ZCZC MIATCDAT3 ALL TTAA00 KNHC DDHHMM Tropical Storm Lee Discussion Number 3 NWS National Hurricane Center Miami FL AL132023 1100 PM AST Tue Sep 05 2023 The satellite structure of Lee has continued to improve tonight. A prominent curved band of deep convection wraps around the western and southern portions of the circulation. Recent SSMIS and GMI microwave images reveal deep convection is occurring near the center, though it is slightly displaced by some northeasterly shear. There are also hints of a formative inner core trying to take shape, all of which suggest that Lee is strengthening. The initial intensity is raised to 45 kt for this advisory, in best agreement with a T3.0 Dvorak classification from TAFB. Lee continues to move west-northwestward at about 15 kt. A mid-level ridge over the central subtropical Atlantic is expected to be the primary steering mechanism for the next several days, with Lee forecast to continue on a west-northwestward heading across the central tropical Atlantic through the forecast period. Once again, the track guidance is in fairly good agreement on this scenario. Overall, the latest NHC track forecast is very similar to the previous prediction, with only minor adjustments that keep our forecast between the simple and corrected consensus aids. Users are reminded that the average NHC forecast track errors are around 125 and 175 n mi on days 4 and 5, respectively. Thus, it is too soon to determine exactly how close this system will be to the Leeward Islands by the weekend. The atmospheric and oceanic conditions appear extremely favorable for rapid intensification (RI) during the next several days, particularly once the northeasterly shear over Lee subsides in a day or so. The forecast track of Lee brings the cyclone over anomalously warm SSTs during the next several days, with generally low shear and favorable upper diffluence to support significant strengthening. The updated NHC intensity forecast has been adjusted slightly higher than the previous one, toward the latest IVCN and HCCA aids. This forecast calls for Lee to become a hurricane in 24 h and a major hurricane by 60 h, with continued intensification thereafter. It is noted that the regional hurricane models depict even stronger solutions, so future adjustments could be necessary. Regardless, Lee bears close monitoring as there is high confidence it will become a very powerful hurricane by this weekend. KEY MESSAGES: 1. Lee is forecast to become a major hurricane by late this week and could bring impacts to the Leeward Islands this weekend. 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 06/0300Z 13.5N 43.0W 45 KT 50 MPH 12H 06/1200Z 14.1N 44.9W 55 KT 65 MPH 24H 07/0000Z 14.9N 47.2W 65 KT 75 MPH 36H 07/1200Z 15.7N 49.7W 75 KT 85 MPH 48H 08/0000Z 16.6N 52.2W 90 KT 105 MPH 60H 08/1200Z 17.8N 54.8W 105 KT 120 MPH 72H 09/0000Z 18.9N 57.1W 115 KT 130 MPH 96H 10/0000Z 20.8N 61.5W 125 KT 145 MPH 120H 11/0000Z 22.5N 65.0W 130 KT 150 MPH $$ Forecaster Reinhart NNNN