3:00 PM Saturday 20th July 2019 Update
As forecast, hot temperatures and high heat indices continue across T&T today. See below for more information.
On Friday 19th July 2019, hot temperatures were prevalent across Trinidad and Tobago. Across most of Trinidad and Tobago, temperatures between ranged between 31.0°C and 33.0°C, with isolated areas between 33.0°C and 35.0°C, mainly across Trinidad. In urban areas and areas where development is prevalent, temperatures soared above 35.0°C.
In Chatham, Southern Trinidad, an Automated Weather Station (AWS) from the Trinidad and Tobago Meteorological Service recorded a temperature of 34.75°C at 12:00 PM. The highest temperature recorded across Trinidad was at Woodbrook, by another AWS of 38.0°C between 1:00 PM and 3:00 PM.
Temperatures in cities, such as Port of Spain, tend to be much higher than surrounding locations due to a phenomenon called the Urban Heat Island Effect. There are several causes, but the main instigator for this phenomenon tends to be increased dark surfaces such as roads and pavement in cities, which absorb solar radiation more than surrounding areas.
The Heat Index
Several persons across the country took to social media to complain about the heat, or more so what outside felt like. This is called the heat index and is a combination of air temperature and relative humidity determining what the air feels like to a person i.e. how hot it actually feels.
The heat index is important because of sweating. Your body sweats in order to cool the skin and maintain a constant, healthy body temperature. This cooling process means that the sweat has to evaporate off the skin to remove heat. However, if the sweat is unable to evaporate, the body isn’t able to regulate temperature.
With high volumes of moisture in the air, also known as high relative humidity, which T&T regularly experience due to its tropical climate, the rate of sweat evaporation decreased. This is because the atmosphere is unable, or has limited potential to hold additional moisture in the atmosphere.
This results in you feeling warmer in humid conditions and cooler in less humid conditions i.e. when relative humidity decreases. As temperature increases, the heat index increases. As relative humidity increases, so does the heat index.
Heat index is generally classified into four categories: caution, extreme caution, dangerous and extremely dangerous. Generally across Trinidad and Tobago, we experience heat indices of caution to extreme caution in times of hot days, with isolated areas experiencing dangerous heat indices such as urban areas.
Today’s High Heat Indices
On Friday 19th July 2019, high heat indices were prevalent across Trinidad and Tobago. Across most of Trinidad and Tobago, heat indices between ranged between 36.0°C and 40.0°C. In urban areas and areas where development is prevalent, the heat index soared to 46.0°C – dangerous levels. At this level, heat cramp and heat exhaustion are likely. Heatstroke becomes probably with strenuous outdoor activity.
High Temperatures To Continue Through Sunday
A high-pressure system continues to affect the Lesser Antilles, producing mostly stable weather with sunny skies and generally breezy conditions.
This is forecast to continue through Sunday, as Tropical Wave 24 nears the Lesser Antilles.
On Saturday and Sunday, maximum high temperatures are forecast to be near 32-34°C across Trinidad, and 31-33°C across Tobago. Heat indices are also forecast to be high, near 36-38°C across Trinidad, and 34-35°C across Tobago.
Is this a heatwave?
An article from the Pan American Health Organization (PAHO) earlier this week made the rounds on social media, urging Northern Hemisphere countries to prepare for heatwaves.
Today (and tomorrow) are just some hot days in the tropics, as heatwaves are generally prolonged heat with life-threateningly high temperatures.
We shall have a post over the weekend on what PAHO was referencing, and what to expect across Trinidad and Tobago concerning heat waves in the coming months.