 A tropical wave emerged from the west coast of Africa on late on September 4 , 1999 and entered the Atlantic Ocean . The system trekked westward uneventfully and was unable to organize itself due to the influence of outflow from Hurricane Floyd . After Floyd moved northward , however , the system began developing convection as it traversed the Caribbean Sea . By September 16 the disturbance transitioned into a broad area of low pressure while tracking northwestward in the western Caribbean Sea . After two days the low had continued to intensify as it entered the southern Gulf of Mexico . Thunderstorm activity continued to increase in association with the weather system and a buoy in the eastern Gulf of Mexico recorded sustained winds of 35 mph ( 56 km / h ) . At 0600 UTC on September 19 , the system finally developed into Tropical Depression Ten , while located approximately 400 miles ( 640 km ) west @-@ southwest of St. Petersburg , Florida . The National Hurricane Center initiated advisories on the depression approximately four hours later . 
