Moderate to High Levels of Saharan Dust Forecast Across T&T Through Next Week

A surge of Saharan Dust has moved across T&T, as forecast, following yesterday’s passage of Tropical Wave 16 which brought heavy rainfall across the country.

Through the next 10 days, air quality levels are forecast to fluctuate due to passages of tropical waves on Thursday into Friday, and again on Monday.

Over the last 24 hours, air quality has been good to moderate with visibility outside of showers and thunderstorms beyond 10 kilometers in Tobago and around 8 kilometers in Trinidad.

The Environmental Management Agency (EMA) air quality monitoring stations are recording AQI values at levels that are good to moderate in Trinidad and Tobago. 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

Until Sunday, air quality is forecast to be good to moderate with fluctuating concentrations of Saharan Dust as Tropical Wave 17 is forecast to move across the region Thursday into Friday, and similarly on Sunday into Monday as Tropical Waves 18 and 19 merge with a surge of trade winds.

Air quality on Sunday into Monday may return to good levels, but a surge of Saharan Dust follows by late Monday into Tuesday and moderate to high concentrations of Saharan Dust lingers through the end of next week.

Air quality levels will fluctuate between good to moderate through the entire forecast period. As mentioned above, on days with peak concentrations, visibility may be reduced between 7-10 kilometers.

00Z 07th July 2021, NASA GEOS-5 Dust Extinction Model Monitoring Tropical Atlantic Dust Aerosol Optical Depth showing Saharan Dust.
00Z 07th July 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

With high concentrations of Saharan Dust forecast, members of sensitive groups may experience health effects. The general public is not likely to be affected though visibility will be reduced due to increased 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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