It was another quiet week for weather across the state after the landfall of Hurricane Florence on September 14, though most of the focus was on the rivers within the Pee Dee Watershed as the floodwaters from the storm continued to drain through South Carolina on their way to the Atlantic Ocean.
A surface and upper-level ridge was in control of the weather at the start of the workweek. Isolated showers overnight caused rainfall totals up to 1.50 inches in portions of Charleston and Beaufort counties by the morning of Monday, September 24. Despite a backdoor cold front that pushed into the state from the north during the early morning hours, the National Weather Service (NWS) in Spartanburg reported a new record high minimum temperature of 68 degrees, which broke the previous record of 66 from 2009. The front transitioned into a quasi-stationary front and focused afternoon shower activity along the coast, and an approaching low-pressure system from the north caused spotty rainfall across portions of the Upstate.
The high pressure persisted across the state on Tuesday, September 25, keeping rain chances low and temperatures above normal ahead of the slow-moving area of low-pressure. Stations across the Lowcountry, Midlands and Pee Dee reported high temperatures of 5 degrees above normal, such as Florence with a maximum temperature of 87 degrees, and the high of 89 degrees at Aiken. In the Pee Dee River Basin, Florence’s impacts were still being felt. The Lynches River near the Highway 41/51 Bridge crested at 25.93 ft. and the Little Pee Dee River near Conway crested at 22.26 ft. On the morning of September 26, the NWS station in Batesburg measured a low temperature of 70 degrees, which broke the record high minimum temperature record of 69 degrees set back in 1920. Maximum temperatures were roughly 10 degrees above normal across most of the state. The NWS station at the Charleston Airport reported a high of 92 degrees, the third highest temperature for September 26 in the 89-year period of record. Along the rivers, the Pee Dee River crested near Bucksport at 25.00 ft., and the Waccamaw River at Conway crested at 21.16 ft. Both of these crests surpassed their previous records, set during Hurricane Matthew in 2016. The crest of 25.00 ft in Bucksport was 2.4 ft. higher than the crest of 22.6 ft., while the crest of 21.16 ft along the Waccamaw smashed the previous record crest of 17.9 ft.
Thunderstorms developed across the Midlands and Pee Dee as the low-pressure moved toward the Mid-Atlantic, as a trailing cold front that stretched back toward the Gulf of Mexico started to slowly push through the state overnight on Wednesday. By the morning of Thursday, September 27, the CoCoRaHS observer at Aiken 2.9 SSE reported a rainfall total of 4.21 inches from the storms, and up to 2 inches was measured in Darlington and Marlboro counties, falling in many of the areas where floodwaters from Florence had receded. The Intracoastal Waterway at the Highway 544 Bridge in Socastee crested at 21.83 ft., almost 3 feet higher than the listed record value of 19.2 ft.
The upper level pattern supported the formation of strong thunderstorm on September 27. During the early evening, pea-sized hail was reported in Gaston and trees were down near Cameron. The South Carolina Highway Patrol reported trees down on Highway 601 in Richland County and a tree fell on a vehicle in Edgefield County. Duke Energy reported power outages after a tree limb took out powerlines near Quinby in Florence County. In the Upstate, storm damage, mainly downed trees and powerlines, was observed near Blacksburg, Pacolet, Greenville, Fountain Inn and Tega Cay. A trained spotter reported a tornado on the ground near Sandy Springs in Anderson County, and an area of wind damage from a likely tornado stretched between Townville and Northlake, especially near Clemson Blvd. There were damage reports of numerous trees down in the impacted area, with at least one car and house damaged from the event. Additional rainfall of up to 2.50 inches fell in Darlington, Florence and Lee counties.
By Friday, September 28, the front had pushed through the mountainous areas of the Upstate and stalled between Greenville and Columbia. Drier air moved in behind the front, lowering the chances of precipitation for Upstate, but triggering isolated shower activity elsewhere across the state, with some of the thunderstorms producing rainfall totals up to 3 inches. The front finally pushed through the state on September 29, giving the state a break from the above normal temperatures. The Charleston Harbor tidal gauge observed a high astronomical tide of 7.05 ft. mean lower low water (MLLW) at 12:30 p.m on Sunday, September 30. And after 16 days of watching the river, the Pee Dee River at Georgetown finally crested at 15.72 ft., an indication that the floodwaters were finally on their way out of the state, headed toward Winyah Bay.
(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 96 degrees on September 28 in Cades in Williamsburg County.
The lowest temperature reported was 58 degrees at Jocassee in Oconee County on September 24.
The maximum 24-hour precipitation reported was 3.25 inches at the National Weather Service Station in Wagener (Aiken County) ending at 9:00 a.m. on September 27.
The CoCoRaHS Station Aiken 2.9 SSE (SC-AK-57) reported a 24-hour precipitation total of 4.21 inches, ending at 7:40 a.m. on September 27.
The state average precipitation for the seven-day period was 1.50 inches.
| Weekly* | Since Jan 1 | Departure | |
|---|---|---|---|
| Anderson Airport | 1.31 | 41.44 | 8.0 |
| Greer Airport | 1.76 | 41.78 | 5.8 |
| Charlotte, NC Airport | 1.41 | 40.92 | 9.1 |
| Columbia Metro Airport | 2.73 | 29.33 | -6.1 |
| Orangeburg Airport | 1.73 | 33.44 | -3.7 |
| Augusta, GA Airport | 2.83 | 38.34 | 4.3 |
| Florence Airport | 1.63 | 42.31 | 8.2 |
| North Myrtle Beach Airport | 0.76 | 50.88 | 9.3 |
| Charleston Air Force Base | 0.05 | 40.18 | 1.6 |
| Savannah, GA Airport | 0.30 | 28.44 | -10.5 |
| *Weekly precipitation totals ending midnight Sunday. |
4-inch depth soil temperature: Clinton: 74. Columbia: 77 degrees. Barnwell: 73. Mullins: 69 degrees.
Floodwaters from Hurricane Florence continued to move through the Pee Dee Watershed rivers during the week, with many rivers finally cresting nearly two weeks after the storm’s landfall. Areas that had experienced little rainfall and dry conditions during the previous week received some beneficial rainfall due to the passage of a cold front, which brought streamflow values, especially in portions of the Central Savannah River Area, to normal values for this time of year. However, the National Drought monitor continued to hold dry conditions (D0) in the portions of the Lowcountry and introduced moderate drought (D1) conditions in Hampton and Jasper counties.
Charleston Harbor (CHTS1): 81.9 degrees.
Capers Nearshore Buoy (Station 41029): 80.2 degrees.
Fripps Nearshore Buoy (Station 41033): 81.7 degrees.
Average temperatures across South Carolina were above normal during September 2018. Many stations reported their warmest September on record, including the station in Chesnee, which reported an average temperature of 76.9 degrees (the station opened 1928). However, records at some of these stations do not capture the September of 1925, which is the warmest September in South Carolina. The NWS station in Aiken had an average temperature of 85 degrees in 1925, making the 82 degrees measured in 2018 the second warmest on record at the station.
The NWS stations at the Charleston International Airport and Edisto Island Middleton Plantation both reported monthly rainfall totals that were 4 inches below their normal for September. Many stations in the Pee Dee Region measured totals that were well above normal, such as Darlington with a monthly total of 13.61 (9.62 inches above normal) and 18.08 inches at Hartsville (14.05 inches above normal).
Midlands: Columbia Metro Airport
Pee Dee: Florence Airport
Lowcountry: North Charleston Airport
Statewide
