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Forecast: Cloudy Skies, Showers, and Thunderstorms Through Wednesday

June 26, 2023
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An active tropical wave, Tropical Wave 17, is forecast to keep showers and thunderstorms on tap for Trinidad, Tobago and the Windward Islands on Tuesday through Wednesday afternoon, with a surge of Saharan Dust to briefly bring dry conditions on Thursday.

What you need to know

— Rainfall: Forecast models indicate over the next 72 hours, through Thursday night, between 20 and 40 millimeters of rainfall are possible across both islands. Isolated rainfall accumulation could reach and exceed 50 millimeters in localized areas across both islands. As of Monday evening, models keep the highest rainfall accumulations offshore northern T&T.
— Saharan Dust: A surge of Saharan Dust is forecast to return to the area from Wednesday night into Thursday.
— Hazards: Through late Wednesday afternoon, street/flash flooding and gusty winds are forecast to be the main hazards in heavy showers and thunderstorms. In and ahead of heavy showers or thunderstorms, sustained winds can reach 35 KM/H, with wind gusts expected to exceed 45 KM/H, particularly Tuesday into Wednesday, with higher gusts to 55 KM/H possible. There is the potential for landslides in elevated areas, particularly in areas that receive persisting rainfall, with areas across Tobago and northern Trinidad most at risk. On Tuesday afternoon and evening, there is the potential for funnel clouds. From Wednesday night, the main hazard shifts to an increase in Saharan Dust, decreasing air quality through Thursday
— Marine: While the overall sea state is forecast to remain moderate, with waves in open waters between 1.5 and 2 meters while in sheltered areas, below 1.0 meter, on Tuesday into Wednesday, with light winds to winds originating from the south/southeast may cause agitated seas in the Gulf of Paria.

Latest Alerts

2 minute read

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…
October 25, 2024

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

The Forecast

Monday Night

Monday Night
7 10 0 1
Increasingly cloudy conditions across both islands with showers and thunderstorms favoring northern and eastern areas of Trinidad and Tobago initially. Gusty winds, street/flash flooding possible.
Increasingly cloudy conditions across both islands with showers and thunderstorms favoring northern and eastern areas of Trinidad and Tobago initially. Gusty winds, street/flash flooding possible.
7/10
Thunderstorm Chances
High

Tuesday

Tuesday
8 10 0 1
During the early morning hours, scattered showers and isolated thunderstorms are forecast, predominantly across Tobago and northern/eastern Trinidad, moving from the northeast to southwest. Elsewhere, near calm with partly cloudy skies while interior areas experience possible fog. From daybreak, with partly cloudy to mostly sunny skies, warm and humid conditions are forecast. By the late morning, isolated showers and thunderstorms are forecast to develop initially along western, southern and hilly areas, then along eastern after as the afternoon progresses, slowly moving northward. Heavier showers/thunderstorms are forecast along the northern and western halves of Trinidad during the afternoon, with some settling forecast by dusk. After nightfall, showers and thunderstorms are forecast to move off northern Venezuela, moving northward toward and across southern Trinidad and into the Gulf of Paria initially, spreading across the country.
During the early morning hours, scattered showers and isolated thunderstorms are forecast, predominantly across Tobago and northern/eastern Trinidad, moving from the northeast to southwest. Elsewhere, near calm with partly cloudy skies while interior areas experience possible fog. From daybreak, with partly cloudy to mostly sunny skies, warm and humid conditions are forecast. By the late morning, isolated showers and thunderstorms are forecast to develop initially along western, southern and hilly areas, then along eastern after as the afternoon progresses, slowly moving northward. Heavier showers/thunderstorms are forecast along the northern and western halves of Trinidad during the afternoon, with some settling forecast by dusk. After nightfall, showers and thunderstorms are forecast to move off northern Venezuela, moving northward toward and across southern Trinidad and into the Gulf of Paria initially, spreading across the country.
8/10
Thunderstorm Chances
High – Very High

Wednesday

Wednesday
7 10 0 1
Isolated thunderstorms and heavy showers across both islands from after midnight and continuing through the late morning with mostly cloudy to overcast skies. From midday through the afternoon, showers and thunderstorms are forecast to subside, generally favoring Tobago. An increasingly hazy evening and night, with the odd shower/thunderstorm.
Isolated thunderstorms and heavy showers across both islands from after midnight and continuing through the late morning with mostly cloudy to overcast skies. From midday through the afternoon, showers and thunderstorms are forecast to subside, generally favoring Tobago. An increasingly hazy evening and night, with the odd shower/thunderstorm.
7/10
Thunderstorm Chances
High

Thursday

Thursday
4 10 0 1
A few early to mid-morning showers and isolated thunderstorms eastern areas initially, with isolated late morning to afternoon showers and thunderstorms across western areas of Trinidad, interrupting a hazy, warm and breezy day across both islands.
A few early to mid-morning showers and isolated thunderstorms eastern areas initially, with isolated late morning to afternoon showers and thunderstorms across western areas of Trinidad, interrupting a hazy, warm and breezy day across both islands.
4/10
Thunderstorm Chances
Low – Medium

Marine Forecast

Temperatures

Increased cloud cover is forecast on Tuesday into Wednesday, leading to below-average temperatures. However, the heat index will be higher as a result of light to near-calm winds on Tuesday afternoon, and high humidity will lead to warmer-than-average nighttime lows and daytime highs. On Thursday, warm temperatures return, forecast between 31°C and 34°C, trending higher across urbanized areas.

Wednesday through Sunday

Low: 24-27°C

High: 29-34°C

Maximum high temperatures are forecast to range between 29°C to 34°C, with higher temperatures across urbanized areas of Trinidad, where in built-up areas, maximum high temperatures could exceed 33°C. Overall hotter days are forecast from Friday. Minimum lows are forecast to remain mild, ranging between 24°C and 27°C in Trinidad and Tobago, trending cooler in interior areas. The heat index will generally be near or above 34°C.

Forecast Impacts

Flooding

Flooding
7 10 0 1
Forecast models indicate over the next 72 hours, through Thursday night, between 20 and 40 millimeters of rainfall are possible across both islands. Isolated rainfall accumulation could reach and exceed 50 millimeters in localized areas across both islands. As of Monday evening, models keep the highest rainfall accumulations offshore northern T&T.
Forecast models indicate over the next 72 hours, through Thursday night, between 20 and 40 millimeters of rainfall are possible across both islands. Isolated rainfall accumulation could reach and exceed 50 millimeters in localized areas across both islands. As of Monday evening, models keep the highest rainfall accumulations offshore northern T&T.
7/10
Likelihood
High

Forecast Rainfall Totals

  • Tuesday: Between 5 and 15 millimeters of rain across both islands, with isolated totals of up to 30 millimeters favoring Tobago, southern and eastern and western coastal areas. Locally higher totals are possible across south-facing slopes of the Northern Range and Main Ridge.
  • Wednesday: Between 5 and 15 millimeters of rainfall across both islands, with totals nearing 25 millimeters across Tobago, southern and eastern halves of Trinidad, as well as localized areas along western coastal Trinidad.
  • Thursday: Little to no rainfall across the country with isolated totals up to 5 millimeters.

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.

Understanding Rainfall Rates

Strong Thunderstorms

Strong Thunderstorms
5 10 0 1
With veering (clockwise) turning winds through the atmosphere on Tuesday into Wednesday, coupled with favorable upper-level conditions, there is the potential for strong convection. Funnel clouds are possible on Tuesday afternoon. However, model guidance do not anticipate a significant severe threat.
With veering (clockwise) turning winds through the atmosphere on Tuesday into Wednesday, coupled with favorable upper-level conditions, there is the potential for strong convection. Funnel clouds are possible on Tuesday afternoon. However, model guidance do not anticipate a significant severe threat.
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
7 10 0 1
On Tuesday, winds are forecast to be light to near calm, up to 20 KM/H. Winds in heavy showers and thunderstorms are forecast to reach 35 KM/H with gusts exceeding 45 KM/H, and higher gusts are possible particularly across Tobago. By Wednesday through Thursday, sustained winds are forecast to range between 20 and 25 KM/H with gusts to 45 KM/H.
On Tuesday, winds are forecast to be light to near calm, up to 20 KM/H. Winds in heavy showers and thunderstorms are forecast to reach 35 KM/H with gusts exceeding 45 KM/H, and higher gusts are possible particularly across Tobago. By Wednesday through Thursday, sustained winds are forecast to range between 20 and 25 KM/H with gusts to 45 KM/H.
7/10
Likelihood
High

Possible impacts include localized wind damage to trees, power lines, and small structures. Small potted plants may blow over with light outdoor objects becoming airborne in stronger gusts. Tents may jump. Localized power outages are possible.

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.

On Tuesday and Wednesday, isolated to scattered showers and thunderstorms are forecast, with highly isolated rainfall on Thursday.

Forecast Discussion

On Monday night through Wednesday, instability associated with Tropical Wave 17, combined with a favorable upper-level environment associated with an upper-level trough, and high levels of atmospheric moisture, is forecast to support widespread cloudiness with scattered light to moderate showers and isolated to scattered thunderstorms.

By Wednesday night into Thursday, conditions are forecast to improve as a surge of Saharan Dust moves in combined with a ridge pattern. However, sea breeze convergence and daytime heating will initiate showers and isolated thunderstorms along the southern, western, and hilly areas of Trinidad and slowly move northwestward. By Friday, low-level moisture and instability are forecast to increase as the Intertropical Convergence Zone drifts northward, brought on by Tropical Wave 18, supporting showers, thunderstorms and increased cloudy periods.

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