The week started off with all eyes focused on the Atlantic Ocean and Hurricane Florence, as forecasts started to come into agreement that the storm would potentially make landfall along the Carolina Coast during the upcoming week.
On the evening of Monday, September 10, a series of slow-moving thunderstorms along a stationary boundary caused heavy rain and flash flooding in the Aiken/Augusta area. The National Weather Service (NWS) Cooperative Weather Observer in Graniteville measured 4.25 inches of rain in two hours, while another observer in Ridgeway reported 2.40 inches in just 30 minutes. Strong winds from the thunderstorms knocked down trees in Trenton along Highway 25 and Highway 19. King tides, associated with the perigean spring tide, when the new moon is closest to the earth, continued to impact the Charleston area. The Charleston Harbor tidal gauge observed an astronomical high tide value of 7.29 ft. mean lower low water (MLLW) around 7:00 p.m. Monday, and values of 7.20 ft. MLLW and 7.12 ft. MLLW were measured on Tuesday and Wednesday, respectively.
A ship reported a waterspout near Buoy 7, located about 10 miles southeast of Sullivan’s Island on the morning of Tuesday, September 11. Later that day, Governor McMaster issued a mandatory evacuation of the coast ahead of Hurricane Florence, which was located 370 miles south-southwest of Bermuda. The National Hurricane Center issued both a Hurricane Watch and Storm Surge Watch for the entire South Carolina coast. As citizens began to prepare for the impending hurricane, hot and humid conditions were reported across the state as a surface trough set up over the state, and high temperatures reached the mid to upper 90s in portions of the Midlands and Pee Dee regions. On Wednesday, the NWS station at the Columbia Metro Airport had a maximum temperature of 95 degrees, which tied the record that was set in 2010. Isolated thunderstorms developed in the Upstate during the afternoon and the NWS station at Caesars Head reported a 24-hour rainfall of 3.65 inches, setting a new record rainfall value for the day (the previous was 1.24 inches in 2017).
The continued period of below-normal rainfall through the first part of the week led members of the U.S. Drought Monitor to hold the dry (D0) and moderate drought conditions (D1) in to include much of the Pee Dee region, including Lancaster County and parts of Chester, Chesterfield, Fairfield and Kershaw counties. The statewide drought call scheduled for Thursday was canceled due to preparations for Florence. Multiple record high minimum temperatures were tied or broken on Thursday, including the observed low of 74 degrees at the Greenville-Spartanburg Airport, which broke the old record of 71 degrees in 2007.
Hurricane Florence made landfall at 7:15 a.m. on Friday, September 14, near Wilmington as a Category 1 hurricane with winds of about 90 miles an hour. The NWS station in Myrtle Beach reported a peak wind gust of 61 mph and other observing stations recorded gusts up to 50 mph throughout the Pee Dee Region. After making landfall, the storm slowed down, moving at two mph, exacerbating the impacts from the torrential rainfall and flooding across the Carolinas. Rainfall totals across the Pee Dee region the morning of Saturday, September 15, ranged from 3 to 8 inches, and the Marion Airport reported a peak wind gust of 61 mph associated with Hurricane Florence. The NWS stations in Clarks Hill and Laurens recorded new record high minimum temperatures for the day. The Laurens station observed a low of 76 degrees, breaking the previous record of 71 degrees set in 1938 and the 78-degree temperature at the Clarks Hill station beat the previous record of 71 in 1962.
By late Sunday morning, Tropical Storm Florence was centered 20 miles southwest of Columbia and was moving west at eight mph. The impacts from the storm were still felt along the coast, as a waterspout spawned near Myrtle Beach and eventually came ashore near 21st Avenue, and multiple reports of funnel clouds came in from across Horry County. Maximum 24-hour rainfall totals of 10.82 inches in Chesterfield and 10.75 inches in Cheraw were reported Sunday morning. The amount at Cheraw surpassed the previous daily rainfall record by 7.88 inches, set back in 1999 by Hurricane Floyd. Two CoCoRaHS observers in the Loris area measured rainfall totals from Hurricane Florence of over 23 inches, while the storm total from the NWS station in Cheraw was 22.79 inches.
As Florence exited the area late Sunday evening, river levels across the Pee Dee region began to rise as the rainfall from North Carolina and South Carolina drained into the area's river basins.
The staff of the South Carolina State Climatology Office will issue a final report on Hurricane Florence within the coming weeks.
(Note: The highest and lowest official temperatures and highest precipitation totals provided below are based on observations from the National Weather Service Cooperative Observer network and the National Weather Service's Forecast Offices.)
The highest temperature reported was 98 degrees September 10 in Aiken in Aiken County.
The lowest temperature reported was 60 degrees at Jocassee in Oconee County on September 15.
The maximum 24-hour precipitation reported was 10.82 inches at the National Weather Service Station in Chesterfield ending at 7:00 a.m. on September 16. This is the highest 24-hour rainfall total ever recorded at the station and replaced the previous record of 7.20 inches on October 3, 2015.
The CoCoRaHS Station Dillon 3.8 NW (SC-DL-4) reported a 24-hour precipitation total of 9.25 inches, ending at 9:30 a.m. on September 16.
The state average precipitation for the seven-day period was 4.20 inches.
| Weekly* | Since Jan 1 | Departure | |
|---|---|---|---|
| Anderson Airport | 0.87 | 40.13 | 8.5 |
| Greer Airport | 3.12 | 39.96 | 5.5 |
| Charlotte, NC Airport | 7.03 | 39.51 | 9.1 |
| Columbia Metro Airport | 2.72 | 26.14 | -7.8 |
| Orangeburg Airport | 1.97 | 31.13 | -4.2 |
| Augusta, GA Airport | 3.17 | 34.55 | 2.0 |
| Florence Airport | 8.60 | 40.62 | 8.1 |
| North Myrtle Beach Airport | 11.47 | 49.90 | 10.8 |
| Charleston Air Force Base | 1.19 | 39.67 | 0.4 |
| Savannah, GA Airport | 0.37 | 28.14 | -8.9 |
| *Weekly precipitation totals ending midnight Sunday. |
4-inch depth soil temperature: Clinton: 75. Columbia: 78 degrees. Barnwell: NA. Mullins: 75 degrees.
The week started off with low streamflow values in some of the creeks and rivers across the state; especially in the upper Pee Dee region. Rainfall was isolated and spotty through September 13, and streamflow values continued to drop off before the landfall of Hurricane Florence. Excessive rainfall from Florence fell across portions of the Pee Dee Region, in the same area that had experienced dry and moderate drought conditions. The rainfall totals across the northern tier of the state ranged from 3 to over 20 inches. Combined with rainfall totals of over 30 inches in portions of the Pee Dee River Basin in North Carolina, many of the state’s rivers went from below normal streamflow to near or above record values by September 16.
Charleston Harbor (CHTS1): 82.6 degrees.
Capers Nearshore Buoy (Station 41029): 82.8 degrees.
Fripps Nearshore Buoy (Station 41033): 83.3 degrees.