The week began with a decaying stationary front draped over the South Carolina-North Carolina border. The National Weather Service office in Greer receiving a report of quarter-sized hail falling in the vicinity of Tigerville before 9 a.m. Monday. Also on Monday morning, the NWS COOP observer in Johnston reported a 24 hour rainfall amount of 4.02 inches since Sunday. Shaw Air Force Base also reported a 24 hour total of 2.31 inches. Tuesday, 3.5 inches of heavy rain fell at the Florence Regional airport
High pressure built in over the state for the rest of the week bringing the warmest high temperatures of 2017 to date. The Santuck NWS COOP station recorded 101 degree afternoon high temperatures on Wednesday, Friday and Saturday. The Beaufort Marine Corps Air Station sweltered Wednesday with a high temperature of 89 degrees coupled with a dew point of 79 degrees. Wednesday morning, visibility fell to a quarter mile in fog at the Newberry County airport and the Florence Regional airport. With a moisture rich south westerly flow at the surface, diurnal heating triggered scattered afternoon convection Monday through Wednesday. These storms were slow moving, with some isolated cells producing torrential rainfall across the Midlands, Pee Dee, and the Lowcountry. Wednesday, the Columbia Metro reported a paltry 0.09 inches of rain while the Florence Regional airport received a 1.37 inches. A CoCoRaHS observer in North Charleston reported a 24-hour rainfall ending Thursday morning of 3.53 inches. Hail, 1.00-1.25 inches in diameter, fell at several locations in Berkeley and Charleston Counties Wednesday afternoon.
An upper level ridge of high pressure strengthened Thursday to suppress the afternoon convection until Sunday. The Clemson-Oconee County airport reported Saturday's highest rainfall amount: 0.16 inches. Most observing sites reported clear skies and no precipitation through Saturday.
Sunday, the upper level ridge of high pressure weakened and slid east. A pre-frontal trough, fueled by deep surface layer of convergent moist air, caused widespread strong convection across the Midlands Sunday. Convection initially formed over the Upstate and strengthened with diurnal heating as it drifted slowly south. Complex storm outflow and back-building increased the thunderstorm coverage across the Midlands. Rainfall totals and rates varied greatly across the state. The USC COOP site recorded a 24 hour total of 4.57 inches. The National Weather Service office in Columbia reported 3.82 inches fell in one hour at a gage in Martin Luther King Jr. Park. The Anderson County and the North Myrtle Beach airports reported only 0.03 inches and a trace of rain respectively. Despite the widespread clouds and rain, Sunday's high temperature reached 97 degrees at the Saluda COOP site.
(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 official temperature reported was 101 degrees at Santuck on July 19, 21 and 22.
The lowest official temperature reported was 58 degrees on Sassafras Mountain on July 19 and 20.
The heaviest official 24-hour rainfall reported was 4.57 inches at the USC Columbia.
The state average rainfall for the seven-day period was 1.2 inches.
| Weekly | Jan 1 | Departure | |
|---|---|---|---|
| Anderson AP | 0.03 | 34.70 | 8.5 |
| Greer AP | 0.36 | 33.09 | 6.4 |
| Charlotte, NC AP | 0.30 | 28.97 | 5.7 |
| Columbia Metro AP | 0.83 | 34.44 | 9.3 |
| Orangeburg AP | 1.34 | 24.35 | -2.5 |
| Augusta, GA Bush AP | 0.44 | 27.85 | 2.5 |
| Florence AP | 4.42 | 27.98 | 4.2 |
| N Myrtle Beach AP | 0.60 | 18.81 | -7.6 |
| Charleston AFB | 2.00 | 27.44 | 0.6 |
| Savannah, GA AP | 1.23 | 35.02 | 8.8 |
Weekly rainfall totals ending midnight Sunday.
4-inch depth soil temperature: Clinton 79 degrees. Columbia 83 degrees. Barnwell 77 degrees. Mullins 72 degrees.
Most South Carolina river stages were normal. Several Upstate rivers and portions the lower Savannah River were below normal.
Charleston Harbor water temperature: 86 degrees.
Fripp Nearshore Buoy (Station 41033): 83.1 degrees.
