Debby updates: Flash flooding, tornadoes target DC, Mid-Atlantic, Northeast

Debby is moving at just 3 mph, with its center located about 10 miles east of Savannah, Georgia, as of 5 p.m. ET.

Tornadoes are possible in South Carolina and North Carolina on Tuesday night.

After a day of heavy rainfall, the coastal cities of Savannah and Charleston, South Carolina, could see a few more inches of rain this week. Both cities are under flash flood warnings.

But going forward, the worst of the rain will be focused further north. Myrtle Beach, South Carolina; Wilmington, North Carolina; and Lumberton, North Carolina, are forecast to get hit the hardest over the next 24 to 36 hours.

More than 1,100 flights have been canceled within, into or out of the U.S. on Tuesday as Debby slams the Southeast and thunderstorms strike the Northeast. Ground stops are in place at the New York City area's three airports.

The threat of severe flooding is very high across South Carolina with Tropical Storm Debby "creeping across our state," South Carolina Gov. Henry McMaster warned on Tuesday.

The rain from the slow-moving storm may be particularly heavy from Myrtle Beach to the North Carolina border, the governor said.

Forty-eight state roads are closed due to flooding and 50 high-water vehicles are at the ready to respond, he said.

The highest rain total so far is south of Tampa, Florida, where about 19 inches of rain fell.

In Georgia, more than 11 inches of rain struck northwest of Savannah, and in South Carolina, 14 inches of rain was recorded between Charleston and Hilton Head Island.

On Tuesday afternoon, Debby is located about 10 miles southeast of Savannah and is crawling north at a very slow speed.

The heavy rain will stretch from Charleston to Wilmington, North Carolina, on Tuesday. Storm surge could reach 4 feet from Savannah to Cape Fear, North Carolina, and tornadoes are possible.

Flash flood warnings are in effect for Savannah, Charleston and Myrtle Beach, South Carolina. Rainfall rates could reach 1 to 2 inches per hour during the heaviest downpours, which will bring more flooding.

The worst of the rain is expected along the South Carolina-North Carolina border through Thursday evening. A rare "high risk" for flash flooding was issued from Charleston to Raleigh, North Carolina, where rain totals could climb to 25 inches through Thursday.

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