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HURRICANE GASTON DISCUSSION NUMBER  34
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL072016
1100 PM AST TUE AUG 30 2016

Gaston's satellite presentation has continued to improve, with a
large clear eye and cloud tops colder than -60C completely
surrounding the center.  Dvorak intensity estimates have risen to
T5.5 from TAFB and SAB and are a little higher from the objective
ADT.  The initial intensity is therefore raised to 105 kt, making
Gaston a major hurricane again.

Gaston is expected to remain over waters warmer than 26C for at
least the next 36 hours.  In addition, vertical shear is not
expected to increase any further than what is already affecting the
system.  Therefore, Gaston should be able to at least maintain its
intensity in the short term, but weakening is likely to commence by
24 hours.  Due to cooler waters, a rather fast weakening trend
is expected after 36 hours, with Gaston likely to weaken to a
tropical storm between 48 and 72 hours.  The cyclone is now
expected to become post-tropical by day 4 since it will be
difficult for it to maintain organized, deep convection over cold
water, and it should become absorbed by another extratropical
cyclone by day 5.  The NHC intensity forecast closely follows the
ICON intensity consensus for the entire forecast period.

The initial motion is 070/9 kt.  Gaston is becoming embedded in the
mid-latitude westerlies, which should cause it to accelerate
toward the east-northeast during the next couple of days.  Some
reduction in speed is then forecast to start by day 3 once Gaston
begins to interact with the separate extratropical cyclone.  The
track guidance is tightly clustered, and no significant changes
were needed from the previous NHC track forecast.  The updated NHC
forecast continues to show a threat to the Azores in about 3 days.

FORECAST POSITIONS AND MAX WINDS

INIT  31/0300Z 32.9N  50.9W  105 KT 120 MPH
 12H  31/1200Z 33.7N  49.2W  105 KT 120 MPH
 24H  01/0000Z 35.4N  46.0W   95 KT 110 MPH
 36H  01/1200Z 36.9N  41.7W   85 KT 100 MPH
 48H  02/0000Z 37.9N  36.9W   75 KT  85 MPH
 72H  03/0000Z 38.7N  29.5W   50 KT  60 MPH
 96H  04/0000Z 40.5N  23.5W   35 KT  40 MPH...POST-TROPICAL
120H  05/0000Z...DISSIPATED

$$
Forecaster Berg

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