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HURRICANE GASTON DISCUSSION NUMBER  27
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL072016
500 AM AST MON AUG 29 2016

Gaston remains a well-organized hurricane.  However, the satellite
appearance is slightly less impressive than 6 hours ago, with the
eye becoming less distinct and the deep convection eroding in the
northwestern quadrant.  While the various satellite intensity
estimates have changed little since the last advisory, the initial
intensity is lowered to 100 kt based on the degraded appearance.

The hurricane is currently drifting northward.  A slow motion is
likely to continue for the next 12 hours or so as Gaston is caught
between two segments of the subtropical ridge.  After that time, a
mid-latitude trough moving southeastward from eastern Canada is
expected to weaken the ridge northwest of Gaston, allowing the
cyclone to move generally east-northeastward along the southern edge
of the westerlies.  The model guidance remains tightly packed
through 72 hours, and little change was made to the previous
forecast for that time.  After 72 hours, the guidance envelope has
shifted a little to the north, and the forecast track was likewise
nudged to stay near the middle of the guidance envelope.

Gaston is expected to remain is a light shear/warm water
environment for the first 24 hours.  During this time, the
intensity forecast calls for slight weakening due to dry air
entrainment and the possibility that the slow-moving hurricane will
upwell cold water.  After 24 hours, Gaston is likely to move over
decreasing sea surface temperatures and into increasing shear,
which should cause a gradual weakening.  The new forecast intensity
is an update of the previous forecast.


FORECAST POSITIONS AND MAX WINDS

INIT  29/0900Z 30.8N  55.2W  100 KT 115 MPH
 12H  29/1800Z 31.1N  55.1W   95 KT 110 MPH
 24H  30/0600Z 31.8N  54.2W   95 KT 110 MPH
 36H  30/1800Z 32.5N  52.5W   95 KT 110 MPH
 48H  31/0600Z 33.5N  50.2W   90 KT 105 MPH
 72H  01/0600Z 36.5N  44.0W   85 KT 100 MPH
 96H  02/0600Z 38.0N  36.5W   70 KT  80 MPH
120H  03/0600Z 38.5N  30.5W   55 KT  65 MPH

$$
Forecaster Beven

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