A massive plume of dust originating in Africa stretches across the tropical Atlantic into the Caribbean. It’s not an uncommon phenomenon this time of year — Saharan Dust season can continue into August — but this dust surge is on the strong side.
The dust layer is normally about 8,000 feet up, plus or minus. If the plume is thick, it dries out that level in the atmosphere, and everything else being equal, fewer thunderstorms can form. We end up with a milky sky and sultry weather.
On the other hand, if only a limited amount of dust arrives, so the drying is light to moderate, extra-strong thunderstorms can form. The cells that punch through the dust cap have enough oomph to grow quite tall and produce gusty winds and very heavy rain.
The current surge of dust is forecast to arrive at the southern Florida peninsula about the middle of next week. Right now, it appears the dust layer will be light enough to allow big thunderstorms to form, but we’ll see.
To the south, the disturbance we were watching early this week is lodged over Central America, and it continues to produce periods of heavy rain over the region. Through the weekend and into next week, the broad disturbance essentially stays put.
Mid to late next week, a tropical disturbance that originated over Africa may push across Central America. The old and new disturbances may join forces and move toward the extreme southwestern Gulf of Mexico. Long-range computer forecast models continue to insist that a system will try and coalesce over the warm Gulf water. It looks logical, but the models have been forecasting development in the long term for days.
High pressure is forecast to stay strong across the Atlantic, so any system that might develop should be confined to the western Gulf. That strong flow across the Atlantic is rotating around the same big high-pressure system that will push the Saharan dust across the Caribbean and toward Florida.
Except for the southwestern corner of the Gulf, and that’s a maybe, no development is expected for the next week.