An upper ridge dictated this week's weather, causing above normal temperatures throughout the state and limiting convective potential with subsidence and dry air. The Midlands experienced temperatures above 100 degrees, with heat index values close to 105 degrees, and other areas of the state reported temperatures in the low to mid-90s for the week. Most of the recording stations in the state noted precipitation totals of less than an inch for the week, with widespread portions of the state reporting no rainfall or a trace. The upper ridge served as a suppressant for most convective potential in the state, by creating a cap and limiting the instability.
Isolated thunderstorms were in the week's forecast for Monday, September 9, due to a weak onshore flow pattern and the persistent ridging. These isolated thunderstorms produced hail and downed trees across the state. Storm spotters in Colleton and Orangeburg counties reported quarter-sized hail (1.00 inch) on September 9. The following morning, dense fog was observed in the Columbia area, with visibilities of less than three miles in parts of the Midlands. During the afternoon, scattered storms dropped nickel-sized hail (0.88 inches) in Anderson County.
By the middle of the week, the upper-level ridge combined with a surface high pressure to produce hot and dry conditions across much of the Southeast. Through Friday, both maximum and minimum temperatures across the state were above normal. Maximum temperatures were up to 15 degrees above normal, with 26 new daily record highs set across the state, including a high of 98 degrees measured at the National Weather Service (NWS) station at the Anderson County Airport. This new record replaced the old value of 95 degrees observed in 1951. Observed minimum temperatures ranged from five to ten degrees above normal, and 13 record high minimum temperatures were tied during September 11 – 13. On Friday, the ridge began to weaken, allowing moisture to move back into the state, and isolated thunderstorms developed across portions of the state. An isolated, severe thunderstorm moved through Lancaster County, where a spotter recorded a 51.4 mph gust and pea-to-quarter-sized hail.
The majority of the rain during the period fell on Saturday, September 14, as the result of the weakening ridge and weak cold front that pushed into the state from North Carolina late Friday, bringing increased moisture over northern South Carolina and helping to slightly weaken the upper ridge that had previously inhibited precipitation. Tropical Storm Humberto passed by the East Coast with its significant wind gusts and precipitation remaining offshore.
(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 | 0.46 | 26.94 | -4.6 |
| Greer Airport | 0.17 | 36.47 | 2.2 |
| Charlotte, NC Airport | 0.19 | 39.33 | 9.1 |
| Columbia Metro Airport | 1.01 | 27.27 | -6.6 |
| Orangeburg Airport | 0.52 | 18.18 | -17.1 |
| Augusta, GA Airport | 0.24 | 35.75 | 3.3 |
| Florence Airport | 0.86 | 32.98 | 0.5 |
| North Myrtle Beach Airport | 0.10 | 42.57 | 3.7 |
| Charleston Air Force Base | 0.15 | 36.05 | -3.0 |
| Savannah, GA Airport | 0.47 | 30.98 | -5.9 |
| *Weekly precipitation totals ending midnight Sunday. M - denotes total with missing values. |
4-inch depth soil temperature: Clinton: 88 degrees. Columbia: 80 degrees. Barnwell: 75 degrees. Mullins: 73 degrees.
Most of the rainfall over the seven days fell in portions of the Upstate and the northwest Midlands. Locations in Spartanburg, Oconee, and Anderson counties reported up to four inches of rain, and observers reported most of those totals coming from one event. Due to the localized nature of the thunderstorms, isolated amounts of roughly an inch fell in several counties in the Pee Dee and northern SC, with less than an inch recorded across the remainder of the state. River levels in those areas that received heavy rain on the 14th rose sharply, while those parts of the state that received sparse rainfall observed declining river levels. Streamflow values continued to drop in many of the state's streams and rivers, with several reported flows in the southern portion of the state below normal for this time of year. Portions of Allendale, Barnwell and Hampton counties in the Lowcountry and Dillon continue to be the driest areas of the state, reporting less than 25 inches since the beginning of the year. Totals of over thirty inches were present along the immediate coast of the southern coastal counties while interior locations within those counties measured lower amounts. Although rainfall totals in the Upstate over the last 30 days are below normal, the year-to-date rainfall totals in the Upstate remained near to above normal for this time of year, with more than thirty inches reported at many locations and over fifty inches in some of the more mountainous areas.
Charleston Harbor (CHTS1): 83.1 degrees.
Capers Nearshore Buoy (Station 41029): 81.9 degrees.
Fripps Nearshore Buoy (Station 41033): 82.2 degrees.
