For the first time since the morning of August 23, no tropical cyclones are active in the Atlantic basin, as Lee and Maria have both transitioned into extratropical lows. There is only one disturbance that has a chance to develop in the short term – Invest 99L, which is located near the coast of Northeastern Florida. 99L has become better organized this evening, with thunderstorm activity increasing to the east of the center.

As of 00:00 UTC Sunday, Invest 99L was centered near 29.6°N 80.8°W. Maximum sustained winds were 35 knots (40 mph), with an estimated minimum pressure of 1012 mb. While 99L is producing winds to tropical storm force, surface pressures remain high, and have not fallen during the past few hours in northeastern Florida. A weak low pressure area has developed with 99L, and shower and thunderstorm activity has increased markedly during the past few hours. However, nearly all of the thunderstorm activity is east of the center due to moderate to strong westerly wind shear. While deep convection has increased, it is unclear how long it will persist. There is still a narrow window for 99L to develop into a tropical cyclone during the next day or so. The National Hurricane Center (NHC) gives 99L a 20 percent chance of development, both within 48 hours and five days. Even though tropical cyclone development is not particularly likely, there is a distinct possibility that 99L could become Tropical Storm Nate by Sunday morning. None of the reliable global models develop 99L into a tropical cyclone. The main threat with 99L, regardless if development occurs, is moderate to heavy rains along the eastern coast of Florida.

I will be back tomorrow with another post.