The fourth tropical depression (TD#4) of the 2015 Atlantic season formed this morning in the far eastern Atlantic Ocean. While it is still a week from impacting the islands of the Lesser Antilles, in the far eastern Caribbean Sea, this one is worth watching over the next several weeks. It is by far the most impressive system to emerge off of Africa and could be upgraded to Tropical Storm Danny pretty quickly. At 10 AM Tuesday, TD#4 was currently located near latitude 10.6 North, longitude 36.5 West, about 1665 miles east of the Windward Islands or over 3800 miles from Berwick Bay. The depression is moving west near 13 mph and will likely follow this course for another day then bend a bit to the west-northwest over days two and three, before coming back to a generally westward track by days four and five of the forecast period. Being down near 10 degrees north, which is pretty far south for storm formation, even with a slight jog to the west-northwest, Danny will likely be threatening the Windward Islands of the Lesser Antilles as a hurricane later this weekend. Maximum sustained winds are near 35 mph (55 km/h) with higher gusts. A 1232 UTC (07:32 CDT), the NOAA Advanced Scatterometer B (ASCAT-B) satellite passed over the system recording a well-defined circulation and a large field of 30-kt to 35-kt wind vectors in the eastern semicircle with several 40-kt vectors which would indicate tropical storm intensity winds.
While TD#4 is currently at least two weeks from impacting the Gulf Coast, if it were to continue its westward motion, the system is worth watching. Being so far out and newly formed, some of the models are having issues getting a good initialization of the system, but the European (ECMWF) and Canadian (CMC) models have a pretty good lock on it. They show a steadily intensifying storm, with winds of around 90 kts or 105 mph approaching the northern Leeward Islands in 5-6 days or so then entering the northern Caribbean Sea and passing south of Puerto Rico. Of course, even that is an educated guess. Afterward, who knows? The US GFS model has had more difficulty coming to grips with TD#4 but should have a better feel for it in the next model run. If you have a cruise planned to the eastern Caribbean for next week, keep a close eye on the Atlantic. We’ll follow the system here at CajunWX and update you every couple of days on the its progress or lack thereof.