Tropical Storm Debby gradually strengthened as it moved over the warm waters of the eastern Gulf of Mexico on Monday, August 5, eventually becoming a hurricane before making landfall near Steinhatchee, Florida. The storm moved through Florida and Georgia before its forward speed slowed it down just off the Georgia coast on August 6. After spending more than a day over the Atlantic, it made a second landfall near Bulls Bay in South Carolina during the early hours of Thursday, August 8. The storm then picked up speed and moved north, away from South Carolina during the day, and was downgraded to a tropical depression that evening. The tropical storm produced seven tornadoes, including four EF1 and three EF0 tornadoes. Four of the seven confirmed tornadoes started as waterspouts that moved onto land. Two waterspouts moved onshore and damaged homes and businesses at Edisto Beach, and a tornado caused damage to businesses in Moncks Corner. The highest wind gusts from Tropical Storm Debby were reported directly along the coast, with gusts of more than 50 mph reported at the National Weather Service station at the Charleston International Airport and by WeatherFlow stations located at Folly Beach, Isle of Palms, and Beaufort. No notable storm surge was reported during the storm. Information on rainfall and riverine impacts is outlined below.
A full Open-File Report with more detailed information on Tropical Storm Debby can be found here: https://www.dnr.sc.gov/climate/sco/Publications/Debby-OFR.pdf.
Behind the storm, a trailing weak low pressure moved from Georgia into southeastern Pennsylvania, triggering storms and heavy rain across areas impacted by the days of heavy rainfall from Debby through the remainder of the period.
(Note: The highest and lowest official temperatures and highest precipitation totals provided below are based on observations from the National Weather Service (NWS) Cooperative Observer network and the National Weather Service's Forecast Offices.)| Weekly* | Since Jan 1 | Departure | |
|---|---|---|---|
| Anderson Airport | 1.21 | 34.47 | 5.6 |
| Greer Airport | 1.99 | 34.56 | 3.5 |
| Charlotte, NC Airport | 4.63 | 33.86 | 6.8 |
| Columbia Metro Airport | 4.50 | 38.06 | 9.1 |
| Orangeburg 2 (COOP) | 8.06 | 35.82 | 3.6 |
| Augusta, GA Airport | 2.35 | 32.91 | 4.2 |
| Florence Airport | 8.13 | 35.91 | 7.7 |
| North Myrtle Beach Airport | 10.17 | 35.95 | 9.0 | Charleston Air Force Base | 12.75 | 44.27 | 12.6 |
| Savannah, GA Airport | 11.03 | 42.03 | 11.1 |
| *Weekly precipitation totals ending midnight Sunday. M - denotes total with missing values. s - denotes total with suspect data. |
4-inch depth soil temperature: Clinton: Not Available. Columbia: 83 degrees. Barnwell: 77 degrees. Mullins: 72 degrees.
Tropical Storm Debby produced heavy rains across the state's eastern half, including all of the Coastal Plain and much of the Pee Dee region. Totals over five inches were measured mainly east of the Interstate 20 corridor, and totals in much of the area east of Interstate 95 were reported to be more than ten inches, with some values over fifteen inches. A CoCoRaHS observer in Moncks Corner reported a storm event total of 22.02 inches of rain from August 5 until the morning of August 9, while an observer in Colleton County reported a one-day total of 12.90 inches of rain and a total of 17.57 inches from the event. However, not all areas of the state received heavy rainfall from Tropical Storm Debby. Portions of the Upper and Central Savannah regions recorded less than an inch of rainfall.
Any changes in the USDM drought designations will be reflected in the map released on Thursday, August 15, because most of the rainfall from Tropical Storm Debby fell after the data cutoff of Tuesday morning.
Rainfall from the previous week and Tropical Storm Debby increased the 14-day average streamflow values at gauges across much of the state, especially those within the eastern half of the state. Many gauges measured flows that were much above normal or high, over 500 percent of normal. However, with the lack of rain and persistent drought conditions in portions of the Upper Savannah River Basin, the 14-day average streamflow values remained below average. River heights in the ACE Basin and Pee Dee watershed rose into major flood stages at gauges where heavy rainfall fell or began working through the watersheds, such as the Edisto River near Givhans and the Little Pee Dee River at Galivants Ferry.
