For a second week in a row, the main weather story for the week was unstable atmospheric conditions, which led to the development of strong to severe afternoon thunderstorms. Temperatures during the period were five to ten degrees above normal, with the majority of observed low temperatures in the low to mid-70's, and the daytime highs reaching the low to mid-90's.
A high pressure continued to build into the area from the east on Monday, July 15, keeping the remains of Barry well to the west of the region. The strong afternoon heating led to the development of some slow-moving storms along a weak coastal trough. The National Weather Service (NWS) Office in Charleston recorded 2.97 inches of rain in one hour from their CoCoRaHS gauge, while the official NWS gauge only reported 1.46 inches. The storms produced wind damage in Colleton and Hampton counties and lightning struck a tree near College Park in Berkeley County. The warm and humid conditions persisted through Tuesday, and heat index values up to 110 degrees were noted in portions of the Lowcountry and Pee Dee. The NWS station located at the Myrtle Beach Airport reported heat index values of 108 degrees for four hours Tuesday afternoon. While the afternoon thunderstorms were not as widespread on July 16, some areas near Charleston picked up an inch of rain and the storms spawned a waterspout in Winyah Bay.
The observed morning low on Wednesday, July 17, in downtown Charleston was 82 degrees, while in the Upstate the minimum temperatures dropped into the upper 60's. The pattern caused heat index values to climb over 100 degrees again, as high temperatures reached the upper 90's in many locations. The NWS station located at the Florence Regional Airport measured a high of 101 degrees, which broke the previous daily record of 98 degrees set back in 1988. The trough remained stationary through the midweek, creating a pattern for showers and thunderstorms to form along the coastal areas in the morning and further inland during the evening. Strong thunderstorm winds downed trees in Oconee and Greenville counties in the Upstate and in Charleston and Colleton counties in the Lowcountry. The unsettled weather shifted into the Midlands on Thursday as evening thunderstorms produced a 45-mph wind gust reported by an RC-Winds station near Pine Ridge and a 48-mph wind gust at the Columbia Metropolitan Airport. Reports of downed trees and power lines came in from across the Midlands, especially near Prosperity in Newberry County. Heavy rains from thunderstorms forced road closures in and around the Charleston area due to standing water.
Heading into the weekend, the interaction between the persistent surface trough and high pressure creating a moderately unstable atmosphere. Strong storms developed in the Midlands during the evening on Friday, July 19. South Carolina High Patrol reported numerous downed trees near Lake Murray in Richland County. The 24-hour CoCoRaHS reports submitted early Saturday morning, showed a widespread two to three inches of rainfall near Lake Murray, including a 3.95-inch total observed just to the northeast of Irmo. By Saturday afternoon, an upper level ridge began to build over the area, helping to reduce the amount of developing afternoon thunderstorms. High temperatures on Saturday and Sunday were a bit cooler across the state, with upper 80's to low 90's reported under partly cloudy skies, though maximum heat index values reached over 100 degrees in some areas.
(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 | 0.21 | 24.45 | -0.4 |
| Greer Airport | 0.71 | 29.09 | 2.7 |
| Charlotte, NC Airport | 2.27 | 30.06 | 7.0 |
| Columbia Metro Airport | 0.12 | 22.38 | -2.4 |
| Orangeburg Airport | 0.76 | 16.34 | -10.2 |
| Augusta, GA Airport | 0.03 | 21.46 | -3.6 |
| Florence Airport | 0.19 | 21.23 | -2.2 |
| North Myrtle Beach Airport | 0.21 | 22.50 | -3.5 |
| Charleston Air Force Base | 2.63 | 23.70 | -2.7 |
| Savannah, GA Airport | 0.15 | 25.29 | -0.5 |
| *Weekly precipitation totals ending midnight Sunday. M - denotes total with missing values. |
4-inch depth soil temperature: Clinton: 79 degrees. Columbia: 82 degrees. Barnwell: 79 degrees. Mullins: 76 degrees.
Rainfall totals over the seven days were varied greatly across the Palmetto State, with some localized areas north of the Interstate 20 corridor receiving up to three inches of rain while some locations in the Central Savannah River Area (CSRA) and Lowcountry received less than half an inch. River and stream levels remain below critical flood thresholds through the period, though the isolated rainfall caused stream levels to continue to slightly rise, while those parts of the state that received sparse rainfall observed low river levels. Similarly, streamflow values in areas that received the heaviest rainfall totals increased and remained slightly above normal and streamflow values in the southern Midlands were slightly below normal through Sunday. The year-to-date rainfall totals in the Upstate remained near to above normal for this time of year, with more than twenty-five inches reported at many locations and over fifty inches in some of the more mountainous areas. Between twenty and thirty inches of rain have fallen since the beginning of the year in the Midlands. However, portions of the Central Savannah River Area are close to ten inches below normal since January 1. Parts of the Lowcountry and Pee Dee continue to be the driest areas of the state, with less than twenty inches of rain for the year in areas from the Interstate 95 corridor to the coast, with isolated totals of over twenty-five inches in portions of Beaufort, Charleston and Colleton counties. In areas that have missed the beneficial rainfall, the totals are six to eight inches below normal for this time of year, with interior portions of Horry and Marion counties reporting totals nearly twelve inches below normal.
