Lee (2017)

Hurricane Lee formed from a tropical wave off the coast of West Africa and was first classified as a tropical depression on 14 September 2017 about 265 nautical miles south of the Cabo Verde Islands. The system weakened and appeared to dissipate over the central Atlantic, then regenerated as a tropical cyclone on 22 September about 825–900 nmi east-southeast of Bermuda. After regeneration Lee wandered under a subtropical ridge, performed a sharp cusp in its track, drifted south-southwestward, then turned west and later northwest before recurving northeastward. The storm existed as a tropical cyclone from 14–30 September 2017 (including the brief dissipation and reformation period).

Lee did not make any landfalls. It remained over the open Atlantic for its entire life, recurving well east of Bermuda and finally becoming post-tropical about 400 nautical miles northwest of the Azores on 30 September before opening into a trough later that day.

The hurricane’s peak intensity was 100 knots (115 mph) with a minimum central pressure of 963–962 mb at its strongest on 27 September. At peak it was a Category 3 hurricane on the Saffir–Simpson scale; it maintained that intensity for roughly 12 hours before gradual weakening began.

There were no storm surge or inland rainfall impacts reported from Lee because it stayed over the open ocean and produced no tropical-storm-force winds at land stations or ships. Consequently, no storm-surge heights or land rainfall totals were recorded in association with Lee.

No deaths or damage were attributed to Hurricane Lee. The cyclone’s impacts were limited to the ocean, and there were no land-based watches or warnings issued.

Noteworthy aspects include Lee’s unusual life cycle — an initial weakening and apparent dissipation followed by regeneration of the mid-level circulation into a new surface cyclone — and its very small size, which contributed to difficulties in early genesis forecasts and higher-than-average track forecast errors around the time of regeneration. The European model (ECMWF) performed particularly well at anticipating Lee’s later left turn, while many global models struggled with its track and intensity.