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| #903326 (Received by flhurricane at: 11:01 AM 16.Sep.2017) TCDAT5 Potential Tropical Cyclone Fifteen Discussion Number 1 NWS National Hurricane Center Miami FL AL152017 1100 AM AST Sat Sep 16 2017 Satellite images indicate that the area of low pressure located several hundred miles east of the Lesser Antilles has become better organized with curved banding features now better established. Since there is still no indication of a well-defined center and because tropical storm watches have been issued for portions of the Leeward Islands, NHC has initiated advisories on this system as a potential tropical cyclone. The initial wind speed is estimated to be 30 kt based on a blend of the Dvorak classifications from TAFB and SAB. The initial motion estimate is 280/19, but this is uncertain due to the lack of a clear center. A slower west-northwestward motion is expected during the next several days as a mid-level ridge to the north of the system weakens but remains nearly stationary. The NHC track forecast takes the system across the Leeward Islands in a few days and then near the Virgin Islands and Puerto Rico by the end of the forecast period. It should be noted that confidence in the track and forward speed of this system is low due to the spread in the models and the current lack of a well-defined center. The disturbance is expected to be in environmental conditions conducive for strengthening during the next several days as the shear is expected to be 10 kt or less while the cyclone moves over warm 29 deg C SSTs. These conditions should allow for at least steady strengthening, and the models unanimously show that trend. The NHC intensity forecast is conservative for now, but does show the system becoming a tropical storm later today and a hurricane by the time it reaches the Leeward Islands. KEY MESSAGES: 1. The disturbance is expected to intensify and will likely bring tropical storm and hurricane conditions as well as flooding rainfall to portions of the Lesser Antilles early next week. These conditions could also spread into the Virgin Islands and Puerto Rico by mid week. Interests in these areas should monitor the progress of this system and follow any advice given by local officials. FORECAST POSITIONS AND MAX WINDS INIT 16/1500Z 12.2N 50.5W 30 KT 35 MPH...POTENTIAL TROP CYCLONE 12H 17/0000Z 12.8N 52.8W 35 KT 40 MPH...TROPICAL STORM 24H 17/1200Z 13.6N 55.1W 40 KT 45 MPH 36H 18/0000Z 14.3N 56.9W 50 KT 60 MPH 48H 18/1200Z 15.0N 58.6W 60 KT 70 MPH 72H 19/1200Z 16.3N 61.3W 75 KT 85 MPH 96H 20/1200Z 17.6N 64.0W 80 KT 90 MPH 120H 21/1200Z 18.7N 67.3W 80 KT 90 MPH $$ Forecaster Cangialosi |