ZCZC MIATCDAT3 ALL TTAA00 KNHC DDHHMM Tropical Storm Rene Discussion Number 20 NWS National Hurricane Center Miami FL AL182020 1100 PM AST Fri Sep 11 2020 Deep convection has persisted near the center of Rene since this afternoon and a couple of earlier microwave overpasses suggest that there has been an increase in banding over the southwestern portion of the circulation. Despite what appears to be an increase in organization, recent ASCAT data indicated that this has not translated into an increase in intensity. The scatterometer data still supports an initial wind speed of 35 kt. Environmental conditions are forecast to generally be conducive for some strengthening over the next 12-24 hours, however with Rene continuing to struggle to intensify the NHC wind speed prediction has again been reduced during the that time. By 36-48 hours, Rene is expected to move beneath an area of strong upper-level west-northwesterly flow, and this increase in shear is expected to cause weakening. The ECMWF and GFS models significantly weaken Rene after 72 hours, with the ECMWF showing dissipation before the end of the forecast period. For now, the official forecast calls for Rene to weaken to a tropical depression by day 4, but it is possible that the system will degenerate into a trough of low pressure before day 5. Rene is moving west-northwestward or 295/12 kt. The cyclone should turn toward the northwest as it moves around the western portion of a mid-level ridge over the eastern Atlantic. In a couple of days, a mid-level high is predicted to build to the northwest of Rene, which should cause the cyclone to slow down and turn westward, and then west-southwestward later in the forecast period. The track guidance is in fairly good agreement and the various consensus aids remained close to the previous official forecast. Therefore, the new NHC forecast is essentially an update of the previous advisory. FORECAST POSITIONS AND MAX WINDS INIT 12/0300Z 21.4N 42.4W 35 KT 40 MPH 12H 12/1200Z 22.4N 44.0W 35 KT 40 MPH 24H 13/0000Z 24.1N 45.8W 40 KT 45 MPH 36H 13/1200Z 25.7N 47.0W 40 KT 45 MPH 48H 14/0000Z 26.8N 47.6W 40 KT 45 MPH 60H 14/1200Z 27.1N 47.8W 35 KT 40 MPH 72H 15/0000Z 26.8N 48.4W 35 KT 40 MPH 96H 16/0000Z 25.9N 50.9W 30 KT 35 MPH 120H 17/0000Z 24.8N 54.0W 30 KT 35 MPH $$ Forecaster Brown NNNN