Next Surge Of Saharan Dust Arrives Late Sunday Across T&T

Minimal levels of Saharan Dust are forecast through the weekend, but another moderate to high concentration surge is forecast to arrive by late Sunday. However, the presence and persistence of the Intertropical Convergence Zone may allow for locally improved air quality in the vicinity of rain, showers, and thunderstorms.

What you need to know

Saharan Dust Surges: While no major or significant surges are forecast to affect T&T over the next several days, a moderate to high concentration surge of Saharan Dust is forecast to arrive across T&T on August 21st with fluctuating concentrations through the upcoming week.
Impacts: Air quality levels across Trinidad and Tobago will vary between good and moderate through the forecast period. Periodic rainfall will also lead to air quality improvements in localized areas.
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 Signal Hill and Port of Spain have recorded good to moderate air quality levels over the last 24 hours. No data was reported at Point Lisas or San Fernando.

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 or above ten kilometers at the Piarco International Airport and A.N.R. Robinson International Airport at Crown Point, Tobago.

Saharan Dust Forecast

00Z Thursday, August 18th, 2022, NASA GEOS-5 Dust Extinction Model Monitoring Tropical Atlantic Sulphates Aerosol Optical Total showing Saharan Dust

Ongoing Surge: Subsides Today

Saharan Dust levels are mild and decreasing across Trinidad and Tobago, with higher concentrations north of the country. Minimal concentrations are forecast to continue through the weekend as a tropical wave and troughs move across the region.

Anticipated intervals of showers and isolated thunderstorms are forecast to aid in air quality improvement. Air quality levels are forecast to remain mostly good, at times dipping to moderate in high traffic areas, with the visibility generally near or above ten kilometers outside of shower or thunderstorm activity.

Surge #2: Late Sunday, August 21st, 2022

Following the passage of Tropical Wave 30/31 over the weekend, a moderate to high concentration surge of dust is set to arrive late Sunday into early Monday, August 22nd, 2022. Fluctuating concentrations of dust are forecast through the upcoming week as rain, showers, and thunderstorms associated with the Intertropical Convergence Zone locally improve dust levels and air quality impacts.

Air quality levels will vary from good to moderate across T&T, with visibility generally remaining near or above nine to ten kilometers outside of shower or thunderstorm activity.

These fluctuating air quality and dust levels are forecast to continue until the end of next weekend.

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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