ZCZC MIATCDAT3 ALL TTAA00 KNHC DDHHMM Hurricane Lee Discussion Number 21 NWS National Hurricane Center Miami FL AL132023 1100 AM AST Sun Sep 10 2023 Earlier SSMIS and GMI microwave overpasses along with reports from a NOAA Hurricane Hunter aircraft indicate that Lee has a larger banded-type eye as compared to yesterday. The ragged eye has become apparent in visible and infrared satellite images within the past hour or so. The NOAA aircraft has measured a peak 700-mb flight-level wind of 106 kt and SFMR winds of 95 kt, and the minimum pressure has been oscillating in the 956-958 mb range during the flight. Based on these data, and the recent improvement in structure, the initial intensity has been raised to 95 kt. The vertical wind shear over Lee appears to have relaxed some since yesterday as there has been an expansion of the upper-level outflow over the southern and southwestern portions of the storm. Most of the guidance suggests that the shear will decrease more over the next couple of days, allowing Lee to re-strengthen. The expected slow motion of the hurricane could cause some upwelling, especially in the 2-3 day time period when Lee is forecast to be moving at only around 5 kt. The NHC wind speed forecast calls for steady restrengthening during the next 24-48 hours, then shows some gradual weakening after that time due to the potential for upwelling. Later in the forecast period, increasing southwesterly shear is likely to cause additional weakening, however Lee is forecast to remain a strong hurricane through most of this week. Recent aircraft center fixes show that the hurricane is beginning to slow down. The initial motion is now west-northwest or 300 degrees at 7 kt. A high pressure ridge to the northwest of Lee is forecast to build southwestward during the next couple of days, further slowing Lee's progress. By midweek, a mid-latitude trough moving into the northeastern United States is expected to weaken the western extent of the ridge, allowing Lee to turn northward. There is still significant uncertainty in the global model guidance regarding the forward speed of Lee later in the forecast period. The NHC track forecast continues to lie between the faster GFS and slower ECMWF, close to the various consensus models. KEY MESSAGES: 1. Lee's core is expected to pass well north of the northern Leeward Islands, the Virgin Islands, and Puerto Rico during the next couple of days. 2. Dangerous surf and life-threatening rip currents are affecting portions of the northern Leeward Islands, the British and U.S. Virgin Islands, Puerto Rico, Hispaniola, the Turks and Caicos Islands, the Bahamas, and Bermuda. 3. It remains too soon to know what level of impacts, if any, Lee might have along the U.S. East Coast, Atlantic Canada, or Bermuda late next 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 beginning later today and continuing through the 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 10/1500Z 21.6N 61.0W 95 KT 110 MPH 12H 11/0000Z 22.3N 62.1W 105 KT 120 MPH 24H 11/1200Z 23.0N 63.3W 110 KT 125 MPH 36H 12/0000Z 23.4N 64.5W 115 KT 130 MPH 48H 12/1200Z 23.8N 65.6W 115 KT 130 MPH 60H 13/0000Z 24.2N 66.5W 110 KT 125 MPH 72H 13/1200Z 24.7N 67.2W 105 KT 120 MPH 96H 14/1200Z 27.3N 67.9W 95 KT 110 MPH 120H 15/1200Z 31.3N 67.7W 80 KT 90 MPH $$ Forecaster Brown NNNN