Forecast: Cloudy Skies, Possible Thunderstorms This Weekend

Continued cloudy periods with showers are forecast over the next 24 hours as another low-level trough brings moisture and instability from the southeast. Conditions may support brief thunderstorm activity during Saturday and Sunday afternoons, favoring Trinidad. Overall heavier rainfall will favor the eastern and southern areas of Trinidad.

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

The Forecast

On Saturday and Sunday, a mostly cloudy day is forecast to be interrupted by isolated to scattered showers and periods of rain. Showers may become moderate to heavy at times, with brief and isolated thunderstorm activity favoring Trinidad. This could bring street flooding, gusty winds, and lightning. Conditions will briefly settle into the evening, with a resurgence of showers possible nearing midnight.

Even with the anticipated rainfall, mild levels of Saharan Dust will remain present with a new surge that arrived on Friday morning, with air quality improvements anticipated during rainfall. Sensitive groups are still advised to take the necessary precautions.

Marine: Seas are forecast to be moderate over the next 48 hours with waves between 1.5 to 2.0 meters in open waters. All marine interests are advised to exercise caution. In heavy showers or thunderstorms, sheltered seas may become choppy with waves near or below 1.0 meters.


Overview: A surface to low-level trough moved across T&T early Thursday, with another trough forecast. This feature will continue to bring moisture and instability at both low- and mid-levels of the atmosphere from equatorial regions, triggering showers and cloudiness.

As both troughs move westward, moisture and instability will linger through weekend, with daytime heating and possible sea breeze convergence allowing for heavier showers and brief thunderstorm activity to develop across Trinidad during the late morning through the afternoon.

At the mid- to upper-levels of the atmosphere on Saturday, a mid- to upper-level trough will be favorably positioned over the islands, providing moisture and instability. Hence, on Saturday, the highest rainfall accumulations are likely.

Dominating the overall wind flow, a high-pressure system will remain in place into the weekend. However, the passage of this trough will weaken the pressure gradient with wind speeds gradually weakening.

The high-pressure system will regain its strength next week with mostly sunny and hazy skies but still, brisk, isolated showers are possible.

Wind shear will be strong, up to 50 knots from the south to southwest through the weekend. This will limit the strength of thunderstorms, keeping heavy showers and thunderstorms brief.

Temperatures

Across both islands, overnight lows are forecast to be mild to cool, with daytime highs cool due to cloud cover through Saturday

The minimum low for Trinidad is forecast to be near 23.0°C, and as low as 21.0°C in valleys and forested areas. In Tobago, a minimum low near 24.0°C is forecast.

On Saturday, the maximum high for Trinidad is forecast to be up to 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 up to 31.0°C.

On Sunday, the maximum high for Trinidad and Tobago is forecast to be up to 31.0°C, up to 34.0°C in urban and built-up areas, particularly between 9:00 AM and 3:00 PM.

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 locally heavy rainfall and gusty winds, particularly in moderate to heavy showers or thunderstorms, bringing the risk of street flooding or flash flooding.

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 Trinidad, between 25 millimeters to 50 millimeters is possible, with overall higher rainfall totals favoring the island’s southern and eastern areas through Monday morning. Isolated totals up to 75 millimeters are possible, favoring southern and eastern Trinidad as well as areas along Western Coastal Trinidad. The highest rainfall accumulations are forecast mainly on Saturday.

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 Saturday through Sunday.

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