What is the Saharan Air Layer and how does it affect the tropics?

by Jennifer Collins

Mon, July 19th 2021, 7:49 PM UTC

Forecast models indicate dust will settle across the Atlantic over the next few days. This will limit any tropical development. (WPEC)

As of Monday afternoon tropical development is expected in the Atlantic over the next 5 days. (WPEC){p}{/p}

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Forecast models indicate dust will settle across the Atlantic over the next few days. This will limit any tropical development. (WPEC)

WEST PALM BEACH, Fla. (CBS12) — It's been an active start to the 2021 hurricane season but the Atlantic is quiet at this time thanks to the Saharan Air Layer covering portions of the Atlantic ocean.

How does the Saharan Air Layer limit the potential for tropical development?

The Saharan Air Layer, or SAL, is a mass of very dry, dusty air that forms over the Sahara Desert in late spring and summer. This layer of dust will travel off the west coast of Africa into the northern Atlantic and can cover an area the size of the continental United States! The Saharan Air Layer can most often be found from the late spring through early fall and peaks from mid-June through late July.

The SAL can reach places as far as the Gulf Coast of the United States. When the dust reaches areas like South Florida, it can help to limit our afternoon thunderstorm activity and can even produce more vibrant sunrises and sunsets as dust scatters light high up in the atmosphere.

The Saharan Air Layer is known to limit tropical development and keep tropical cyclones from intensifying. The hot SAL will lift above the dense marine air of the Atlantic waters and causes an inversion where temperature increases with height. The boundary between the SAL and the marine layer will cap convection or thunderstorm activity.

Though the Saharan Air Layer is good for limiting tropical cyclone formation, sometimes it can have a harmful impact on humans and the marine world.

Like dust in your home, Saharan dust is an irritant. Too much of it in the atmosphere can result in lower air quality. This can cause respiratory issues for those in sensitive groups such as those with asthma.

The Saharan dust can host plenty of nutrients to provide food for creatures in the ocean, but too many nutrients can cause algae problems and red tide blooms. It’s important to note that Saharan dust is just one source of fuel for algae blooms. Large red tide years have occurred without Saharan dust present.

So, while the Saharan Air Layer remains in the Atlantic early this hurricane season, you can expect less tropical activity. The Saharan Air Layer doesn’t have as much of an influence closer to the peak of hurricane season, so stay with the Storm Trac Weather Team to keep you updated with the latest in the tropics. You can also download the CBS 12 Hurricane Guide here.

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