During the period, the main weather stories were the record-breaking above normal temperatures and heavy rainfall associated with the passage of Tropical Storm Eta. From Monday, November 9, through Thursday, November 12, both minimum and maximum temperatures were well above normal for November. Typically, daytime temperatures range in the mid to upper 60s for normal, with morning lows in the upper 40s to low 50s. However, during the period there were seventy-five high minimum temperatures and eleven maximum temperatures broken. Minimum temperatures in some locations on Wednesday and Thursday were more than twenty-five degrees above normal. The National Weather Service (NWS) station at the Charleston International Airport reported a low temperature of 74 degrees on Wednesday, smashing the previous high minimum temperature record of 65 degrees in 1975. High temperatures ranged between ten and fifteen degrees above normal, with low to mid-80s observed in the Midlands and Upstate. On Thursday, the NWS station in Laurens reported a high of 82 degrees, breaking the previous record of 80 degrees set back in 1927. On the same day, the station in Saluda also tied the maximum daily record of 83 degrees set in 1931.
As Tropical Storm Eta meandered in the Gulf of Mexico, the southerly flow helped funnel moisture back into the Southeast. There were scattered rain chances at the beginning of the week, which increased as Eta made landfall north of the Tampa Bay area on Thursday and pushed across the peninsula, reemerging into the Atlantic near Jacksonville. Eta's deep moisture combined with a cold front moving across the Appalachians and caused heavy rain and flash flooding across most of the state. Multiple flood watches and warnings were issued by the National Weather Service Offices in the region. Tropical-storm-force wind gusts were measured along the coast, including a gust of 55 mph reported by the WeatherFlow station at Fort Sumter in Charleston Harbor.
By Friday, November 13, the rainfall from Tropical Storm Eta had set fifteen new daily precipitation records across South Carolina and at locations such as Bamberg, Cleveland, Lockhart, Marion, Myrtle Beach, and Orangeburg. Much drier and cooler air moved into the Upstate and Midlands by Saturday, and temperatures moderated to near normal. On Sunday, dense fog was observed across parts of the state, with visibilities less than an eighth of a mile. Temperatures outside of the Upstate warmed into the upper 70s, ahead of a secondary cold front, which produced strong gusts as it pushed through the region Sunday evening.
Another round of King Tide events started on Friday and lasted through the weekend, with saltwater flooding reported in low-lying areas. The tidal gauge at the Charleston Harbor reported a maximum of 7.23 feet mean lower low water (MLLW) on Friday, 7.71 feet on Saturday, and 8.13 feet on Sunday morning.
(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 | 1.90 | 55.48 | 17.4 |
| Greer Airport | 3.02 | 68.10 | 27.0 |
| Charlotte, NC Airport | 5.00 | 54.55 | 17.8 |
| Columbia Metro Airport | 1.14 | 50.61 | 10.7 |
| Orangeburg Airport | 5.11 | 40.94 | -1.0 |
| Augusta, GA Airport | 0.91 | 52.22 | 13.5 |
| Florence Airport | 3.35 | 58.34 | 19.8 |
| North Myrtle Beach Airport | 4.44 | 51.34 | 4.3 |
| Charleston Air Force Base | 2.47 | 51.71 | 5.0 |
| Savannah, GA Airport | 1.27 | 47.76 | 4.0 |
| *Weekly precipitation totals ending midnight Sunday. M - denotes total with missing values. |
4-inch depth soil temperature: Clinton: Not Available. Columbia: 74 degrees. Barnwell: 62 degrees. Mullins: 61 degrees.
For the second time this month, another tropical system made landfall along the Gulf Coast as Tropical Storm Eta came ashore near Cedar Key, Florida, on November 12. Eta's moisture combined with a slow-moving cold front positioned near the Appalachian Mountains, creating an environment conducive to produce heavy rain across the region. A CoCoRaHS observer near Conway in Horry County measured 7.50 inches of rain from November 11 to November 13, while observers in Charleston, Georgetown, and Orangeburg counties reported over six inches over the three days. The overall totals for most locations were more than two inches, though some portions of the Upper and Central Savannah River Areas recorded less. The year-to-date rainfall totals across the state continued to be above-normal values, mainly due to the wet start to 2020, and the recent rainfall helped alleviate some of the drier parts of the state, especially those in the Lowcountry.
With the widespread, heavy rain from Tropical Storm Eta falling over the Carolinas, flash flooding was reported along much of the Upper Broad and Yadkin-Pee Dee river basins. Gauges showed many of the rivers in the basins at minor or moderate flood stages and streamflow values well above normal for November. By Saturday and Sunday, some of the gauges along the rivers had crested in portions of the Midlands, and continued to rise as the water moved through the systems to empty into the Atlantic.
