Over the next 10 days, mild to high concentration surges of Saharan Dust are forecast to move across the Lesser Antilles, typically following the passages of tropical waves.
Over the last 24-48 hours, air quality has been good with visibility outside of showers and thunderstorms beyond 10 kilometers.
On days with moderate to high concentrations of dust, air quality may reach moderate levels and visibility diminish to moderate levels.
The Environmental Management Agency (EMA) air quality monitoring stations are recording AQI values at levels that are good 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
Good air quality with minimal to no dust is forecast through the next two days or so, with a surge of dust forecast to move across the region beginning Saturday, following the passage and trailing moisture of Tropical Wave 11. This surge will be brief but with moderate to high levels of dust. Dust levels will decline through the weekend due to the passages of Tropical Wave 12 south of T&T on Saturday and the passage of Tropical Wave 13 on Monday.
Following the passage of Tropical Wave 13, another brief surge of moderate to high concentrations of Saharan Dust following. By Tuesday, moisture ahead of Tropical Wave 14 will begin to move across T&T, with the wave axis moving across the Lesser Antilles on Wednesday into Thursday. The presence and passage of Tropical Wave 14 are forecast to diminish dust concentrations across the region, with mild to moderate concentrations remaining across the area into the weekend.
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 the Saharan 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 Saharan dust begin to occur in April and continue through November.