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| #1152066 (Received by flhurricane at: 4:48 PM 09.Sep.2023) TCDAT3 Hurricane Lee Discussion Number 18 NWS National Hurricane Center Miami FL AL132023 500 PM AST Sat Sep 09 2023 Lee`s satellite presentation has changed little today. The center is embedded within an area of cloud tops below -75C, and the Air Force Reserve reconnaissance aircraft that was in the storm earlier this afternoon continued to report that Lee has a small eye. However, the eye remains obscured in both visible and infrared satellite imagery. A blend of the flight-level and SFMR winds, as well as dropsonde data from the earlier mission, yields an intensity of around 100 kt, and the advisory intensity remains that value. Dropsonde data in the center just before 1700 UTC supported a minimum pressure of 958 mb. A NOAA P-3 aircraft is scheduled to be in the storm environment again this evening to provide additional information on the structure and strength of the hurricane. Shear analysis from UW/CIMSS indicates that there is still about 15-20 kt of southwesterly shear over Lee. The GFS continues to suggest that the shear will lessen during the next couple of days, creating a more favorable environment for Lee to strengthen. However, the ECMWF and UKMET still favor the notion that the upper-level wind pattern will not become quite as conducive for a couple of more days. Most of the intensity guidance calls for gradual restrengthening and the NHC forecast follows suit. The NHC intensity forecast is close to the consensus models, but not as high as some of the dynamical model guidance and the HFIP corrected consensus. Satellite and aircraft fixes show that Lee is moving west- northwestward at about 9 kt. There has been no change to the track forecast philosophy. A mid-level ridge to the north of Lee is foreast to shift west-southwestward during the next few days, causing Lee`s forward speed to slow considerably through early next week. By midweek, a mid-latitude trough moving across the Great Lakes region and into the eastern United States is expected to weaken the ridge and allow Lee to turn north-northwestward and northward on days 4 and 5. There is still a significant amount of spread in the deterministic guidance and global model ensembles as to exactly when and where the northward turn takes place. In fact, the GFS and ECMWF models are about 275 n mi apart at day 5, primarily due to along-track spread related to how fast Lee begins moving northward. The NHC track forecast continues to lie near the latest consensus aids, and the new track is very similar to the previous forecast. The center of Lee passed about 75 n mi south of NOAA buoy 41044 this afternoon, and that buoy has reported peak 1-minute sustained winds of 47 kt with a gust to 58 kt. That data along with a couple of earlier scatterometer overpass have shown that the tropical-storm force wind field has expanded outward over the eastern semicircle, and that has been reflected in the latest analysis and forecast. KEY MESSAGES: 1. Lee`s core is expected to move well north of the northern Leeward Islands, the Virgin Islands, and Puerto Rico this weekend and early next week. 2. Dangerous surf and life-threatening rip currents are affecting portions of the northern Leeward Islands. These conditions are spreading westward and northward and will affect Puerto Rico, 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, particularly 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 Sunday and Monday. Users should continue to monitor updates to the forecast of Lee during the next several days. FORECAST POSITIONS AND MAX WINDS INIT 09/2100Z 20.7N 59.1W 100 KT 115 MPH 12H 10/0600Z 21.4N 60.3W 105 KT 120 MPH 24H 10/1800Z 22.1N 61.6W 110 KT 125 MPH 36H 11/0600Z 22.9N 62.9W 115 KT 130 MPH 48H 11/1800Z 23.3N 64.1W 120 KT 140 MPH 60H 12/0600Z 23.6N 65.3W 120 KT 140 MPH 72H 12/1800Z 23.9N 66.3W 115 KT 130 MPH 96H 13/1800Z 25.1N 67.8W 105 KT 120 MPH 120H 14/1800Z 27.9N 68.2W 100 KT 115 MPH $$ Forecaster Brown |
