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Hurricane Maria Discussion Number  20
NWS National Hurricane Center Miami FL       AL152017
1100 PM AST Wed Sep 20 2017

The satellite presentation is a little better organized than
a few hours ago, and Maria now has a large ragged eye.  However,
data from an Air Force Hurricane Hunter plane indicate that the
winds are still 95 kt, while the central pressure has remained
unchanged oscillating near 959 mb.  Even with the current favorable
low-shear environment and warm ocean, it takes in general about 24
hours for the boundary layer of the hurricane to recover from the
passage over high terrain, in this case Puerto Rico.  In addition,
the reconnaissance plane reported two wind maxima and two concentric
eyewalls in the previous penetration, and it just reported that the
inner one has collapsed in the last fix.  This suggest that an
eyewall replacement cyclone has occurred.  With this complex
scenario, the NHC forecast allows for some small increase in
intensity as suggested by guidance and brings Maria back to category
3 status in about 24 hours.

Maria continues right on track, moving toward the northwest or 310
degrees at 8 kt.  The hurricane is expected to be steered
north-northwestward and northward around a subtropical ridge over
the Atlantic for the next 2 to 3 days. The only change to the
previous forecast is a small shift to the east by the end of the
forecast period as indicated by most of the track models.  By then,
Maria should have reached the northwestern edge of the ridge. The
NHC forecast is basically on top of the multi-model consensus and
very near the HFIP corrected consensus.


KEY MESSAGES:

1. Maria is moving away from the northwestern coast of Puerto
Rico, and strong winds and storm surge flooding should continue to
subside through early Thursday.  However, heavy rainfall is expected
to continue, and catastrophic flash flooding is occurring on the
island, especially in areas of mountainous terrain.  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  21/0300Z 19.2N  67.9W   95 KT 110 MPH
 12H  21/1200Z 19.9N  68.8W   95 KT 110 MPH
 24H  22/0000Z 21.0N  70.0W  100 KT 115 MPH
 36H  22/1200Z 22.3N  70.8W  100 KT 115 MPH
 48H  23/0000Z 23.7N  71.5W  100 KT 115 MPH
 72H  24/0000Z 26.8N  72.2W  100 KT 115 MPH
 96H  25/0000Z 29.5N  72.0W   90 KT 105 MPH
120H  26/0000Z 32.0N  71.0W   80 KT  90 MPH

$$
Forecaster Avila

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