Forecast: Cluster of Showers, Thunderstorms To Affect Trinidad

A persisting cluster of showers and thunderstorms along the northern coast of South America has been drifting towards the northwest, towards T&T. Increase cloudiness is forecast to affect Trinidad shortly after nightfall, with light to moderate rain and isolated heavy showers and thunderstorms later tonight.

Higher rainfall totals are forecast to remain south of T&T, mainly affecting the southern half of Trinidad. Conditions to settle into Wednesday.

Tropical Wave 53 west of the Lesser Antilles seen on GOES-EAST IR Satellite Imagery with the ITCZ affecting the Southern Windwards (Weathernerds.org)

There are no alerts, watches, or warnings from the Trinidad and Tobago Meteorological Service in effect for T&T as of 6:00 PM Tuesday 6th October 2020

Short Term Forecast
(Through Wednesday Morning)

Forecast: Increasing cloudiness is forecast to spread across Trinidad and Tobago through the evening and night. Light rainfall is possible across southern and eastern areas. Through the night, isolated showers and the odd thunderstorm will favor southern and eastern halves of Trinidad initially, moving across the remainder of the island through the night. Note that any heavy rainfall will be brisk.

Conditions are forecast to gradually settle into the early morning, with partly cloudy and settle conditions by daybreak.


Forecast Discussion: A cluster of thunderstorms have been drifting northwestward over the last 5 hours, towards Trinidad and Tobago. However, the heaviest showers and strongest thunderstorms have remains and will remain south of Trinidad.

As shower and thunderstorms periodically weaken, gust fronts from the outflow will move across Trinidad, as winds pick up at low levels from the south to north. Stronger winds will favor the immediate southern coast. However, as these winds move along hilly terrain, orographic lift will allow for convergence and possibly trigger shower and thunderstorm development along southern facing slopes of the Central and Northern Ranges. Sea breeze convergence may also aid in some shower and thunderstorm development.

Highly favorable upper level conditions are in place due to T&T being positioned on the favorable side of an upper level trough to our northwest. There is still sufficient surface to low-level instability to facilitate shower and thunderstorm development overnight.

By tomorrow, a deep-layered high-pressure will move across the Lesser Antilles, including T&T, leading to a mostly hot, settled and sunny day.


Marine: Seas are forecast to be slight, with waves up to 1.25 meters and near calm in sheltered areas. However, in areas where thunderstorms occur, seas can become choppy and locally rough.

Winds are forecast to be light, between 10 and 15 knots prevailing from the east to southeast tonight through Wednesday, though tonight, southerly winds are forecast.

Hazards: The main hazards include isolated, heavy rainfall, which may reduce visibility and gusty winds up to and in excess of 45 KM/H. Street or flash flooding will be possible in violent showers and thunderstorms, particularly across Southern Trinidad. In thunderstorm activity, frequent lightning is also possible. Gusty winds may cause power dips/outages, downed trees, and localized wind damage. With heavy rainfall across elevated areas, landslides and fallen trees if thunderstorms also develop across Northern Trinidad.

Forecast Impacts

Winds

Sustained surface winds will increase tonight due to outflow boundaries but weaken into tomorrow. Generally, winds between 15 KM/H and 25 KM/H with gusts up to and in excess of 45 KM/H are possible.

With wind gusts in excess of 45 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

Higher rainfall totals are forecast to remain south of T&T, mainly affecting the southern half of Trinidad.

Across much of Trinidad and Tobago, rainfall totals over the next 12 hours are forecast to be near 0 with isolated totals up to 10 millimeters. Across Southern Trinidad, as well as areas where isolated thunderstorms develop, totals up to and in excess of 15-20 millimeters are possible, particularly if violent (>50 mm/hr) rainfall rates occur.

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. There is no threat of riverine flooding at this time.

Frequent Lightning: Frequent 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 tonight, meaning partly cloudy skies are possible.

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

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