The Atlantic is extremely active today, with six – SIX! – systems currently being monitored by the National Hurricane Center. The most serious and strongest of these systems is Hurricane Florence, which has weakened to a Category 3 hurricane but is still expected to bring potentially catastrophic impact to the coast of the Carolinas. In addition, Hurricane Helene is gradually weakening as it heads for a less favorable environment, and Tropical Storm Isaac east of the Caribbean has become very poorly organized this afternoon due to wind shear. The National Hurricane Center (NHC) has also initiated advisories on newly formed Subtropical Storm Joyce over the central subtropical Atlantic. This makes 2018 the first Atlantic season since 2008 to feature four named storms active at once. There are also two systems being monitored by the NHC for development: Invest 95L in the Gulf of Mexico, and the potential for a low pressure area to form near Bermuda in a few days.

Florence weakens slightly, but is still a very powerful hurricane

Hurricane Florence is gradually losing strength as it moves quickly northwestward towards the eastern United States. As of 8:00 p.m. EDT Wednesday, Hurricane Florence was centered near 31.5°N 73.2°W, and was moving northwestward at about 16 mph. Maximum sustained winds were 100 knots (115 mph), with an estimated minimum pressure of 956 mb. Florence has not strengthened as much as anticipated, likely due to persistent eyewall replacement cycles and dry air entrainment. Though Florence is expected to remain in a low-shear, warm water environment for the next 24 hours or so, a recent microwave pass indicated that inner core structure of Florence has degraded somewhat, which is an indicator that significant restrengthening is unlikely at this point. As Florence approaches the coast, some additional weakening is possible. Even though Florence has weakened slightly, it remains a very dangerous major hurricane, and its wind field has actually expanded. Florence could produce life-threatening storm surge of up to 13 feet along parts of southeastern North Carolina and northeastern South Carolina.

Models have come into better agreement on Florence’s track. There is now high confidence that Florence will make landfall, but the exact location of landfall remains uncertain. Florence should continue on its quick northwestward motion through late Thursday. At that time, Florence is expected to slow down and take a turn to the west-southwest, passing south of New Hanover and Brunswick Counties. It is possible Florence could make landfall in this area, but the current NHC forecast predicts that the center of Florence will remain just south of this area. Florence is expected to continue on its west-southwestward motion, and it is possible Florence could actually make landfall in Northeastern South Carolina on Saturday. It is important to stress that Florence is a large storm and impacts will be felt far from the center. The highest storm surge with Florence is likely to be along the Crystal Coast of North Carolina, where a surge of up to 13 feet is possible.

For more detailed information on Florence for your area, check your local weather office. There are also many watches and warnings currently in effect, you can read them here.

Helene weakening over the eastern Atlantic

Hurricane Helene is gradually weakening over the eastern Atlantic as it moves into cooler waters and stronger shear. As of 5:00 p.m. EDT Wednesday, Hurricane Helene was centered near 21.4°N 36.7°W, and was moving northward at about 14 mph. Maximum sustained winds were 75 knots (85 mph), with an estimated minimum pressure of 980 mb. Helene should gradually weaken over the coming days, but is likely to remain a tropical cyclone for the next four days or so. Interests in the Azores should monitor the progress of Helene, as it could pass very near the northwestern Azores as a tropical storm. It is possible that Helene could interact with Subtropical Storm Joyce later this week.

Isaac very poorly organized east of the Caribbean, could open up into a wave at any time

Due to strong wind shear, the low-level circulation of Isaac has become exposed to the west of the poorly organized convective mass. As of 8:00 p.m. EDT Wednesday, Tropical Storm Isaac was centered near 15.4°N 57.2°W, and was moving westward at about 20 mph. Maximum sustained winds were 50 knots (60 mph), with an estimated minimum pressure of 1003 mb. Isaac is likely to continue to weaken during the next couple days as it enters the Caribbean due to continued strong shear. The official National Hurricane Center (NHC) forecast predicts Isaac will survive in the Caribbean for several days as a tropical storm, though this is uncertain. In my opinion, it is possible Isaac could open up into a wave as soon as tomorrow. It is possible that environmental conditions could become more favorable in a few days, but there may not be enough left of Isaac to take advantage of the improved environment. A Tropical Storm Warning remains in effect for Martinique, Dominica, and Guadeloupe.

SS Joyce forms in the Northeastern Atlantic, likely no threat to land

The Atlantic’s tenth named storm of 2018 was named Wednesday afternoon. As of 5:00 p.m. EDT Wednesday, Subtropical Storm Joyce was centered near 34.3°N 41.9°W, and was moving southwestward at about 6 mph. Maximum sustained winds were 40 knots (45 mph), with an estimated minimum pressure of 1006 mb. Some slight strengthening is possible before Joyce likely dissipates in a few days. Joyce is not expected to pose any threat to any land areas.

Invest 95L may develop over the Western Gulf of Mexico tomorrow

A broad area of low pressure over the Northwestern Gulf of Mexico – Invest 95L – could develop into a tropical cyclone on Thursday. The NHC gives 95L a 70 percent chance of development, within both 48 hours and five days. 95L only has a narrow window to develop, and global models show little to no development. The next name on the Atlantic naming list is Kirk.