ZCZC MIATCDAT3 ALL TTAA00 KNHC DDHHMM Tropical Storm Lee Discussion Number 2 NWS National Hurricane Center Miami FL AL132023 500 PM AST Tue Sep 05 2023 1-min GOES-16 satellite imagery shows that the tropical cyclone has been improving in structure throughout the day, with additional curved banding features and a new burst of convection near the center. A late-arriving ASCAT-C pass indicated maximum winds supporting 35 kt, and the satellite presentation has notably improved since that time. The initial wind speed is set to 40 kt to match the satellite trends. Lee is moving west-northwestward at about 14 kt. There are no significant changes to the NHC track forecast with a mid-level ridge over the central Atlantic likely to persist to the north of the storm. This ridge should provide a steady steering current, with a general west-northwestward course expected through the weekend with some reduction in forward speed. The spread in the model guidance remains low, and the official forecast is adjusted a bit to the northeast closer to the model consensus. Still, it is too early to determine exactly how close this system will be to the Leeward Islands given the average track forecast error at those time ranges. It is becoming a question of when and not if rapid intensification (RI) occurs with Lee. A well-defined outflow pattern has developed over the circulation, and there are some hints on a recent SSMI/S microwave pass that parts of an inner core are forming. There's still some notable northeasterly shear that could keep Lee in check for the next day or two, so the NHC intensity forecast will stay at a more moderate rate of intensification during that time. All of the models decrease the shear by Friday, so RI is explicitly forecast at that time frame while Lee is moving over extremely warm waters. The new forecast is adjusted higher than the last advisory, near the model consensus, but there's a notable contingent of guidance higher than this forecast. There is increasing confidence on Lee becoming a very powerful hurricane by this weekend. KEY MESSAGES: 1. Lee is forecast to become a major hurricane by this weekend and could bring impacts to the Leeward Islands by that time. While it is too soon to determine the location and magnitude of these possible impacts, interests in this area should monitor the progress of Lee and further updates to the forecast. FORECAST POSITIONS AND MAX WINDS INIT 05/2100Z 13.2N 41.8W 40 KT 45 MPH 12H 06/0600Z 13.7N 43.7W 50 KT 60 MPH 24H 06/1800Z 14.4N 46.2W 60 KT 70 MPH 36H 07/0600Z 15.2N 48.5W 70 KT 80 MPH 48H 07/1800Z 16.2N 51.0W 80 KT 90 MPH 60H 08/0600Z 17.2N 53.6W 90 KT 105 MPH 72H 08/1800Z 18.3N 56.0W 110 KT 125 MPH 96H 09/1800Z 20.4N 60.5W 120 KT 140 MPH 120H 10/1800Z 22.2N 64.3W 125 KT 145 MPH $$ Forecaster Blake NNNN