Forecast: Hot With Afternoon Showers, Thunderstorms

Another day of light southerly winds, strong daytime heating, and high atmospheric moisture forecast, which may bring late morning through afternoon showers and thunderstorms across Western and Northern Trinidad.

These conditions will interrupt a very hot day across both islands. Street/flash flooding and gusty winds are possible, particularly across the south-facing slopes of the Northern Range, as well as parts of Central and Southern Trinidad, along the western half of the island. With light winds, funnel clouds are also possible.

There are no alerts, watches, or warnings from the Trinidad and Tobago Meteorological Service at this time.

The Forecast


Overview: The ITCZ remains to the north of T&T, slowly drifting to the south. A tropical wave is approaching the region, forecast to move across T&T on Thursday. Abundant low-level moisture continues to remain present with light winds from the south. Strong daytime heating across parts of Western and Central Trinidad is forecast. By the late morning, these features will trigger shower and thunderstorm development, with activity generally moving toward the north. By nightfall, thunderstorms across Northern Venezuela will begin to move northward, initially affecting southwestern Trinidad, gradually affecting the island as the ITCZ also drifts south.


Forecast: A mostly hot and sunny start to Wednesday is forecast, becoming increasingly cloudy as the morning progresses. With light to no winds and sunny skies, temperatures may soar into the mid-thirties, higher in urban areas. However, but the late morning, closer to midday and through the afternoon, isolated thunderstorms are possible mainly across the Western and Northern halves of Trinidad. These thunderstorms may produce damaging wind gusts, flooding rainfall, and frequent, dangerous lightning.

By the evening, conditions are forecast to initially settle across the islands. However, evening thunderstorms from Venezuela will begin to move northward. This will initially affect Southern Trinidad, but gradually move across the island by nightfall. Isolated areas of heavy rainfall possible.


Seas forecast to be slight, with waves up to just over 1 meter in open waters. In sheltered areas, near calm but choppy in areas of heavy showers or thunderstorms.

The main hazards include heavy rainfall, which may reduce visibility and gusty winds up to and in excess of 55 KM/H. Street or flash flooding will be possible in slow-moving showers and thunderstorms. In thunderstorm activity, frequent lightning is also possible. Gusty winds may cause power dips/outages, downed trees, and localized wind damage. Landslides are possible in heavy rainfall, particularly along the south-facing slopes of the Northern Range.

Note that with weak winds, from the south to southeast, with sea breeze convergence, heat, and orographic effects may act as triggers for shower and thunderstorm development across the south-facing slopes of the Northern Range, which could also intensify thunderstorms.

Temperatures

Across both islands, hot and humid conditions are forecast. The maximum high for Trinidad is forecast to be near 34.0°C, up to 36°C in urbanized areas. In Tobago, the maximum high is forecast to be near 33.0°C

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

The heat index will be very high on Wednesday across Trinidad and Tobago. 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.

Across Trinidad, the maximum heat index is forecast to be between 37.0°C and 40.0°C, and even higher in urbanized areas. In Tobago, the maximum heat index is forecast to be between 35.0°C and 38.0°C

The heat index is important because of sweating. Your body sweats 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.

 Heat Index Values Explained
Heat Index Values Explained

Heat index is generally classified into four categories: caution, extreme caution, dangerous, and extremely dangerous. On Wednesday, the heat index is forecast to be between levels where extreme caution is needed to dangerous levels for sensitive groups. Remain hydrated!

Forecast Impacts

Winds

Sustained surface winds will be light to nonexistent. However, during heavy showers and thunderstorms, sustained winds between 25 KM/H and 35 KM/H with gusts up to and in excess of 55 KM/H are possible.

With wind gusts in excess of 55 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

Across most areas of Trinidad and Tobago, little to no rainfall is forecast, with accumulations less than 5 millimeters. However, across parts of Western and Northern Trinidad, particularly along the south-facing slopes of the Northern Range and parts of West-Central Trinidad, rainfall totals of 25 millimeters are possible, with isolated totals up to 50 millimeters, particularly in slow-moving downpours or thunderstorms.

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 are possible in heavy rainfall, particularly along the south-facing slopes of the Northern Range.

Frequent Lightning: In addition, with forecast thunderstorms, frequent lightning is likely. Lightning can cause power outages, voltage dips, damage to life and property, particularly during cloud-to-ground lightning strikes.

Why I May Not/Will Not See 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. Widespread showers mean that nearly all persons and areas may experience rainfall.

Isolated activity is forecast by the late morning through the afternoon on Wednesday, with scattered activity possible overnight into Thursday.

Forecast - Isolated, Scattered, Widespread - What do they mean?

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