200 WTNT43 KNHC 300243 TCDAT3 Tropical Storm Leslie Discussion Number 15 NWS National Hurricane Center Miami FL AL132018 1100 PM AST Sat Sep 29 2018 The structure of Leslie consists of a large, broken outer band wrapped around the eastern semicircle of the cyclone, with little convection west of the center. ASCAT data recently showed 40-45 kt within that band, so the maximum winds will stay at 45 kt. The storm should gradually move over somewhat warmer waters within a lighter shear environment during the next few days. Thus gradual intensification is shown, similar to the model consensus. The only notable change to the previous forecast is to move up the peak intensity close to Leslie's southernmost position before it stalls. It would seem that after that time, the relatively large system would be moving close to its previous track over its self-generated cooler upwelled waters, and weaken somewhat at long range. Leslie continues to move southwestward, and its initial motion is 235/5 kt. This storm should move slowly to the southwest through Sunday, then creep southward by late Monday due to steering partially by northerly flow from a distant ridge over the western Atlantic and a nearby large mid- to upper-level trough. Eventually, a new ridge rebuilds over the east-central Atlantic east of Leslie, which causes the cyclone to move to the north at a faster pace by day 5. As you could imagine in such a complex pattern, the models aren't in good agreement on how quickly the storm ejects, and this is a pretty uncertain forecast at long range. Until some forecast scenarios become clear, the forecast will stay close to the corrected-consensus aids, resulting in mostly cosmetic changes to the last forecast. Large swells generated by Leslie when it was a strong extratropical low will affect Bermuda, the east coast of the United States, and most of the Greater and Lesser Antilles through at least the weekend. These swells could cause life-threatening surf and rip currents. FORECAST POSITIONS AND MAX WINDS INIT 30/0300Z 33.9N 52.0W 45 KT 50 MPH 12H 30/1200Z 33.4N 52.8W 45 KT 50 MPH 24H 01/0000Z 33.0N 53.4W 50 KT 60 MPH 36H 01/1200Z 32.6N 53.9W 50 KT 60 MPH 48H 02/0000Z 32.2N 54.2W 55 KT 65 MPH 72H 03/0000Z 31.0N 54.5W 65 KT 75 MPH 96H 04/0000Z 31.7N 54.2W 60 KT 70 MPH 120H 05/0000Z 34.5N 53.5W 60 KT 70 MPH $$ Forecaster Blake