Based on infrared satellite presentation and a QuikSCAT pass (active microwave scatterometer that can measure surface winds over water), TD4 has been held at Depression status as of 15Z today. It is definitely on the threshold of being named though. The latest intensity estimate is 30kts and 1007mb.
The most recent visible satellite imagery as of this writing shows deep convection over the low-level center, rather well consolidated. There's healthy outflow everywhere, but moreso to the south, as was the case yesterday. Two negatives for it are stable air to the west and north, and slight southeasterly vertical shear. It's tracking WNW at 14kts, and is located just southwest of the Cape Verde Islands.
It's still forecast to gradually intensify and track WNW for a few more days, then recurve northward through an anticipated weakness in the subtropical ridge.
Elsewhere, there are two points of interest, one in the central part of the basin, near 50W, and one still over the heart of Africa, at about 5W. The one still over Africa obviously has a few days before it even hits the ocean, but it looks ominous. And the one nearing the Lesser Antilles is definitely worth keeping an eye on. In fact, there's a broad elongated envelope of enhanced cyclonic vorticity from about 45-60W along ~12N, and there appears to be at least two embedded mid-level circulations.
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