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#801751 (Received by flhurricane at: 10:35 AM 08.Sep.2015) TCDAT2 TROPICAL DEPRESSION GRACE DISCUSSION NUMBER 13 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072015 1100 AM AST TUE SEP 08 2015 After the overnight burst of deep convection, thunderstorm activity has diminished and the overall cloud pattern remains disorganized. Data from a recent ASCAT overpass show that Grace's maximum winds have decreased to near 30 kt, so the system is being downgraded to a tropical depression on this advisory. The cyclone is forecast to move through an environment of increasing vertical shear and dry mid-level air for the next few days. These unfavorable factors should cause the system to weaken further, and to degenerate into a remnant low pressure area over the next day or two. The official intensity forecast is the same as the previous one, and is slightly below the latest intensity model consensus. It is possible that Grace could open up into a wave during the next few days, as indicated by the global models. The cyclone continues to move westward at a fairly rapid pace, with the motion estimate remaining at 275/17 kt. The steering pattern is expected to remain uncomplicated. Grace or its remnant should continue to move west or slightly north of west, to the south of a low- to mid-level subtropical ridge throughout the forecast period. The official track forecast is an update of the previous one and remains close to the dynamical model consensus. FORECAST POSITIONS AND MAX WINDS INIT 08/1500Z 14.3N 42.8W 30 KT 35 MPH 12H 09/0000Z 14.4N 45.4W 30 KT 35 MPH 24H 09/1200Z 14.8N 48.8W 30 KT 35 MPH 36H 10/0000Z 15.3N 52.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 10/1200Z 15.8N 55.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 11/1200Z 16.6N 62.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 12/1200Z...DISSIPATED $$ Forecaster Pasch |