On Monday, September 20, a high tide of 7.23 feet MLLW was observed at the Charleston Harbor tidal gauge, causing shallow coastal flooding in low-lying areas. Easterly and southeasterly flow around a surface high pressure centered in the Northeast helped funnel moisture into the region along a stalled frontal boundary in Georgia. This atmospheric setup created widespread showers and thunderstorms across the state. The wet pattern continued overnight and into Tuesday morning. The frontal boundary slowly drifted to the north near Hilton Head and helped trigger steady showers and thunderstorms over Beaufort County. Some of these storms produced significant rainfall with up to eight inches of rain reported by observers in the area. A cold front slowly approached the Southeast on Tuesday, and by Wednesday it pushed through the state. The front triggered isolated thunderstorms and drove the axis of heavy rain associated with the old frontal boundary up the South Carolina coast as it moved through.
Behind the cold front, a high pressure settled across the area on Thursday, September 23, which then dominated the weather pattern with beautiful blue skies through the remainder of the period. Dry air gave the Palmetto State a break from the multiple days of rain. Under clear skies, radiational cooling allowed temperatures Friday morning to fall into the upper 40s and low 50s, about ten degrees below normal. The National Weather Service (NWS) station at Jocassee recorded a brisk morning low of 38 degrees. Daytime temperatures on Thursday and Friday ranged from the mid to upper 70s, with a few locations reaching the low 80s.
The fall-like conditions continued into the weekend, with low temperatures in the 50s, close to ten degrees below normal. The NWS station at the Charleston International Airport measured a low of 54 degrees on Saturday, the fourth coldest minimum temperature on record for the day. However, high temperatures on Saturday and Sunday began to moderate to near normal values for the end of September.
(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 | 0.94 | 33.13 | -1.6 |
| Greer Airport | 1.04 | 40.32 | 3.2 |
| Charlotte, NC Airport | 0.77 | 31.40 | -1.6 |
| Columbia Metro Airport | 0.98 | 42.02 | 6.9 |
| Orangeburg Airport | 0.59 | 35.59M | 1.3M |
| Augusta, GA Airport | 1.05 | 47.50 | 13.0 |
| Florence Airport | 1.95 | 37.65 | 2.5 |
| North Myrtle Beach Airport | 1.28 | 40.24 | 3.2 |
| Charleston Air Force Base | 3.22 | 50.04 | 8.7 |
| Savannah, GA Airport | 7.28 | 42.32M | 4.1M |
| *Weekly precipitation totals ending midnight Sunday. M - denotes total with missing values. |
4-inch depth soil temperature: Clinton: 71 degrees. Columbia: 74 degrees. Barnwell: 67 degrees. Mullins: 58 degrees.
Most of the rain that fell during the period came during the first part of the week, with half an inch of rain falling across the state, with locally higher amounts in the Lowcountry and Pee Dee. During the period, CoCoRaHS observers in Beaufort County reported seven-day rainfall totals between six and ten inches, with most of the rain coming from one event. Portions of Chesterfield, Darlington, and Horry counties recorded three to five inches of rain during the first part of the week. The rain alleviated some of the abnormally dry conditions that had started to develop in the Lowcountry and Pee Dee regions after a few weeks of little rainfall in the area.
During the period, most of the streamflow gauges across the state reported values near normal. Gauges along the streams and tributaries of the Edisto River measured above normal flows, where some of the higher rainfall totals were observed during the period. Some of the gauges in the Central Savannah River Area continued to report streamflow values slightly above normal. Streamflows in the Midlands and Pee Dee regions rebounded to near normal levels thanks to the recent rain. Most of the rivers in the state recorded heights below the flood stage during the period.
