On Monday, September 14, another cold front started to drift across the area slowly but provided one more day of summer-like temperatures before unseasonably cool weather would enter the Carolinas. Daytime highs in the Midlands rose into the upper-80s and low-90s. As the front pushed through on Tuesday, partly cloudy skies gave way to some drier air in the region ahead of the remnants of Hurricane Sally.
During most of the period, low-lying coastal areas were affected by a King Tide event. The high astronomical tides combined with onshore winds caused saltwater flooding in Charleston and other locations along the coast. The tidal gauge at the Charleston Harbor reported values of 7.31 feet mean lower low water (MLLW) on Monday evening, 8.09 ft. on Tuesday evening, and 7.43 feet during the evening hours on Wednesday. The crest on Tuesday was the highest at that location since December 2019 and preceded two additional gauge measurements over 8 ft. during the period, both occurring on beautiful clear days: 8.07 ft. on Saturday and 8.12 ft. on Sunday.
Remnants of Sally worked their way eastward across the Gulf and the Southeast on Thursday, September 17, producing heavy rain across the Palmetto State. The most intense storms were centered mainly over the Midlands during the morning and afternoon, transitioning to portions of the Pee Dee in the evening, dropping up to nine inches of rain in some localized areas. Sally spawned at least ten confirmed tornadoes, with most of them rated as an EF0, with maximum winds between 75 and 85 mph. Most of the damage from these tornadoes was confined to uprooting and snapping trees with minimal damage to structures. One tornado in Dorchester County near Reevesville was rated as an EF1 with maximum winds estimated around 105 mph.
After Sally’s passage through the area, low-level moisture trailed across the region, and the lingering cloud cover kept temperatures slightly cooler than normal on Friday. Skies began to clear on Saturday as a high pressure centered over the Great Lakes built into the region. The northerly winds ushered in dry and cool conditions that would hold through the beginning of the new work week. Maximum temperatures on Saturday, September 19, were up to 15 degrees below normal for this time of year, and daytime temperatures were like those usually observed during late October. A new record low maximum temperature was established at the National Weather Service (NWS) station at the Florence Regional Airport of 68 degrees, breaking 73 degrees in 1989. The NWS station at the Columbia Metropolitan Airport had a high of only 70 degrees; 68 degrees was reported at the Greenville-Spartanburg International Airport; and closer to the coast, the Charleston International Airport registered 76 degrees.
(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 | 3.27 | 49.43 | 17.3 |
| Greer Airport | 3.12 | 57.58 | 22.8 |
| Charlotte, NC Airport | 1.88 | 40.84 | 10.1 |
| Columbia Metro Airport | 3.04 | 47.55 | 13.2 |
| Orangeburg Airport | 3.94 | 35.16 | -0.7 |
| Augusta, GA Airport | 4.93 | 49.65 | 16.7 |
| Florence Airport | 2.82 | 50.12 | 17.1 |
| North Myrtle Beach Airport | 5.05 | 42.82 | 3.0 |
| Charleston Air Force Base | 4.64 | 44.78 | 4.8 |
| Savannah, GA Airport | 1.67 | 42.59 | 5.0 |
| *Weekly precipitation totals ending midnight Sunday. M - denotes total with missing values. |
4-inch depth soil temperature: Clinton: 66 degrees. Columbia: 70 degrees. Barnwell: 65 degrees. Mullins: 55 degrees.
The main precipitation event during the period occurred with the passage of the remnant low associated with Hurricane Sally on Thursday and Friday. Rainfall over the two days was widespread, with most of the state reporting at least an inch of rainfall. Some parts of the state received over four inches of rain, with locations in the Central Savannah River Area and Sandhills measuring more than six inches. CoCoRaHS observers in Orangeburg and Sumter counties reported storm totals over eight inches, and two observers near Longs in Horry County recorded between seven and eight inches of rainfall. Most of the year-to-date rainfall totals across the state continued to be above-normal through the middle of September, with the recent rain bringing totals in areas that were drier closer to normal.
With the rainfall from the remnants of Hurricane Sally, most of the USGS streamflow data across the state rose from normal conditions to above-normal conditions. These streamflow values will continue to be elevated as the rainfall moves through the river basins. Some of the gauges in the Upstate and Midlands reached minor to moderate flood stage, but had been steadily dropping through the end of the period. As the water pushed through the basins, gauges in the Lowcountry started to rise slightly.
