Showers, Thunderstorms Forecast to Interrupt a Very Hot Day Across T&T

As of 7:00 AM Tuesday 27th August 2019, hazy skies and fog are ongoing across much of Central and Northern Trinidad, gradually becoming more clear. A mostly hot and sunny morning is forecast to give way to showers and thunderstorms by midday through the evening across Trinidad. This activity will focus along the Western and Northern halves of Trinidad, as well as Tobago.

A developing feeder band of Tropical Storm Dorian forecast to bring cloudy skies, isolated to scattered showers, and thunderstorms to Tobago through the day.

Hot temperatures are forecast across Trinidad and Tobago as a result of initially clear skies and near calm winds.

Street and flash flooding, gusty winds and landslides are possible in the vicinity of or accompanying heavy showers and thunderstorms.

There are NO alerts, watches or warnings in effect for Trinidad and Tobago from the Trinidad and Tobago Meteorological Service at this time.

Showers and isolated thunderstorms developing east of Trinidad, south of Tobago associated with a feeder band of Tropical Storm Dorian. It is forecast to move across Tobago, bringing locally heavy showers, possible gusty winds, and overcast skies. Image: Trinidad and Tobago Meteorological Service
Showers and isolated thunderstorms developing east of Trinidad, south of Tobago associated with a feeder band of Tropical Storm Dorian. It is forecast to move across Tobago, bringing locally heavy showers, possible gusty winds, and overcast skies. Image: Trinidad and Tobago Meteorological Service

Throughout the early and mid-morning, mostly settled conditions are forecast across Trinidad and Tobago. This morning through the early afternoon, conditions are forecast to get very hot across mainly Trinidad due to light winds and sunny skies.

Winds are forecast to be near calm initially, then from the south as Tropical Storm Dorian remains north of T&T. This means that sea breeze convergence is forecast to initiate showers across the Northern Range and the northern coast of Tobago and the prevailing winds will cause orographic lift (air being forced upwards by the mountainous terrain).

These factors, combined with our usual local climate regime and increased moisture may result in locally heavy showers and thunderstorms across the northern and western halves of Trinidad, as well as parts of Tobago.

This localized activity will be enhanced by Tropical Storm Dorian’s moisture field and possible feeder band activity on the tail end of the storm.

Note that in heavier showers or a thunderstorm, locally heavy rain and gusty winds can trigger street flooding and down trees or utility poles.

Temperatures

Last night’s minimum temperatures were warm at 24°C at Piarco, Trinidad, and 26°C at Crown Point, Tobago. Minimum low temperatures across Trinidad and Tobago tomorrow are forecast to range between 24°C-26°C, with temperatures at the upper end of the minimum low-temperature range favoring Tobago. Low temperatures are likely to be lower across inland and mountainous areas. Light winds and clear skies will allow for a cool night.

Today, maximum high temperatures across T&T are forecast to be near a hot 34°C at Piarco, Trinidad and a heat index of ranging from 35°C to 48°C. Across Tobago, maximum high temperatures are forecast to be a warm 32°C with a heat index of 34-37°C. The heat index is an index that combines air temperature and relative humidity, generating a “feel’s like” temperature.

To give an idea of how hot we forecast today, across Trinidad to be, records from the Trinidad and Tobago Meteorological Service dating back to 1945, temperatures across Trinidad have only topped 34°C twice on August 27th – in 2010 at 35.3°C and 2011 at 34.5°C. Temperatures have reached 34°C on August 27th three times in recent recorded history – in 2007, 2005 and 1989.

The Heat Index

Quite a few persons across the country will likely take to social media to complain about the heat today, or more so what outside feels 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 Values Explained
Heat Index Values Explained

The 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, heat index levels are between extreme cautious to dangerous levels. Heat cramps and heat exhaustion are likely. Heatstroke may be probable with continued outdoor activity.

Heat Safety

Graphic: Beat the Heat. Heat related deaths are preventable.

Graphic: Beat the Heat. Heat related deaths are preventable.

Source: MEMA
Heat Safety Tips and Resources
Heat Safety Graphic. Source: Heat Safety Tips and Resources

Is this a heatwave?

No.

An article from the Pan American Health Organization (PAHO) earlier last month made the rounds on social media, urging Northern Hemisphere countries to prepare for heatwaves.

We are experiencing just another hot day in the tropics, which is normal for this time of year. Heatwaves are generally prolonged heat with life-threateningly high temperatures.

Seas

Seas are forecast to become moderate with waves up to 2.0-2.5 meters in open waters. Occasional large waves up to 3.0 meters and dangerous rip-tides are possible, particularly along the North Coast of Trinidad. These will create unsafe conditions for small-craft operators and fishermen and persons with marine interests. Extreme caution is advised.

Note that King Tides are forecast to begin on Wednesday, which means higher than normal high tides are expected. Coastal flooding possible, particularly along the northern and eastern coastlines of Trinidad and Tobago.

Over the Next 24 Hours

Winds: Sustained surface winds between 20 KM/H and 40 KM/H with higher gusts up to 65 KM/H are possible in heavy showers or thunderstorms across Trinidad and Tobago on Tuesday as Tropical Storm Dorian traverses the region.

With wind gusts up to 65 KM/H, whole trees are expected to be in motion and there may be some inconvenience when walking against the wind gusts. Light outdoor objects may topple or become airborne such as garbage cans, potted plants, loose galvanize or construction material and other outdoor furniture. Tents may jump. Older/weaker trees may fall, bringing down utility poles and lines.

High Wind Event Precautions
High Wind Event Precautions

Rainfall: In addition, pockets of moderate to heavy showers, and isolated thunderstorms are expected. Rainfall accumulations of at least 15 mm are possible with isolated higher amounts. As a result, some street and flash flooding are possible.

Generally, with heavy showers and thunderstorm activity, street flooding, particularly in flood-prone areas or areas with poor drainage, is possible as well as flash flooding in areas where more prolonged heavy rainfall may occur.

Landslides: Heavy showers across the Northern Range may trigger landslides in landslide-prone areas. Particularly in areas that receive heavy rainfall, landslides and/or mudflows may occur across both islands. These landslides, in addition to gusty winds, may down trees, utility poles and impede traffic on roadways.

Frequent Lightning: In addition, with thunderstorms, frequent lightning is likely.

Why I May Not/Will Not See Constant Rainfall?

A frequent complaint is the forecast is wrong because I didn’t experience any rainfall. Scattered showers mean that you, individually, may experience some showers intermittently throughout the day and there is a higher chance for this activity than isolated activity.

Over the next day, isolated to scattered activity is forecast – a combination of sea breeze convergence, day time heating and intermittent feeder band activity from Tropical Storm Dorian.

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