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| #873343 (Received by flhurricane at: 4:50 AM 30.Aug.2016) TCDAT2 HURRICANE GASTON DISCUSSION NUMBER 31 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072016 500 AM AST TUE AUG 30 2016 Gaston is completing an eyewall replacement cycle and currently features a well-defined 35 n mi wide eye. The convective clouds have eroded somewhat west of the eye since the last advisory, and the various subjective and objective intensity estimates have also decreased. The initial intensity is thus lowered to 85 kt. The initial motion is now 055/5. A mid- to upper-level trough currently seen in water vapor images near Atlantic Canada is expected to approach Gaston during the next 12 to 24 hours, and that should cause the hurricane to become embedded in the mid-latitude westerlies. As a result, Gaston should accelerate generally east-northeastward through 72 hours. At 96 hours, a building ridge southwest of Gaston may cause a more easterly motion as the cyclone approaches the Azores Islands. This should be followed by a northeastward turn by 120 hours as a second mid-latitude trough approaches the tropical cyclone. The track guidance generally agrees with this scenario, although the model spread increases after 72 hours. The new forecast track is changed little from the previous track and lies near the center of the guidance envelope. The intensity guidance suggests that little change in strength is likely for the next 36-48 hours as Gaston moves over relatively warm water in a light or moderate westerly shear environment. After that time, increasing shear and decreasing sea surface temperatures should cause a steady decay. The new intensity forecast is an update of the previous forecast in best agreement with the SHIPS and LGEM models. FORECAST POSITIONS AND MAX WINDS INIT 30/0900Z 32.0N 54.0W 85 KT 100 MPH 12H 30/1800Z 32.4N 52.7W 85 KT 100 MPH 24H 31/0600Z 33.4N 50.6W 85 KT 100 MPH 36H 31/1800Z 35.0N 47.7W 85 KT 100 MPH 48H 01/0600Z 36.8N 43.5W 85 KT 100 MPH 72H 02/0600Z 39.5N 34.0W 70 KT 80 MPH 96H 03/0600Z 39.5N 28.5W 50 KT 60 MPH 120H 04/0600Z 42.5N 23.5W 35 KT 40 MPH $$ Forecaster Beven |