Debby continues to slam most of South Carolina with extreme rainfall. Gusty winds have been affecting coastal areas, and we've seen several tornadoes hit near our coast. Storm surge has been surprisingly absent so far, but our coastline remains at risk. We'll continue to deal with these impacts for another 48 hours or so as Debby wanders over our coast or just offshore.
This will bring much of the state another 48-72 hours of heavy rainfall, so the extreme rain and flooding remain our primary problem from Debby.
The forecast rainfall above (for this morning through Friday night) comes on top of 48-hour rainfall totals of generally 8-14 inches (through 8 a.m. today) across the Lowcountry, where severe flooding is ongoing. Another 6-12 inches of rainfall will make the flooding much worse. Flash flooding will also be widespread across the Pee Dee region, and major river flooding is likely to occur in the coming days across this region, especially considering the amount of rain that will fall on the land of vinegar sauce that drains into our rivers. Comparisons to October 2015, Matthew, and Florence you'll hear for this area are all valid as we have a historic rain and flooding event underway.
Adjacent areas of the Central Savannah River Area and Midlands also will see extreme rainfall and flooding, along with the Catawba River Area. Less rain, mostly beneficial, will fall over the Upstate, but isolated flash flooding is a concern there.
Storm surge hasn't been much of an issue so far despite gusty onshore winds, and I will entertain no complaints about that. However, it remains a concern for our coastline. A surge of about two feet remains possible across the Lowcountry coastal areas, and a 2-4 foot surge may occur along the Grand Strand Wednesday night into Thursday, assuming Debby follows the forecast track.
Gusty winds have caused damage over parts of South Carolina, and minor wind damage remains a concern. With Debby forecast to track out over the Atlantic and regain some strength before moving ashore again, another period of gusty winds is a threat, mostly for the Grand Strand and further inland over the Pee Dee region Wednesday night into Thursday. The odds of Debby becoming a hurricane before moving back ashore have dropped to near zero, but there is a risk for minor to moderate wind damage.
So far, we have reports of up to six tornadoes in South Carolina from Debby, five in the Lowcountry, and one in Horry County. The actual count of tornadoes won't be known until the National Weather Service surveys the damage and that won't happen until after Debby moves away. The risk for isolated tornadoes continues this afternoon along our coast, especially along the Grand Strand, and a tornado watch is currently in effect.
This watch is in effect until 5 p.m., but we will see more watches issued through the next two days, especially for the Pee Dee region. So, remain alert for more tornado watches and warnings; be ready to take shelter and decide on a place to go in advance because you often don't get much lead time for tornado warnings. You can find more tornado safety information from the National Weather Service.
Flooding, tornadoes, and wind, oh my! Debby is bringing a variety of serious hazards to South Carolina. However, you shouldn't be caught unprepared. If you need help with preparation or advice on what to do during a storm, SCEMD and Ready.gov have you covered.
We continue to track the tropical wave over the Caribbean Sea. It's not causing much thunderstorm activity today, and it's increasingly looking like it will take the low road through Central America and pass nowhere near us. Two other tropical waves are over the middle of the tropical Atlantic and off the West African coastline. While both need to be monitored and could develop in several days, it is far too soon to say whether either will affect South Carolina.
This loop of visible satellite images from midday Tuesday shows Debby over South Carolina and tropical waves over the Caribbean and tropical Atlantic.
Source: University of Wisconsin RealEarth