Forecast: Low-Level Trough To Bring Few Showers To T&T Through Thursday

Increased cloudy periods with brisk showers are forecast over the next 24-48 hours as a low-level trough moves across T&T. Favorable upper-level conditions will also be in place on Thursday. Heavier rainfall will favor the eastern and southern areas of Trinidad.

With strong low-level winds, seas remain agitated though long period swells have temporarily subsided.

The Trinidad and Tobago Meteorological Service has extended the Hazardous Seas Alert #2 (Yellow Level) for T&T until 12:00 PM Friday.

The Forecast

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

On both Wednesday and Thursday, brisk lines of showers are forecast to move across T&T, bringing breezy to gusty conditions, interrupting hazy and partly cloudy skies. Saharan dust concentrations are forecast to remain at moderate levels. Sensitive groups are advised to take the necessary precautions.

Marine: Seas are forecast to be moderate to rough over the next 48 hours with waves between 2.5 and 3.0 meters in open waters, at times above 3.0 meters particularly on Thursday. 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 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.

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 Wednesday, low-level moisture and instability will trail, fuelling variably cloudy conditions with brisk showers. On Thursday, an upper-level jet may support additional shower activity and cloudiness before the high-pressure ridge dominates on Friday.

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 20.0°C in valleys and forested areas. In Tobago, a minimum low near 24.0°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 30 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 Wednesday through Thursday.

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

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