ZCZC MIATCDAT3 ALL TTAA00 KNHC DDHHMM Hurricane Lee Discussion Number 20 NWS National Hurricane Center Miami FL AL132023 500 AM AST Sun Sep 10 2023 Lee still seems to be feeling the effects of moderate southwesterly wind shear, dry air, and internal structural changes. An Air Force Reserve Hurricane Hunter aircraft reported earlier that the eyewall had deteriorated to only a few curved bands. Geostationary satellite imagery and earlier dropsonde data suggested that some dry air is wrapping around the eastern and northern portion of the circulation. The aircraft found maximum surface winds of 86 kt, and a minimum central pressure of 957 mb. The initial intensity is held at a possibly generous 90 kt based on these data. The hurricane is moving to the west-northwest at 8 kt on the southern side of a mid-level high pressure system. The high is expected to build west-southwestward over the next day or so, which should slow Lee's forward speed. By mid-week, a mid-latitude trough is forecast to weaken the ridge and gradually turn Lee northward. Global models differ significantly in the forward speed of the hurricane, especially by the end of the forecast period. The official track forecast is similar to the previous advisory and generally favors the slower guidance, lying between the HCCA and TCVN consensus aid. A satellite analysis product from UW/CIMSS indicates that there is a gradient of moderate-to-strong southwesterly shear over Lee. This product suggests that the GFS, which is analyzing lower values of shear, may not be accurately representing the environment near the hurricane. Still, most of the model guidance predicts the shear should relax, allowing Lee to strengthen in the next 36-48 h. The latest intensity forecast has been lowered slightly from the previous advisory, now showing a peak intensity of 115 kt. Beyond day 2, environmental and oceanic conditions are expected to become less conducive and cause Lee to gradually weaken. The NHC track forecast remains in the middle of guidance envelop, near the various consensus aids. KEY MESSAGES: 1. Lee's core is expected to move well north of the northern Leeward Islands, the Virgin Islands, and Puerto Rico early this week. 2. Dangerous surf and life-threatening rip currents are affecting portions of the northern Leeward Islands and Puerto Rico. These conditions are spreading westward and northward and will affect Hispaniola, the Turks and Caicos, the Bahamas, and Bermuda during the next several days. 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 soon 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 10/0900Z 21.4N 60.5W 90 KT 105 MPH 12H 10/1800Z 22.0N 61.5W 95 KT 110 MPH 24H 11/0600Z 22.8N 62.8W 105 KT 120 MPH 36H 11/1800Z 23.3N 64.0W 115 KT 130 MPH 48H 12/0600Z 23.6N 65.2W 115 KT 130 MPH 60H 12/1800Z 23.9N 66.1W 110 KT 125 MPH 72H 13/0600Z 24.5N 66.9W 105 KT 120 MPH 96H 14/0600Z 26.5N 68.0W 95 KT 110 MPH 120H 15/0600Z 30.2N 68.0W 80 KT 90 MPH $$ Forecaster Bucci NNNN