From Larry Logan at the Liberty County Emergency Management Agency:
A weak Tropical Depression Four is tracking west toward the Bahamas. Tropical Depression Four — the fourth tropical cyclone of the 2017 season — developed late Wednesday east of the Caribbean. If the storm strengthens, which seems unlikely, it would become Tropical Storm Don.
On Thursday morning, the depression was about halfway between the Lesser Antilles and the coast of Africa.
The wind shear around the storm has weakened, which should allow it to maintain its intensity over the next day or so. But the shear, which acts to tear storms apart and keep them from strengthening, is expected to increase as the storm drifts west. That alone would probably be enough to keep this weak tropical depression at bay.
But it’s also surrounded by very dry air with origins in the Sahara Desert, and that will probably be the nail in the coffin for Tropical Depression Four. These cyclones need warm, moist air to strengthen and grow, and it looks like the Saharan air layer is going to wrap around the system over the next couple of days and extinguish thunderstorm development.
A few of the forecast models are predicting that the system will strengthen modestly, though these particular models tend to not perform well in situations like this. The global models (GFS, UKMET and European) are all predicting that the storm will dissipate before it reaches the Bahamas.
For the time being, the National Hurricane Center predicts that Tropical Depression Four will maintain its weak intensity over the next 48 hours before dissipating by Saturday or Sunday.