Complex sentence: A broad cyclone, Charley gradually intensified, and a single ring of convection around the center developed into an eyewall; at 1200 UTC on August 17 it attained hurricane status about 13 mi (21 km) off the North Carolina coastline.
Split into simpler sentences: A broad cyclone, Charley gradually intensified, and a single ring of convection around the center developed into an eyewall. At 1200 UTC on August 17, it attained hurricane status about 13 mi (21 km) off the North Carolina coastline.