African dust cloud moving over Texas

July 20th, 2012 at 4:35 pm by under Weather

If you notice  a hazier sky or more colorful sunset over the next couple of days, you can attribute it to fine dust particles, which winds have carried here all the way from the Sahara desert in Africa.

Huge dust cloud leaves Africa early this week (NOAA)

Saharan dust often travels across the Atlantic thanks to a hot, dry, dusty layer of air known as the Saharan Air Layer. Extreme daytime heating of the Sahara creates instability in the lowest layer of the atmosphere, lofting dust particles into the air. The dust-laden air layer continues warming as it travels westward across the Sahara. As the Saharan Air Layer moves off the west coast of Africa, it passes over a cooler, wetter layer of air. This temperature inversion (air usually cools with altitude) prevents mixing, enabling the dust layer to travel across the ocean intact. Across the Atlantic, dust brings problems and benefits: respiratory illness and coral bleaching, but also rich soils. (Source: NOAA)

Dust cloud reaches W. Gulf of Mexico July 19 – Courtesy: Dr. Gordon Wells, UT Center for Space Research

Here is the Air Quality Forecast from the Texas Commission on Environmental Quality:

Friday 07/20/12
The leading edge of a large African dust cloud is covering much of South Texas this morning and will likely move into Central and Southeast Texas this afternoon and evening and could raise the daily PM2.5 AQI to “Moderate” in much of this area. Elsewhere in the state, moderate winds and low incoming background levels should help to keep air quality in the “Good” range.

Saturday 07/21/12
A large African dust cloud should cover most of the southern half of the state from Big Bend to Waco to Lufkin and should raise daily PM2.5 AQI levels to “Moderate” in most of this area. Elsewhere in the state, moderate winds and low incoming background levels should help to keep air quality in the “Good” range.¬†

Sunday 07/22/12 Outlook
The large African dust cloud should cover most of the state south and east of a line from Van Horn to Odessa to Sherman and will likely raise daily PM2.5 AQI levels to “Moderate” in most of this area. Elsewhere in the state, moderate winds and low incoming background levels should help to keep air quality in the “Good” range.

Monday 07/23/12 Outlook
The large African dust cloud should cover most of the state and will likely raise daily PM2.5 AQI levels to “Moderate” across much of the state except far West Texas. Fine particulate levels should be decreasing along the coast in the afternoon and evening. In far West Texas, moderate winds and low incoming background levels should help to keep air quality in the “Good” range.

Tuesday 07/24/12 Extended Outlook
The large African dust cloud may continue over much of the northern half of the state in the morning with “Moderate” fine particulate levels, but concentrations should decrease in the afternoon and evening as the dust cloud moves northward out of the state. Elsewhere in the state, moderate winds and low incoming background levels should help to keep air quality in the “Good” range.

 

 

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