494 WTNT44 KNHC 122046 TCDAT4 Potential Tropical Cyclone Nine Discussion Number 1 NWS National Hurricane Center Miami FL AL092019 500 PM EDT Thu Sep 12 2019 The disturbance in the southeastern Bahamas has not developed a closed circulation yet, but the cloud pattern is gradually becoming better organized. An Air Force plane is currently approaching the disturbance, and will give NHC more details on the structure of the system. Advisories are being initiated on this system as a Potential Tropical Cyclone to allow for the issuance of a tropical storm warning for a portion of the northwest Bahamas after consultation with the meteorological service of that country. The system is still under the influence of strong shear caused by an upper-level low in the Gulf of Mexico. As the disturbance moves away from the upper low, conditions are expected to be a little more conducive for development as indicated in the intensity forecast. With the exception of the GFS, which forecasts a vigorous trough crossing Florida into the Gulf of Mexico, the remainder of the global models develop a tropical cyclone near the northwestern Bahamas and move it as an intensifying system very close to the east coast of Florida. The NHC forecast opted for the solution of these latter models, however, it is emphasized that given the model discrepancy, both the track and intensity forecasts are highly uncertain, more than usual I would say. Key Messages: 1. The disturbance is expected to become a tropical storm and bring tropical storm force winds to portions of the northwest Bahamas within 36 hours. As a result, advisories have been initiated on Potential Tropical Cyclone Nine. Note that forecast uncertainty for these disturbances is generally larger than for tropical cyclones, especially beyond 48-72 hours. 2. The system is expected to bring tropical-storm-force winds and heavy rainfall to portions of the northwest Bahamas on Friday and Saturday. Significant storm surge is not expected in the northwest Bahamas from this system. Residents there should follow any advice given by local officials. 3. The system could bring tropical-storm-force winds and rainfall to portions of the Florida east coast over the weekend. Residents there should monitor the progress of this system. FORECAST POSITIONS AND MAX WINDS INIT 12/2100Z 23.7N 74.8W 25 KT 30 MPH...POTENTIAL TROP CYCLONE 12H 13/0600Z 24.5N 76.0W 25 KT 30 MPH 24H 13/1800Z 25.5N 77.2W 30 KT 35 MPH...TROPICAL CYCLONE 36H 14/0600Z 26.5N 78.9W 40 KT 45 MPH 48H 14/1800Z 27.5N 80.2W 45 KT 50 MPH 72H 15/1800Z 30.0N 82.0W 30 KT 35 MPH...INLAND 96H 16/1800Z 31.0N 82.0W 25 KT 30 MPH...INLAND 120H 17/1800Z 31.5N 80.0W 30 KT 35 MPH...OVER WATER $$ Forecaster Avila