Debby's Flood Threat To Spread Across Southeast, Northeast | Weather.com (2024)

Tropical Storm Debby has slowed to a crawl off the Southeast coast and its flooding rain threat will continue in that region the next couple of days while also spreading toward the mid-Atlantic and Northeast by Friday.

(L​IVE UPDATES: The Latest On Debby's Impacts)

H​ere's where Debby is now and where it will head next. Debby is centered south-southeast of Charleston, South Carolina. It's producing scattered bands of rain from South Carolina to eastern North Carolina right now, but no flash flood warnings are in effect. Some drier air has wrapped into Debby, so it lacks the core of thunderstorms near its center most tropical storms have.

T​he top storm rainfall totals for each state so far are 19.67 inches near Lake City, Florida; 17.27 inches near Summerville, South Carolina; 13.44 inches near Rincon, Georgia; and 7.22 inches near Calabash, North Carolina.

(​MAPS: Rainfall Tracker And Historical Perspective)

D​ebby will remain just offshore of the Southeast coast Wednesday, where it will meander before sliding back inland early Thursday. While it could restrengthen a tad more, the main result of the slowed forward motion is that its impacts in the Southeast, especially serious flooding, will be prolonged.

The slower a tropical system moves, the greater the rainfall. A study released last year by the NHC found rainfall flooding was responsible for the most direct U.S. deaths from tropical storms and hurricanes since 2013.

D​ebby's remnants will then spread toward the mid-Atlantic and Northeast Friday into early Saturday while interacting with a pair of fronts, resulting in heavy rain across those regions.

Major flooding is the number one concern with Debby going forward. NOAA has issued their highest level of flood outlook called a high risk for the next couple of days in the Southeast, shown in pink on the map below. Much of the mid-Atlantic and Northeast, especially from central Pennsylvania to upstate New York and Vermont, is also under a heightened flood risk Friday.

C​onsiderable flash flooding and river flooding is possible in all of those areas.

(MORE: Why You Should Pay Attention To High Risk Flood Forecasts)

H​ere's the timing of the most serious flood threat for the next few days, based on excessive rainfall outlooks from NOAA's Weather Prediction Center.

• W​ednesday-Wednesday Night: middle and lower South Carolina and eastern North Carolina into southeast Virginia.

• T​hursday-Thursday Night: much of eastern South Carolina, central and eastern North Carolina and southern and central Virginia.

• Friday-Friday Night: Northern South Carolina and North Carolina northward through the mid-Atlantic, central Appalachians and Northeast.

H​ere's a look at how much rainfall to expect, based on the latest National Hurricane Center Forecast:

• S​outh Carolina and southeast North Carolina: Expect an additional 3 to 9 inches with locally higher amounts. Storm totals including what has already fallen could be as high as 25 inches in South Carolina and 15 inches in southeast North Carolina.
• P​iedmont of South Carolina to Virginia: Totals could be 3 to 7 inches, with locally higher amounts up to 10 inches possible.
• M​aryland to upstate New York and Vermont: These areas could see 2 to 4 inches of rain, with local amounts up to 6 inches.

Tropical-storm-force winds continue to be a threat along the Southeast coast. Tropical storm warnings cover parts of South Carolina to southeast North Carolina as far north as Surf City, as shown below. The warnings include Charleston and Myrtle Beach.

Tropical storm conditions (39 to 73 mph sustained winds) could last into Thursday in these areas.

Stronger wind gusts over 40 mph, coupled with increasingly soaked ground from heavy rain, will trigger more power outages, downed trees and tree damage.

Storm-surge flooding is possible in low-lying areas of the Southeast coast. Inundation from storm surge could reach 1 to 3 feet above normal tide levels if the peak surge arrives at high tide from the northeast South Carolina coast to Ocraco*ke Inlet. High tides along the South Carolina coast are generally around 10 a.m. and p.m. EDT the next few days.

I​solated tornadoes remain a possible threat. Through Wednesday night, and a tornado or two could spin up from northeast South Carolina into eastern North Carolina. Thursday's chance for a few tornadoes will be in eastern North Carolina and southeast Virginia.

H​ere's a recap of Debby so far. Debby formed from a tropical wave the National Hurricane Center first started highlighting for possible development in the Atlantic on July 26.

Dry air kept it from developing for days as it tracked toward the northern Caribbean Islands. Tropical Depression Four then formed at 11 p.m. EDT on Aug. 2 near Cuba and strengthened into Tropical Storm Debby late on Aug. 3 in the southeast Gulf of Mexico.

D​ebby intensified into a hurricane at 11 p.m. on Aug. 4 ahead of its landfall near Steinhatchee, Florida, on the morning of Aug. 5.

• S​unday's notable impacts: Wind gusts reached between 50 to 70 mph along the immediate Florida Gulf Coast in the evening, including a gust to 70 mph at the Skyway fishing pier in Manatee County. Gusts to 60 mph gusts were reported in Clearwater, Sarasota and St. Petersburg. Several feet of storm surge was reported from Fort Myers Beach to Cedar Key. More than a foot of rain fell in parts of western Florida, including the Sarasota metro area.
• M​onday's notable impacts: Winds gusted over 60 mph in Florida's Big Bend region, with a top gust to 76 mph near Chiefland in Levy County. Moderate coastal flooding from a water rise 6 feet above normal was observed in Cedar Key. A rain-wrapped tornado downed trees, power lines and damaged structures in Edisto Beach, South Carolina, late Monday night, according to the National Weather Service. Downed trees and some downed power lines were reported across Berrien and Thomas Counties, Georgia. Rainfall totaled up to 13 inches in parts of north Florida near the track Debby's center. Flash flood emergencies, the highest level flood alert, were issued in north Florida's Baker, Columbia, Hamilton and Suwannee Counties. Flood water entered homes and other structures throughout Suwannee County, according to the National Weather Service. Flood water entered some structures in Valdosta, Georgia, early Monday evening. Street flooding was reported in parts of Charleston, South Carolina; and Savannah, Georgia, Monday. At least two tornadoes caused damage Monday night on Edisto Island and in Moncks Corner, among other locations near the South Carolina coast.

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