Fluctuating Saharan Dust Concentrations Forecast Over Next 10 Days

Varying levels of Saharan Dust continue to affect Trinidad and Tobago. Over the next several days, even with multiple tropical waves moving across the region, the dust is here to say – at least for the next ten days.

What you need to know

Saharan Dust Surges: Dust levels are set to fluctuate across Trinidad and Tobago over the next ten days. Mild to moderate surges of dust are forecast to arrive on Wednesday, July 6th, with improvement by Friday, July 8th though mild dust levels are forecast to remain present through the weekend. Two significant dust surges are forecast to arrive by July 11th and July 15th.
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 next week.
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 near ten kilometers at the Piarco International Airport and A.N.R. Robinson International Airport at Crown Point, Tobago.

Saharan Dust Forecast

00Z Monday, July 4th, 2022, NASA GEOS-5 Dust Extinction Model Monitoring Tropical Atlantic Sulphates Aerosol Optical Total showing Saharan Dust
00Z Monday, July 4th, 2022, NASA GEOS-5 Dust Extinction Model Monitoring Tropical Atlantic Sulphates Aerosol Optical Total showing Saharan Dust

Ongoing Surge: Through Friday, July 8th, 2022

A moderate dust surge arrived across Trinidad and Tobago on Saturday, July 2nd, 2022. Air quality levels have fluctuated between good to moderate, with the visibility near ten kilometers outside of shower or thunderstorm activity over the last several days. Through this week, similar conditions are forecast, even with the passage and lingering instability from Tropical Wave 15 today, Tuesday, July 5th, 2022.

A reinforcing dust surge is set to arrive tomorrow, Wednesday, July 6th, 2022 but no significant change in air quality or visibility is forecast. Higher dust levels are forecast to remain north of T&T.

On Friday, July 8th, 2022, Saharan Dust will still be present, particularly across northern Trinidad and Tobago, but higher dust levels are forecast to remain north of the country. Through the weekend, Tropical Wave 16 is forecast to traverse the region, gradually diminishing dust levels until the start of the upcoming week.

Surge #2: Monday, July 11th, 2022

Following Tropical Wave 16 over the upcoming weekend, a significant surge of Saharan Dust is forecast to begin moving across the Lesser Antilles, with higher concentrations affecting countries north of Trinidad and Tobago. Peak dust concentrations are forecast between Tuesday, July 12th, and Wednesday, July 13th, with gradually diminishing dust levels.

Air quality levels will vary from good to unhealthy for sensitive groups, with the visibility dropping to six kilometers outside of shower or thunderstorm activity.

Surge #3: Friday, July 15th, 2022

While this tropical wave is yet to be analyzed or even move off the African Coast, forecast models indicate another tropical wave moving across the Lesser Antilles between Wednesday, July 13th and Thursday, July 14th. The wave’s passage will reduce – but not remove – Saharan Dust from our area.

Instead, another significant surge of dust is set to follow on Friday, July 15th, 2022, and linger through the middle of July.

Air quality levels will vary from good to unhealthy for sensitive groups, with the visibility dropping to six 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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