Morning lows across Trinidad have dipped near or below 20°C, with a few areas at 19°C on Thursday morning as of 7:00 AM. At Piarco, temperatures dipped to 19.7°C.
Parts of interior Trinidad, such as Penal and Caroni saw morning low temperatures as low as 18.0°C.
Temperatures across Tobago, albeit still cool, have remained above 20°C
Low temperatures during this time of year are normal, as the Northern Hemisphere experiences winter.
Cool temperatures across Trinidad result of several factors occurring:
- Calm/near calm winds
- Almost no cloud coverage
- Winds originating from the Northeast to the north at some of the lower levels of the atmosphere (over Trinidad)
- Low amounts of low-level moisture (water vapor)
The dew point, which is the atmospheric temperature below which water droplets begin to condense and dew can form, meteorologists can determine both the moisture content of the atmosphere near the surface, as well as an estimate for the minimum temperature.
A lower dew point means that there is less water vapor in the air. Water vapor can absorb and radiate heat back to the surface. Hence, the lower the water vapor content, the more infrared radiation (i.e. long-wave radiation) can escape from the surface of the earth and cause rapid cooling.
Calm winds and no cloud coverage are due to a persistent sub-tropical high-pressure system that will begin to dominate the weather for much of January, causing dry air at mid and upper levels of the atmosphere, inhibiting cloud formation.
Lack of cloud coverage also leads to fairly warm days, where temperatures can reach 30-32°C.
Particularly during El Niño years (we are in ENSO neutral conditions, with an El Niño possible later this year), winter storms move further southward across the United States, increasing the likelihood of cold frontal systems moving across the Caribbean and further dipping temperatures. On the rare occasion, a cold front does manage to make it as far south as Trinidad and Tobago, cold conditions would be due to a process called advection, where there is a horizontal mass movement of air.
For vulnerable persons, who might be especially susceptible to cooler temperatures, such as babies or people suffering from arthritis, it may be best to layer up as a way to keep warm at night.
Forecast for This Weekend
For tonight, across Trinidad, mostly clear and mostly dry conditions are expected to persist, with minimal cloud cover expected, particularly across Central and Southern Trinidad. This would result in temperatures in the upper teens (18°C to 20°C) across Trinidad. Across Tobago, a shearline is forecast to begin affecting the island, resulting in periodic showers and cloudy conditions, which will keep conditions warmer, with lows near or at 22°C across Tobago.
On Friday night into Saturday, cloudy conditions are forecast to spread across both islands with intermittent light to moderate showers and periods of rain. With cloud cover and rain, temperatures will still be cool but it may not dip below that 20°C mark but still cool and rainy conditions are forecast.
By Saturday into Sunday and again Sunday into Monday, conditions are forecast to become somewhat clear again, with minimal cloud cover and a reduction in low-level moisture. This will result in another night of cooler than usual temperatures in the upper teens (18°C to 20°C) across Trinidad and near 22°C in Tobago. Note that lower temperatures are likely in valleys and interior areas of both islands.
Seas will remain slight to moderate in open waters, with waves between 1.0 meters and 1.5 meters and near calm in sheltered areas. Winds will be mainly from the east to northeast at times, at 10-15 knots.