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Tropical Storm Maria Discussion Number  52
NWS National Hurricane Center Miami FL       AL152017
1100 PM AST Thu Sep 28 2017

The satellite presentation of Maria has degraded over the past
12 hours or so, with the area of deep convection decreasing in
coverage and becoming displaced to the east of the center due to
some westerly shear.  Subjective Dvorak intensity estimates from
TAFB and SAB are 45 kt, while the UW-CIMSS ADT is 50-55 kt. Based on
the latter, the initial wind speed is maintained at 55 kt for this
advisory.

Maria is beginning to accelerate eastward, with an initial motion
estimate of 080/15 kt.  The tropical storm is forecast to turn
east-northeastward on Friday ahead of an approaching deep-layer
trough.  Maria should continue to accelerate east-northeastward to
northeast over the north Atlantic on Saturday before it is absorbed
by a frontal boundary over the northeastern Atlantic.  The track
guidance continues to be tightly clustered and the NHC forecast is
essentially an update of the previous advisory.

Maria is forecast to change little in intensity over the next
day or so while it moves over marginal SSTs and remains in low to
moderate shear conditions.  After that time, baroclinic forcing
and the rapid forward speed of the cyclone should again help Maria
maintain its intensity until it completes extratropical transition
in about 48 hours.  The global models indicate that the
extratropical low will weaken over the northeastern Atlantic
by day 72 h, and be absorbed by a frontal system by day 4.

The post-tropical intensity and wind radii forecasts at 48 and 72 h
are based on guidance provided by the NOAA Ocean Prediction Center.


FORECAST POSITIONS AND MAX WINDS

INIT  29/0300Z 37.1N  65.5W   55 KT  65 MPH
 12H  29/1200Z 37.5N  61.7W   55 KT  65 MPH
 24H  30/0000Z 39.1N  55.4W   55 KT  65 MPH
 36H  30/1200Z 41.5N  48.0W   55 KT  65 MPH
 48H  01/0000Z 44.0N  40.0W   55 KT  65 MPH...POST-TROP/EXTRATROP
 72H  02/0000Z 50.0N  20.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
 96H  03/0000Z...ABSORBED

$$
Forecaster Brown

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