Cool Temperatures Across T&T As Themometers Drop Below 20°C

A surge of dry air across Trinidad and Tobago is forecast to bring cooler than average temperatures to the country into the weekend. On Wednesday morning, minimum low temperatures below 20°C were recorded across much of the country. As expected, interior areas of the country saw temperatures in the upper teens with Penal, El Reposo, and Bonne Aventure recording some of the lowest temperatures.

However, cooler temperatures were likely across eastern and central parts of Trinidad where instrumentation is not available.

Preliminary minimum low temperatures across Trinidad and Tobago on Wednesday, January 5th, 2022.

Tuesday 4th January 2022 Temperatures

Minimum low temperatures were recorded across Trinidad and Tobago during the morning of Tuesday 4th January 2022.
Minimum low temperatures were recorded across Trinidad and Tobago on Tuesday, January 4th, 2022.

The above data was collected from publicly reporting automated weather stations (AWS) across Trinidad and Tobago that are both privately and publicly owned. Specifically, data collected from Piarco, Crown Point, El Reposo, and Penal are from AWS sites owned and operated by the Trinidad and Tobago Meteorological Service.

What’s causing the cool temperatures?

Back-trajectory of the air currently at low-levels of the atmosphere across Trinidad and Tobago (Weathernerds)
Back-trajectory of the air currently at low-levels of the atmosphere across Trinidad and Tobago (Weathernerds)

Cool and dry air from the north Atlantic has gradually moved towards the Southern Windward Islands, embedded within the large sub-tropical Atlantic high-pressure system.

This high-pressure system has brought brisk winds across the region. While moisture and temperature increased on its journey to T&T, the conditions remained dry and stable enough to hinder clouds’ development, leading to mostly sunny days and clear nights over the next three days.

As we head into the weekend, areas of increased moisture and elevated winds are forecast to move across T&T, inhibiting the conditions that usually cause cooler than average nighttime temperatures.

Total atmospheric moisture content over the next 7 days, showing pulses of moisture moving across T&T with areas of dry air. (weathermodels.com)
Total atmospheric moisture content over the next seven days, showing pulses of moisture moving across T&T with areas of dry air. (weathermodels.com)

Why the cool temperatures? It all has to do with 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 earth’s surface and cause rapid cooling.

The pressure gradient is forecast to be relatively weak through Thursday, allowing calmer than usual winds to occur.

On clear nights, radiative cooling can cause temperatures across Trinidad to dip below 20°C, which happens less than three to five days annually on average.

Low temperatures are normal during this time of year, as the Northern Hemisphere experiences winter.

Cool temperatures across Trinidad result of several factors occurring:

  • Calm/near calm winds overnight (though over the last 3 days, it has been quite windy across T&T);
  • Little to no cloud coverage;
  • Winds originating from the northeast to the north at the lower levels of the atmosphere (over Trinidad);
  • Low amounts of low-level moisture (water vapor).

Lack of cloud coverage also leads to fairly warm days, where temperatures can reach 30-32°C.

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 Through This Week

Forecast minimum and maximum temperatures for Trinidad through January 8th, 2022.

Mostly clear skies are expected overnight into Wednesday. Generally, dry conditions are expected to persist for tonight and tomorrow, with minimal cloud cover expected. This would result in temperatures in the upper teens (17°C to 21°C) across Trinidad and lows near or at 21°C across Tobago.

However, models indicate an increase in moisture on Thursday morning and persist into the weekend due to a series of low-level perturbations affecting the Windward Islands. Drier air is forecast across Tobago on Friday night into Saturday, potentially causing cooler temperatures over the island on Saturday morning. With this increase in moisture, lows are forecast to be in the low twenties across Trinidad and Tobago.

Interestingly, one year ago, on January 5th, 2021, T&T recorded the coldest night in a decade, where temperatures at Piarco dipped to 19.0°C. The lowest minimum temperature on record at Piarco is 16.1°C, which occurred on the nights of January 21st and 30th, 1964, followed by 16.4°C on January 28th, 1976.

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