Another unsettled weather pattern was the main story during the period. Temperatures were near normal at the beginning of the week but warmed to slightly above average values through the work week. High temperatures were mainly in the low to mid-90s, with overnight lows in the lower 70s.
On Monday, July 4, a front stalled over the state to help promote unsettled weather for the holiday. Thunderstorms produced waterspouts along the Grand Strand, and lightning caused structural fires and damage in Loris, Socastee, and Surfside. Heavy rain in coastal Georgetown and Horry counties caused flash flooding and prompted road closures in Murrells Inlet and North Myrtle Beach. In Columbia, a thunderstorm dumped over four inches of rain in downtown Columbia in an hour, causing flash flooding. Preliminary data from the USGS gauge on Rocky Branch Creek at Whaley and Main streets crested at 12.8 feet, higher than the record set in 2011 and the value during the October 2015 Floods. Heavy rain and minor wind damage were reported in Colleton and Dorchester counties.
Conditions on Tuesday led to the development of waterspouts, prompting multiple reports of waterspouts off Fripp Island and Sullivans Island, along with moderate rip currents along Lowcountry beaches. By midweek, a more organized system moved through the Mid-Atlantic and New England areas. A weak surface boundary helped increase the risk of severe weather, triggering thunderstorms that caused wind damage in Anderson, Chesterfield, Greenville, Kershaw, Laurens, Lexington, and Union counties. The Fairfield County Fire Chief reported that 3.50 inches of rain fell in 35 minutes near Winnsboro.
High humidity and warmer than average temperatures on Thursday combined to cause excessive heat warnings and heat advisories to be issued for much of the state, with heat index values as high as 111 degrees. This led to the possibility for strong to severe thunderstorms. Thunderstorms near the Aiken-Augusta area not only produced wind damage but also caused flash flooding near the Beech Island Community. The National Weather Service (NWS) station at Augusta Bush Field reported a 1-hour total of 4.67”, and a nearby CoCoRaHS observer in Aiken County measured 5.66 inches in 24 hours. The unsettled weather continued on Friday, and afternoon showers and thunderstorms downed trees in Anderson County.
A cold front moved through the state on Saturday, and thunderstorms in the Lowcountry produced heavy rain, frequent lightning, and strong winds. The front stalled near the coast, causing heavy rain in the Charleston area during Sunday evening, and rainfall reports ranged from four to seven inches. Additional showers in the Midlands caused flooding along the Edisto River in Orangeburg County. The widespread cloud cover and rain helped keep temperatures below average, with maximum temperatures in the upper 80s on Saturday and the upper 70s to mid-80s on Sunday.
(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 | 1.35 | 21.22 | -3.9 |
| Greer Airport | 3.54 | 30.08 | 4.2 |
| Charlotte, NC Airport | 1.12 | 21.47 | -1.4 |
| Columbia Metro Airport | 2.36 | 23.75 | 0.4 |
| Orangeburg 2 (COOP) | 5.27s | 31.98s | 5.6s |
| Augusta, GA Airport | 7.89 | 29.65 | 5.9 |
| Florence Airport | 3.39 | 22.76 | 0.4 |
| North Myrtle Beach Airport | 3.22 | 22.15 | 0.9 | Charleston Air Force Base | 4.60 | 23.00 | -1.7 |
| Savannah, GA Airport | 0.73 | 12.84 | -12.3 |
| *Weekly precipitation totals ending midnight Sunday. M - denotes total with missing values. s - denotes total with suspect data. |
4-inch depth soil temperature: Clinton: 79 degrees. Columbia: 81 degrees. Barnwell: 77 degrees. Mullins: 73 degrees.
For the second period in a row, beneficial rain fell, with at least half an inch of rain reported across most of the state. However, some isolated locations in and along the Interstate 95 corridor reported less than a quarter of an inch of rain. Areas to the north and west of Interstate 95 measured more than two inches of precipitation, and some places recorded between five and eight inches of rain. CoCoRaHS observers near Hartsville reported measurable precipitation every day of the period, with totals between seven and eight inches of rain. The rainfall helped improve the abnormally dry conditions (D0), along with moderate (D1) and severe drought (D2) conditions in parts of the Lowcountry, Midlands, and Pee Dee regions. However, drought conditions persist in South Carolina due to weeks of warm weather and below-normal precipitation.
Widespread rainfall across the state during the last two periods has helped increase the 14-day streamflow averages at many of the gauges of the four main watersheds. While streamflow returned to within the normal percentile range in the Midlands and Upstate, some gauges still reported values at or below 50% of their average flow. However, the number of streamflow gauges in the Lowcountry and Pee Dee that continued to record values below their average streamflow increased during the period, with the gauge on the Little Pee Dee River at Galivants Ferry reporting values much below average. With heavy rain falling across portions of the Midlands and Pee Dee, the North Fork of the Edisto rose to action stage near Orangeburg, and the Black Creek near Quinby rose to minor flood stage by the end of the period. Elsewhere, the state’s rivers observed heights below the flood stage.
