Debby could cause life-threatening flash flooding, ‘catastrophic’ rainfall in Myrtle Beach
The National Weather Service’s flood forecast for the Myrtle Beach area is bleak as Tropical Storm Debby approaches Tuesday, Aug. 6, 2024.
The NWS released its daily storm briefing with updated threat levels for flash flooding due to “catastrophic amounts of rainfall” and storm surge.
The report listed the expected amount of rainfall between 10 to 15 inches, while some areas might experience 15 to 20. The NWS rates threat levels in five categories in increasing order of severity. ‘Little to No Impact’ is the lowest level, and ‘Extreme Impact’ is the highest. Based on the report’s assessment of threat levels, anticipated rain will have an Extreme Impact Tuesday, Aug. 6, 2024, through Thursday, Aug. 8, 2024.
NWS’s report also added that the flash flooding threat will remain until Friday. Steven Pfaff is the meteorologist-in-charge at the National Weather Service’s Wilmington Office, and he said that the rainfall had heightened the level of threatening flash flooding, as anticipated.
Indeed, the NWS marked all of Horry County for ‘Potential for extreme flooding rain’ in its Tuesday, Aug. 6, 2024 report. The report divided threat levels into four categories, with potential localized flooding rain presenting the slightest danger and potential for extreme flooding rain presenting the most.
Due to this rain, the Grand Strand area near the Waccamaw River and Little Pee Dee River are at risk of moderate to major flooding. The NWS tracks river levels for the Waccamaw River near Conway and the Little Pee Dee near Galivants Ferry.
The NWS categorizes flood-stage levels in order of severity, with the lowest being the ‘Action’ stage and the highest being’ Major Flooding.’
Currently, the NWS forecasts the Waccamaw River to reach a peak of 13.3 feet, designated as ‘Moderate Flooding’ sometime Friday, Aug. 9, 2024. The NWS forecasts the Little Pee Dee River to reach the ‘Major Flooding’ peak of 13.4 feet sometime Saturday, Aug. 10, 2024. The record water level for the Little Pee Dee River is 17.2 feet.
However, Pfaff added that the forecast river levels could change as the storm progresses.
The NWS is also projecting a serious storm surge of between 2 and 4 feet in Horry and Georgetown Counties, beginning Wednesday into Friday. Pfaff said the surge could impact areas near swashes, North Myrtle Beach, and Cherry Grove.
“Some coastal roads can become flooded, especially with high tide Wednesday into Friday morning pronounced, pronounced around the times of high tide versus the low tide timeframes,” Pfaff said. “Areas that have had significant erosion before, you know they’re going to be vulnerable spots.”
Indeed, the rain-induced flooding could be impacted as the storm reaches a specific weather phenomenon along the Grand Strand. Known as a “Col” or weather region where winds and high and low-pressure areas counteract each other.
A Col impacts the storm’s direction, and if Tropical Storm Debby moves towards the coastline after it exits, storm surge and winds could be more severe. Pfaff said Tropical Storm Debby is approaching the Col, slowing it until Thursday.
“The storm’s down to moving at six miles per hour, and it will continue to slow down here today and through Thursday, unfortunately,” Pfaff added.
