Mild Surge of Saharan Dust Forecast To Arrive On Tuesday

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 3:00 PM Monday 14th September 2020.

Due to a number of tropical cyclones and the ITCZ, dense concentrations are forecast to remain north of T&T and the Windward Islands. However, a mild surge of dust, ahead of Tropical Storm Teddy, will move across the region and linger into Thursday. Higher concentrations will remain north of T&T and beginning on Wednesday, an active ITCZ and Tropical Storm Teddy’s influence on our winds and weather may quell dust concentrations particularly across Trinidad and Tobago.

The Environmental Management Agency (EMA) air quality monitoring stations are recording AQI values at levels that are good 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 morning of Tuesday 15th September through Thursday 18th September 2020, where moderate air quality is possible as mild concentrations of Saharan Dust forecast to move through the region.

There are no major surges of Saharan dust forecast over the next 10 days across the Lesser Antilles, including Trinidad and Tobago.

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 after midweek.

02Z September 7th, 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 Tuesday through Thursday night.

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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