The potential impacts of Hurricane Florence caused Hurricane Watches to be issued for the Carolinas on Tuesday morning while the approach of Tropical Storm Isaac also caused Watches to be issued for some of the Lesser Antilles. At 11:00 a.m. EDT on Tuesday the center of Hurricane Florence was located at latitude 26.7°N and longitude 65.3°W which put it about 905 miles (1455 km) east-southeast of Cape Fear, North Carolina. Florence was moving toward the west-northwest at 16 m.p.h. (26 km/h). The maximum sustained wind speed was 130 m.p.h. (210 km/h) and there were wind gusts to 155 m.p.h. (250 km/h). The minimum surface pressure was 950 mb. A Hurricane Watch was in effect for the portion of the coast from Edisto Beach, South Carolina to the North Carolina-Virginia border including Pamlico and Albemarle Sounds.
Hurricane Florence was nearing the end of an eyewall replacement cycle on Tuesday morning. A thin ring of showers and thunderstorms around the center of circulation was all that was left of the original eyewall. A larger ring of thunderstorms surrounded an eye with a diameter of 36 miles (58 km). Several other bands of showers and thunderstorms surround the new, larger eyewall. Storms near the core of Hurricane Florence generated strong upper level divergence which pumped mass away from the hurricane.
The eyewall replacement cycle temporarily weakened Hurricane Florence, but it also made the circulation larger. Winds to hurricane force extended out about 40 miles (65 km) from the center of circulation. Winds to tropical storm force extended out about 150 miles (240 km) from the center. The Hurricane Intensity Index (HII) for Hurricane Florence was 25.1. The Hurricane Size Index (HSI) was 15.3 and the Hurricane Wind Intensity Size Index (HWISI) was 40.4.
Hurricane Florence will be moving through an environment favorable for strong hurricanes. Florence will move over water where the Sea Surface Temperature is near 29°C. It will move through a region where the upper level winds are weak and there will be little vertical wind shear. Hurricane Florence is likely to strengthen during the next 24 hours, but additional eyewall replacement cycles could cause the intensity to fluctuate.
Hurricane Florence will move around the western end of the subtropical high pressure system over the western Atlantic Ocean. The high will steer Florence in a general west-northwesterly direction. On its anticipated track the center of Hurricane Florence could approach the coast of North Carolina and South Carolina on Thursday. It will very likely be a major hurricane at that time.
Tropical Storm Isaac moved steadily toward the Lesser Antilles and Watches were issued for some of those islands. At 11:00 p.m. EDT on Tuesday the center of Tropical Storm Isaac was located at latitude 14.6°N and longitude 49.7°W which put it about 775 miles (1250 km) east of the Lesser Antilles. Isaac was moving toward the west at 16 m.p.h. (26 km/h). The maximum sustained wind speed was 70 m.p.h. (110 km/h) and there were wind gusts to 85 m.p.h. (135 km/h). The minimum surface pressure was 996 mb. Hurricane Watches were in effect for Guadeloupe, Martinique and Dominica. Tropical Storm Watches were in effect for Antigua and Montserrat.
Elsewhere over the tropical Atlantic Ocean, Hurricane Helene moved far south of the Azores. At 11:00 a.m. EDT on Tuesday the center of Hurricane Helene was located at latitude 16.5°N and longitude 34.3°W which put it about 1550 miles (2495 km) south-southwest of the Azores. Helene was moving toward the northwest at 12 m.p.h. (19 km/h). The maximum sustained wind speed was 110 m.p.h. (175 km/h) and there were wind gusts to 130 m.p.h. (210 km/h). The minimum surface pressure was 966 mb.