A low-level trough and two tropical waves are forecast to keep Saharan Dust concentration low across Trinidad, Tobago, and the Windward Islands over the next five to seven days, with mild concentrations surging between tropical wave passages.
However, by mid-next week, a significant surge of dust is forecast to follow the larger Tropical Wave 04, with high concentrations lingering into the middle to June.
Air quality through next Tuesday may vary between good to moderate, but from Tuesday onwards, air quality may be reduced to moderate levels, with the lowest visibility at 7-8 kilometers.
The Environmental Management Agency (EMA) air quality monitoring stations are recording AQI values at levels that are good to moderate in Trinidad and Tobago. 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.
The Saharan Dust Forecast
The passage of a merged low-level trough and Tropical Wave 03 is forecast to keep Saharan Dust concentrations low from Thursday evening through Saturday evening. However, following the passage of Tropical Wave 03, a mild to moderate surge will move in across Trinidad and Tobago, reducing air quality to moderate levels. This surge will be short-lived as Tropical Wave 04 is forecast to move across Trinidad and Tobago Monday night into Tuesday, improving air quality once again.
Following the passage of Tropical Wave 04, a significant surge of Saharan Dust is forecast to begin moving into Trinidad, Tobago, and the Lesser Antilles, diminishing visibility and air quality. High concentrations will linger through the end of the forecast period. Longer range modeling shows a reinforcing significant surge of dust arriving across T&T and the Windward Islands by June 12th, lingering into the mid-month.
Air quality levels will fluctuate between good to moderate. By mid-month, air quality may dip further to levels that are moderate to unhealthy for sensitive groups. On days with peak concentrations, visibility may be reduced between 7-10 kilometers.
What does this mean for you?
For the general population, with moderate to high Saharan dust concentrations forecast, little to no impacts are forecast beyond hazy skies. For sensitive groups, such as children, the elderly, and persons who suffer from respiratory ailments and allergies, you may need to avoid prolonged exertion outdoors.
Closer to the middle of the month, with high concentrations of Saharan Dust forecast, members of sensitive groups may experience health effects. The general public is not likely to be affected though visibility will be reduced due to increased dust. There is an increasing likelihood of respiratory symptoms in sensitive individuals, aggravation of heart or lung disease, and premature mortality in persons with cardiopulmonary disease & the elderly.
We’re in a period where the ITCZ 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 the strength of the wave 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 to occur in April and continue through November.