ZCZC MIATCDAT3 ALL TTAA00 KNHC DDHHMM Hurricane Lee Discussion Number 24 NWS National Hurricane Center Miami FL AL132023 500 AM AST Mon Sep 11 2023 The eye of the hurricane became more ragged and less distinct overnight, but in recent satellite images there appears to be some warming near the center once again. A 0619 UTC AMSR2 microwave pass showed the eyewall was open to the south, but a new convective burst is currently wrapping around the western portion of the eyewall. The latest objective and subjective satellite intensity estimates have leveled off due to recent fluctuations in the structure of the hurricane. The initial intensity is held at 105 kt, which is consistent with the earlier aircraft data. This intensity also lies between the latest subjective Dvorak data-T and current intensity estimates from TAFB and SAB that range from 90-115 kt. Lee is moving slowly northwestward (310/6 kt) while being steered by a mid-level ridge over the western and central subtropical Atlantic. A slow west-northwestward to northwestward motion should continue for the next day or two before a deep-layer trough moves across the eastern U.S. and begins eroding the steering ridge by midweek. This should allow Lee to gradually turn northward by 72 h. The guidance is in good agreement through midweek with little cross-track spread noted, and the updated NHC forecast lies just a bit right of the previous prediction. This takes the core of Lee to the west of Bermuda, although its expanding tropical-storm-force wind field could bring some impacts to the island during the latter part of the week. On days 4-5, Lee should continue moving generally northward with a ridge positioned to its east. For this portion of the forecast, the NHC prediction was adjusted slightly west, keeping the forecast track near the center of the guidance envelope and in best agreement with the TVCA simple consensus aid. In the near term, very warm SSTs of 29-30C and weaker deep-layer shear appear conducive for at least modest strengthening of the hurricane, although inner-core structural changes and bouts of dry air entrainment could cause some short-term intensity fluctuations. Most of the intensity models support an intensity peak within the next day or so, and this is reflected in the latest NHC forecast. Thereafter, the large wind field and slow motion of Lee could cause upwelling of cooler waters. In addition, the hurricane is likely to encounter increasing southwesterly shear from the aforementioned trough later in the period, as well as the cool wake left behind by recent western Atlantic hurricanes (Idalia and Franklin). All of these factors point toward weakening later this week, and the NHC forecast follows the IVCN and HCCA trends with gradual weakening beyond 48 h. Although the peak winds are forecast to decrease, the outer wind field is expected to expand as the hurricane interacts with the upper trough and gains latitude over the western Atlantic, with strong winds extending far from the center of the cyclone. KEY MESSAGES: 1. Dangerous surf and life-threatening rip currents will affect portions of the northern Leeward Islands, the Virgin Islands, Puerto Rico, Hispaniola, the Turks and Caicos Islands, the Bahamas, and Bermuda through much of the week. 2. Lee could bring wind, rainfall, and high surf impacts to Bermuda later this week. Although it is too soon to determine the specific timing and level of those impacts, interests on Bermuda should monitor the latest forecasts for Lee. 3. It remains too soon to know what level of impacts, if any, Lee might have along the U.S. East Coast and Atlantic Canada late this week, especially since the hurricane is expected to slow down considerably over the southwestern Atlantic. Regardless, dangerous surf and rip currents are expected along most of the U.S. East Coast this week as Lee grows in size. Users should continue to monitor updates to the forecast of Lee during the next several days. FORECAST POSITIONS AND MAX WINDS INIT 11/0900Z 23.1N 62.6W 105 KT 120 MPH 12H 11/1800Z 23.5N 63.5W 115 KT 130 MPH 24H 12/0600Z 24.0N 64.8W 115 KT 130 MPH 36H 12/1800Z 24.5N 65.8W 115 KT 130 MPH 48H 13/0600Z 25.1N 66.7W 110 KT 125 MPH 60H 13/1800Z 26.1N 67.3W 100 KT 115 MPH 72H 14/0600Z 27.6N 67.6W 95 KT 110 MPH 96H 15/0600Z 31.8N 67.6W 85 KT 100 MPH 120H 16/0600Z 37.5N 67.0W 70 KT 80 MPH $$ Forecaster Reinhart NNNN