Tropical Storm Ian strengthened south of Grand Cayman on Sunday evening. At 11:00 p.m. EDT on Sunday the center of Tropical Storm Ian was located at latitude 17.3°N and longitude 81.4°W which put it about 140 miles (225 km) south of Grand Cayman. Ian was moving toward the northwest at 13 m.p.h. (20 km/h). The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h). The minimum surface pressure was 989 mb.
Hurricane Warnings were in effect for Grand Cayman and for the Cuban provinces of Isla Juventud, Pinar del Rio and Artemisa. Tropical Storm Warnings were in effect for the Lower Florida Keys from Seven Mile Bridge to Key West including the Dry Tortugas. Tropical Storm Warnings were also in effect for the Cuban provinces of La Habana, Mayabeque and Matanzas. A Tropical Storm Watch was in effect for the portion of the coast from Englewood to Chokoloskee, Florida. Tropical Storm Watches were also in effect for Little Cayman and Cayman Brac.
Tropical Storm Ian began to intensify quickly on Sunday evening. Microwave satellite images indicated that an eye was forming at the center of Ian’s circulation. The developing eye was surrounded by broken ring of thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the center of Tropical Storm Ian. Storms near the center of circulation generated strong upper level divergence that pumped large quantities of mass away from the tropical storm. The removal of mass was allowing the surface pressure to decrease rapidly. Winds to tropical storm force extended out 70 miles (110 km) from the center of Ian’ circulation.
Tropical Storm Ian will move through an environment very favorable for intensification during the next 36 hours. Ian will move over water where the Sea Surface Temperatures are near 30˚C. It will move through a region where the upper level winds are weak and there will be little vertical wind shear. Tropical Storm Ian is likely to intensify rapidly during the next 36 hours. Ian is likely to strengthen to a hurricane during the next 12 hours. Ian is likely to intensify to a major hurricane during the next 36 hours.
Tropical Storm Ian will move around the western end of a high pressure system over the western Atlantic Ocean. The high pressure system will steer Ian toward the northwest during the next 24 hours. Ian will move toward the north when it reaches the western end of the high pressure system. On its anticipated track the center of Tropical Storm Ian will pass west of Grand Cayman on Monday. Ian could be near western Cuba on Tuesday morning. Ian could be a major hurricane when it approaches western Cuba. Ian could be southwest of Tampa, Florida on Wednesday afternoon.