Periodic Showers, Thunderstorms Forecast Through The Week Across T&T

A deep-layered trough system across the Lesser Antilles is forecast to maintain unstable conditions across the region. This trough system will interact with the Intertropical Convergence Zone (south of T&T), with the potential for heavy showers and isolated strong thunderstorms. As a result, street/flash flooding will be a concern near-daily, with gusty winds accompanying heavy/violent rainfall.

What you need to know

Rainfall: Over the next five days, between 25 and 75 millimeters are forecast across T&T, with higher totals trending across eastern Trinidad and Tobago. In isolated areas across eastern Trinidad and Tobago, up to 150 millimeters are forecast over the five days. In highly isolated heavy showers and thunderstorms, 24-hour rainfall totals could exceed 50 millimeters.
— Saharan Dust: Little to no Saharan Dust is forecast across T&T over the next five days.
— Hazards: The main hazards into the weekend will originate from heavy showers and thunderstorms, producing cloud-to-ground lightning, gusty winds up to 50 KM/H, and periods of heavy/violent rainfall, which can trigger street/flash flooding. Though concerns are low now, eastern river basins will be monitored closely. In elevated areas of northern and southern Trinidad, as well as Tobago, landslides are also possible, particularly as the week progresses.
— Marine: Seas are forecast to be moderate, with waves in open waters generally reaching as high as 2.0 meters through the week. In sheltered areas, waves are forecast to be up to 1.0 meter but choppy in heavy showers and thunderstorms and along north-facing coastlines of T&T.

Latest Alert

Adverse Weather Alert Discontinued For T&T

The Trinidad and Tobago Meteorological Service (TTMS) has discontinued the Adverse Weather Alert for Trinidad and Tobago. — What has happened: Fast-moving showers and thunderstorms affected…

Trinidad and Tobago is NOT under any tropical storm or hurricane threat, watch, or warning at this time.

The Forecast

Monday night

Monday night
6 10 0 1
Mostly cloudy to overcast with isolated to scattered showers and isolated thunderstorms across both islands. Heavier rainfall to favor eastern areas of Trinidad and Tobago.
Mostly cloudy to overcast with isolated to scattered showers and isolated thunderstorms across both islands. Heavier rainfall to favor eastern areas of Trinidad and Tobago.
6/10
Thunderstorm Chances
Medium – High

Tuesday

Tuesday
6 10 0 1
Early morning showers and isolated thunderstorms to move in across Tobago and eastern Trinidad, settling by the mid-morning. By the late morning, additional showers and thunderstorms to develop across both islands, settling by the evening with partly cloudy skies. After nightfall, increasingly cloudy skies with isolated showers and thunderstorms are possible, favoring eastern areas.
Early morning showers and isolated thunderstorms to move in across Tobago and eastern Trinidad, settling by the mid-morning. By the late morning, additional showers and thunderstorms to develop across both islands, settling by the evening with partly cloudy skies. After nightfall, increasingly cloudy skies with isolated showers and thunderstorms are possible, favoring eastern areas.
6/10
Thunderstorm Chances
Medium – High

Wednesday

Wednesday
5 10 0 1
Early morning showers and thunderstorms across both islands are forecast to give way to a partly cloudy morning, still with a few isolated showers favoring eastern areas. Partly cloudy skies to be interrupted by isolated late morning through afternoon showers and the odd thunderstorm, favoring western and hilly areas of Trinidad. A mostly settled evening and night, barring the odd shower or thunderstorm favoring eastern areas.
Early morning showers and thunderstorms across both islands are forecast to give way to a partly cloudy morning, still with a few isolated showers favoring eastern areas. Partly cloudy skies to be interrupted by isolated late morning through afternoon showers and the odd thunderstorm, favoring western and hilly areas of Trinidad. A mostly settled evening and night, barring the odd shower or thunderstorm favoring eastern areas.
5/10
Thunderstorm Chances
Medium

Thursday

Thursday
4 10 0 1
A few early morning showers and offshore thunderstorms to lead to a partly cloudy day. Isolated late morning through afternoon showers is possible across both islands, with heavier activity favoring southern and western halves of Trinidad initially, then across eastern areas toward the evening. A mostly settled evening and night, barring the odd shower favoring eastern areas of T&T.
A few early morning showers and offshore thunderstorms to lead to a partly cloudy day. Isolated late morning through afternoon showers is possible across both islands, with heavier activity favoring southern and western halves of Trinidad initially, then across eastern areas toward the evening. A mostly settled evening and night, barring the odd shower favoring eastern areas of T&T.
4/10
Thunderstorm Chances
Low – Medium

Friday

Friday
5 10 0 1
Variably cloudy day with isolated showers and thunderstorms beginning from mid-morning and continuing into the night, interrupting cloudy skies.
Variably cloudy day with isolated showers and thunderstorms beginning from mid-morning and continuing into the night, interrupting cloudy skies.
5/10
Thunderstorm Chances
Medium

Saturday

Saturday
5 10 0 1
Variably cloudy day with isolated showers and thunderstorms beginning from mid-morning and continuing into the night, interrupting cloudy skies.
Variably cloudy day with isolated showers and thunderstorms beginning from mid-morning and continuing into the night, interrupting cloudy skies.
5/10
Thunderstorm Chances
Medium

Marine Forecast

Temperatures

Tuesday

Low: 25-26°C

High: 29-31°C

Wednesday

Low: 25-26°C

High: 30-32°C

Thursday

Low: 25-26°C

High: 30-32°C

Friday

Low: 25-26°C

High: 29-31°C

Saturday

Low: 25-26°C

High: 29-31°C

Maximum high temperatures are forecast to return to near to below-average levels for November across Trinidad and Tobago over the next five days due to forecast rainfall and cloudy skies, with actual temperatures reaching as high as 32°C across both islands. Across the country, over the next five days, the heat index, or feels like temperature, is forecast to range between 34°C and 38°C, as some days, particularly Wednesday, partly cloudy skies will allow for warming. Minimum lows are forecast to range between 25°C and 26°C daily but can trend lower in interior areas of the country and across eastern Tobago, where rainfall persists.

Forecast Impacts

Flooding

Flooding
7 10 0 1
Over the next five days, between 25 and 75 millimeters are forecast across T&T, with higher totals trending across eastern Trinidad and Tobago. In isolated areas across eastern Trinidad and Tobago, up to 150 millimeters are forecast over the five days. In highly isolated heavy showers and thunderstorms, 24-hour rainfall totals could exceed 50 millimeters. While these rainfall totals would usually warrant a medium to high risk for flooding, given across T&T, between 25 and 75 millimeters of rainfall has fallen over the last 5 days, with isolated totals up to 150 millimeters, soils are becoming increasingly saturated, raising the flooding risk to high for street/flash flooding, but low for riverine flooding at this time, mainly for eastern river basins.
Over the next five days, between 25 and 75 millimeters are forecast across T&T, with higher totals trending across eastern Trinidad and Tobago. In isolated areas across eastern Trinidad and Tobago, up to 150 millimeters are forecast over the five days. In highly isolated heavy showers and thunderstorms, 24-hour rainfall totals could exceed 50 millimeters. While these rainfall totals would usually warrant a medium to high risk for flooding, given across T&T, between 25 and 75 millimeters of rainfall has fallen over the last 5 days, with isolated totals up to 150 millimeters, soils are becoming increasingly saturated, raising the flooding risk to high for street/flash flooding, but low for riverine flooding at this time, mainly for eastern river basins.
7/10
Likelihood
High

Forecast Rainfall Totals

  • Tuesday: Between 5 and 15 millimeters across the country, totals between 15 and 35 millimeters across Trinidad. Locally higher amounts (between 50 and 100 millimeters) are likely in areas that receive persisting heavy showers or thunderstorms, favoring eastern Trinidad.
  • Wednesday: Between 5 and 15 millimeters across the country and isolated totals up to 25 millimeters favoring eastern areas of Trinidad and Tobago. Locally higher amounts in areas that receive persisting heavy showers or thunderstorms.
  • Thursday: Between 5 and 15 millimeters across the country and isolated totals up to 25 millimeters favoring eastern and western coastal areas of Trinidad. Locally higher amounts in areas that receive persisting heavy showers or thunderstorms.
  • Friday: Between 5 and 15 millimeters across the country and isolated totals up to 25 millimeters favoring eastern and western coastal areas of Trinidad, as well as Tobago. Locally higher amounts in areas that receive persisting heavy showers or thunderstorms.
  • Saturday: Little to no significant rainfall across the western half of Trinidad. Between 5 and 15 millimeters across the remainder of the country and isolated totals up to 25 millimeters favoring eastern coastal areas of Trinidad, as well as Tobago. Locally higher amounts in areas that receive persisting heavy showers or thunderstorms.

Understanding Rainfall Accumulations

Putting the rainfall forecast into context, rainfall rates in excess of 50 millimeters per hour or areas that receive in excess of 25 millimeters within an hour tend to trigger street flooding across the country or flash flooding in northern Trinidad. For riverine flooding to occur, a large area of the country (not just in highly localized areas of western coastal Trinidad) would have to record upwards of 75 millimeters within 24 hours, and rainfall would have to fall across major rivers’ catchment areas.

Strong Thunderstorms

Strong Thunderstorms
5 10 0 1
There is a medium chance of isolated strong thunderstorms, mainly through Wednesday due to favorable mid to upper-level conditions, high CAPE, low wind shear and high moisture levels through the atmosphere.
There is a medium chance of isolated strong thunderstorms, mainly through Wednesday due to favorable mid to upper-level conditions, high CAPE, low wind shear and high moisture levels through the atmosphere.
5/10
Likelihood
Medium
What is a strong or severe thunderstorm?

Given how rare these types of thunderstorms are in our region – we classify a severe or strong thunderstorm as one that produces any of the following:

  • Damaging wind gusts exceeding 55 KM/H;
  • Frequent lightning (more than 30 cloud-to-ground strikes within a 10-minute period);
  • Hail (of any size);
  • Rainfall of more than 50 millimeters or more within an hour or exceeding 75 millimeters or more within three hours;
  • The sighting of a funnel cloud or touchdown of a waterspout/tornado associated with the thunderstorm.

Gusty Winds

Gusty Winds
5 10 0 1
Mid-level winds are forecast to increase through the week, which can translate to the surface in showers and thunderstorms. As a result, through the forecast period, sustained winds are forecast to reach as high as 35 KM/H mainly in heavy/violent showers or thunderstorms with gusts as high as 55 KM/H. Generally, winds speeds are forecast to reach as high as 30 KM/H outside of rainfall activity, particularly toward the end of the week.
Mid-level winds are forecast to increase through the week, which can translate to the surface in showers and thunderstorms. As a result, through the forecast period, sustained winds are forecast to reach as high as 35 KM/H mainly in heavy/violent showers or thunderstorms with gusts as high as 55 KM/H. Generally, winds speeds are forecast to reach as high as 30 KM/H outside of rainfall activity, particularly toward the end of the week.
5/10
Likelihood
Medium

With winds gusting to 55 KM/H and occasionally above, whole trees can be in motion, with larger trees and weaker branches falling. Light outdoor objects can topple or become airborne, such as garbage cans, loose galvanize, construction material, and outdoor furniture. Tents may also jump. Note these impacts are mainly possible ahead of and during heavy/violent showers and thunderstorms.

Other Hazards

Saharan Dust Forecast

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.

Over the next five days, isolated to scattered rainfall is forecast.

Forecast Discussion

On Monday night through Wednesday, a mid to upper-level trough will be present across the Windward Islands, including Trinidad and Tobago. This trough will interact with the Intertropical Convergence Zone south of T&T with favorable upper-level conditions, low-level convergence, deep-layered moisture, and light wind shear, leading to increased cloudiness with scattered showers and thunderstorms. Rainfall may also be slow-moving, leading to very localized high rainfall totals where heavy showers or thunderstorms occur.

By Wednesday into Thursday, this mid to upper-level trough will weaken across the Windwards and T&T, with wind shear increasing and a marginal decrease in atmospheric moisture. Still, conditions remain somewhat favorable due to low-level convergence for isolated showers and thunderstorms, generally favoring eastern Trinidad and Tobago during the first half of the day and overnight and western coastal areas during the afternoon.

On Friday and Saturday, successive low-level troughs are forecast to move across the Wdinwards, including T&T, leading to another increase in showers and thunderstorms across both islands, with heavier showers favoring Tobago and eastern Trinidad during the early morning and night and across western Trinidad during the late morning through afternoon hours.

From Wednesday into the weekend, low to mid-level winds are forecast to increase, which can make it to the surface in showers or thunderstorms. As a result, forecast winds will reach as high as 35 KM/H and gust to 55 KM/H.

Note that as an extended forecast goes further into the future, it is normal for the certainty to be reduced relative to the extended time period.

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