Lee — 2023

Hurricane Lee formed from a tropical wave that moved off the west coast of Africa on 1 September 2023. A surface low became well defined and the system became a tropical depression on 5 September about midway between the Windward Islands and Africa; it became a tropical storm later that day. Lee strengthened rapidly, becoming a hurricane within 24 hours and a major hurricane within 48 hours. It explosively intensified to a Category 5 hurricane with peak winds on 8 September while several hundred miles east of the Leeward Islands, then weakened, re-intensified to a secondary peak, grew very large, turned north, became post-tropical during extratropical transition, and tracked northward into Atlantic Canada before dissipating on 19 September. Lee did not make hurricane landfall in the Caribbean or the U.S. as a tropical hurricane. Its only landfall was as a powerful post-tropical (extratropical) cyclone on Long Island in southwestern Nova Scotia around 2000 UTC 16 September, with maximum sustained winds near 55 kt (about 63 mph). After that landfall the system moved across the Bay of Fundy, New Brunswick, Prince Edward Island and northern Newfoundland on 16–17 September as it gradually weakened. The storm’s maximum intensity was estimated at 145 kt (167 mph) with a minimum central pressure of 926 mb at 0600 UTC 8 September, making Lee a Category 5 hurricane at peak intensity. That peak is based on aircraft flight-level winds and corrected surface estimates and supported by high SFMR values and dropsonde data. Storm surge and rainfall impacts were modest for the U.S. but more notable in eastern Canada. In Nova Scotia coastal water levels of 3 to 5 ft above mean water level were reported, including a Halifax tide gauge measurement of 4.8 ft above mean water level. Along the U.S. New England coast, measured inundation above Mean Higher High Water included 1.62 ft at Chatham, Massachusetts; 1.58 ft at Provincetown; and 1.43 ft on Nantucket. Rainfall totals peaked at 6.50 inches near Steuben, Maine, and 5.56 inches near Hanwell, New Brunswick, producing flash flooding and road closures in eastern Maine and parts of New Brunswick. There were four direct deaths attributed to Lee: two drownings from rip currents (one in Fernandina Beach, Florida; one in Poza del Obispo, Puerto Rico), one drowning when a boat capsized near Manasquan Inlet, New Jersey, and one fatal tree-related crash near Searsport, Maine. Injuries and localized damage included downed trees and power lines, coastal roadway damage and destroyed boardwalk sections in parts of Nova Scotia, and power outages peaking around 200,000 customers in the U.S. and similar numbers in Nova Scotia. No tornadoes were reported. AON estimated total damage at about $50 million, though no official consolidated damage estimate was provided. Noteworthy aspects include Lee’s explosive intensification to Category 5 over the open Atlantic and its subsequent growth into a very large hurricane with hurricane-force winds extending up to about 110 nautical miles from the center at one point. Forecast track accuracy was very good (errors well below recent averages through 72–120 hours), though intensity forecasts had larger errors than typical, with forecasters correctly anticipating rapid intensification and later extratropical transition but with timing and magnitude challenges as Lee evolved.