Wilmington, N.C. ? Shawn Spencer gazed across the lake covering his front yard and wondered how to drain the 2 feet of floodwaters left by heavy thunderstorms.

But he knew more water was on the way.

“The bad thing is, the storm isn’t even here yet,” Spencer said Thursday, referring to Tropical Storm Ernesto as it swirled toward the Carolinas and picked up steam with surprising speed in the warm waters of the Atlantic.

While Ernesto built toward hurricane strength, forecasters worried it could bring half a foot of rain, swelling rivers across North Carolina just a day after thunderstorms soaked the state with 3 to 8 inches.

Virginia’s governor declared a state of emergency and hundreds of National Guardsmen were activated there and in the Carolinas. Forecasters issued a hurricane watch for the northern half of the South Carolina coast and the southern portion of the North Carolina shore.

By midafternoon, Ernesto’s northern edge brought rain to the states’ eastern counties, causing some flooding and forcing residents in Spencer’s neighborhood to wade or use kayaks to reach dry land.

The storm’s winds were 70 mph, just short of the 74 mph threshold for a hurricane. Its winds increased steadily through the day from around 40 mph as the storm drew energy from the warm water.

“In the world of meteorology, it’s just one surprise after another,” said Tom Matheson with the National Weather Service in Wilmington.

Surfer Ian Howers carries his board under the pier in Tybee Island, Ga., before surfing the waves of Tropical Storm Ernesto. A hurricane watch was issued Thursday for the Carolina coast as Ernesto gained strength over the Atlantic and headed toward land.

By 9:45 p.m. CDT, Ernesto had dumped 8.19 inches of rain on the Wilmington area, a record for the date, the service said. The previous Aug. 31 record of 2.27 inches was set in 2002. The record one-day rainfall for the area was 13.38 inches from Hurricane Floyd on Sept. 15, 1999.

Just a day earlier, Ernesto had been downgraded to a tropical depression, not even making the grade as a tropical storm.

Ernesto’s wind was less a concern than the threat of flooding.

“We need some rain around here – just not all at once,” said Jean Evans, a convenience store worker on North Carolina’s Holden Beach.

The National Hurricane Center also warned of a storm surge of 3 feet to 5 feet in the Carolinas.

Ernesto briefly reached hurricane strength Sunday, but lost much of its punch crossing mountainous eastern Cuba and was a tropical storm of about 45 mph by the time it blew ashore Tuesday night in Florida. It weakened further as it moved over the state.