WEEKLY SOUTH CAROLINA WEATHER 2018
August 13, 2018 - August 19, 2018
The seven-day period was rather quiet after a few weeks of active weather. The week started off with fair conditions, accompanied by warm and drier air in the Upstate, while a weak surface trough provided an environment for afternoon and evening showers and thunderstorms across the rest of the state through the first part of the week.
On the morning of Monday, August 13, multiple CoCoRaHS observers in and near the city of Sumter reported heavy rainfall amounts, over 2.50 inches, and minor flooding from an overnight severe thunderstorm. Along the coast, the Isle of Palms Fire Department reported two waterspouts offshore of 18th Avenue within 15 minutes of one another. Widespread fog in the Pee Dee region reduced visibility to 0.25 miles during the early morning hours on August 13, while the overcast skies during the afternoon kept maximum temperatures across portions of the upper Midlands in the mid-to-upper 80's. An upper-level disturbance and surface front moved across the Upstate late in the evening, leading to drier conditions the following morning. Most locations in the Upstate awoke to temperatures in the lower to mid-60's on August 14, such as the National Weather Service (NWS) stations at Table Rock and Walhalla, which reported minimum temperatures of 62 degrees. Closer to the coast, strong winds from isolated afternoon thunderstorms knocked down trees and blocked roads in Dorchester, Jamestown, Grays, West Ashley, and Hardeeville. Localized heavy rains in Ladson and Knightsville in Dorchester County flooded some low-lying roads in area neighborhoods. Later the same evening, the South Carolina Highway Patrol reported flooding on Henderson Highway and Highway 17 in Colleton County.
By Wednesday, August 15, the weak cold front had moved into the southern Midlands and became stationary along the Interstate 95 corridor. Most of the shower activity was confined to areas east of the interstate during the early evening hours. CoCoRaHS stations in Beaufort County reported up to an inch of rain from these storms. Isolated and scattered thunderstorms developed near the sea breeze and along various outflow boundaries through the latter half of the week. Localized thunderstorms produced 0.5 inches to an inch in portions of Lexington and Richland counties observed by CoCoRaHS stations on August 16, though the official NWS station at the Columbia Metropolitan Airport reported no rainfall for the day. The combination of the stationary front and the placement of the Atlantic high-pressure caused hot and humid conditions in portions of the Midlands and Lowcountry, with heat index values reaching 100 degrees in some locations. The Columbia Metropolitan Airport observed a maximum heat index value of 104 degrees during the afternoon of August 16. While the maximum temperature at the Charleston International Airport only reached 91 degrees on Friday, August 17, when combined with dewpoints in the mid-70's, they experienced heat index values of 100 degrees or more for five consecutive hours.
Over the weekend, the increased moisture from the combination of an approaching upper-level trough and the stagnant synoptic pattern created the environment for convection to form and produce a period of unsettled weather. On Saturday, August 18, temperatures ranged from the upper-80's to mid-90's across much of the state. However, the automated weather station on top of Sassafras Mountain recorded a maximum temperature of 74 degrees. Near and inland of the coast, thunderstorms developed along the sea breeze circulation. Evening thunderstorms on Saturday in the Lowcountry produced strong winds in Dorchester and Colleton counties, with multiple towns reporting trees down on power lines and roads. In Greenwood County, severe thunderstorms caused a tree limb to fall on a car in the town of Greenwood. On the morning of Sunday, August 19, minimum temperatures across the state were in the mid-70's, and the minimum temperature of 72 degrees at the Greenville-Spartanburg Airport was the 5th warmest on record for the day. Later Sunday evening, the Department of Transportation reported winds from thunderstorms caused downed trees on Interstate 95 near mile marker 14, just south of Ridgeland.
(Note: The highest and lowest official temperatures and highest precipitation totals provided below are based on observations from the National Weather Service Cooperative Observer network and the National Weather Service's Forecast Offices.)
The highest temperature reported was 97 degrees at the University of South Carolina - Columbia Campus in Richland County on August 17.
The lowest temperature reported was 54 degrees at Jocassee in Oconee County on August 16.
The maximum 24-hour precipitation reported was 2.15 inches at the National Weather Service Cooperative Weather Station in Walterboro in Colleton County ending at 8:30 a.m. on August 15. A total of 4.01 inches over the 7-day period was reported at this station.
The CoCoRaHS Station Sumter 3.6 SSW (SC-SM-20) reported a 24-hour precipitation total of 4.71 inches, ending at 6:30 a.m. on August 13.
The state average precipitation for the seven-day period was 0.50 inches.
| ||Weekly*||Since Jan 1||Departure
|Charlotte, NC Airport||0.81||29.26||2.3
|Columbia Metro Airport||0.97||23.24||-6.8
|Augusta, GA Airport||0.06||30.79||1.5
|North Myrtle Beach Airport||0.60||37.63||5.5
|Charleston Air Force Base||0.75||37.78||5.1
|Savannah, GA Airport||1.19||26.07||-5.8
| *Weekly precipitation totals ending midnight Sunday.
| M - Missing precipitation value during the week.
4-inch depth soil temperature: Clinton: 78 degrees. Columbia: 79 degrees. Barnwell: 76 degrees. Mullins: 74 degrees.
Over the week of August 13 - 19, the only areas to receive moderate rainfall were inland from the coast, in portions of Berkeley, Colleton, Dorchester, and Williamsburg counties; and Sumter County in the Midlands. The lack of rainfall elsewhere across the state over the last seven days led to a drop off in streamflow values in some of the area creeks and rivers; especially in the Pee Dee region along the Lynches River near Bishopville and near Effingham and Black Creek near Hartsville. The continued dry out along the coast and Upstate allowed most area rivers to fall back to within normal levels. Only a few rivers across the state, like the Reedy River near Greenville and Santee River near Pineville, were reporting slightly above normal stream flows going into the week of August 20.
COASTAL OCEAN TEMPERATURES:
Charleston Harbor (CHTS1): 83.5 degrees.
Capers Nearshore Buoy (Station 41029): 82.2 degrees.
Fripps Nearshore Buoy (Station 41033): 85.3 degrees.