officials to avoid these
life-threatening flooding conditions.

2. A Hurricane Warning is in effect for the northern coast of the
Dominican Republic, the Turks and Caicos Islands, and the
southeastern Bahamas, where Maria is expected to bring dangerous
wind, storm surge, and heavy rainfall.

FORECAST POSITIONS AND MAX WINDS

INIT  21/1500Z 20.2N  69.1W  100 KT 115 MPH
 12H  22/0000Z 21.0N  69.9W  105 KT 120 MPH
 24H  22/1200Z 22.2N  70.7W  105 KT 120 MPH
 36H  23/0000Z 23.6N  71.4W  100 KT 115 MPH
 48H  23/1200Z 25.1N  71.9W   95 KT 110 MPH
 72H  24/1200Z 28.2N  72.3W   95 KT 110 MPH
 96H  25/1200Z 30.5N  71.5W   85 KT 100 MPH
120H  26/1200Z 33.0N  70.0W   75 KT  85 MPH

$$
Forecaster Berg

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