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#801695 (Received by flhurricane at: 4:41 AM 08.Sep.2015) TCDAT2 TROPICAL STORM GRACE DISCUSSION NUMBER 12 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072015 500 AM AST TUE SEP 08 2015 The deep convection that developed during the evening hours has expanded in coverage overnight, but very little banding or overall organization of the thunderstorm activity exists. The initial wind speed remains 35 kt, which is supported by a TAFB subjective Dvorak intensity estimate and a UW/CIMSS ADT current intensity number. The intensity forecast reasoning remains unchanged from the previous advisory. Increasing southwesterly to westerly vertical wind shear and dry mid-level air along the forecast track should cause Grace to weaken during the next few days. Grace is forecast to weaken to a tropical depression later today, and become a remnant low within the next couple of days. The system is expected to degenerate to a trough by the time it reaches the eastern Caribbean. Given the fast motion of the system and the expected hostile conditions, this could occur much sooner than shown in the official forecast. The initial motion estimate remains 275/17 kt. Grace or its remnant is forecast to continue moving quickly westward to the south of a low- to mid-level ridge that is over the central Atlantic. The model guidance is again tightly clustered and the NHC forecast is essentially an update of the previous track. FORECAST POSITIONS AND MAX WINDS INIT 08/0900Z 14.1N 41.0W 35 KT 40 MPH 12H 08/1800Z 14.2N 43.7W 30 KT 35 MPH 24H 09/0600Z 14.5N 47.2W 30 KT 35 MPH 36H 09/1800Z 14.9N 50.6W 30 KT 35 MPH 48H 10/0600Z 15.3N 54.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 11/0600Z 16.3N 60.8W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 12/0600Z...DISSIPATED $$ Forecaster Brown |