TROPICS STAY QUIET THROUGH THE WEEKEND

A combination of dry Saharan air and a strong high-pressure system stretching across the Atlantic will keep the tropics quiet through the weekend, and likely well beyond.

The first surge of Saharan dust that we have been tracking all week is forecast to loop around the Gulf of Mexico and move down the Florida peninsula over the weekend. We may notice it beginning Sunday and into next week.

The dust is no longer concentrated like it was in the Caribbean. The main effect will likely be a milky sky.

A second plume of dust will move through the Caribbean over the next few days. Most of this surge will slide by to the south of Florida, but the fringe of it will likely affect the southern peninsula as well. This is a much less dense plume than the first big one, so again, the effects are not expected to be anything dramatic.

The computer forecast models can be used to track the dust by analyzing the general dryness or moistness of the atmosphere. We can also see moisture surges from disturbances coming off Africa. Generally these disturbances can’t organize because of the Saharan Air Layer of dusty air they have to plow through.

In Florida, when there is a layer of Saharan air in the atmosphere, we normally have lower thunderstorm chances than normal. But if a storm pops up, it can be quite strong – with unusually gusty winds, hail, and intense lightning. The dust acts like a cap, but if an updraft is strong enough to break through, it often creates an extra-intense cell.

Because there are fewer thunderstorms, and clouds in general, it will be quite hot, especially away from the coast. In addition, when there are fewer thunderstorms, the atmosphere does not get stirred up, so the humidity also stays extra high. Inland high temperatures over the weekend will push into mid 90s once again, with feels-like temperatures well above 100.

Long-range computer forecast models show one or more non-tropical low-pressure systems forming off the Mid Atlantic coast related to a frontal system. As we’ve seen, sometimes these systems become somewhat tropical in nature. But it doesn’t appear that anything would threaten land through midweek or longer.