Complex sentence: Shortly after reaching hurricane strength, the hurricane began undergoing explosive deepening subsequent to the development of a "pinhole" eye 9 miles (14 km) in diameter, surrounded by a ring of deep convection of about -125 ° F (-87 ° C).
Split into simpler sentences: Shortly after reaching hurricane strength, the hurricane began undergoing explosive deepening, subsequent to the development of a "pinhole" eye 9 miles (14 km) in diameter. This small eye was surrounded by a ring of deep convection, with cloud-top temperatures of about -125 ° F (-87 ° C).