Complex sentence: The system continued to organize early on July 28, and that afternoon, it developed a surface circulation and was declared Tropical Depression Four with the center located about 345 miles (555 km) southeast of New Orleans.
Split into simpler sentences: The system continued to organize early on July 28, and that afternoon it developed a surface circulation. It was declared Tropical Depression Four that same day with the center located about 345 miles (555 km) southeast of New Orleans.