10:00 AM Update: Minimum low temperatures, as forecast, reached as low as 18°C across parts of Trinidad. Piarco recorded a minimum low of 19.5°C.
Morning lows across Trinidad are already dipping below 20°C, with a few areas nearing 19°C on Saturday morning as of 1:00 AM.
Parts of interior Trinidad, such as Penal and Caroni may see morning low temperatures near 18.0°C.
Temperatures across Tobago, albeit still cool, have remained near 23°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, 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.
This post will be updated to reflect the minimum low temperatures later this morning. However, as of 1:00 AM, temperatures are already between 19°C and 21°C.
Forecast for This Weekend
For tonight, generally dry conditions are expected to persist, with minimal cloud cover expected. This would result in temperatures in the upper teens (18°C to 20°C) across Trinidad, and lows near or at 23°C across Tobago. Mostly clear skies are expected overnight Saturday into Sunday.
On Sunday, models continue to indicate a weak low-level trough affecting the Southern Windwards, including Trinidad and Tobago. However analysis shows little moisture and instability along the axis itself as the feature drifts northwards across the island chain. Some partly cloudy skies and brisk light to moderate showers are expected to interrupt generally sunny day and mostly clear and cool night.
This mild increase in moisture, as well as the increase in cloud coverage, will limit cooling at the surface. Hence, lows are forecast to be in the low twenties (20°C to 22°C) across Trinidad, with lows near or at 23°C across Tobago.
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.