On Monday, May 25, isolated severe thunderstorms, with the primary threat for wind and hail, started the week. Some CoCoRaHS observers in the central Midlands reported up to two inches of rain from some of these slow-moving thunderstorms. A coastal trough resulted in rain across the region on Tuesday, as temperatures continued to be unseasonably cool with the increased clouds, with highs topping out in the 70s, close to ten degrees below normal across much of the state. The trough strengthened overnight and by the early morning of Wednesday, May 27, Tropical Storm Bertha had formed off the South Carolina coast. The Edisto offshore buoy, located 41 nautical miles southeast of Charleston, reported a wind gust of 51 mph, and the buoy at Capers recorded a 45-mph gust. The storm, while short-lived, made landfall near Bulls Bay and tracked northwest across the southern Pee Dee region into the Midlands before moving into west-central North Carolina. Bertha produced heavy rain in Berkeley, Charleston, Clarendon, Chesterfield, Kershaw, Lancaster, Lee, and Sumter counties. This round of heavy rain, on top of already saturated soils in the area, contributed to additional flooding issues across portions of the Catawba and Pee Dee basins.
Thunderstorms developed due to the moisture brought into the region from southerly flow. The additional rainfall caused flash flooding, washing out multiple roads near Jefferson in Chesterfield County and near the city of Marion on Thursday. The unsettled weather conditions continue on Friday and lasted through the weekend. Thunderstorms caused wind damage in Greenville and in Greenville, Cherokee, and Spartanburg counties, and a storm spotter reported pea-to-quarter sized hail near Simpsonville. Another round of slow-moving thunderstorms caused flooding in parts of Richland County. By Saturday, a cold front pushed through the region, bringing a cooler and drier air mass into the Southeast, setting the stage for a beautiful Sunday and the beginning of the new work week.
(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 | 1.39 | 37.08 | 18.7 |
| Greer Airport | 1.24 | 41.24 | 21.8 |
| Charlotte, NC Airport | 2.11 | 27.93 | 11.0 |
| Columbia Metro Airport | 3.85 | 27.79 | 11.3 |
| Orangeburg Airport | 1.02 | 19.17 | 1.6 |
| Augusta, GA Airport | 2.80 | 28.90 | 11.4 |
| Florence Airport | 4.16 | 27.89 | 12.5 |
| North Myrtle Beach Airport | 3.00 | 21.41 | 4.0 |
| Charleston Air Force Base | 2.27 | 22.10 | 5.8 |
| Savannah, GA Airport | 0.70 | 23.05 | 6.8 |
| *Weekly precipitation totals ending midnight Sunday. M - denotes total with missing values. |
4-inch depth soil temperature: Clinton: 73 degrees. Columbia: 74 degrees. Barnwell: 71 degrees. Mullins: 65 degrees.
Tropical Storm Bertha produced heavy rains in the Catawba and Pee Dee basins, exacerbating the ongoing flooding within the watersheds. The highest rainfall totals were reported in Clarendon and Williamsburg counties, with localized amounts of ten inches. Other parts of the state received at least half an inch; however, areas of the Lowcountry, Midlands, and Upstate observed less. While the past two to three months have had normal to above normal rainfall across much of the state, the rainfall totals over the month of May were below normal in the Lowcountry, especially in Beaufort and Jasper counties. The CoCoRaHS Condition Monitoring reports this week showed the areas that received the heavy rainfall (with mildly to severely wet reports) and near normal to dry conditions in Beaufort County. The observers noted that the recent rain helped ease some of the dry conditions.
Several rivers reached minor to moderate flood stage due to the rainfall across the state and within the headwaters in North Carolina. The USGS streamflow data from the gauges above the Fall Line show the values were much above normal to high values at 14- and 28-day average streamflow compared to historical data.
