Today, June 1st, marks the official start of the 2023 Atlantic hurricane season, and right on time, there is a system with a serious chance of tropical development. The 2023 Atlantic hurricane season is shaping up to be a very unique one, with near-record warmth over the tropical Atlantic in spite of a a developing El Niño. I will provide more thoughts on the season as a whole in my forecast update next Tuesday. Among expert forecasters, there has been no consensus this season – I’ll provide more info about this in a future blog post.

An area of low pressure has formed over the northeastern Gulf of Mexico, and has been designated Invest 91L by the National Hurricane Center (NHC). 91L currently has a 50 percent chance of development, both within 48 hours and 7 days. Starting this season, the NHC will issue Tropical Weather Outlooks out to 7 days, rather than 5 days as had been previously done since 2014. 91L is showing some signs of organization today, with buoys reporting pressure falls and convection has persisted overnight. An Air Force Hurricane Hunter Aircraft is scheduled to visit 91L later this afternoon, and will determine if 91L can be classified as a tropical depression or storm.

As of 12:00 UTC (8:00 a.m. EDT) Thursday, Invest 91L was located near 27.9°N 86.4°W. Maximum sustained winds were 30 knots (35 mph), with an estimated minimum pressure of 1007 mb. Based on the 12z Thursday run of the SHIPS tropical cyclone model, the environment for 91L is only marginally conducive for development. Wind shear is expected to remain high, greater than 30 knots, over the next day and increase to over 40 knots tomorrow. Therefore, 91L is unlikely to become anything more than a weak, short-lived tropical storm at most. 91L will be taking an unusual track, as it is expected to drift southeastward before turning northeastward through the Florida Straits as it weakens. 91L is likely going to just be a minor event for south Florida.

If 91L becomes a tropical storm, it will be named Arlene. However, it would technically not be the first system of the season, as the NHC recently determined an area of low pressure over the northwestern Atlantic in mid-January was actually a subtropical storm. Because of this, if 91L is classified, it will be designated 02L rather than 01L.