Hurricane Dennis weakened and was dowgraded to a tropical storm tonight, but was still dangerous and had taken an ominous turn toward the west, raising fears that it might yet strike the Virginia coast and cause widespread damage here.

Late tonight, the National Weather Service said that "any short-term intensification could bring [Dennis] back to hurricane strength" and hurricane watches remained in effect.

Forecasters puzzled over a half-dozen different and equally likely scenarios as the day wore on. The most serious suggested that Dennis could continue today's westward course and head toward Hampton Roads and then up the James River toward Richmond. Forecasters say that would cause widespread flooding and wind damage throughout a lower Chesapeake Bay region already battered by two days of high winds, dangerous surf and occasional rain.

As powerful waves and gale-force winds flattened beaches along the coast, washing sand out to sea, many vacationers packed up minivans with barely used boogie boards and beach umbrellas and headed home. [Story, Page B1.]

The National Weather Service, charting the storm's westward drift, issued a hurricane watch from Cape Lookout, N.C., to Chincoteague, Va., including the lower Chesapeake. A tropical storm warning was already in effect for those areas. Dennis's top winds were down to 70 miles per hour late tonight, just below hurricane strength.

"It's an incredibly, incredibly difficult forecast," said Tim Armstrong, a National Weather Ser-vice meteorologist.

Emergency officials said they were carefully watching Dennis's travel pattern because the stall and drift reminded them uncomfortably of last August's Hurricane Bonnie, which turned back to land after briefly heading to sea.

Mark Marchbank, deputy coordinator of emergency management for Virginia Beach, said that if Dennis is still drifting toward the coast on Wednesday, officials will order low-lying areas near the shore evacuated and begin battening down public buildings.

"Bonnie taught us, `Never say never,' " Marchbank said. "We got a good lesson in the unpredictability of storms."

Dennis sat about 105 miles east of Cape Hatteras, N.C., tonight -- too far to cause serious damage but too close for comfort for much of the mid-Atlantic coast.

In North Carolina, vacationers and business owners who had believed the storm threat was over prepared instead for a possible new onslaught. Tourists were ordered to evacuate low-lying sections of Nags Head along the Outer Banks. About 4,000 customers in Dare and Currituck counties along the northern Outer Banks were already without power, and five beachfront houses in Rodanthe, on the north end of Hatteras Island, collapsed into the sea.

At Assateague State Park in Maryland, dozens of campers were evacuated due to flooding and sand drifts.

Some beach tourists tried to salvage a holiday that seemed -- at best -- likely to remain gray, windy and soggy into the weekend.

Barbara Levengood, of Reading, Pa., spent most of the day in Rehoboth Beach, Del., driving around with her husband and their two young sons. She said they had no idea whether they should stay or go because no one could tell them whether Dennis would stay or go.

"We were going to wait this afternoon to see what would happen, but we still don't know," she said. "We'll probably just drive home."

She said it was difficult to find activities for the family when the beaches were flooded. "They're too young to go to the movies," she said, gesturing toward her sons, one sitting in a stroller facing the ocean and the other in his father's arms. "And we can't go bowling."

Monica and Stephen Purcell also were fighting the boredom of an overcast day at the beach. The Philadelphia couple and their two children, Stephen, 7, and Jennifer, 5, are spending the week at Cape May, N.J. The waters there also were off-limits to swimmers, so the family took the ferry to Lewes, Del., to check out Rehoboth.

They said they had no intentions of letting the unpredictable storm ruin their fun. "We'll stay, absolutely," Stephen Purcell said. "There's no reason to go home. What would we do there?"

In Virginia Beach, tourists and locals alike tried to squeeze some recreation out of the last week of vacation -- filling malls, climbing lighthouses and visiting the Virginia Marine Science Museum.

"I'm just bummed out," said 17-year-old Joe Iszkiewicz, who drove all the way from Buffalo in search of sun, swimming and girls. Instead, he spent the day at the museum, where an equally cranky seal used its flippers to splash water on Iszkiewicz and other guests ogling its pool.

Virginia Beach began the day looking like the victim of a tan blizzard, with drifts of sand giving the battered boardwalk the soft, rounded edges of a winter storm. Waves swelled two to four feet higher than normal, making swimming impossible. Salty spray shorted out electrical lines, causing thousands to lose power. The beach shops and hotels along Atlantic Avenue, the beach's main drag, went dark for part of the afternoon.

Churning seas caused beach erosion ranging from mild to moderate, far worse than that caused last year by Bonnie, whose winds stripped off roofs and knocked out power to hundreds of thousands of customers.

Dennis is acting more like the northeasters that regularly menace the coast with days of high surf and winds. Virginia Beach officials say they budget $1.5 million to $2 million each year to replenish lost sand.

"It already is much worse than Bonnie," said Phill Roehrs, coastal engineer for Virginia Beach. "Bonnie was a fast strike. She blew through here."

Andy Booth, 19, sat on his front porch with two friends in the beachfront community of Willoughby Spit, a sliver of land that juts out from Norfolk. Ocean water filled the street in front of his home. Frequent flooding from storms long ago filled his once-finished basement with sand, but he still grumbled about losing the last summer weekend before returning to school in Massachusetts.

"It's a pain," said Booth, who last year during Bonnie kayaked around his neighborhood. "It ruins my tanning schedule."

But keeping a stiff upper lip were Clive Seagers, 46, and his wife, Linda, 39. Rain followed their vacation from Miami to Virginia Beach, but they resisted the urge to complain.

"We're from England," Linda Seagers explained.

"This is normal weather," Clive added.

Staff writers Sue Anne Pressley in North Carolina and Jackie Spinner in Rehoboth Beach and wire services contributed to this report.