Tropical Storm Debby is back over water where it could restrengthen some off the Southeast coast, but its main threat continues to be potentially historic heavy rainfall that could produce catastrophic flooding in parts of the Southeast the next several days.
Debby’s moisture will also fuel a threat of flooding rain in the Northeast U.S. in the days ahead.
Debby is centered near Hilton Head Island, South Carolina, as a tropical storm. Its shield of rain extends from southeast Georgia and extreme northeast Florida to much of South Carolina, eastern and southern North Carolina and southern Virginia.
Flash flood warnings are in effect from eastern Georgia, including Savannah into the Lowcountry of South Carolina, including Charleston.
Parts of the Charleston metro have seen up to 14 inches of rain and more than 8 inches has fallen in Savannah, Georgia.
A tornado watch is in effect until 1 a.m. EDT from northeastern South Carolina to southeastern North Carolina.
Debby will remain just offshore of the Southeast coast, where it will meander before sliding back inland on Thursday. While it could restrengthen a little, 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.
The National Hurricane Center stated in their Tuesday discussion that “Debby is expected to produce potentially historic rainfall totals of 10 to 20 inches, with maximum amounts of 25 inches, bringing areas of catastrophic flooding across portions of the eastern half of South Carolina and southeast North Carolina through Friday”.
Moisture from Debby will also fuel a threat of significant flash flooding into the mid-Atlantic and Northeast U.S. along a pair of fronts with one sweeping through the region Tuesday, then lingering over the region into late week, followed by another front that will arrive Friday.
NOAA has issued their highest level of flood outlook called a high risk for the next few days, shown in pink on the maps below. These areas could experience damaging and life-threatening flash flooding and major river flooding.