Tropical Storm Maria restrengthened into a minimal hurricane on Wednesday as it turned to the northeast over the subtropical Atlantic. Maria is heading out to sea, and is likely to become an extratropical cyclone on Saturday. Hurricane Lee became the fifth major hurricane of the 2017 Atlantic hurricane season on Wednesday morning when it strengthened into a category 3 hurricane over the open Atlantic, but has since weakened to a category 2 hurricane. Lee, like Maria, is expected to transition into an extratropical cyclone on Saturday.

Watches and Warnings discontinued as Maria accelerates northeast

Despite a ragged appearance, data from an Air Force Hurricane Hunter mission from this morning suggests that Maria has restrengthened into a category 1 hurricane. As of 11:00 p.m. EDT Wednesday, Maria was centered near 36.8°N 71.5°W, and was moving northeastward at about 7 mph. Maximum sustained winds were 65 knots (75 mph), with an estimated minimum pressure of 979 mb. Maria is expected to weaken only slowly during the next couple days as it accelerates to the east-northeast. Maria is expected to become post-tropical by Saturday evening as it moves over cooler waters, but baroclinic processes may slow the weakening rate after that time. It is possible that Maria’s extratropical remnants could affect the British Isles next week.

Lee becomes a major hurricane, but now weakening

On Wednesday morning, Lee strengthened into a category 3 major hurricane – the fifth of this very active 2017 Atlantic hurricane season. 2017 is now the first Atlantic hurricane season since 2010 with at least five major hurricanes. As of 11:00 p.m. EDT Wednesday, Lee was centered near 31.7°N 57.3°W, and was moving north-northwest at about 7 mph. Lee’s appearance has degraded a little during the last few hours, as the eye has become less distinct. Lee is likely to continue to gradually weaken through Friday as shear increases and waters cool. At that time, Lee is expected to accelerate to the northeast and become a post-tropical cyclone on Saturday.

A new disturbance to watch in the Atlantic

A trough of low pressure is producing an area of disturbed weather over the Northwestern Caribbean Sea south of Cuba. The disturbance is expected to move northward for the next couple of days, passing over Cuba and the Florida Straits. Some slight development of this disturbance is possible this weekend as it nears the eastern coast of Florida and the northwestern Bahamas. The National Hurricane Center (NHC) gives this disturbance a 10 percent chance of development within 48 hours, and a 20 percent chance within five days. Conditions are likely to become unfavorable for development by early next week, however. The 18Z Wednesday GFS model run predicted that this system would become a tropical cyclone over the weekend. The ECMWF model also supported some limited development. The 12Z Wednesday UKMET model run did not predict any development would occur. If this disturbance becomes a tropical storm, it will be named Nate. I believe this storm will be weak if it develops, and the primary threat will be heavy rain and flooding.

There are also some indications that a tropical cyclone could form over the Western Caribbean Sea at some point next week, but this genesis possibility remains fairly far out and it has not been mentioned on the NHC Tropical Weather Outlook.