Tropical Storm Bonnie was a weak but persistent tropical cyclone that brought heavy rains to the Southeastern United States in May 2016. The second storm of the season, Bonnie formed from an area of low pressure northeast of the Bahamas on May 27, a few days before the official hurricane season began on June 1. Moving steadily west-northwestwards, Bonnie intensified into a tropical storm on May 28 and attained peak winds six hours later. However, due to hostile environmental conditions, Bonnie weakened to a depression hours before making landfall just east of Charleston, South Carolina, on May 29. Steering currents collapsed afterwards, causing the storm to meander over South Carolina for two days. The storm weakened further into a post-tropical cyclone on May 31, before emerging off the coast while moving generally east-northeastwards. On June 2, Bonnie regenerated into a tropical depression just offshore North Carolina as conditions became slightly more favorable. The next day, despite increasing wind shear and cooling sea surface temperatures, Bonnie reintensified into a tropical storm and reached its peak intensity. The storm hung on to tropical storm strength for another day, before weakening into a depression late on June 4 and became post-tropical early the next day.
Lingering over South Carolina for a few days, Bonnie brought heavy rains and widespread floods to the Southeastern United States. Rainfall totals hit in much of South Carolina, and exceeded in some areas. Flooding resulted in the closure of the southbound lanes of Interstate 95 in Jasper County, and also inundated the Jasper County Sheriff's Office and Detention Center. In Ridgeland, several buildings were damaged and the local wastewater treatment plant overflowed, spilling discharge into the nearby Captain Bill Creek. Damage in this county alone exceeded $640,000 (2016 USD). Record-breaking rainfall was observed across much of the Outer Banks; on Hatteras Island, Cape Point Campground was closed for a week due to flooding. Two people drowned in rip currents along the coastline of the Southeast United States.
Meteorological history
On May 24, the National Hurricane Center (NHC) began monitoring an area of disturbed weather resulting from the interaction of a weakening cold front and an upper-level trough. A surface area of low pressure formed late the next day, and the low eventually gained sufficient organization to be declared a tropical depression at 18:00 UTC on May 27. At the time, the depression was located about southeast of Charleston, South Carolina, and moving west-northwestwards in response to a low over the northwestern Bahamas and a ridge near the coast of North Carolina. Strong vertical wind shear and dry air in the region hindered strengthening, however, the depression was located over the warm waters of the Gulf Stream. In the afternoon of May 28, a burst of deep convection developed near the northwestern part of the exposed low-level circulation center (LLCC), and the NHC upgraded the depression to Tropical Storm Bonnie.
Despite strong southerly wind shear exposing the LLCC, Bonnie intensified slightly to reach its initial peak intensity with winds of as it turned towards the north. However, the continued effects of high wind shear and dry air caused the cyclone's appearance to significantly degrade early on May 29, as deep convection dissipated due to more than of southerly shear. Bonnie weakened back to tropical depression strength about half an hour prior to its landfall just east of Charleston, South Carolina. Caught in weak steering currents, the depression meandered over South Carolina for over a day before degenerating to a remnant low over the northeastern portion of the state at 12:00 UTC on May 30.
