There continues to be two “Invests” – short for Area of Investigation – being monitored by the National Hurricane Center for potential tropical or subtropical development. Invest 90L is located northeast of Bermuda, and Invest 91L is located over the northwestern Gulf of Mexico. Both of the systems have developed well-defined circulation centers, but lack sufficient organized deep convection as of this time. It appears likely that the Atlantic will have at least one subtropical or tropical cyclone develop prior to the official start date of June 1, for the seventh straight year.

As of 18:00 UTC Friday, Invest 90L was centered near 35.0°N 61.2°W. Maximum sustained winds were 45 knots (50 mph), with an estimated minimum pressure of 1004 mb. Although 90L has become less associated with nearby frontal boundaries, thunderstorm activity near the center remains very weak, which is why the NHC has not classified it as a subtropical storm yet. The NHC gives 90L a 90 percent chance of development within 48 hours. Due to the marginal thermodynamic environment, I’d place the chances slightly lower, at 80 percent. The model guidance shows little change in intensity with 90L for the next 36 hours or so as it meanders, before likely dissipating late Sunday or early Monday as it tracks northeastward into a more hostile environment. Although sea surface temperatures are quite cool – near 21°C (69.8°F) – wind shear is expected to remain fairly light, less than 15 knots, which is likely going to allow 91L to develop into a short-lived subtropical storm. Due to 90L’s small size and expected track northeast of Bermuda, impacts on the island are expected to be very limited.

As of 18:00 UTC Friday, Invest 91L was centered near 26.4°N 94.2°W. Maximum sustained winds were 30 knots (35 mph), with an estimated minimum pressure of 1009 mb. Although visible satellite imagery and scatterometer data clearly indicates that 91L has developed a well-defined circulation, thunderstorm activity associated with the system remains very limited. The NHC gave 90L a 60 percent chance of development within 48 hours at their 2:00 p.m. EDT Tropical Weather Outlook. The NHC had considered designating 91L as a Potential Tropical Cyclone this afternoon, but ultimately decided against it for now. Based on the latest GFS-based SHIPS model run, 91L is heading into sea surface temperatures cooler than 26°C (78.8°F), along with a fairly dry mid-level environment. This will likely continue to put a limit on convective activity before 91L moves inland over southeastern Texas late tonight or early Saturday. I personally think it is unlikely 91L reaches tropical storm status due to the cool sea surface temperatures and dry environment. 91L has not become any better organized since this morning. Considering the lack of thunderstorm activity, rainfall amounts will likely be somewhat limited with 91L. Regardless, interests in southeastern Texas should continue to monitor 91L, in case thunderstorm activity increases significantly this evening which would make it a tropical depression.