Complex sentence: Upon reaching peak strength, the hurricane possessed a 12 mile (19 km) wide surrounded by very deep convection, with the National Hurricane Center predicting it to attain major hurricane status and potentially significantly stronger if the center remained over open water.
Split into simpler sentences: Upon reaching peak strength, the hurricane possessed a 12 mile (19 km) wide surrounded by very deep convection. The National Hurricane Center predicted it to attain major hurricane status and potentially reach significantly higher winds if the center remained over open water.