It’s not dust in the wind but it’s Sahara Desert dust in the sky
WACO, Texas (KWTX) - Hazy skies have returned to Central Texas and it’s all thanks to dust that’s been transported all the way across the Atlantic Ocean from the Sahara Desert! Dusty and hazy skies aren’t uncommon during the early summer months, but it’s the first time in 2022 that dust has emerged.
Africa says “SAL-utations, America!”
It may be a mind boggling concept that something as small as dust can travel over 7,000 miles and still make a difference in our weather, but the weather phenomenon has been well documented recently thanks to high resolution satellites.
The dust is a part of the Saharan Air Layer, or SAL for short, and is usually about 2 miles thick in the atmosphere starting about a mile above the surface. Nearly half of all dust in the atmosphere comes from around Lake Chad and is picked up by the easterly trade winds.
The trade winds, which is a long conveyor belt of easterly winds that moves from Africa toward the Caribbean, is able to pick up dust and suspend it in the atmosphere. Large particles of dust roughly the size of hairspray (around 5 micrometers and larger) typically fall out of the atmosphere within a day but particles that are the size of auto emissions (near 1 micrometer) can stay suspended in the atmosphere for weeks.
High resolution satellite imagery, like we receive from NOAA’s GOES-East satellite, can easily pick up on large concentrations of dust in the atmosphere. In fact, the newer satellites have a way to differentiate dust from other things in the atmosphere! In the screenshot below of the Northern Hemisphere on June 14th at 10:30 AM Central Time, the true-color image (which essentially is a photo of the Earth) shows the sandy color of the dust across parts of the Atlantic Ocean.
In just the same way that meteorologists use forecast models to determine what kind of weather may arrive over the coming days, NASA has created a model, called the Goddard Earth Observing System, that can track and forecast the movement of dust in the atmosphere. The latest GEOS model below shows multiple plumes of dust over the Gulf of Mexico, Caribbean Sea, and Atlantic right now with potentially another dust plume coming off of Africa in a few days.
How long will dust hang around Texas?
Despite the abundance of dust that’s currently in the atmosphere and moving across the ocean, Texas is too far north to see the dust as frequently as the Caribbean does. In order for dust to be transported north, the upper-level weather pattern needs to be set up to pull the dust northward.
High pressure is off to our east right now and the clockwise flow around the high causes the winds aloft to come from the south. The south winds open the door to pull the dust in but it’s actually an area of low pressure moving through South Texas that’s bringing us the hazy skies. Dust has been trapped in this low as it’s moved across the Caribbean and it’s now impacting us.
The current wave of dusty skies should be around through the end of the day today and will then pull away Wednesday. The next plume of dust arrives Thursday and Friday and should bring the dust concentrations back up again.
Dust, schmust... How does this impact me?
If you didn’t know about the dusty skies, you would probably miss the impacts it brings! Whenever the SAL moves through the atmosphere, sunrises and sunsets typically become a more vibrant reddish-yellow because of the low sun angle. During the day, when the sun is high and light can easily pass through the atmosphere, the sky looks much more milky and hazy.
For some of us, especially those who are sensitive to air quality changes, the dust can cause difficulty breathing. If this applies to you, it’s a good idea to either limit your time outdoors or wear a (K)N-95 mask to filter out the dust. For the majority of Central Texans, the dust won’t impact your health at all.
Even if you struggle with air quality changes, the dust should be far enough up in the atmosphere to be of minimal consequence. If you remember back to June 2020, when one of the largest dust plumes ever observed in North America and the Caribbean moved through Texas, the sky was quite dull and sandy and it almost looked like we were in a dust storm! That’s not happening this go around, but we’ll have to see if another large dust plume will make it into Central Texas next week.
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