ZCZC MIATCDAT3 ALL TTAA00 KNHC DDHHMM Post-Tropical Cyclone Lee Discussion Number 44 NWS National Hurricane Center Miami FL AL132023 500 AM AST Sat Sep 16 2023 Lee appears to have completed its transition to a post-tropical cyclone. The cloud pattern is comma shaped, and there has been no significant central deep convection for the past 12 hours or so. The cyclone is now frontal but likely still has a warm core, indicating that it is a warm seclusion-type of extratropical cyclone. Despite this transition, it remains a potent cyclone, and the initial intensity remains 70 kt since the Air Force Reserve Hurricane Hunters measured SFMR winds as high as 66 kt about 110 n mi southwest of the center. Lee accelerated more than expected during the past 6-12 hours, and the current motion is estimated to be northward (355 degrees) at 22 kt. The aircraft fixes and recent satellite imagery indicate that the center has bent back to the west by just a bit, which was expected, likely due to interaction with a mid-level trough which moved off the U.S. Mid-Atlantic coast. A general northward motion, but at a slower forward speed, is expected today, and Lee's center is now forecast to reach western Nova Scotia around midday. The cyclone is then expected to turn toward the north-northeast and then northeast, moving across Atlantic Canada and the Gulf of St. Lawrence tonight through Sunday. Due to the recent acceleration, the new NHC track forecast is faster than, but still otherwise on top of, the previous prediction. Lee's center has moved north of the Gulf Stream, and water temperatures along the cyclone's path are down to 20 degrees Celsius and decreasing. Intensity models indicate that Lee should begin gradually weakening very soon, although the maximum winds are likely to still be at or just below hurricane strength (mainly over water) when Lee's center reaches Nova Scotia later today. The NHC intensity forecast closely follows the GFS and ECMWF solutions, and Lee is expected to continue producing gale-force winds while it moves across Atlantic Canada tonight through Sunday. KEY MESSAGES: 1. Hurricane conditions are possible across portions southern New Brunswick and Nova Scotia later today within the Hurricane Watch areas. Tropical storm conditions and coastal flooding are occurring across portions of coastal New England and Atlantic Canada, and will continue to spread northward within the Tropical Storm Warning areas. The strong winds are likely to lead to downed trees and potential power outages. 2. Heavy rainfall from Lee may produce localized urban and small stream flooding in portions of far eastern Massachusetts, eastern Maine, New Brunswick, and western Nova Scotia today. 3. Dangerous surf and life-threatening rip currents will continue to affect the U.S. East Coast, Atlantic Canada, Bermuda, the Bahamas, the Turks and Caicos Islands, Hispaniola, Puerto Rico, the Virgin Islands, and the northern Leeward Islands through the weekend. FORECAST POSITIONS AND MAX WINDS INIT 16/0900Z 41.8N 66.0W 70 KT 80 MPH...POST-TROP/EXTRATROP 12H 16/1800Z 44.1N 65.6W 55 KT 65 MPH...POST-TROP/EXTRATROP 24H 17/0600Z 46.8N 64.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 36H 17/1800Z 49.5N 60.1W 40 KT 45 MPH...POST-TROP/EXTRATROP 48H 18/0600Z 52.3N 53.4W 40 KT 45 MPH...POST-TROP/EXTRATROP 60H 18/1800Z...ABSORBED BY ANOTHER LOW $$ Forecaster Berg NNNN