Significant Surge of Saharan Dust Forecast To Affect T&T, Lesser Antilles

Beginning Saturday night, a significant and prolonged surge of Saharan Dust is forecast to affect Trinidad, Tobago, and the remainder of the Lesser Antilles into next week.

For Barbados, a Significant Dust Haze Advisory was issued by the Barbados Meteorological Service as they forecast visibilities to dip between 5 to 10 kilometers within the next 48 hours across the island and the respective marine area.

In the interim, over the next 24 hours, air quality is forecast to be mostly good levels as low levels of Saharan Dust concentrations remain present across T&T and the Windward Islands.

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

Over the next 24 hours, lingering mild concentrations of dust will remain present across T&T. The air quality will generally be at good levels, though it may dip to moderate levels in areas with high traffic or fires occur.

From Saturday night through Sunday afternoon, a rapid increase in dust concentrations is forecast with skies becoming increasingly hazy. Air quality is forecast to decrease to moderate levels during this period.

The initial peak of this dust event is forecast Sunday evening through Monday morning, with air quality dipping to levels that are unhealthy for sensitive groups. Across Tobago, air quality may dip to unhealthy levels.

A gradual, but not significant, decrease in dust concentrations will occur through Friday. The air quality will vary between moderate to unhealthy for sensitive groups through the remainder of the week.

By Friday evening, another dense surge of dust will arrive with high concentrations persisting through the weekend.

00Z Friday 19th February 2021, NASA GEOS-5 Dust Extinction Model Monitoring Tropical Atlantic Dust Aerosol Optical Depth showing Saharan Dust.
00Z Friday 19th February 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 through the weekend, with mild 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.

Beginning Sunday evening, 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. There is an increasing likelihood of respiratory symptoms in sensitive individuals, aggravation of heart or lung disease, and premature mortality in persons with cardiopulmonary disease & the elderly.

We’re in a period where a ridge of high pressure stays over the central Sahara Desert, and the Intertropical Convergence Zone (ITCZ) remains over the Gulf of Guinea.

The Harmattan wind accelerates when it blows across the mountain massifs of Northwest Africa. If its speed is high enough and it blows over dust source regions, it lifts the dust and disperses it.

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

These Saharan Dust outbreaks tend to be milder in the Eastern Caribbean than the dust outbreaks associated with West African thunderstorms driving dust into the upper atmosphere from April through November.

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