New Delhi, July 21 -- Forecasters at the National Hurricane Center said on Monday (local time) that Tropical Storm Bertha formed over the Gulf of Mexico, south of the Florida Panhandle, in the evening. The storm is moving erratically toward populated coastal communities, raising concerns over heavy rainfall, storm surge, and strong wind gusts.

According to the Miami-based agency, the center of the tropical storm was situated at around 8 pm, some 110 miles (180 kilometers) south of Panama City, Florida, in the northern Gulf. The storm was packing sustained winds of around 40 mph (65 kph), and some additional strengthening is expected as it approaches land, news agency AP reported.

On Monday, the slow-moving system, which became the Atlan...