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#873400 (Received by flhurricane at: 5:05 PM 30.Aug.2016) TCDAT4 TROPICAL DEPRESSION NINE DISCUSSION NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092016 400 PM CDT TUE AUG 30 2016 The system has still not become better organized on satellite imagery, with limited evidence of banding features. There is an apparent mid-level center of circulation located south of the low-level center. The highest flight-level wind reported by a NOAA Hurricane Hunter aircraft was 34 kt and the highest SFMR-observed surface winds were 30 kt, which continues to be used for the advisory intensity. There is some evidence of increasing upper-level outflow to the north. The latest intensity guidance is a little more aggressive than before, with a little less shear forecast over the northern Gulf coast region. The official intensity forecast has been increased slightly in comparison to the previous one, and is a little below the latest model consensus. Given that a couple of the models show the system becoming a hurricane, and the 48-hour forecast point implies tropical-storm-force winds near the coast, it is prudent to issue a hurricane watch for a portion of the northeast Gulf of Mexico coast at this time. Fixes from the NOAA aircraft show that the initial motion is northwestward, or 320/4 kt. The global models continue to show a mid-tropospheric trough developing over the southeastern United States during the next couple of days. This should cause the tropical cyclone to turn toward the north and north-northeast in 24-48 hours. The dynamical track guidance models have shifted a bit to the west compared to their earlier runs, as has the multi-model consensus. Therefore the official track forecast is also west of the previous one. 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 30/2100Z 24.4N 87.3W 30 KT 35 MPH 12H 31/0600Z 24.9N 87.5W 35 KT 40 MPH 24H 31/1800Z 26.0N 87.0W 40 KT 45 MPH 36H 01/0600Z 27.5N 86.0W 45 KT 50 MPH 48H 01/1800Z 29.0N 84.8W 55 KT 65 MPH 72H 02/1800Z 32.9N 79.2W 60 KT 70 MPH 96H 03/1800Z 36.5N 71.0W 60 KT 70 MPH 120H 04/1800Z 39.0N 68.0W 60 KT 70 MPH...POST-TROP/EXTRATROP $$ Forecaster Pasch |