 Later that day, Hurricane Daniel organized into a very symmetric cyclone with a distinct eye about 30 miles (45 km) in diameter.Upon attaining Category 4 status on the Saffir-Simpson Hurricane Scale, the cyclone resembled the appearance of an annular hurricane; an annular hurricane is one with a large and symmetric eye, surrounded by a thick ring of intense convection, and usually is able to maintain its intensity and structure for several days.On July 21 the hurricane underwent another eyewall replacement cycle.