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#873461 (Received by flhurricane at: 4:59 AM 31.Aug.2016) TCDAT4 TROPICAL DEPRESSION NINE DISCUSSION NUMBER 11 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092016 400 AM CDT WED AUG 31 2016 Although clusters of deep convection continue to pulsate near and to the southeast of the center of the tropical cyclone, there has been little overall change in organization overnight. A couple of ASCAT passes since the previous advisory revealed peak winds of 30 kt, so the system remains a 30-kt tropical depression for this advisory. The upper-level outflow has expanded to the northwest and north of the cyclone, which suggests that the upper-level wind pattern is becoming more favorable for strengthening. The SHIPS model indicates that the shear should remain low during the next day or so, while the cyclone moves over warm water. This should allow for strengthening, and the NHC forecast calls for steady intensification during the next day or so, which is also supported by the global models. The updated intensity forecast is in good agreement with the multi-model consensus. The depresssion has been meandering overnight, but is expected to begin a northward or northeastward motion later today. A deepening trough over the southeastern United States should cause the tropical cyclone to accelerate north-northeastward or northeastward by tonight. Although the track guidance is in good agreement on this scenario, the model envelope has shifted slightly westward this cycle, and the NHC forecast track has been nudged in that direction. The new forecast has required the issuance of a Tropical Storm Warning for a portion of the Florida Gulf coast. The Hurricane Watch remains in effect since there is still a possibility that the system could become a hurricane before landfall. It is important not to focus on the forecast landfall point of this system. Among other reasons, dangerous storm surge flooding is likely along the coast well to the east and south of the path of the center. FORECAST POSITIONS AND MAX WINDS INIT 31/0900Z 24.5N 88.1W 30 KT 35 MPH 12H 31/1800Z 25.4N 87.8W 40 KT 45 MPH 24H 01/0600Z 26.9N 86.9W 45 KT 50 MPH 36H 01/1800Z 28.4N 85.6W 55 KT 65 MPH 48H 02/0600Z 30.3N 83.6W 55 KT 65 MPH...INLAND 72H 03/0600Z 34.2N 76.8W 60 KT 70 MPH...OVER WATER 96H 04/0600Z 37.0N 70.2W 60 KT 70 MPH 120H 05/0600Z 39.0N 68.0W 55 KT 65 MPH...POST-TROP/EXTRATROP $$ Forecaster Brown |