Forecast: Tropical Wave 07 Moves In On Friday, Rains Continue Early Next Week

Tropical Wave 07 is forecast to bring showers, thunderstorms, and decreasing Saharan Dust on Friday into Saturday, returning to high dust levels by Sunday. By Monday, deep, tropical moisture from the southeast is forecast to move across T&T ahead of Tropical Wave 08 on Tuesday, setting a relatively wet start to the upcoming week.

What you need to know

Saharan Dust: High levels of Saharan Dust is forecast to remain present across T&T early Friday and on Sunday, with moderate to low levels on Friday night into Saturday and again from Monday through late Tuesday.
Rainfall: Over the next five days, mostly hazy and variably cloudy skies are forecast to be interrupted by periods of light to moderate rain, isolated heavy/violent showers, and isolated thunderstorms. The heaviest rainfall is forecast on Friday into Saturday and on Monday.
Hazards: The chances for street/flash flooding are high, particularly on Friday into Saturday and Monday, while the chances for riverine flooding remain low at this time. Gusty winds are forecast on Friday through Sunday, up to and in excess of 45 KM/H accompanying heavy showers or thunderstorms. 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.

The Forecast

Friday – Approach of Tropical Wave 07

Friday – Approach of Tropical Wave 07
5 10 0 1
Variably cloudy and hazy conditions are forecast to be interrupted by isolated showers and thunderstorms during the early morning, favoring eastern and southern Trinidad. Partly cloudy and hazy conditions are forecast throughout the day, with mostly cloudy skies across southern Trinidad. Increasingly cloudy and showery conditions are forecast by the late evening into the night. Street/flash flooding, gusty winds possible.
Variably cloudy and hazy conditions are forecast to be interrupted by isolated showers and thunderstorms during the early morning, favoring eastern and southern Trinidad. Partly cloudy and hazy conditions are forecast throughout the day, with mostly cloudy skies across southern Trinidad. Increasingly cloudy and showery conditions are forecast by the late evening into the night. Street/flash flooding, gusty winds possible.
5/10
Thunderstorm Chances
Medium

Saturday – Tropical Wave 07

Saturday – Tropical Wave 07
7 10 0 1
Periods of light to moderate rain with isolated heavy/violent showers and isolated thunderstorms are forecast from the early morning through the early afternoon, favoring southern and eastern Trinidad, as well as Tobago. These conditions will interrupt cloudy and hazy skies. Improvement is forecast by the late afternoon with brief showers through the night. Gusty winds >45 KM/H likely accompanying heavy showers/thunderstorms. Street/flash flooding possible.
Periods of light to moderate rain with isolated heavy/violent showers and isolated thunderstorms are forecast from the early morning through the early afternoon, favoring southern and eastern Trinidad, as well as Tobago. These conditions will interrupt cloudy and hazy skies. Improvement is forecast by the late afternoon with brief showers through the night. Gusty winds >45 KM/H likely accompanying heavy showers/thunderstorms. Street/flash flooding possible.
7/10
Thunderstorm Chances
High

Sunday – Saharan Dust Surge

Sunday – Saharan Dust Surge
3 10 0 1
Partly cloudy and hazy conditions, interrupted by brief cloudy periods with isolated showers and gusty winds. There is a low chance of thunderstorms favoring southern Trinidad through the afternoon. A mostly settled and partly cloudy night initially, barring the odd shower with cloudiness increasing into Monday.
Partly cloudy and hazy conditions, interrupted by brief cloudy periods with isolated showers and gusty winds. There is a low chance of thunderstorms favoring southern Trinidad through the afternoon. A mostly settled and partly cloudy night initially, barring the odd shower with cloudiness increasing into Monday.
3/10
Thunderstorm Chances
Low

Monday – Approach of Tropical Wave 08

Monday – Approach of Tropical Wave 08
6 10 0 1
Initially settled, variably cloudy and hazy skies are forecast to become increasingly cloudy with showers. By the late morning, isolated to scattered showers and isolated thunderstorms are forecast, favoring eastern and northern areas initially, gradually spreading across the country through the afternoon and into the night. Street/flash flooding, gusty winds possible.
Initially settled, variably cloudy and hazy skies are forecast to become increasingly cloudy with showers. By the late morning, isolated to scattered showers and isolated thunderstorms are forecast, favoring eastern and northern areas initially, gradually spreading across the country through the afternoon and into the night. Street/flash flooding, gusty winds possible.
6/10
Thunderstorm Chances
Medium – High

Tuesday – Tropical Wave 08

Tuesday – Tropical Wave 08
6 10 0 1
Variably cloudy and hazy conditions interrupted by brisk, isolated to scattered showers initially. By the afternoon, isolated to scattered heavy/violent showers and thunderstorms are forecast across the country, settling into the evening barring lingering isolated showers. Street/flash flooding, gusty winds possible.
Variably cloudy and hazy conditions interrupted by brisk, isolated to scattered showers initially. By the afternoon, isolated to scattered heavy/violent showers and thunderstorms are forecast across the country, settling into the evening barring lingering isolated showers. Street/flash flooding, gusty winds possible.
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. King tides are also forecast to begin over the weekend, with a surge in low-level winds agitating seas on Saturday into Sunday.

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 31.0°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.

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

Forecast Impacts

Flooding

Flooding
7 10 0 1
Over the next five days, between 25 and 80 millimeters of rainfall is forecast across most of the country. Lower rainfall totals are forecast across northwestern areas of Trinidad while higher totals are forecast across eastern and southern halves of Trinidad. In highly isolated areas, overall five-day rainfall totals could exceed 100 millimeters.
Over the next five days, between 25 and 80 millimeters of rainfall is forecast across most of the country. Lower rainfall totals are forecast across northwestern areas of Trinidad while higher totals are forecast across eastern and southern halves of Trinidad. In highly isolated areas, overall five-day rainfall totals could exceed 100 millimeters.
7/10
Likelihood
High

There is a high chance of street and flash flooding, mainly Friday into Saturday, when the heaviest rainfall is expected over the five-day forecast period. Chances of riverine flooding remain low.

Forecast Rainfall Totals

  • Friday: Across the western half of Trinidad, less than 10 millimeters of rainfall is forecast outside of isolated thunderstorm activity. Across the eastern half of Trinidad and Tobago, between 10 and 25 millimeters of rainfall is forecast, with isolated higher totals.
  • Saturday: Between 5 and 15 millimeters across the country, trending higher across eastern and southern areas of Trinidad and Tobago with isolated totals up to and in excess of 25 millimeters.
  • Sunday: Between 5 and 10 millimeters across the country, trending higher across eastern and southern areas of Trinidad and Tobago.
  • Monday: Between 10 and 20 millimeters across the country, trending higher across eastern and southern areas of Trinidad and across Tobago with totals up to and in excess of 35 millimeters.
  • Tuesday: Between 5 and 15 millimeters across the country, trending higher across eastern and southern halves of Trinidad and Tobago with isolated totals up to 25 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.

Strong Thunderstorms

Strong Thunderstorms
2 10 0 1
With Saharan Dust remaining present, as well as strong low-level winds, strong thunderstorms are unlikely to develop across Trinidad and Tobago.
With Saharan Dust remaining present, as well as strong low-level winds, strong thunderstorms are unlikely to develop across Trinidad and Tobago.
2/10
Likelihood
Very Low – Low

While thunderstorms are forecast over the next five days, strong wind shear, Saharan Dust, and a generally unfavorable environment (outside of Friday night/Saturday morning) will limit strong thunderstorms from forming.

Still, frequent cloud-to-ground lightning will be likely, with heavy to violent rainfall rates in thunderstorms. Funnel cloud development is possible mainly on Monday. 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 remain elevated over the next five days. Sustained winds up to 35 KM/H are forecast, with gusts up to and in excess of 50 KM/H are likely, mainly accompanying heavy shower or thunderstorm activity on Saturday. Low-level winds are forecast to decrease by Monday.
Low-level winds are forecast to remain elevated over the next five days. Sustained winds up to 35 KM/H are forecast, with gusts up to and in excess of 50 KM/H are likely, mainly accompanying heavy shower or thunderstorm activity on Saturday. Low-level winds are forecast to decrease by Monday.
7/10
Likelihood
High

With wind gusts up to and in excess of 50 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 will remain present across the region with a reinforcing surge by late 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.

Isolated to scattered rainfall is forecast into next week.

Forecast Discussion

Tropical Waves East of T&T: Based on the Tropical Analysis and Forecast Branch’s 18Z surface analysis on June 9th, 2022:

  • The seventh tropical wave for 2022 is along 52/53°W, south of 14°N, moving west at 15 to 20 knots (27.8-37 KM/H). This wave is forecast to move across Trinidad and Tobago by Friday night into Saturday morning. Two areas of scattered showers and isolated thunderstorms have been observed with this wave, near the coast of Guyana and further northeast, east of the wave axis near 11-13°N.
  • The eighth tropical wave for 2022 is along 28/29°W, south of 16°N, and moving west at 15 to 20 knots (27.8-37 KM/H). This wave is forecast to move across T&T overnight from Monday, June 13th, 2022, into Tuesday, June 14th, 2022. Isolated showers and thunderstorms have been observed near the wave axis.

A mid to upper-level trough anchored just northeast of the Leewards continues to bring mid to upper-level moisture and clouds across the Lesser Antilles from the southwest. These mid- to upper-level conditions will enhance showers and thunderstorms over the next five days associated with Tropical Wave 07 and Tropical Wave 08.

On Friday into Saturday, Tropical Wave 07 will move across Trinidad and Tobago with abundant atmospheric moisture and instability, fuelling cloudy skies, isolated to scattered showers, and isolated thunderstorms. A surge of low-level winds is forecast to accompany this tropical wave resulting in elevated winds through the weekend.

While rainfall is not forecast to be particularly severe, strong winds continue to prevail at low levels of the atmosphere this weekend, which can make their way down to the surface in heavy showers and thunderstorms. These winds remain a hazard through the weekend, with wind gusts in excess of 45 KM/H forecast, gusts in excess of 50 KM/H likely, and gusts in excess of 55 KM/H possible, mainly on Saturday.

A surface to mid-level high-pressure system will build by late Saturday through Sunday while a moderate to high concentration surge of Saharan Dust returns. Low to mid-levels will dry out while upper-level conditions remain fairly moist, with a canopy of upper-level clouds continuing to stream across the country from the southwest.

On Monday, increasing deep, tropical moisture will fuel increased cloudiness, showers, and isolated thunderstorms ahead of Tropical Wave 08, which moves across the region on Tuesday. While some suggest the Intertropical Convergence Zone (ITCZ) may affect T&T on Monday, the latest model guidance shows the ITCZ remaining well south of T&T, hugging the coast of French Guiana and Suriname on Monday through Tuesday.

Strong westerly to southwesterly wind shear (up to 40 knots) will persist, keeping most of the heavy rainfall, showers, and thunderstorms south and east of the country.

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