In early July, a new surge of Saharan dust will reach the western and northern Gulf Coast. Some areas could see hazy skies, reduced air quality and vibrant sunrises and sunsets. June’s dust plume brought hazy skies and poor air quality as far north as the Midwest.
According to NOAA’s Atlantic Oceanographic and Meteorological Laboratory the Saharan Air Layer is a mass of very dry, dusty air that forms over the Sahara Desert during the late spring, summer, and early fall, and moves over the tropical North Atlantic every three to five days. The outbreaks usually occupy a 2 to 2.5-mile-thick layer of the atmosphere with the base starting about 1 mile above the surface. The warmth, dryness, and strong winds associated with the Saharan Air Layer have been shown to suppress tropical cyclone formation and intensification.
The activity usually ramps up in mid-June, peaks from late June to mid-August, and begins to rapidly subside after mid-August. During this peak period, individual Saharan Air Layer outbreaks reach farther to the west (as far west as Florida, Central America and even Texas) and cover vast areas of the Atlantic (sometimes as large as the lower 48 United States).
The Saharan Air Layer (SAL) can form when ripples in the lower-to-middle atmosphere, called tropical waves, track along the southern edge of the Sahara Desert and loft vast amounts of dust into the atmosphere.
Photo courtesy of NASA Earth Observatory