Forecast: Sunny Skies Change By Thursday As Tropical Wave 04 Moves Across T&T

Since the declaration of the 2022 Wet Season, T&T has seen more sunny skies and Saharan Dust than rain. However, this is forecast to change this week as a tropical wave moves across the region, with moisture lingering well into next week.

What you need to know

Saharan Dust: Mild to moderate dust lingers across T&T through late Wednesday/early Thursday. By late Friday/early Saturday, another dust surge is forecast to affect the country.
Rainfall: Through Wednesday, mostly sunny skies are forecast with the odd, brief isolated shower moving across the country. From Thursday, isolated to scattered showers, isolated thunderstorms, and periods of rain are forecast to affect T&T through the upcoming weekend.
Hazards: Street/flash flooding is possible from Thursday. Chances for riverine flooding remain low at this time. Gusty winds, up to 45 KM/H accompanying heavy showers or thunderstorms are also possible. Lightning will accompany thunderstorms. Severe thunderstorms are possible on Thursday. Landslides are possible mainly from the weekend.
Alerts/Watches/Warnings: There are no alerts, watches, or warnings in effect for the country from the Trinidad and Tobago Meteorological Service at this time.

The Forecast

Tuesday

Tuesday
1 10 0 1
Initially, brief showers and variably cloudy skies. As the day progresses, mostly hot and sunny conditions, interrupted by the odd passing shower.
Initially, brief showers and variably cloudy skies. As the day progresses, mostly hot and sunny conditions, interrupted by the odd passing shower.
1/10
Thunderstorm Chances
Very Low

Wednesday

Wednesday
2 10 0 1
Mostly hot and sunny conditions through the late afternoon. By the evening, partly cloudy conditions are forecast, with increasing cloudiness. An isolated shower or two is possible, nearing midnight.
Mostly hot and sunny conditions through the late afternoon. By the evening, partly cloudy conditions are forecast, with increasing cloudiness. An isolated shower or two is possible, nearing midnight.
2/10
Thunderstorm Chances
Very Low – Low

Thursday

Thursday
7 10 0 1
Mostly cloudy to overcast. Periods of showers and isolated thunderstorms from the early to mid-morning, favoring eastern and southern Trinidad initially, gradually spreading northwestward. Conditions to briefly settle by the late afternoon, with a resurgence of showers/thunderstorms after nightfall. Street/flash flooding, gusty winds possible.
Mostly cloudy to overcast. Periods of showers and isolated thunderstorms from the early to mid-morning, favoring eastern and southern Trinidad initially, gradually spreading northwestward. Conditions to briefly settle by the late afternoon, with a resurgence of showers/thunderstorms after nightfall. Street/flash flooding, gusty winds possible.
7/10
Thunderstorm Chances
High

Friday

Friday
6 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. Conditions to briefly settle by the late afternoon, with a resurgence of showers/thunderstorms nearing midnight. Street/flash flooding, gusty winds possible.
Mostly cloudy to overcast. Isolated to scattered showers and isolated thunderstorms are possible. Heavier showers/thunderstorms to favor southern and eastern Trinidad. Conditions to briefly settle by the late afternoon, with a resurgence of showers/thunderstorms nearing midnight. Street/flash flooding, gusty winds possible.
6/10
Thunderstorm Chances
Medium – High

Saturday

Saturday
5 10 0 1
Hazy and cloudy. Isolated to scattered showers and isolated thunderstorms are possible throughout the day. Heavier showers/thunderstorms to favor southern and eastern Trinidad. Conditions to briefly settle by the late afternoon, with a resurgence of showers/thunderstorms nearing midnight. Street/flash flooding, gusty winds possible.
Hazy and cloudy. Isolated to scattered showers and isolated thunderstorms are possible throughout the day. Heavier showers/thunderstorms to favor southern and eastern Trinidad. Conditions to briefly settle by the late afternoon, with a resurgence of showers/thunderstorms nearing midnight. Street/flash flooding, gusty winds possible.
5/10
Thunderstorm Chances
Medium

Marine: Seas are forecast to be moderate, with waves generally up to 1.5 meters, during the forecast period in open waters. In sheltered areas, waves are forecast to be below 1 meter but occasionally choppy during heavy showers or thunderstorms on Monday night into Tuesday.

Temperatures

Through the forecast period, the minimum low in Trinidad and Tobago is forecast to be between 24.0°C and 26.0°C, trending warmer across Tobago.

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 34.0°C.

From Thursday, temperatures are forecast to be cooler overall, with minimum lows near 24.0°C and maximum highs near 30.0°C due to increased cloud cover and forecast rainfall.

Forecast Impacts

Flooding

Flooding
7 10 0 1
Over the next five days across Trinidad and Tobago, mainly from Thursday, between 30 and 75 millimeters of rainfall is forecast, with upwards of 75 millimeters across southern and eastern areas of both islands. Isolated heavy pockets nearing and exceeding 100 millimeters are possible in thunderstorm activity.
Over the next five days across Trinidad and Tobago, mainly from Thursday, between 30 and 75 millimeters of rainfall is forecast, with upwards of 75 millimeters across southern and eastern areas of both islands. Isolated heavy pockets nearing and exceeding 100 millimeters are possible in thunderstorm activity.
7/10
Likelihood
High

There is a high chance of street/flash flooding from Thursday into the weekend across Trinidad and Tobago. There is a very low to a low chance of riverine flooding based on forecast rainfall accumulations as soils are fairly dry at this time.

Forecast Rainfall Totals

  • Tuesday: Less than 5 millimeters across the country.
  • Wednesday: Less than 5 millimeters of rainfall across the country.
  • Thursday: Between 10 and 30 millimeters across the country, trending higher across southern and eastern areas of Trinidad. Isolated totals upwards of 50 millimeters are possible along western coastal Trinidad.
  • Friday: Between 10 and 25 millimeters across the country, trending higher across eastern and southern areas of Trinidad and Tobago. Isolated totals up to 50 millimeters are possible, favoring eastern Trinidad and western coastal areas.
  • Saturday: Up to 25 millimeters across the country, trending higher across eastern and southern areas of Trinidad and Tobago.

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
Favorable atmospheric conditions on Thursday are forecast, increasing the potential for stronger thunderstorms to develop Thursday.
Favorable atmospheric conditions on Thursday are forecast, increasing the potential for stronger thunderstorms to develop Thursday.
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, 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.

Gusty Winds

Gusty Winds
7 10 0 1
Low-level winds are forecast to be typical for this time of year. Sustained winds up to 30 KM/H are forecast, with gusts up to and in excess of 45 KM/H are possible, mainly accompanying heavy shower or thunderstorm activity.
Low-level winds are forecast to be typical for this time of year. Sustained winds up to 30 KM/H are forecast, with gusts up to and in excess of 45 KM/H are possible, mainly accompanying heavy shower or thunderstorm activity.
7/10
Likelihood
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

As rainfall continues through the weekend 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, 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.

Highly isolated rainfall is forecast through Wednesday, with isolated to scattered rainfall forecast from Thursday into the weekend.

Forecast Discussion

Tropical Waves: Based on the Tropical Analysis and Forecast Branch’s 06Z surface analysis on May 31st, 2022, the third tropical wave for 2022 is along 65°W, south of 13°N, moving west at 15 knots (27.8 KM/H). The fourth tropical wave for 2022 is analyzed along 45°W, south of 14°N, moving west at 20 knots (37 KM/H). Scattered strong showers and isolated thunderstorms have been observed with this wave, mainly east of the wave axis.

The third tropical wave for the 2022 Atlantic Hurricane Season moved across Trinidad and Tobago on Monday, May 30th, 2022, with no significant rainfall outside of a few light overnight showers into Tuesday.

A surface to low-level ridge remains dominant across the region through Wednesday, with low-level cloud patches bringing occasionally cloudy periods and brief showers. A weakening trough is transporting upper-level clouds across the Windwards on Tuesday into Wednesday, causing partly cloudy skies.

By Wednesday, a weak low-level trough will be present across the Lesser Antilles, triggering a few brief showers and occasionally cloudy skies mainly north of T&T. By the evening, Tropical Wave 04 will be approaching the region. This tropical wave will bring abundant atmospheric moisture to the region, particularly across T&T.

Wind shear is forecast to diminish, with favorable low and mid-level conditions on Thursday, allowing for stronger shower and thunderstorm development. High levels of atmospheric moisture and instability will linger across T&T on Friday through the weekend, maintaining cloudy skies with isolated to scattered showers and isolated thunderstorms.

The wild card will be the influence of Saharan Dust, mainly from Saturday onwards. Saharan Dust generally brings a drier low to mid-level atmosphere. Dust models show a moderate to high concentration surge, which should significantly reduce atmospheric moisture across T&T. However, numerical weather prediction models (which typically don’t accurately factor in the influence of Saharan Dust) show a reasonably moist atmosphere through the weekend.

While cloudy skies will remain, rainfall is forecast, based on our analysis, to diminish to some extent. However, with a southwesterly low-level flow, ample moisture will remain to fuel additional showers or thunderstorms. By Saturday, wind shear will begin to marginally increase across T&T, coming from the northwest to north, resulting in overall heavier rainfall remaining south and east of the country.

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