Forecast: Rainfall Today, Sunshine Tomorrow, Showers Return By Friday

Saharan Dust is doing its best to quell rainfall across Trinidad and Tobago, but as Tropical Waves continue to move off the African coast and the Intertropical Convergence Zone (ITCZ) lingers nearby, occasionally wet days remain in the forecast.

What you need to know

Saharan Dust: Moderate Saharan Dust is forecast to linger across the region through the next five days, with gradually decreasing concentrations toward the end of the week.
Rainfall: The wettest days this week are forecast to be on Tuesday (today) and Friday into Saturday due to tropical waves and by the end of the week, the ITCZ as well.
Hazards: The main hazards remain street/flash flooding, landslides in elevated areas, particularly across northern Trinidad, and gusty winds (up to and in excess of 45 KM/H), particularly on Thursday into Friday, accompanying heavy showers or thunderstorms. The chances for riverine flooding remain low at this time. Lightning will accompany thunderstorms.
Alerts/Watches/Warnings: There are no alerts, watches, or warnings in effect for T&T from the Trinidad and Tobago Meteorological Service at this time. There are also no tropical storm or hurricane watches or warnings in effect for T&T.

The Forecast

Tuesday – Tropical Wave 15 & The ITCZ

Tuesday – Tropical Wave 15 & The ITCZ
7 10 0 1
Mostly cloudy to overcast and slightly hazy skies, interrupted by periods of light to moderate rain, isolated heavy to violent showers and isolated thunderstorms. Overall heavier activity to favor eastern and southern Trinidad, as well as Tobago. Conditions to gradually settle into the late afternoon and evening, barring the lingering light to moderate rain and odd moderate to heavy shower. Isolated overnight thunderstorms are possible in the Gulf of Paria, moving away from T&T, as well as across eastern coastal Trinidad and Tobago. Street/flash flooding, gusty winds, and landslides are possible.
Mostly cloudy to overcast and slightly hazy skies, interrupted by periods of light to moderate rain, isolated heavy to violent showers and isolated thunderstorms. Overall heavier activity to favor eastern and southern Trinidad, as well as Tobago. Conditions to gradually settle into the late afternoon and evening, barring the lingering light to moderate rain and odd moderate to heavy shower. Isolated overnight thunderstorms are possible in the Gulf of Paria, moving away from T&T, as well as across eastern coastal Trinidad and Tobago. Street/flash flooding, gusty winds, and landslides are possible.
7/10
Thunderstorm Chances
High

Wednesday

Wednesday
2 10 0 1
Mostly sunny, hazy and breezy becoming partly cloudy with isolated showers possible during the late morning through the afternoon. A mostly settled, hazy and slightly breezy night.
Mostly sunny, hazy and breezy becoming partly cloudy with isolated showers possible during the late morning through the afternoon. A mostly settled, hazy and slightly breezy night.
2/10
Thunderstorm Chances
Very Low – Low

Thursday

Thursday
3 10 0 1
Mostly sunny, hazy and breezy becoming partly cloudy during the late morning through the afternoon. Increasing cloudiness is forecast nearing midnight, with isolated showers and the odd thunderstorm possible, favoring southern and eastern areas of Trinidad.
Mostly sunny, hazy and breezy becoming partly cloudy during the late morning through the afternoon. Increasing cloudiness is forecast nearing midnight, with isolated showers and the odd thunderstorm possible, favoring southern and eastern areas of Trinidad.
3/10
Thunderstorm Chances
Low

Friday – The ITCZ

Friday – The ITCZ
5 10 0 1
Initially partly cloudy, hazy, interrupted by a few isolated showers and the odd thunderstorm favoring southern and eastern Trinidad. By the mid-morning through the afternoon, isolated heavy showers and isolated thunderstorms are forecast to develop across the eastern and southern halves of Trinidad, as well as Tobago and gradually move westward. Conditions are forecast to gradually settle by the late afternoon barring the odd shower. Isolated thunderstorms and heavy showers are possible nearing midnight, favoring eastern Trinidad and Tobago. Street/flash flooding and landslides in elevated areas are possible. Gusty winds likely, mainly accompanying heavy shower/thunderstorm activity.
Initially partly cloudy, hazy, interrupted by a few isolated showers and the odd thunderstorm favoring southern and eastern Trinidad. By the mid-morning through the afternoon, isolated heavy showers and isolated thunderstorms are forecast to develop across the eastern and southern halves of Trinidad, as well as Tobago and gradually move westward. Conditions are forecast to gradually settle by the late afternoon barring the odd shower. Isolated thunderstorms and heavy showers are possible nearing midnight, favoring eastern Trinidad and Tobago. Street/flash flooding and landslides in elevated areas are possible. Gusty winds likely, mainly accompanying heavy shower/thunderstorm activity.
5/10
Thunderstorm Chances
Medium

Saturday – ITCZ & Approaching Tropical Wave 16

Saturday – ITCZ & Approaching Tropical Wave 16
5 10 0 1
Variably cloudy skies, interrupted by light to moderate rain, isolated heavy to violent showers and isolated thunderstorms. Conditions to gradually settle by the late afternoon with a resurgence of rainfall nearing midnight. Street/flash flooding and landslides in elevated areas are possible. Gusty winds likely, mainly accompanying heavy shower/thunderstorm activity.
Variably cloudy skies, interrupted by light to moderate rain, isolated heavy to violent showers and isolated thunderstorms. Conditions to gradually settle by the late afternoon with a resurgence of rainfall nearing midnight. Street/flash flooding and landslides in elevated areas are possible. Gusty winds likely, mainly accompanying heavy shower/thunderstorm activity.
5/10
Thunderstorm Chances
Medium

Marine: Through Saturday, seas are forecast to be moderate with waves in open waters up to 2.0 meters, occasionally exceeding 2.0 meters from late Thursday. In sheltered areas, waves are forecast to be near or below 1.0 meter, becoming choppy by late Thursday into Friday, associated with increased low-level winds and rainfall activity.

Temperatures

Through the forecast period, the minimum low in Trinidad and Tobago is forecast to be between 24.0°C and 27.0°C.

Maximum highs across the country are forecast to be generally up to 32.0°C in Trinidad and Tobago. In urbanized areas like Port of Spain, Scarborough, San Fernando, and Chaguanas, the maximum high temperatures could exceed 32.0°C.

On Tuesday and Friday into Saturday, temperatures are forecast to be cooler due to increased cloud cover and anticipated rainfall.

Forecast Impacts

Flooding

Flooding
7 10 0 1
Over the next five days, between 25 and 50 millimeters of rainfall is forecast across most of the country. Lower rainfall totals are forecast across northwestern/west-central areas of Trinidad while higher totals are forecast across the eastern and southern halves of Trinidad, where overall rainfall totals up to 100 millimeters are forecast. In isolated areas, overall five-day rainfall totals could exceed 125 millimeters.
Over the next five days, between 25 and 50 millimeters of rainfall is forecast across most of the country. Lower rainfall totals are forecast across northwestern/west-central areas of Trinidad while higher totals are forecast across the eastern and southern halves of Trinidad, where overall rainfall totals up to 100 millimeters are forecast. In isolated areas, overall five-day rainfall totals could exceed 125 millimeters.
7/10
Likelihood
High

There is a high chance of street and flash flooding, mainly on Tuesday and Friday into Saturday. Chances for riverine flooding remain low as major rivers across the country are well within their banks.

Forecast Rainfall Totals

  • Tuesday: Between 15 and 25 millimeters across the country, trending higher across southern and eastern areas of Trinidad and across Tobago with totals up to and in excess of 35 millimeters. In highly isolated areas, mainly across eastern Trinidad, totals upwards of 50 millimeters are forecast. Note that the GFS model, which has been more reliable with precipitation forecasts, shows widespread totals of 30+ mm of rainfall across Trinidad, with isolated pockets of 50+ mm across southern Trinidad. If these totals materialize, Trinidad may see impactful street and flash flooding on Tuesday. However, the GFS run remains an outlier at this time, and our forecast is more conservative for now.
  • Wednesday: Less than 10 millimeters of rainfall across the country, trending higher across eastern areas of Trinidad, as well as southern coastal locations.
  • Thursday: Less than 10 millimeters of rainfall across the country, trending higher across eastern areas of Trinidad. Across southeastern Trinidad, isolated totals up to 15 millimeters are possible.
  • Friday: Across the western half of Trinidad, between zero and 15 millimeters of rainfall is forecast, with isolated totals exceeding 25 millimeters in thunderstorms or heavy/violent shower activity. Across the eastern half of Trinidad, isolated southern coastal areas, and across Tobago, rainfall totals between 15 and 25 millimeters are forecast, with isolated totals up to 35 millimeters possible.
  • Saturday: Across the western half of Trinidad, between zero and 15 millimeters of rainfall is forecast, with isolated totals exceeding 25 millimeters in thunderstorms or heavy/violent shower activity. Across the eastern half of Trinidad, isolated southern coastal areas, and across Tobago, rainfall totals between 15 and 25 millimeters are forecast, with isolated totals up to 35 millimeters possible.

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
4 10 0 1
A moderately to highly favorable atmospheric set up is forecast to be present across T&T on Tuesday, which may lead to the development of isolated strong thunderstorms. However, activity is forecast to mainly remain offshore. By Wednesday, through the week, strong wind shear and a drier low to mid-level atmosphere will limit strong thunderstorms from developing.
A moderately to highly favorable atmospheric set up is forecast to be present across T&T on Tuesday, which may lead to the development of isolated strong thunderstorms. However, activity is forecast to mainly remain offshore. By Wednesday, through the week, strong wind shear and a drier low to mid-level atmosphere will limit strong thunderstorms from developing.
4/10
Likelihood
Low – Medium

With minimal to no wind shear, a highly moist atmosphere, and light to moderate low-level winds, there is a low to medium chance of a strong thunderstorm on Tuesday. Funnel cloud development is possible, particularly on Friday. If a funnel cloud touches down on a body of water, it becomes a waterspout; if it touches down on land, it becomes a tornado. Frequent cloud-to-ground lightning will be possible in thunderstorm activity.

Increasing wind shear and a drier low to mid-level environment are forecast to limit strong thunderstorm development by Wednesday into the weekend.

Gusty Winds

Gusty Winds
6 10 0 1
While low-level winds across the region are forecast to increase with peak winds by late Thursday through Saturday. Strong gusts could accompany heavier thunderstorms or shower activity. Sustained winds up to 35 KM/H are forecast, with gusts up to 45 KM/H likely. Stronger winds and gusts, in excess of 45 KM/H are possible, accompanying heavy shower or thunderstorm activity on Tuesday and Friday.
While low-level winds across the region are forecast to increase with peak winds by late Thursday through Saturday. Strong gusts could accompany heavier thunderstorms or shower activity. Sustained winds up to 35 KM/H are forecast, with gusts up to 45 KM/H likely. Stronger winds and gusts, in excess of 45 KM/H are possible, accompanying heavy shower or thunderstorm activity on Tuesday and Friday.
6/10
Likelihood
Medium – High

With wind gusts up to and 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.

Other Hazards

Saharan Dust will remain across the region through the forecast period, reducing air quality and affecting visibility.

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 over the next five days.

Forecast Discussion

2:00 AM Tropical Weather Outlook from the National Hurricane Center
2:00 AM Tropical Weather Outlook from the National Hurricane Center

Tropical Waves East of T&T: Based on the Tropical Analysis and Forecast Branch’s 00Z surface analysis on July 5th, 2022, as well as the latest satellite and model guidance:

  • The 15th tropical wave for 2022 (TW15) is along 62°W, south of 22°N, moving west at 15 knots (27 KM/H). On Monday night, this wave moved across Trinidad and Tobago and the remainder of the Lesser Antilles. Scattered moderate convection is ongoing behind the wave axis, mainly east of Trinidad and Tobago.
  • The 16th tropical wave for 2022 (TW16) is along 25°W, south of 18°N, moving west at 15 knots (27 KM/H). This wave is forecast to move across Trinidad and Tobago on Saturday, July 9th, 2022, into Sunday, June 10th, 2022. Scattered moderate convection has been observed near the southern portion of the wave axis, while dense Saharan Dust limits convection elsewhere.

Showers and isolated thunderstorms have begun to affect Trinidad and Tobago early Tuesday morning associated with the passage of Tropical Wave 15 on Monday, July 4th, 2022, which dragged the ITCZ closer to the country. The strongest activity remains east of Trinidad and Tobago, with light to moderate rain spreading across parts of the country, while isolated heavy showers and thunderstorms favor eastern Trinidad.

Over the next 18 hours, a highly favorable mid- to upper-level atmosphere is forecast to support heavier showers and thunderstorms across T&T under a low-shear and high-moisture environment. On Tuesday morning, strong upper-level divergence and favorable low-level convergence were noted across Trinidad and Tobago. All of these ingredients coming together results in elevated chances for showers and thunderstorms through Tuesday night.

By Wednesday, a high-pressure ridge is set to return across T&T with a surge of Saharan Dust drying out the mid to low-level atmosphere, quelling rainfall chances until Friday when the ITCZ returns. On Wednesday through Thursday, wind shear is forecast to increase, keeping heavier rainfall activity localized to the East Coast while moisture remains capped to the lowest levels of the atmosphere.

By Friday, wind shear decreases somewhat, and moisture levels increase as the ITCZ nears the country. Additionally, low-level winds increase to 25 knots, which leads to breezy/windy conditions near the surface and gusty winds accompanying showers/thunderstorms. Marginally favorable atmospheric conditions will support isolated thunderstorm activity, with scattered showers forecast from Friday through Sunday due to the ITCZ and forecast passage of Tropical Wave 16.

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