Dust all the way from the Sahara Desert has moved in
It hasn’t been thick, but dust in our atmosphere will be possible at times through August
MONTGOMERY, Ala. (WSFA) - It’s that time of year again! Dust all the way from the Sahara Desert in Africa has arrived in the skies above the eastern Atlantic, Caribbean, Gulf of Mexico, and Southeast US.
That includes Alabama, which is more than 6,000 miles from the Sahara Desert!
It may seem impossible for dust to travel from Africa to the United States, but it is a normal yearly phenomenon. Plumes of dust continuously push westward off the coast of Africa during the months of June, July and August.
This happens as tropical waves and their corresponding stronger winds over Central Africa loft vast amounts of dust into the atmosphere. The Saharan Air Layer (SAL) then pushes across the Atlantic Ocean courtesy of easterly winds.
Each plume of dust differs in size, thickness and concentration, but we usually see dust outbreaks push off the African coast every 3-5 days during the mid-June to mid-August period. The dust outbreaks typically occupy a 2 to 2.5-mile thick layer of the atmosphere beginning just over a mile off the surface, according to NOAA.
The heavier and larger plumes of dust oftentimes make it all the way to the Caribbean, Gulf of Mexico, Florida, and other southern states, but the extent of their impacts differs every time.
We can use forecast models to look at potential impacts by analyzing dust particle concentrations in the atmosphere and where outbreaks of that dust will likely move out to about 10 days. Any details on dust outbreaks beyond 10 days are impossible to know.
It’s important to know when and where the Saharan dust will go because it has multiple impacts -- both good and not so good.
If the dust concentration is thick enough, air quality problems and breathing/health issues can arise. That is especially true for those who suffer from respiratory problems. If the dust concentration is high enough, some folks may have to avoid outdoor exposure.
Rarely is the dust concentration high enough in Alabama to cause significant issues in terms of our air quality, however. Poor air quality is only one effect of these annual Saharan dust invasions...
The dust is thought to help build beaches in the Caribbean and enrich soils and oceanic ecosystems courtesy of the minerals and nutrients it contains.
Those ingredients aid in the fertilization of the Amazon Rainforest, especially the limited amounts of phosphorus. Some scientists suggest the iron in the dust may fertilize the ocean, feeding microorganisms in the water.
For us here in Alabama, the noticeable impacts of Saharan dust are vividly colorful sunrises and sunsets, a milky/hazy sky during the day and a suppression of tropical cyclone development in the Atlantic basin.
The hot, dusty SAL creates very dry conditions in the atmosphere. This helps significantly suppress tropical storm and hurricane development. Tropical systems need warm, moist air to form, strengthen and maintain themselves. With the hot, dry and dusty air in place, the Atlantic is typically quiet this time of year.
As we get closer to the arrival of any significant dust outbreak, we will provide more information. What you need to know for now is we are only expecting minimal amounts of Saharan dust in the atmosphere here in Alabama and neighboring locations for at least the next 7-10 days!
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