Shelf clouds seen for a second time this week moving across the Gulf of Paria as moderate to heavy showers affect the area on Tuesday evening. Credit: Karen Johnstone
Forecast for the next 12 hours
Isolated showers continue across mainly Trinidad for now, generally remaining light to moderate through the evening. Some isolated heavy pockets have occurred and are possible through the evening. These isolated showers are forecast through the night and into tomorrow, remaining light to moderate.
These showers will interrupt partly cloudy to cloudy skies at times over the next 24 hours, initially favoring Trinidad. Showery activity is expected across Tobago overnight into Wednesday.
Some street flooding is possible. Street flooding is typically a result of poor or blocked drainage, where even a few minutes of heavy rainfall can trigger nuisance flooding. However, street flooding typically quickly subsides, within 30-90 minutes after rainfall ends.
Forecast for Wednesday
Showers will continue across mainly Trinidad, with similar chances for shower activity over Tobago. This will be due to a forecast shearline moving over the area, in conjunction with increased low-level moisture.
These showers will interrupt partly cloudy to cloudy periods. Conditions are forecast to improve by nightfall.
Model guidance for rainfall accumulation generally agree on 5-10 millimeters of rainfall occurring between 2:00PM Tuesday into 2:00AM Thursday, with the highest accumulations occurring across Northern and Eastern Trinidad, as well as Eastern Tobago. It won’t be surprising to see rainfall totals up to 15 millimeters in isolated areas where a prolonged heavy shower, or repeated showers occur.
Why the change from mostly sunny skies?
The dominant high pressure influence across the Eastern Caribbean will begin to weaken due to a developing low pressure system northeast of the island chain. This weakening will cause a wind speeds across the region, including Trinidad and Tobago, to decrease marginally.
In addition, a mid-level trough is forecast to enhance showery activity across the Windward islands, including Trinidad and Tobago. Low-level moisture will be ample for shower development, near 20-25 millimeters but intense convective activity (i.e. thunderstorms) are not forecast due to drier mid- and upper-level environment.
Minimum low temperatures across Trinidad and Tobago, over the next 48 hours, 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 mild, between 29°C-31°C.
Seas are forecast to remain moderate in open waters. Waves in open waters are forecast to remain up to 1.5 meters, occasionally 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 10-15 knots.
Seas may become locally rough in the vicinity of heavy showers, particularly in the Gulf of Paria.
Long range Saharan Dust models continue to show minimal to no dust over Trinidad and Tobago through Friday 16th March 2019. However, by later Saturday, a moderate plume of Saharan Dust is forecast to move across the Lesser Antilles. The highest concentrations of dust from this plume will move over the Southern Windwards, including Trinidad and Tobago. This Saharan dust is forecast to blanket the region with air quality to be reduced to unhealthy for sensitive groups and at times, unhealthy.
Over the next 4 days however, air quality will generally remain good to moderate so enjoy the outside air while it lasts!