Complex sentence: Radar data obtained the next day, however, showed convection deepening in the northern semicircle of the storm; bands of thunderstorms developed closer to the center over the southeastern periphery, and surface, buoy and ship observations indicated sustained tropical-storm-force winds.
Split into simpler sentences: Radar data obtained the next day, however, showed convection deepening in the northern semicircle of the storm; over time, bands of thunderstorms also developed closer to the center over the southeastern periphery. Furthermore, surface, buoy and ship observations indicated sustained tropical-storm-force winds.