Why Saharan Dust shuts down the Tropics

Why Saharan Dust shuts down the Tropics
Due to the Saharan Dust the tropics are quiet for the time being. (Source: KSLA News 12)

SHREVEPORT, La. (KSLA) - A topic of discussion over the past week has been the impending arrival of a large cloud of Saharan Dust that has been moving across the Atlantic Basin towards the southeast portion of the United States. While there has been a lot of talk over the impacts on our sunrises and sunsets as well as the impacts on our respiratory systems especially in the age of COVID-19, one of the biggest impacts of the dust will be on the tropics.

The Saharan Dust is highlighted by the magenta color.
The Saharan Dust is highlighted by the magenta color. (Source: KSLA News 12)

The Saharan Dust is going to have two major impacts on the tropics. First what the Saharan Dust does is inject a lot of dry air into the tropics. This is significant for a couple of reasons. First is the obvious fact that dry air is not very helpful for systems that rely on moist air in order to feed their organized thunderstorms. With so much dry air in the atmosphere these thunderstorms can literally be choked off and prevent any further development.

The Saharan Dust represents are large area of dry air.
The Saharan Dust represents are large area of dry air. (Source: KSLA News 12)

Another aspect of the dry air is the impact it has on convective development in the tropics. Dry air is more dense moist air, so drier air has a tendency to sink when it comes in contact with warm and moist air. Now most of the Saharan Dust is located in the middle to upper levels of the atmosphere meaning as the dry air moves west it will creating a general sinking environment all across the Atlantic Basin further preventing tropical development.

Now another aspect of the Saharan Dust is the fact that it highlight elevated amounts of wind shear in the tropics. Wind shear is how the speed and direction of wind changes with height. Higher amounts of wind shear make it much more difficult for storms to develop and get organized, and blow off the tops of thunderstorms. What the Saharan Dust is highlighting due to its quick movement through the tropics is the high winds in the middle to upper levels of the atmosphere. This means there are high levels of wind shear are preventing any consistent organization of thunderstorms that are so crucial for development.

The Saharan Dust highlights strong upper level winds moving through the Atlantic Basin
The Saharan Dust highlights strong upper level winds moving through the Atlantic Basin (Source: KSLA News 12)

But just because we have very unfavorable conditions for tropical development right now that doesn’t mean it will stay that way for all of hurricane season. We are still anticipating an above average season and the fact we have already had four named storms is a strong indication of this. So enjoy the quiet tropics while they last.

We have already seen an active season with four named storms already.
We have already seen an active season with four named storms already. (Source: KSLA News 12)

The KSLA First Alert Weather Team will keep you updated on the potential impacts of the Saharan Dust on the ArkLaTex. Here’s how you can get the First Alert with the latest forecast:

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