South Florida disturbance; African dust

An area of disturbed weather over South Florida, the Bahama Islands, and Cuba is associated with a broad trough of surface low pressure and an upper-level low pressure system. Wind shear is down to 5-15 knots, which is marginally favorable for development. Water temperatures are very favorable, 28 - 29 C. The center of the upper low has drifted to a position at the extreme southwestern corner of Florida. There are a few impressive thunderstorms kicking up near the center of circulation, but this activity is of pretty limited coverage, and development into a tropical depression is unlikely today. Winds at the surface do show a U-shaped pattern (a trough) curving around an axis of low pressure in the region, but there is no closed circulation at the surface. There is only a closed circulation in the upper atmosphere.

Development is being hindered by the system's close proximity to land, and it will do better if it can move away from the coast. The NOGAPS model is suggesting that the low may move more into the Gulf of Mexico and show some slow development, but the rest of the models disagree. They indicate that the current low will not develop at all, but that a new low associated with the same surface trough of low pressure will develop on Saturday south of the Carolinas. This system would then get swept up the coast this weekend, possibly bringing strong winds to Cape Hatteras. The storm would continue moving up the coast, passing several hundred miles east of Cape Cod on Sunday night.


Figure 1. Current satellite image of the blob of disturbed weather over South Florida.

The rest of the tropical Atlantic is quiet today. A large area of African dust covers the entire Atlantic between Africa and the eastern Caribbean, and will act to suppress tropical storm formation in those regions over the next few days.

Jeff Masters