From Watts Up With That?
Meteorologist Ross Hays writes on Facebook:
This is a satellite picture with the colors showing dry air & Sahara Dust coming across the Tropical Atlantic. This has prohibited the development of tropical storms over the region. The water is very warm so after the dust disperses there is a risk for strong hurricane to develop as we get later in the month!
And there you have it, “dust in the wind” is preventing formation of “Cape Verde” type hurricanes. NOAA has a description here.
At MyFoxHurricane, they have this to say:
The Saharan Air Layer, also known as Saharan Dust, is made of sand, dirt, and other dust that is lifted into the atmosphere from the vast desert area that covers most of North Africa. This dust is carried in the African Waves which push westward into the Atlantic Ocean.
The Saharan Air Layer is a well-mixed dry pocket of air that usually resides between 5,000 and 15,000 feet above sea level. Since one of the key ingredients for tropical cyclone development is a deep feed of moisture, Saharan Dust often acts to inhibit tropical development.
Once a pocket a Saharan Dust begins moving westward over the Atlantic, it is relatively easy to track using infrared satellite products.