A significant surge of Saharan Dust is forecast to affect Trinidad and Tobago from tomorrow (Saturday, December 23rd, 2023), with decreasing dust concentration through the Christmas holiday.
What you need to know
— Saharan Dust Surges: A significant surge of dust is forecast to move across the Windwards, with peak concentrations across T&T, on Saturday, December 23rd, 2023, with dust levels decreasing through the end of the year.
— Impacts: Between Saturday and Monday, air quality levels across Trinidad and Tobago are forecast to remain near moderate, at times dipping to levels that are unhealthy for sensitive groups. From Boxing Day (December 26th), air quality will generally improve from moderate to good levels.
— What Should You Do: Sensitive groups are advised to take the necessary precautions, particularly on Saturday into Sunday.
Current AQI Levels Across T&T
The official air quality monitoring stations from the Environmental Management Agency (EMA) at Arima and Point Lisas report good air quality levels, while at San Fernando, air quality is moderate. Stations at Beetham and Signal Hill, Tobago, are not reporting PM2.5 or PM10 data as of Friday afternoon.
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 unaffected by Saharan Dust and smoke at the A.N.R. Robinson International Airport at Crown Point, Tobago, and at the Piarco International Airport, Trinidad.
Saharan Dust Forecast
A significant surge of Saharan Dust is forecast to move across the Windward islands, including T&T, from Saturday, December 23rd, 2023, with peak concentrations on Saturday into Sunday, December 24th, 2023.
Dust levels are forecast to remain elevated but decrease from December 25th, 2023, through December 28th, 2023. By December 29th, 2023, little to no dust is forecast to be present across T&T. However, longer range modelling suggests a mild surge of dust to arrive across T&T sometime by late January 1st into January 2nd.
What does this mean for you?
Between Saturday and Monday, air quality levels across Trinidad and Tobago are forecast to remain near moderate, at times dipping to levels that are unhealthy for sensitive groups. From Boxing Day (December 26th), air quality will generally improve from moderate to good levels. Visibility may also drop to as low as 7 kilometers on Saturday.
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.
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.
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 associated with West African thunderstorms driving dust into the upper atmosphere from April through November.
