Trough Forecast To Bring Cloudiness, Showers & Possible Thunderstorms

Cloudiness, showers and possible thunderstorms are forecast over the next 24-36 hours as a surface to low-level trough moves across T&T, with a favorable upper-level environment.

With a favorable atmosphere, isolated heavy showers and thunderstorms are possible after near midnight tonight (Monday) through Tuesday afternoon, favoring eastern areas of both islands initially.

With strong low-level winds, seas are also agitated with long period swells affecting our northern and eastern coastlines.

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

The Forecast

For tonight, partly cloudy to mostly cloudy skies are forecast with brisk, isolated showers moving across both islands. Heavier activity to favor eastern Trinidad and Tobago.

After midnight through Tuesday afternoon, partly to mostly cloudy skies across Trinidad and Tobago, interrupted by periods of showers throughout the day. Isolated heavy showers and thunderstorms are possible across Trinidad by the late morning through the afternoon, with brief, heavier activity favoring the western areas of Trinidad while overall higher accumulations across southern and eastern areas.

Marine: Seas are forecast to be moderate on Tuesday, becoming rough on Wednesday through Thursday. Generally, in open waters, waves are forecast to be between 2.0 to 2.5 meters. In sheltered areas, near 1.0 meter but choppy at times in heavy shower or thunderstorm activity. Along northern and eastern coasts, waves in nearshore areas may exceed 2.0 meters.


Overview: At the surface to low-levels of the atmosphere, favorable low-level convergence with ample moisture is in place as a surface to low-level trough is forecast to move across the Lesser Antilles overnight. This has brought moisture from the equatorial regions across T&T and the Windward Islands.

Dominating the overall wind flow, a surface to low-level high-pressure system will remain in place through the week, with wind speeds gradually strengthening. Embedded convergence and confluence will bring shallow (capped to low- to mid-levels of the atmosphere) showers to T&T, remaining fairly brisk.

At the mid- to upper-level atmosphere, a tropical upper tropospheric trough (TUTT) will remain east of the Lesser Antilles, allowing for some enhancement of convection (strong showers and thunderstorms). However, very strong wind shear from the west will also limit the intensity and duration of stronger showers or thunderstorms.

Temperatures

Across both islands, cool conditions are forecast on Tuesday. The maximum high for Trinidad is forecast to be near 30.0°C, up to 33.0°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 30.0°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.

Forecast Impacts

On Tuesday, street flooding is possible in thunderstorms and/or heavy showers. With strong winds at low-levels of the atmosphere, gusty winds up to and in excess of 50 KM/H are possible, which may down trees and cause minor wind damage.

Winds

Sustained surface winds gentle to moderate (10-35 KM/H). In heavy shower or thunderstorm activity, gusts up to and in excess of 50 KM/H are possible.

With wind gusts in excess of 50 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, between 5 to 15 millimeters of rainfall is anticipated over the next 24-36 hours, with maximum accumulation totals near 25 millimeters. In areas where isolated heavy showers or thunderstorms occur, accumulations up to 50 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 Tuesday.

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

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