Saharan Dust concentrations are forecast to increase from Wednesday, though forecast rainfall may temper air quality impacts. However, from mid-Saturday, April 20th, 2024, a significant surge of Saharan Dust is forecast to move across the Lesser Antilles, including Trinidad and Tobago, reducing visibility and air quality. This major surge is forecast to rival the intensity last seen just before and on Christmas Eve 2023 and just before Carnival 2024 in Trinidad and Tobago.
What you need to know
— Saharan Dust Surges: A moderate to high-concentration surge is forecast to move across Trinidad and Tobago overnight tonight (Tuesday night into Wednesday), with increasing concentrations into the weekend. From mid-Saturday, April 20th, 2024, and perhaps even as early as during the morning, a significant surge of Saharan Dust is forecast to move across Trinidad and Tobago, the Windwards and southern Leewards. High Saharan Dust concentrations are forecast to remain present through April 26th.
— Impacts: Through April 19th, air quality across T&T will range between moderate and unhealthy for sensitive groups, with occasional improvement in areas that receive rainfall. From Saturday through next week, air quality is forecast to range from moderate to unhealthy, with a further localized reduction in air quality levels near fires through the forecast period
— 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
The official air quality monitoring stations from the Environmental Management Agency (EMA) at Mayaro, Toco, Beetham, Scarborough and San Fernando are all reporting good levels, while at Arima and Point Lisas, no data (based on PM2.5 and PM10) are being reported.
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 the Piarco International Airport, Trinidad, outside of shower activity.
Saharan Dust Forecast
Tuesday PM (Apr. 16th) through Friday (Apr. 19th): Moderate to high concentrations of Saharan Dust are forecast to be present through this period, with air quality generally moderate to unhealthy for sensitive groups. Note that pollen may also aggravate allergies and those sensitive to air quality changes. However, with forecast rainfall, particularly Thursday through the first half of Saturday, air quality in localized areas that receive rainfall may briefly improve to good levels.
Saturday (Apr. 20th) through Sunday (Apr. 21st): A major Saharan Dust surge is forecast to affect Trinidad and Tobago, greatly affecting air quality and visibility. Unhealthy air quality is likely from midday Saturday through late Sunday, with further reductions possible in the vicinity of fires and blowing dust. Visibility is forecast to reduce as low as four kilometers, but lower visibility is possible near dawn and dusk. Everyone should take all precautions during this period.
Monday (Apr. 22nd) through Friday (Apr 26th): High concentrations of Saharan Dust are forecast, with concentrations fluctuating between moderate and high as the week progresses. Air quality is forecast to vary between moderate and unhealthy, with visibility as low as six kilometers forecast.
What does this mean for you?
Unhealthy air quality is forecast this weekend, and in areas where blowing smoke occurs or near fires. Everyone may begin to experience health effects, and members of sensitive groups may experience more serious health effects.
Mainly from April 17th, air quality is forecast to reach generally moderate to unhealthy for sensitive groups. With elevated concentrations present and drier and breezier conditions bringing the risk of fires, air quality is still forecast to be reduced, with further reductions in localized areas of fires, blowing smoke and dust, and high traffic.
During this period, 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.
The surges of dust during this time of year are due to the Harmattan, a season in the West African subcontinent that occurs between the end of November and the middle of March. During this season, a predominant northeasterly trade wind (dubbed the Harmattan Winds) blows from the Sahara Desert over Western Africa into the Gulf of Guinea.
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.
