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#943783 (Received by flhurricane at: 10:54 PM 09.Oct.2018) TCDAT5 Tropical Storm Nadine Discussion Number 4 NWS National Hurricane Center Miami FL AL152018 1100 PM AST Tue Oct 09 2018 Deep convection has been increasing in the eastern semicircle of Nadine, with the center close to the western edge of large convective band. Overall, the satellite presentation has improved in the past several hours, although the outflow is limited west of the center. While subjective estimates are unchanged from the last advisory, microwave-based estimates suggest Nadine is somewhat stronger, so the initial wind speed is set to 40 kt. Light or moderate shear is anticipated during the next day or so, along with sufficiently warm waters, which should promote strengthening. However, Nadine should encounter a large upper trough after that time, which will likely cause weakening to begin on Thursday. Later on, cooler SSTs and strong shear are expected to cause Nadine to degenerate into a trough of low pressure by the weekend. The most significant change is that the model guidance is notably higher than the last cycle, with a few models even making Nadine a hurricane eventually. That seems unlikely given the strength of the forecast shear, but the forecast is nudged higher than the previous one and the model consensus. Nadine continues to turn rightward and is now moving northwestward at about 7 kt. This general course is forecast for the next couple of days due to steering from a mid-level ridge near the Cabo Verde Islands. After that time, a west-northwestward or westward turn is expected as Nadine becomes a shallow system and dissipates. The model spread is still fairly wide, with the stronger guidance generally on the eastern side of the model envelope, and the weaker guidance on the western side. There is definitely a slight trend to the northeast with the latest model guidance, and since we are expecting a stronger system, the official forecast is adjusted in that direction, but not nearly as far to the right as most of the GFS-based guidance. FORECAST POSITIONS AND MAX WINDS INIT 10/0300Z 11.6N 31.0W 40 KT 45 MPH 12H 10/1200Z 12.3N 31.7W 45 KT 50 MPH 24H 11/0000Z 13.4N 32.7W 50 KT 60 MPH 36H 11/1200Z 14.8N 33.7W 45 KT 50 MPH 48H 12/0000Z 16.0N 35.0W 35 KT 40 MPH 72H 13/0000Z 17.5N 38.0W 25 KT 30 MPH 96H 14/0000Z...DISSIPATED $$ Forecaster Blake |