Forecast: Saharan Dust Concentrations On the Decrease, Isolated Showers Possible Overnight

Weather Forecast

Weather Forecast valid for the next 24 hours beginning 3:45PM Tuesday 19th March 2019.

For the remainder of Tuesday, mostly sunny and hazy conditions are to persist. By the late evening into nightfall, a low-level cloud patch is forecast to move across Trinidad and Tobago.

This patch will bring some brief cloudy skies and possible isolated showers. Showers will largely remain light to moderate. However, with the presence of Saharan dust in the atmosphere, you may awaken to spotted cars like the images below, as the rainfall brings the dust to the surface.

Photos posted by Pat All Brew, showing her spotted car after showers across Barbados on Monday 18th March 2019. Rainfall in the presence of Saharan dust is known to cause this effect.

On Wednesday, similar hazy skies are forecast to continue as Saharan dust concentrations decrease. However, by the late afternoon through the evening, an easterly wave is forecast to bring increased low-level moisture. While mid and upper level environments aren’t conducive for shower development across T&T, some isolated showers will be possible on Wednesday and Thursday, favoring Southern Trinidad and hilly areas.

A weak surface to low level ridge will remain in place, producing light breeze from the east.

Temperatures

Minimum low temperatures across Trinidad and Tobago through the weekend are forecast to be between 23°C-24°C and likely lower across inland and mountainous areas.

Maximum high temperatures across both islands are forecast to be warm, between 30°C-32°C.

Seas

Seas are forecast to remain moderate in open waters. Waves in open waters are forecast to be up to 2.0 meters. In sheltered areas, seas are forecast to remain smooth, below 1.0 meters.

Winds are forecast to be from the east at 15 to 20 knots.

Saharan Dust

Saharan Dust continues to dominate the weather news this week as hazy skies persist across Trinidad and Tobago, as well as the Southern Windwards.

The good news for Trinidad and Tobago is that the peak of this event is well behind us. Long range dust models show that there is another large plume nearing the Southern Caribbean by the end of this week. However, much of the dust associated with this plume is forecast to be deposited across the Atlantic and into South America. Countries like Guyana and Suriname could see unhealthy air quality yet again.

Saharan Dust forecast from the University of Athens SKIRON model, valid on 0Z UTC 19th March 2019 for Sunday 24th March 2019.

The bad news is that the mild concentrations of dust that is present in the atmosphere is enough to reduce air quality to unhealthy for sensitive groups. Low air quality is forecast through Thursday 21st March 2019.

Air Quality Forecast

Saharan Dust Concentration Forecast. EPA AQI colours indicated.

As previously indicated, peak concentrations are behind us. Models continue to indicate that moderate concentrations of Saharan Dust will remain in the atmosphere through the week. Concentrations will continue to decrease as the week progresses.

EPA Air Quality Index Risk Levels

Generally, PM2.5 levels (dust or particulate matter (PM) with a diameter of less than 2.5 micrometers) are forecast to remain at unhealthy for sensitive groups level through Thursday 21st March 2019.

PM10 levels (dust or particulate matter (PM) with a diameter of less than 10 micrometers) are forecast to return to good air quality levels by late Wednesday 20th March 2019.

Note that in the presence of bush fires, air quality can be reduced to unhealthy levels.

At unhealthy levels: There will be increased aggravation of heart or lung disease. Possible premature mortality in persons with cardiopulmonary disease and the elderly. There will also be increased respiratory effects in the general population. People with respiratory or heart disease, the elderly and children should avoid prolonged exertion. Everyone else should limit prolonged exertion

Related: Saharan Dust

At unhealthy for sensitive groups: There is the increasing likelihood of respiratory symptoms in sensitive individuals. Aggravation of heart or lung disease and possible premature mortality in persons with cardiopulmonary disease and the elderly. People with respiratory or heart disease, the elderly and children should limit prolonged exertion.

Larger, more concentrated plumes of Saharan dust begin to occur in April, and continue through November. This is due to stronger thunderstorms across interior Africa sending dust into the upper atmosphere.

As of 4:00PM Tuesday, Trinidad and Tobago, Grenada, St. Vincent and the Grenadines, Barbados, Guyana and Suriname are all experiencing air quality levels at moderate or unhealthy for sensitive groups.

Persons with respiratory ailments are advised to take the necessary precautions, not limited to those listed below.

Saharan Dust Precautions
Saharan Dust Precautions
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