A huge cloud of dust blown up from the Sahara Desert in Africa is expected to arrive in the U.S. late this week.
The dust plume, which is about 2,000 miles wide from east to west, is forecast to sweep up through the Caribbean and into the southeastern U.S. as early as Wednesday.
The dust is driven by waves of low pressure that move westward from Africa across the tropics, gathered into a phenomenon called the Saharan Air Layer. The windy conditions pick up dust from the desert and spread it over the Atlantic Ocean, sometimes as far west as the United States.
This year, the dust has already caused hazy skies and some respiratory trouble for residents on Caribbean islands. The plume is forecast to reach Florida and parts of Louisiana, Alabama and Mississippi this week and into the weekend. Florida may expect to see hazy air and affected sunsets at the time.
June and July are the most active months for the phenomenon, during which clouds can reach between 5,000 feet to 20,000 feet high. Most of the dust is too high in the atmosphere to cause significant health or breathing trouble, experts say.
But rain that falls through the dust layer may carry it to the ground and deposit it as dry residue that's left behind the storm.
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The dusty conditions are also known to suppress the potential formation of tropical disturbances and storms. Forecasters can incorporate the behavior of the Saharan Air Layer into their models to get a better estimate of how storms may evolve while the dust is airborne.
Florida, meanwhile, is also experiencing air quality problems from the other direction: A plume of wildfire smoke blown down from fires burning in Canada is having a moderate impact on air quality.
