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#796759 (Received by flhurricane at: 4:37 AM 20.Aug.2015) TCDAT4 TROPICAL STORM DANNY DISCUSSION NUMBER 8 NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015 500 AM AST THU AUG 20 2015 The cloud pattern resembles a tropical cyclone much more than 12 hours ago. An irregular Central Dense Overcast(CDO) has formed, and the center continues to be remarkably well depicted in microwave images. In fact, it has a much better structure than earlier. The outflow remains fair. Dvorak numbers suggest that the winds are still 45 kt. Danny has the opportunity to strengthen a little during the next 2 to 3 days while embedded within very light shear. Models in general, however, no longer intensify the cyclone as much as they did in earlier runs and, in fact, the GFS and ECMWF weaken Danny to a tropical wave in the eastern Caribbean Sea. The NHC forecast calls for some intensification for the next 3 days, and calls for slight weakening as Danny encounters high shear and dry air in the eastern Caribbean Sea. Microwave fixes indicate that Danny is moving toward the west or 280 degrees at 9 kt. A turn toward the west-northwest toward a weakness in the subtropical ridge is expected soon. After 48 hours, most of the global models forecast the subtropical ridge to expand westward, forcing Danny to turn back to the west as indicated in the NHC forecast. The multi-model consensus as well as the consensus of the GFS and the ECMWF depict the expansion of the ridge, and bring Danny to the eastern Caribbean, while the UK and the GFDL models insist on taking the cyclone north of the islands. In summary, it appears that a tropical cyclone or a perhaps a wave will be moving over the Leeward Islands between 4 and 5 days. FORECAST POSITIONS AND MAX WINDS INIT 20/0900Z 12.2N 43.7W 45 KT 50 MPH 12H 20/1800Z 12.6N 44.9W 50 KT 60 MPH 24H 21/0600Z 13.5N 46.3W 55 KT 65 MPH 36H 21/1800Z 14.3N 47.8W 60 KT 70 MPH 48H 22/0600Z 15.0N 50.0W 65 KT 75 MPH 72H 23/0600Z 15.5N 54.4W 65 KT 75 MPH 96H 24/0600Z 16.3N 60.0W 65 KT 75 MPH 120H 25/0600Z 17.0N 65.0W 50 KT 60 MPH $$ Forecaster Avila |