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Saharan dust controls the tropics but watching a system over the Southeast

July 7, 2020, satellite image of the tropics.
July 7, 2020, satellite image of the tropics. (TropicalTidbits.com)

A belt of Saharan dust continues to spread across the tropical Atlantic, the Caribbean Sea and the Gulf of Mexico. The dry, dusty air is expected to keep the tropics quiet through this week, at least.

Tropical disturbances are moving off Africa on schedule, but they can only exist at low latitudes, south of the dust belt. The robust disturbance – the same well-defined tropical wave that we tracked moving off Africa late last week – is over the southern Caribbean islands today as a healthy moisture surge. It will produce gusty tropical downpours on some of the islands before it moves into the Caribbean.

Moisture from the disturbance is forecast to be pulled north over or near South Florida around the weekend as the core of the system tracks across Central America into the Pacific Ocean. We may see an increase in tropical downpours due to the surge in atmospheric moisture.

Elsewhere, the tropics are quiet. Former Tropical Storm Edouard has transitioned to a non-tropical North Atlantic system.

There is another non-tropical system over the Southeast U.S. This was the mother system that spawned the disturbance that eventually became Edouard. Now, that original broad low-pressure system is consolidating and will track over the Carolinas today. 

The main circulation and the trailing cold front are producing very heavy rain over the Southeast and across much of the Florida Panhandle, which will produce a flood threat in some areas today.

Over the next couple of days, the system is forecast to consolidate over or near the North Carolina coast and track north as a coastal storm. If it moves over the warm water of the Gulf Stream, it might gain some aspects of a tropical system. The computer forecast models consistently show some organization and consolidation.

If it comes together, whether it gains tropical characteristics or not, tropical moisture and gusty winds are forecast to surge north across the Mid-Atlantic coast late in the week and coastal New England over the weekend.


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