Dusty Start To October As Mild Surge of Saharan Dust Forecast

Saharan dust concentrations remain very low across T&T and the Southern Windwards as we are in a time of the year where dust levels are at a climatological low. Across the country, air quality is at good levels with visibility above 10 kilometers as of 1:00 PM Wednesday 23rd September 2020.

A mild increase in Saharan Dust is forecast on Monday 28th September 2020, following the passage of Tropical Wave 51. A mild to moderate surge of dust is forecast to traverse the Lesser Antilles beginning September 30th through the first week of October, with higher concentrations remaining north of T&T.

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

Air Quality Index at Environmental Management Agency‘s (EMA) Air Quality Monitoring Stations Across Trinidad. Note these AQI values are to Trinidad and Tobago air quality standards.

The Saharan Dust Forecast

Based on the latest dust modeling, air quality across Trinidad and Tobago is forecast to remain at mostly good levels through the forecast period. The exception being from the night of Sunday 27th September through the evening of Monday 28th September, with a brief, mild surge of dust.

A more prolonged, but still mild to moderate, surge of dust will arrive beginning the night of Wednesday 30th September and remain mainly north of T&T through the first few days of October.

Across Trinidad and Tobago, showers and isolated thunderstorms are forecast to temper any air quality impacts, with higher concentrations still remaining north of T&T particularly late next week.

02Z September 23rd, 2020, NASA GEOS-5 Dust Extinction Model Monitoring Tropical Atlantic Dust Aerosol Optical Depth showing Saharan Dust. (Weathermodels)
02Z September 23rd, 2020, NASA GEOS-5 Dust Extinction Model Monitoring Tropical Atlantic Dust Aerosol Optical Depth showing Saharan Dust. (Weathermodels)

What does this mean for you?

For the general population, little to no impacts are forecast beyond reduced visibility. 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. Air quality may dip to moderate levels on Monday 28th September 2020 and from Wednesday 30th September through the first couple of days of October.

We’re in a period where the ITCZ, tropical waves and occasional tropical cyclones 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 frequent tropical waves also aid in improving 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.

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

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