Tropical storm Dennis, its top wind gusts at 55 mph, spread gale-force winds and torrential rains over the Florida Keys and the state's southern peninsula yesterday, giving residents a scare but causing little immediate damage.

Dennis meandered northward during the afternoon. It had strengthened during the morning but stabilized by midafternoon, forecasters said. However, they emphasized that the storm could get stronger and reach hurricane force at any time. Hundreds of people were evacuated from low-lying oceanside campgrounds.

At 9 p.m., the center of the storm was located near latitude 24.9 north, longitude 81.3 west, over Florida Bay, just north of the lower keys, or 110 miles southwest of Miami. Forecasters said Dennis remained stationary during the evening but was expected to resume a slow northward drift during the night. Tides remained two to four feet above normal along the southeast coast and along the keys.

Although National Hurricane Center director Neil Frank said, "the strengthening trend noticed this morning has stabilized . . . conditions remain favorable for strengthening."

"It's getting fairly close to land, and the eye essentially is over the lower part of the Florida Keys," Frank said. "If it stays close to the coastline, it would certainly prohibit any kind of great strengthening.

"But if the center forms and the winds concentrate someplace in the keys or Floriday Bay, then we might have to post warnings for the Florida west coast," Frank said.

But even if Dennis reached hurricane status -- sustained winds of more than 74 mph -- Frank said the effect on southern Florida probably would not be severe.

"The threat primarily is to the marine community," Frank said. "The storm already has made landfall partly -- the squalls all over south Florida are the outer fringes."

A hurricane watch remained in effect for all of South Florida below a line from West Palm Beach to Fort Myers.

A steady stream of traffic flowed north on U.S. 1 through this island in the center of the chain between Key Largo and Key West. Most vehicles towed small boats, mobile homes or trailers.