Saharan Dust Forecast Through End of July For T&T

Saharan Dust levels across the Main Development Region have reached the climatological peak for the year, with significant dust moving generally north of T&T.

Over the next two weeks, generally moderate concentrations of dust are forecast to remain across T&T, reducing air quality.

What you need to know

— Saharan Dust Surges: A moderate to high concentration surge of dust is forecast to move in tonight through tomorrow, July 20th, with generally moderate dust levels across T&T through July 29th.
— Impacts: Air quality is forecast to remain good to moderate throughout the forecast period. Between July 20th and 21st, air quality may reach unhealthy for sensitive groups.
What Should You Do: In times of unhealthy air quality, everyone should take the necessary precautions. Throughout the forecast period, sensitive groups are advised to take the necessary precautions, particularly during high traffic and in the vicinity of fires.

Current AQI Levels Across T&T

As of 3:00 PM Friday, July 19th, 2024, the official air quality monitoring stations from the Environmental Management Agency (EMA) at Arima, Point Lisas, and Toco all report good air quality. San Fernando reports moderate air quality, while Signal Hill, Mayaro, and Beetham do not currently transmit PM2.5 or PM10 data.

Unofficial air quality monitoring stations at Longdenville, St. Augustine, and Woodbrook are reporting good air quality.

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.

Over the last 24 hours, visibility has remained at 10 kilometers at the A.N.R. Robinson International Airport at Crown Point, Tobago, and at the Piarco International Airport, Trinidad, outside of rainfall activity.

Saharan Dust Forecast For T&T

Current Saharan Dust levels across the Atlantic's Main Development Region (east of T&T) as of July 2024. (Michael Lowry)
Current Saharan Dust levels across the Atlantic’s Main Development Region (east of T&T) as of July 2024. (Michael Lowry)

Across the remainder of the Atlantic, Saharan Dust levels remain well above normal for this time of year as we move past the climatological peak for dust east of T&T.

The ongoing outbreak has at least temporarily turned off the tropics and has likely contributed to some cooling of Atlantic waters – especially closer to Africa. The dry, dust-laden air from the deserts of North Africa usually peaks in late June and July and is an anticipated part of the seasonal cycle. In 2023 Saharan dust was largely a no-show, with the lowest coverage of dust over the tropical Atlantic in at least 20 years (since satellites began measuring dust).

Tropical Waves 22 and 23’s passage this past week kept the Intertropical Convergence Zone across T&T, which limited dust across the country. However, as a high-pressure system rebuilds across T&T, Saharan Dust is forecast to return at higher concentrations.

00Z Friday, July 19th, 2024, NASA GEOS-5 Dust Extinction Monitoring Tropical Atlantic Dust Aerosol Optical Depth showing Saharan Dust.

Saturday (July 20th) through Sunday (July 21st): On Saturday and Sunday, generally moderate to occasionally high concentrations of Saharan Dust across both islands, with generally moderate air quality to occasionally unhealthy for sensitive groups.

Monday (July 22nd) through Monday (July 29th): Generally mild to moderate concentrations of Saharan Dust across both islands, with generally moderate air quality.

What does this mean for you?

Elevated concentrations of Saharan Dust periodically over the next seven to ten days are likely to bring air quality to moderate levels, chiefly affecting the most sensitive groups of the population. The general public is not required to take action.

We’re in a period where the Intertropical Convergence Zonetropical waves, and occasional tropical cyclones may shield Trinidad and Tobago from the Saharan Dust events. While tropical waves are notable 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 its strength 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 in April and continue through November.

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