Bonnie (2016)

A low-pressure area that formed northeast of the central Bahamas on 27 May 2016 became a tropical depression that evening and then Tropical Storm Bonnie on 28 May while well south-southeast of Charleston, South Carolina. Bonnie reached its initial peak strength on 28–29 May, weakened under wind shear, made a slow loop over coastal South Carolina, became post-tropical on 30 May, then regenerated to a tropical cyclone near the North Carolina coast on 2 June. The system moved eastward off the U.S. coast, regained tropical-storm strength on 3 June, and weakened to a remnant low on 5 June before dissipating south-southwest of the Azores on 9 June.

Bonnie made landfall on 29 May at about 1230 UTC on the Isle of Palms, near Charleston, South Carolina. At landfall the cyclone was a tropical depression with maximum sustained winds of about 30 kt (35 mph). Earlier and later coastal passes brought the center close to Cape Hatteras and areas off the North Carolina coast during its brief re-strengthening on 2–3 June, but no additional U.S. landfalls at tropical-storm strength were recorded.

The storm’s maximum analyzed intensity was 40 kt (about 46 mph) with a minimum central pressure near 1006–1008 mb around 28–29 May, corresponding to a moderate tropical storm (below hurricane strength). The 40-kt peak is based on an SFMR flight measurement at 0124 UTC 29 May; an earlier higher SFMR value was discounted due to rain contamination.

Storm surge and coastal water levels were modest. The highest observed storm surge was 1.80 ft above normal at Oyster Landing, South Carolina; the largest storm tide reported was 3.95 ft NAVD88 at Fort Pulaski, Georgia. Charleston reported a storm tide of 3.36 ft and Fernandina Beach, Florida reported 3.30 ft. Rainfall was heavier: much of central and southern South Carolina and adjacent eastern Georgia received 4–10 inches, with a maximum of 10.36 inches near Ridgeland in Jasper County, South Carolina. Coastal North Carolina saw widespread 3–5 inches, with localized totals over 10 inches near Cape Hatteras (13.95 inches at Billy Mitchell Airport in Frisco).

There was one confirmed fatality associated with Bonnie: a drowning in the surf at Carolina Beach, North Carolina, on 29 May. Several rescues were reported at Wrightsville Beach, Carolina Beach, and Myrtle Beach due to strong rip currents. Flooding from heavy rain caused notable local impacts in South Carolina and Georgia — Jasper County reported extensive flooding that closed portions of I‑95 and U.S. 17 and a media estimate of about $640,000 in damage in Ridgeland; other road flooding occurred in Dorchester, Charleston, Hampton Counties (SC) and Bulloch County (GA).

Noteworthy items: Bonnie formed from a cutoff upper-level low rather than a typical tropical wave, and it briefly lost and then regained tropical status — the re-generation on 2 June was not anticipated in advance. Forecast track and intensity errors for Bonnie were generally below or near recent averages; official track forecasts performed well compared with guidance, and intensity forecasts were better than recent mean errors at most lead times.