Trough Forecast To Bring Showers, Cloudiness To T&T

Cloudy skies and showers seen from northwestern Trinidad on December 7th, 2020. (Alice Son)

Increased cloudy periods with brisk showers are forecast over the next 24-48 hours as a low-level trough moves across T&T. Heavier rainfall will favor the eastern and southern areas of Trinidad.

With strong low-level winds and long period swells, seas remain agitated and will gradually increase through the weekend.

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

The Forecast

For tonight, partly to mostly cloudy skies are forecast to be interrupted by brisk showers moving across both islands with heavier activity favoring eastern and southern areas of Trinidad and Tobago.

On both Friday and Saturday, brisk lines of showers are forecast to move across T&T, bringing breezy to gusty conditions, interrupting variably cloudy skies, with few sunny periods.

Marine: Through the next 48 hours, seas are forecast to increase, with waves in open waters of Trinidad moderate, up to 2.5 meters and across Tobago, rough up to 3.0 meters. Along northern, eastern, and sheltered coastlines, waves near 1.0 meter are likely, with higher waves possible due to long-period northerly swells.


Overview: Dominating the overall wind flow, a deep layered high-pressure system will remain in place into the weekend, 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.

Over the next 48 hours, a low-level trough will move across the Windwards, bringing increased moisture from South America and instability. While this trough axis will move to the west by late Friday, low-level moisture and instability will trail, fuelling variably cloudy conditions with brisk showers.

Temperatures

Across both islands, overnight lows are forecast to be mild to cool with daytime highs warm.

The minimum low for Trinidad is forecast to be near 22.0°C, and as low as 19.0°C in valleys and forested areas. In Tobago, a minimum low near 23.0°C is forecast.

The maximum high for Trinidad is forecast to be near 31.0°C, up to 34.0°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.

Forecast Impacts

The main hazards over the next 48 hours would be gusty winds, particularly in showers on land and for mariners, hazardous seas. Rainfall is forecast to remain fairly brisk so the risk of street flooding is low.

Winds

Sustained surface winds moderate to fresh (20-38 KM/H). In shower activity, 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.

Rainfall

Across most areas of Trinidad and Tobago, less than 5 to 10 millimeters of rainfall is anticipated over the next 24-48 hours, with maximum accumulation totals up to 25 millimeters favoring eastern areas.

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 through Saturday.

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

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