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WTNT42 KNHC 310253
TCDAT2

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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