Forecast: Tropical Waves To Bring Showers, Thunderstorms To T&T Over Next 5 Days

An active tropical wave is forecast to move across Trinidad and Tobago on Thursday, with another arriving by Monday. Both will usher in a period of unsettled weather well into next week.

What you need to know

Saharan Dust: By late Friday/early Saturday, a moderate to high concentration dust surge is forecast to affect the country. Concentrations will briefly subside on Monday before a new surge moves in by Tuesday.
Rainfall: Over the next 36 hours (through Friday afternoon), periods of light to moderate rain, isolated to scattered heavy/violent showers, and isolated thunderstorms are forecast to affect T&T. Rainfall will briefly subside on Saturday, with a return in showers and thunderstorms by Sunday evening through Monday.
Hazards: Street/flash flooding is likely from Thursday. Chances for riverine flooding remain low at this time but increase through the weekend. Gusty winds, up to and in excess of 55 KM/H accompanying heavy showers or thunderstorms are forecast. Lightning will accompany thunderstorms. Severe thunderstorms are possible on Thursday and Monday. Landslides are possible mainly from the weekend.
Alerts/Watches/Warnings: An Adverse Weather Alert is in effect for T&T from 8:00 AM Thursday, June 2nd, 2022, through 2:00 PM Friday, June 3rd, 2022, from the Trinidad and Tobago Meteorological Service.

The Forecast

Thursday – Tropical Wave 04

Thursday – Tropical Wave 04
8 10 0 1
Mostly cloudy to overcast. Periods of showers from the early morning with heavier showers and isolated thunderstorms mainly after dawn, favoring eastern and southern Trinidad initially, gradually spreading northwestward. Conditions to briefly settle by the evening, with a resurgence of showers/thunderstorms after midnight. Street/flash flooding, gusty winds expected.
Mostly cloudy to overcast. Periods of showers from the early morning with heavier showers and isolated thunderstorms mainly after dawn, favoring eastern and southern Trinidad initially, gradually spreading northwestward. Conditions to briefly settle by the evening, with a resurgence of showers/thunderstorms after midnight. Street/flash flooding, gusty winds expected.
8/10
Thunderstorm Chances
High – Very High

Friday

Friday
7 10 0 1
Mostly cloudy to overcast. Isolated to scattered showers and isolated thunderstorms are possible. Heavier showers/thunderstorms to favor southern and eastern Trinidad initially, gradually increasing in coverage through the morning. Conditions to briefly settle by the late afternoon, becoming increasingly hazy. A mostly hazy and cloudy night, barring the odd shower. Street/flash flooding, gusty winds likely.
Mostly cloudy to overcast. Isolated to scattered showers and isolated thunderstorms are possible. Heavier showers/thunderstorms to favor southern and eastern Trinidad initially, gradually increasing in coverage through the morning. Conditions to briefly settle by the late afternoon, becoming increasingly hazy. A mostly hazy and cloudy night, barring the odd shower. Street/flash flooding, gusty winds likely.
7/10
Thunderstorm Chances
High

Saturday

Saturday
4 10 0 1
Hazy and cloudy interrupted by isolated to scattered showers throughout the day. Isolated thunderstorms are possible, favoring southern and easter offshore waters, particularly during the early morning and after nightfall. Street/flash flooding, gusty winds possible.
Hazy and cloudy interrupted by isolated to scattered showers throughout the day. Isolated thunderstorms are possible, favoring southern and easter offshore waters, particularly during the early morning and after nightfall. Street/flash flooding, gusty winds possible.
4/10
Thunderstorm Chances
Low – Medium

Sunday

Sunday
5 10 0 1
Hazy and cloudy interrupted by isolated to scattered showers and isolated thunderstorms throughout the day. Conditions to gradually settle by the late afternoon into the evening, barring the odd showers.
Hazy and cloudy interrupted by isolated to scattered showers and isolated thunderstorms throughout the day. Conditions to gradually settle by the late afternoon into the evening, barring the odd showers.
5/10
Thunderstorm Chances
Medium

Monday – Tropical Wave 05

Monday – Tropical Wave 05
6 10 0 1
Mostly cloudy to cloudy. Periods of light to moderate rain, isolated to scattered showers of varying intensities and isolated thunderstorms are forecast across the country, beginning from the early morning through the early afternoon. Showers/thunderstorms to become more isolated by the evening into the night. Gusty winds, street/flash flooding expected.
Mostly cloudy to cloudy. Periods of light to moderate rain, isolated to scattered showers of varying intensities and isolated thunderstorms are forecast across the country, beginning from the early morning through the early afternoon. Showers/thunderstorms to become more isolated by the evening into the night. Gusty winds, street/flash flooding expected.
6/10
Thunderstorm Chances
Medium – High

Marine: Seas are forecast to be moderate, with waves generally up to 2.0 meters, during the forecast period in open waters. In sheltered areas, waves are forecast to be near 1 meter but occasionally choppy during heavy showers or thunderstorms.

Temperatures

Through the forecast period, the minimum low in Trinidad and Tobago is forecast to be between 23.0°C and 26.0°C.

Maximum highs across the country are forecast to be generally up to 30.0°C in Trinidad and Tobago. In urbanized areas like Port of Spain, Scarborough, San Fernando, and Chaguanas, the maximum high temperatures could exceed 30.0°C.

Over the next five days, temperatures are forecast to be cooler overall due to increased cloud cover and anticipated rainfall.

Forecast Impacts

Flooding

Flooding
10 10 0 1
Over the next five days, between 30 and 85 millimeters of rainfall is forecast across most of the country. For southern and eastern halves of Trinidad, as well as highly isolated areas of western Trinidad, overall five-day rainfall totals could exceed 125 millimeters.
Over the next five days, between 30 and 85 millimeters of rainfall is forecast across most of the country. For southern and eastern halves of Trinidad, as well as highly isolated areas of western Trinidad, overall five-day rainfall totals could exceed 125 millimeters.
10/10
Likelihood
Expected

Updated: With the very high rainfall accumulations that occurred during the first half of Thursday, street/flash flooding is now expected Thursday into Friday, and then again on Monday across Trinidad and Tobago. Chances of riverine flooding has now increased to medium, and remaining there through the weekend.

Forecast Rainfall Totals

  • Thursday*: Between 25 and 75 millimeters across the country, trending higher across southern and eastern areas of Trinidad. Isolated totals upwards of 100 millimeters are possible, favoring southern, eastern, and western coastal Trinidad.
  • Friday: Between 5 and 20 millimeters across the country, trending higher across eastern areas of Trinidad and Tobago. Isolated totals up to 25 millimeters are possible.
  • Saturday: Between 5 and 20 millimeters across the country, trending higher across eastern and southern areas of Trinidad and Tobago.
  • Sunday*: Between 5 and 20 millimeters across the country, trending higher across eastern and southern areas of Trinidad and Tobago.
  • Monday: Between 10 and 30 millimeters across the country, trending higher across southern and eastern areas of Trinidad. Isolated totals upwards of 30 millimeters are possible, favoring southern, eastern, and western coastal Trinidad.

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.

On Thursday and Sunday, indicated by the asterisk (*), the GFS (American) model remains the outlier, showing significantly more rain than our current forecast. If it materializes and overall rainfall substantially rises over the next five days, the risk of riverine flooding will also increase. Since it is the outlier at this time, we’re placing less weight on it.

Strong Thunderstorms

Strong Thunderstorms
5 10 0 1
Favorable atmospheric conditions on Thursday and Monday are forecast, increasing the potential for stronger thunderstorms to develop on both days.
Favorable atmospheric conditions on Thursday and Monday are forecast, increasing the potential for stronger thunderstorms to develop on both days.
5/10
Likelihood
Medium

Mainly on Thursday, thunderstorms are forecast to develop under a low-shear, high moisture, and highly favorable low to mid-level environment. Frequent cloud-to-ground lightning will be likely and heavy to violent rainfall rates.

With light winds at low levels earlier on Thursday, funnel cloud development is possible. If a funnel cloud touches down on a body of water, it becomes a waterspout, and if it touches down on land, it becomes a tornado.

On Monday, a highly favorable mid to upper-level environment will be in place with a high moisture environment. While funnel cloud development becomes more unlikely on Monday, strong, fast-moving showers and thunderstorms are possible, capable of producing damaging wind gusts.

Gusty Winds

Gusty Winds
8 10 0 1
Low-level winds are forecast to increase over the next five days. Sustained winds up to 40 KM/H are forecast, with gusts up to and in excess of 55 KM/H are likely, mainly accompanying heavy shower or thunderstorm activity on Thursday and Monday.
Low-level winds are forecast to increase over the next five days. Sustained winds up to 40 KM/H are forecast, with gusts up to and in excess of 55 KM/H are likely, mainly accompanying heavy shower or thunderstorm activity on Thursday and Monday.
8/10
Likelihood
High – Very High

With wind gusts up to and 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.

Other Hazards

As rainfall continues through the weekend and into next week and soils become increasingly saturated, landslides are possible across elevated areas of Tobago, southern and northern Trinidad.

Saharan Dust is also forecast to increase across the region from Saturday, with a reinforcing surge on Tuesday, 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 from Thursday into next week.

Forecast Discussion

Tropical Waves: Based on the Tropical Analysis and Forecast Branch’s 06Z surface analysis on June 2nd, 2022, the fourth tropical wave for 2022 is along 58°W, south of 13°N, moving west at 15 knots (27.8 KM/H). Scattered strong showers and isolated thunderstorms have been observed with this wave, mainly east of the wave axis. The fifth tropical wave for 2022 is along 26°W, south of 13°N, and moving west at 15 knots (27.8 KM/H). This wave is forecast to move across T&T by Monday, June 6th, 2022.

Over the next five days, Trinidad and Tobago is set to experience a fairly active weather period. On Thursday into Friday, under a high-moisture, low shear, and highly favorable low to mid-level environment accompanying the passage of Tropical Wave 04, inclement weather is forecast to affect the country. A surge of low-level winds is also forecast to sweep across the Windwards following the passage of the wave axis on Thursday, elevating the risk of gusty winds.

Though the tropical wave is forecast to depart our area by Saturday, high atmospheric moisture and a generally favorable environment will allow for persisting showers, cloudy skies, and even isolated thunderstorms. However, a moderate to high concentration surge of Saharan Dust may reduce moisture levels at low- to mid-levels of the atmosphere, but this will be short-lived.

By Sunday, an amplified upper-level trough will be favorably positioned across Trinidad and Tobago, creating a highly favorable upper-level environment across and just east of the country. At lower levels of the atmosphere, Tropical Wave 05 will bring a fresh surge of deep, tropical moisture to combat the dry, Saharan Dust across the area.

On Monday, highly favorable upper-level conditions coincide with the passage of Tropical Wave 05 and a low-level trade wind surge. This setup will allow for strong thunderstorms and showers capable of producing strong to severe wind gusts (>55 KM/H) and torrential rainfall rates, interrupting overcast skies.

Moisture will continue to linger across the region Tuesday through the upcoming week but fluctuating moderate to high concentrations of Saharan Dust may limit rainfall, leading to a mostly cloudy, humid, and hazy week ahead following the anticipated inclement weather on Monday.

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