THIS WEEK'S TOP STORIES
The flood: Caught between two storm, area avoided the worst
It was a storm with no name.
In three and a half days, it dumped between 12 and 17 inches of rain on the Waccamaw Neck.
“Everybody was making the assumption it was Joaquin. It was not. It was an upper-level low,” said Michael Caropolo, meteorologist in charge at the National Weather Service office in Wilmington, N.C.
What state officials called a “1,000-year storm,” actually had less of an impact on the Waccamaw Neck because of the storm’s structure. “The upper-level low over the Southeast was tapping a moisture plume from the Gulf of Mexico and the Caribbean,” Caropolo said. “Another plume was being fed by Joaquin,” a hurricane that passed off the East Coast.
“There was one to the north and one to the south, so you guys were lucky,” Caropolo said.
The plumes of moisture pivoted over the course of the storm, moving from south to east to southeast. “Certain areas were under that plume for the whole week,” he said. That included Kingstree, where nearly 25 inches of rain was recorded. “You guys were close to being pummeled with another 10 inches of rain,” Caropolo added.
The records in the Wilmington office, which is responsible for eastern South Carolina, go back 144 years.
The term “100-year storm” is a statistical expression of a storm that has a 1 percent chance of occurring in a given year. “A 1,000-year storm makes people understand the severity. That’s how rare an event like this is,” Caropolo said. “For most people, this is a once-in-a-lifetime event. It could happen next year, but the odds are very small.”
The concept is similar to the Saffir-Simpson scale that classifies hurricanes by wind speed. They are large-scale events so not everyone experiences the same level of severity. “We run into that all the time,” Caropolo said. “People say ‘I lived through a Cat. 3.’ No you didn’t.” At least not if they were on the outer edge of the storm.
For the Waccamaw Neck, the rainfall figures were similar to Hurricane Floyd and other “tropical events,” he said.
The National Weather Service figures come from citizen observers who are part of the Community Collaborative Rain, Hail and Snow Network, known as CoCoRaHS.
The agency does use Doppler radar to measure rainfall, “but it isn’t 100 percent accurate,” Caropolo said. “Rainfall is variable if you get under a cell. It’s highly variable.”
The Wilmington office lists five network sites in the Pawleys Island area and three in the Murrells Inlet area.
One off the South Causeway reported 14.9 inches of the rain during the storm. In the 10 months prior to the storm, the station reported 41.9 inches of rain and in 2014 the total was 51.6 inches.
At a site on Wachesaw Road, 16.7 inches of rain was reported during the storm, with totals for the year-to-date (41.9) and in 2014 (51.6) matching those at the South Causeway station.
The highest rainfall in the county during the storm was 19.9 inches, reported at a site 5 miles outside Georgetown.
Speaking by phone from his office in Wilmington, Caropolo paused Tuesday to take a call from Gov. Nikki Haley during a briefing with emergency management officials. The focus was on the rivers, he said.
“There is a lot of water in the channels and it’s not draining quickly,” Caropolo said. The east wind that came with the storm also forced water into Winyah Bay and the Waccamaw River.
Because they are influenced by the tides, “the water doesn’t have enough time to drain out,” he said.
Rivers are expected to reach their peak flood stage next week. “We’re talking historic amounts here,” he added.
But the forecast for the next several days includes sunshine, Caropolo said. “It’s going to be good conditions for drying out.”