Saharan Dust Concentrations To Gradually Decrease Across T&T Until Saturday

Tropical waves and the Intertropical Convergence Zone are forecast to keep Trinidad and Tobago relatively shielded from dense Saharan Dust until Saturday, July 16th, 2022.

What you need to know

Saharan Dust Surges: A significant dust surge is forecast to move away from Trinidad and Tobago on Wednesday, July 13th, 2022. Another moderate to high concentration dust surge is forecast across the Lesser Antilles by early Thursday, July 14th, 2022, but high levels of Saharan Dust will only begin to affect T&T by late Saturday, July 16th, 2022. After some improvement over the upcoming weekend, a third surge of dust is set to arrive by July 19th. In all dust surges, higher concentrations are forecast to remain north of T&T, across the French Antilles and Leewards.
Impacts: Air quality levels across Trinidad and Tobago will vary between good and moderate through the forecast period, dipping to unhealthy levels for sensitive groups mainly across the Leewards and French Antilles.
What Should You Do: Sensitive groups will have brief periods during the upcoming forecast period where good air quality is anticipated. However, they should take the necessary precautions during dust surges. The general population will remain unaffected.

Current AQI Levels Across T&T

The Environmental Management Agency (EMA) air quality monitoring stations at San Fernando, Port of Spain, Point Lisas, and Signal Hill have all recorded good to moderate air quality levels over the last 24 hours.

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 remained between eight and ten kilometers at the Piarco International Airport and A.N.R. Robinson International Airport at Crown Point, Tobago.

Saharan Dust Forecast

00Z Tuesday, July 12th, 2022, NASA GEOS-5 Dust Extinction Model Monitoring Tropical Atlantic Sulphates Aerosol Optical Total showing Saharan Dust

Ongoing Surge: Through Early Wednesday, July 13th, 2022

A significant surge of Saharan Dust has affected the Lesser Antilles, with higher concentrations affecting countries north of Trinidad and Tobago since Sunday, July 9th, 2022.

Air quality levels will vary from good to moderate, with visibility as low as eight kilometers outside of shower or thunderstorm activity.

This dust surge is forecast to briefly decrease – but Saharan Dust will not go away – by Wednesday, July 13th, 2022 as an upper-level low pressure that has been anchored across the Central Caribbean Sea pulls west and Tropical Wave 18 moves across the Lesser Antilles.

Surge #2: Early Thursday, July 14th, 2022

A moderate to high-concentration surge of dust is set to follow on Thursday, July 14th, 2022, and linger through Monday afternoon, on July 18th, 2022. Higher dust levels are generally forecast to remain north of Trinidad and Tobago, at least until early Saturday, when peak concentrations are set to begin across the country.

A strong low-level trough embedded within the Intertropical Convergence Zone and Tropical Wave 19 are forecast to move across the region on Friday, July 15th, 2022 and Saturday into Sunday, July 16th into 17th, 2022, respectively. These systems are forecast to produce intervals of showers and isolated thunderstorms, with brief air quality improvement.

Still, air quality levels will vary from good to moderate, with the visibility dropping to six kilometers outside of shower or thunderstorm activity.

Some brief improvement is forecast by Monday night, July 18th, 2022 across Trinidad and Tobago, ahead of the Intertropical Convergence Zone.

Surge #3: By Wednesday, July 20th, 2022

Following the passage of Tropical Wave 20 (yet to move off the African Coast) and the modulation of the Intertropical Convergence Zone across T&T, another moderate to high-concentration surge of dust is set to arrive by late Tuesday, July 19th, 2022 with some improvement by Saturday, July 23rd, 2022.

Air quality levels will vary from good to moderate, with the visibility dropping between six to eight kilometers outside of shower or thunderstorm activity.

What does this mean for you?

The air quality will be degraded through the forecast period. During high traffic periods, particularly between 6:00 AM and 9:00 AM, and again from 3:00 PM through 6:30 PM, air quality may be further reduced in localized areas.

According to the Trinidad and Tobago Meteorological Service, “the 2022 Saharan Dust Haze Season is likely to peak from June to August with the number of Saharan dust haze days expected to increase significantly. The duration of the plumes of Saharan dust haze visiting both islands is also likely to be more prolonged than earlier in the year, with increased odds for higher dust haze concentration during plumes visitation.”

We’re in a period where the Intertropical Convergence Zone 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 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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