Isolated Showers To Interrupt A Mostly Sunny Weekend

Through the weekend, the weather across T&T is forecast to be generally stable with drier than usual air at mid and upper levels, with a surface to a low-level ridge in place across the region.

With areas of low-level convergence, showers are possible Friday night into Saturday afternoon, as well as on Sunday afternoon. Isolated thunderstorms are also possible, favoring western coastal Trinidad during the afternoon hours. Activity is forecast to remain brief.

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

The Forecast (Through Monday)

Friday night: Partly to mostly cloudy periods, with brisk showers moving across T&T. Rainfall will be brief, with isolated heavy pockets.

Saturday: Brisk showers are forecast from the early morning (pre-dawn) through the afternoon. Thunderstorm and heavy shower activity are possible after midday, favoring the western half of Trinidad. These conditions will interrupt partly to mostly cloudy skies at times. Conditions to settle into the late afternoon and night, with mostly clear skies.

Sunday & Monday: Mostly sunny skies across Trinidad and Tobago, with brisk, isolated showers across the islands, favoring the late morning through the afternoon.

Marine: Seas are forecast to be slight to moderate through Monday. Generally, in open waters, waves are forecast to be between 1.5 and 2.0 meters. In sheltered areas, near 1.0 meter and choppy due to long period swells affecting our northern and eastern coasts. More on the marine forecast, as a hazardous seas event is possible next week due to long period swells.


Overview: At the surface to low-levels of the atmosphere, favorable low-level convergence with ample moisture is in place on Friday night through Saturday, gradually drying on Sunday. These conditions will support a few showers and brief, weak thunderstorms.

Dominating the overall wind flow, a surface to low-level high-pressure system will gradually strengthen through the weekend. However, light winds are possible on Saturday, allowing for daytime heating and sea breeze convergence across Western Trinidad, as well as orographic effects along northern Trinidad and the northern coasts of Tobago to develop showers and the possible weak thunderstorm.

At the mid- to upper-level atmosphere, dry conditions are in place and will remain in place through the weekend, capping the development of deep convection (strong showers and thunderstorms). Strong wind shear from the northwest, up to 60 knots, will also limit the development of stronger showers or thunderstorms.

The high pressure system, as it regains dominance on Sunday into Monday, only weak, brief showers are possible due to areas of low-level convergence embedded in the trade wind flow.

Temperatures

Across both islands, warm conditions are forecast over the next 3 days. The maximum high for Trinidad is forecast to be near 32.0°C, up to 35.0°C in urban and built-up areas, particularly between 9:00 AM and 3:00 PM. In Tobago, the maximum high is forecast to be near 31.0°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 between levels that require extreme caution to near dangerous levels through 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 35°C and 38°C and even higher in urbanized areas. In Tobago, the maximum heat index is forecast to be between 32°C and 36°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.

Forecast Impacts

On Saturday, street flooding and funnel clouds are possible with light low-level winds, possible thunderstorms and/or heavy showers. With heat-driven showers, gusty winds in downburst-like fashion, up to and in excess of 45 KM/H are possible.

On Sunday, with mostly settled conditions, maximum high temperatures and heat indices will be the main hazard so particularly between 9:00 AM and 3:00 PM, stay cool and hydrated! With sunny skies, the UV Index will also be very high so wear sunscreen and eye protection when heading outdoors!

Winds

Sustained surface winds will be light to near calm during the nights and early morning. During the afternoons, up to 20 KM/H likely. In heavy shower or thunderstorm activity, gusts up to and in excess of 45 KM/H are possible.

With wind gusts in excess of 45 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.

Rainfall

Across most areas of Trinidad and Tobago, little rainfall is anticipated over the next 3 days, with maximum accumulation totals near 10 millimeters and most falling on Saturday. In areas where isolated heavy showers or thunderstorms occur, accumulations up to 25 millimeters 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.

Lightning: Lightning is possible in thunderstorm activity. 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 to scattered rainfall is forecast on Friday night into Saturday, with highly isolated rainfall on Sunday and Monday.

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

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