000 WTNT44 KNHC 171440 TCDAT4 Potential Tropical Cyclone Nine Discussion Number 1 NWS National Hurricane Center Miami FL AL092017 1100 AM AST Thu Aug 17 2017 Satellite imagery, including experimental 1-minute data from GOES-16, indicates that the circulation of the low pressure area east of the Lesser Antilles is becoming better defined, and that a cluster of strong convection has formed just west of the center. Based on this and the potential for the system to become a tropical storm before reaching the Lesser Antilles, advisories are being initiated as a potential tropical cyclone. An Air Force Reserve Hurricane Hunter aircraft is scheduled to investigate the system this afternoon, and it is likely the aircraft will find a tropical cyclone has formed. The initial motion is 270/15. A deep-layer ridge to the north of the system should steer it generally just north of due west through the forecast period, with this motion expected to bring the system through the Lesser Antilles and into the eastern Caribbean Sea in 24-36 h, into the central Caribbean by 72 h, and to the western Caribbean by 96-120 h. The forecast track lies near the center of the tightly clustered guidance envelope and lies near the various consensus models. The system is in an area of moderate easterly vertical shear, and the large-scale models suggest that light/moderate shear should continue through the forecast period. This seems favorable for strengthening, and the SHIPS and LGEM models show slow, but steady, intensification. However, the GFS and ECMWF models forecast the system to degenerate to an easterly wave over the central Caribbean Sea, possibly due to dry air entrainment. The intensity forecast follows the trend of the SHIPS/LGEM models, but it respects the GFS/ECMWF forecasts by being on the low side of the intensity guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 17/1500Z 13.1N 54.1W 30 KT 35 MPH...POTENTIAL TROP CYCLONE 12H 18/0000Z 13.1N 56.4W 30 KT 35 MPH...TROPICAL DEPRESSION 24H 18/1200Z 13.2N 59.8W 35 KT 40 MPH 36H 19/0000Z 13.5N 63.2W 40 KT 45 MPH 48H 19/1200Z 13.9N 66.7W 45 KT 50 MPH 72H 20/1200Z 14.5N 74.5W 55 KT 65 MPH 96H 21/1200Z 15.5N 82.0W 65 KT 75 MPH 120H 22/1200Z 17.0N 87.5W 65 KT 75 MPH $$ Forecaster Beven