Surge of Saharan Dust To Arrive On Thursday

A surge of Saharan Dust is forecast to affect Trinidad and Tobago from late Thursday morning and persist into part of the weekend. A tropical wave and the Intertropical Convergence Zone is forecast to temper the impact of dust across T&T, with higher concentrations remaining north of the country.

Over the last 24 hours, air quality has been good with visibility near and above 10 kilometers across Trinidad and Tobago. The Environmental Management Agency (EMA) air quality monitoring stations are recording AQI values at levels that are good across the country. These measurements are based on PM2.5 (particulates the size of 2.5 micrometers and smaller, usually associated with increases in Saharan Dust, vehicle exhaust, and smoke) and PM10 particulates.

The Saharan Dust Forecast

Air quality across the country is forecast to decrease from Thursday through Saturday, improving from late Saturday night as the ITCZ and abundant moisture moves across T&T.

From Sunday onward through next Thursday, mostly good air quality is forecast across T&T as the ITCZ shields the country, with higher concentrations of dust still remaining north of T&T.

Towards the end of next week, a mild to a moderate surge of dust is forecast to move across the Lesser Antilles again.

Air quality levels will fluctuate between good to moderate on Thursday through Saturday, and again next Thursday into the weekend. On days with peak concentrations, visibility may be reduced between 7-10 kilometers.

12Z 25th August 2021, NASA GEOS-5 Dust Extinction Model Monitoring Tropical Atlantic Dust Aerosol Optical Depth showing Saharan Dust.
12Z 25th August 2021, NASA GEOS-5 Dust Extinction Model Monitoring Tropical Atlantic Dust Aerosol Optical Depth showing Saharan Dust.

What does this mean for you?

For the general population, with moderate to high Saharan dust concentrations forecast, little to no impacts are forecast beyond hazy skies. For sensitive groups, such as children, the elderly, and persons who suffer from respiratory ailments and allergies, you may need to avoid prolonged exertion outdoors on days with high concentrations of Saharan Dust.

We’re in a period where the ITCZ and tropical waves may shield Trinidad and Tobago from significant dust events. While tropical waves play a notable role in moving dust across the Atlantic and the Eastern Caribbean, these periodic tropical waves also improve air quality.

The concentration of the dust that follows the wave depends on the strength of the wave as it moves off the West African Coast. This is because of stronger thunderstorms across Central Africa. As strong winds move downward and outward from these thunderstorms, the wind kicks up dust as it moves across parts of the Saharan Desert and transports it into the upper atmosphere. This “plume” of dust follows the axis of the wave as it progresses westward into the Atlantic.

Dust that makes it into the upper levels of the atmosphere can then get transported across the Atlantic Ocean. The plumes of dust eventually affect the Eastern Caribbean.

Larger, more concentrated plumes of dust begin to occur in April and continue through November.

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