Hurricane Irma strengthened rapidly as it moved over the tropical Atlantic Ocean. At 11:00 a.m. EDT on Thursday the center of Hurricane Irma was located at latitude 16.9°N and longitude 33.8°W which put it about 1845 miles (2975 km) east of the Leeward Islands. Irma was moving toward the west-northwest at 10 m.p.h. (16 km/h). The maximum sustained wind speed was 100 m.p.h. (160 km/h) and there were wind gusts to 120 m.p.h. (195 km/h). The minimum surface pressure was 979 mb.
Hurricane Irma intensified rapidly on Thursday morning. A circular eye developed at the center of circulation and a ring of strong thunderstorms surrounded the eye. Numerous bands of showers and thunderstorms developed outside the core of Irma. Hurricane Irma has a very circular, symmetrical shape. Thunderstorms in the core of Irma were generating strong upper level divergence which was pumping mass away in all directions from the hurricane.
Hurricane Irma will move through an environment favorable for intensification during the next few days. Irma will move over water where the Sea Surface Temperature is near 28°C. Irma is under the western end of an upper level ridge, but the upper level winds are weak and there is not much vertical wind shear. Irma is likely to intensify during the next few days and it is forecast to become a major hurricane. Hurricanes that intensify rapidly often develop concentric eyewalls, which cause fluctuations in their intensity. It is highly likely that Hurricane Irma will go through one of more eyewall replacement cycles which will cause temporary fluctuations in the wind speed. Eyewall replacement cycles often result in a larger hurricane and Hurricane Irma has the potential to develop into a big classic Cape Verde hurricane.
Hurricane Irma is nearing a weaker region in the subtropical ridge to its north. The weakness is allowing Irma to move toward the west-northwest. The ridge is expected to strengthen and steer Hurricane Irma more toward the west or west-southwest during the next few days. On its anticipated track Hurricane Irma is forecast to be a major hurricane east of the Leeward Islands in five days. The uncertainty about the future track of Hurricane Irma increases after that time. People around the western Atlantic need to monitor the progress of Hurricane Irma.