Forecast: Mostly Cloudy Skies, Scattered Showers & Isolated Thunderstorms

An unstable atmosphere with elevated low-level moisture is forecast to create optimal conditions over the next 5 days for isolated to scattered showers and isolated thunderstorms across Trinidad and Tobago. Forecast models show today, Thursday, being one of the wetter days.

Overall, heavier rainfall will favor the southern and eastern areas of Trinidad and Tobago. In areas where isolated heavy showers or thunderstorms occur, isolated higher rainfall totals may also occur, particularly along Western Coastal Trinidad.

At this time, there are no alerts, watches, or warnings issued for T&T from the Trinidad and Tobago Meteorological Service.

The Forecast

On Thursday, mostly cloudy to overcast skies are forecast with periods of light rain and isolated to scattered showers. Isolated heavy showers and thunderstorms are possible, favoring eastern offshore Trinidad initially and across Western Coastal Trinidad by the late morning through the afternoon. Conditions will somewhat subside by the evening, with mostly cloudy skies continuing but lingering showery activity is forecast.

On Friday through Sunday, partly cloudy to mostly cloudy skies are forecast, with overnight showers subsiding by daybreak. Isolated showers and thunderstorms are possible by the late morning through the afternoon, generally favoring Western and Central Trinidad but possible across the entire island. Conditions will settle by nightfall, barring the odd isolated shower overnight.

On Monday into next week, wet conditions continue with mostly cloudy skies interrupted by periods of rain, light to moderate showers scattered across the country, and isolated late morning through afternoon thunderstorms favoring Trinidad – a typical wet season pattern. However, we are still very much in the Dry Season.

Note that Saharan Dust levels are forecast to gradually diminish into the weekend, with no major surges forecast over the next 10 days.

Marine: Seas are forecast to be moderate over the next 24 hours, with waves between 1.5 to 2.0 meters in Trinidad and Tobago’s open waters. Across sheltered coastlines, waves below 1.0 meter are likely. In heavy showers or thunderstorms, sheltered seas may become choppy. Note that King Tides remain ongoing through the weekend.


Overview: A surface to low-level trough is west of the Lesser Antilles, allowing abundant moisture and instability to stream in from the southeast. This pattern of easterly to southeasterly moisture flow is forecast to hold through the next seven days. In fact, forecast models show during this period, high amounts of atmospheric moisture will be present across Trinidad and Tobago, providing fuel for localized showers and possible isolated thunderstorms.

At the mid-to-upper levels, a trough is favorably positioned into the weekend west of the Lesser Antilles, bringing moisture and cloudiness from the southwest across T&T. This trough and associated upper-level jet is forecast to lift northward into this weekend gradually. Ample mid to upper-level instability will be present across our area from Thursday through Saturday, but wind shear will be high.

As the weekend progresses, wind shear will gradually subside to moderate levels, supporting localized heavy shower and possible thunderstorm development due to localized climatic effects such as sea breeze convergence, orographic effects, and daytime heating.

Through the forecast period, wind shear will be moderate to strong, up to 50 knots from the southwest, bringing upper-level clouds from South America. This will limit the strength of thunderstorms, keeping heavy showers and thunderstorms relatively brief through Saturday and most of the heavy rainfall east of T&T. Still, isolated heavy rainfall is forecast across Southern and Eastern areas generally and across Western Coastal Trinidad during the late morning through the afternoons.

Temperatures

Across both islands, overnight lows are forecast to be mild, with daytime highs cool due to cloud cover through on Thursday. As skies clear somewhat at times on Friday, through the weekend, and into next week, temperatures may trend warmer during the day.

The minimum low for Trinidad is forecast to be near 24.0°C, and as low as 23.0°C in valleys and forested areas. In Tobago, a minimum low near 25.0°C is forecast.

For Thursday, the maximum high for Trinidad and Tobago is forecast to be below 30.0°C.

On Friday through Monday, the maximum high for Trinidad and Tobago is forecast to be near 31.0°C, up to 33.0°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 through the weekend would be 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

Between Thursday and Monday next week, across the eastern and southern halves of Trinidad and Tobago, rainfall accumulations between 20 to 50 millimeters are possible. In isolated areas, 5-day rainfall accumulations could reach up to and in excess of 75 millimeters. Across Northwestern Trinidad and Western Tobago, rainfall accumulations less than 25 millimeters are possible, with higher isolated accumulations in heavy shower or thunderstorm activity. Of the five days, Thursday and Monday are forecast to have the overall highest totals.

Thursday: Less than 15 millimeters across the entire country, with isolated totals up to 25 millimeters across Eastern and Southern Trinidad as well as in areas of isolated heavy shower or thunderstorm activity.

Friday: Less than 10 millimeters across the entire country. Isolated totals up to 15 millimeters across Central Trinidad and Tobago as well as in areas of isolated heavy shower or thunderstorm activity.

Saturday: Less than 10 millimeters across the entire country. Isolated totals up to 25 millimeters across Southern and Western Trinidad, particularly in areas of isolated heavy shower or thunderstorm activity.

Sunday: Less than 10 millimeters across the entire country. Isolated totals up to 25 millimeters across Southern and isolated areas of Western and Northern Trinidad, in areas of isolated heavy shower or thunderstorm activity.

Monday: Up to 20 millimeters across the entire country but trending higher in eastern and southern areas. Isolated totals up to and in excess of 25 millimeters are possible across Eastern and Southern Trinidad as well as in areas of isolated heavy shower or thunderstorm activity along Western Coastal Trinidad.

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.

Scattered rainfall is forecast on Thursday and Monday, with isolated to scattered activity Friday through Sunday.

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

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