A vigorous tropical wave over the central Atlantic acquired a sufficiently well-defined circulation Monday morning to be classified as Tropical Depression Three. It should be noted that it is quite unusual to see tropical development in this part of the basin this early in the season, with only two systems of at least tropical storm strength recorded in the tropical Atlantic east of the Lesser Antilles in the satellite era during June: Ana (1979) and Bret (2017). Coincidentally, if Three becomes a tropical storm as expected, it would be named Bret.

As of 11:00 a.m. EDT Monday, Tropical Depression Three was centered near 11.0°N 40.3°W, and was moving westward at about 21 mph. Maximum sustained winds were 30 knots (35 mph), with an estimated minimum pressure of 1009 mb. The depression is gradually becoming better organized, with banding features and thunderstorm activity increasing near the center. During the next 60 hours or so, the environment should be very conducive for the depression to intensify. The 12z Monday SHIPS model predicted that vertical shear would be less than 10 knots, sea surface temperatures of 27-28°C (80.6-82.4°F), and a fairly moist environment. Therefore, Three should be able to intensify during that time, as long as it does not move too fast or ingest dry air. How much Three intensifies over the next three days will have significant track implications. A stronger storm, as the GFS has shown in many runs, could potentially turn to the north or northwest and miss the Lesser Antilles entirely. A weaker storm, probably the more likely scenario considering climatology, would enter the Caribbean and likely struggle with wind shear. The SHIPS model predicted that shear would increase to greater than 20 knots by Thursday, which would likely weaken the cyclone. The current National Hurricane Center (NHC) forecast brings Three to Category 1 hurricane intensity by Wednesday night, which would make it the earliest hurricane in the Atlantic Main Development Region (MDR) on record, and the first June Atlantic hurricane since 2012. However, it should be noted that hurricane intensity is far from a guarantee at this point, and some models, like the ECMWF, keep Three much weaker than the current NHC forecast. Regardless, interests in the Lesser Antilles, Puerto Rico, and Hispaniola should closely monitor the progress of Three, and have a hurricane plan ready in case. It is too soon to determine if Three will impact the Continental United States, though that seems very unlikely at this point since Three may not survive as a cyclone if it tracks into the Caribbean Sea.

Despite being June, Tropical Depression Three is not the only system to watch in the tropical Atlantic. Another tropical wave, Invest 93L, also has a chance to develop into a weak tropical cyclone. The NHC currently gives 93L a 30 percent chance of development within 48 hours, and a 40 percent chance within 7 days. Recent GFS and ECMWF runs have both showed some slight development with 93L, though it will likely not get as strong as TD Three. Vertical wind shear is expected to be light-to-moderate with sea surface temperatures warmer than 28°C (82.2°F), however, 93L’s proximity to TD Three may limit development if Three becomes a stronger system. 93L is currently unlikely to affect any land areas, and is likely to turn to the northwest well east of the Lesser Antilles.