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#801286 (Received by flhurricane at: 10:34 AM 06.Sep.2015) TCDAT2 TROPICAL STORM GRACE DISCUSSION NUMBER 5 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072015 1100 AM AST SUN SEP 06 2015 The cloud pattern of the storm has changed little in organization over the past several hours. There are fairly well-defined curved bands over both the northern and southern portions of the circulation. The deep convection is not very impressive, however, with a limited amount of cold cloud tops and there is a dry slot in the western semicircle. The current intensity is kept at 40 kt, which is the average of Dvorak estimates from TAFB and SAB. Over the next 1 to 2 days, Grace is forecast to move through a low vertical wind shear environment with sea surface temperatures sufficiently warm for strengthening. Thereafter, the tropical cyclone should be encountering increasing west-southwesterly shear associated with a large upper-tropospheric trough over the eastern Caribbean Sea. So, whereas intensification is probable in the short term, Grace is likely to weaken later in the forecast period. The official intensity forecast is the same as the previous one, and is slightly above the latest model consensus. Visible satellite fixes indicate that the westward motion continues. The steering scenario appears to be straightforward. Grace should remain situated to the south of a subtropical ridge, and embedded in mid- to low-level easterly flow throughout the forecast period. The track guidance is in good agreement on a continued westward motion for the next 5 days, and the NHC forecast is close to the dynamical model consensus. FORECAST POSITIONS AND MAX WINDS INIT 06/1500Z 12.9N 29.9W 40 KT 45 MPH 12H 07/0000Z 13.0N 32.0W 45 KT 50 MPH 24H 07/1200Z 13.3N 34.7W 50 KT 60 MPH 36H 08/0000Z 13.6N 37.4W 55 KT 65 MPH 48H 08/1200Z 13.8N 40.1W 55 KT 65 MPH 72H 09/1200Z 14.3N 45.3W 50 KT 60 MPH 96H 10/1200Z 15.0N 50.5W 40 KT 45 MPH 120H 11/1200Z 15.5N 55.5W 35 KT 40 MPH $$ Forecaster Pasch |