The fourth tropical wave for the year is forecast to move across Trinidad and Tobago by late Monday, ushering in a wet period for the country. However, as is typical with these early-season waves, activity tends to be more scattered, mainly staying south of Trinidad and Tobago. However, as this wave pulls moisture from equatorial regions and the Intertropical Convergence Zone to the south, with subsequent low-level troughs moving across T&T, activity may increase during the pre-dawn through early afternoon hours.
What you need to know
— Rainfall: Over the next five days, through Saturday morning, overall rainfall accumulations across Trinidad and Tobago are forecast to range between 50 and 100 millimeters. Across the central and southern thirds of Trinidad, rainfall of 75 to 150 millimeters is possible.
— Saharan Dust: Significant Saharan Dust concentrations are forecast to decrease by late Monday, with mild to moderate dust remaining present through the next five days. Higher dust levels are likely to be present across Tobago compared to Trinidad.
— Hazards: With heavy showers and thunderstorms, as well as periods of rain, many of the typical Wet Season hazards are on the table for the next five days. Street and flash flooding is likely in heavy rain, showers, and thunderstorms, accompanied by wind gusts exceeding 50 km/h, and lightning during thunderstorm activity. From Wednesday, as soils become increasingly saturated, landslides are possible in elevated areas. As river levels rise, smaller watercourses may approach their threshold levels by mid-week. Spring tides may lead to reduced runoff during high tide periods, and elevated low-level winds are also forecast to agitate marine conditions.
— Marine: Moderate seas are forecast in Trinidad and Tobago’s open waters, while choppy conditions are forecast in sheltered areas. All marine interests are advised to exercise caution in the vicinity of heavy showers and thunderstorms.
Latest Alerts
Flooding Continues To Subside As Riverine Flood Alert Discontinued
Trinidad and Tobago is NOT under any tropical storm or hurricane threat, watch, or warning at this time.
The Forecast
Monday
MondayTuesday
TuesdayWednesday
WednesdayThursday
ThursdayFriday
FridayMarine Forecast
Agitated Seas Forecast For T&T Over Next 7 Days
Temperatures
Monday
Low: 25-26°C
High: 31-32°C
Tuesday
Low: 23-25°C
High: 28-29°C
Wednesday
Low: 23-24°C
High: 26-28°C
Thursday
Low: 23-24°C
High: 26-29°C
Friday
Low: 23-24°C
High: 26-29°C
Forecast Impacts
Flooding
Over the next five days, through Saturday morning, overall rainfall accumulations across Trinidad and Tobago are forecast to range between 50 and 100 millimeters. Across the central and southern thirds of Trinidad, rainfall of 75 to 150 millimeters is possible.
Street & Flash Flooding
Street & Flash FloodingRiverine Flooding
Riverine FloodingForecast Rainfall Totals
- Monday: Across the western half of Trinidad, as well as across Tobago, up to 10 millimeters of rainfall, with isolated higher totals in heavy showers or thunderstorms. Across the southern and eastern halves of Trinidad, between 5 and 15 millimeters of rainfall, with isolated higher totals in heavy showers and thunderstorms.
- Tuesday: Across both islands, between 10 and 25 millimeters of rainfall is likely, with totals of up to 35 millimeters expected in the southern and eastern halves of Trinidad, eastern areas of Tobago, and isolated areas of western Trinidad, particularly where thunderstorms are present. In persisting, particularly heavy, showers and thunderstorms, localized rainfall totals exceeding 75 millimeters are possible, favoring Trinidad.
- Wednesday: Across Tobago, between 10 and 25 millimeters of rainfall is forecast. Across Trinidad, between 25 and 50 millimeters of rainfall is forecast. Isolated totals, favoring southern and eastern areas, may exceed 50 millimeters. Flooding is likely.
- Thursday: Between 10 and 25 millimeters of rainfall across both islands, with isolated totals between 25 and 50 millimeters, favoring eastern Trinidad, across Tobago, and isolated areas along western coastal Trinidad.
- Friday: Between 15 and 35 millimeters of rainfall across Trinidad and Tobago, with higher totals favoring the eastern halves of both islands. In isolated areas, totals up to 50 millimeters are possible. The forecast confidence for this day is lower than average.
Understanding Rainfall Accumulations
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 ThunderstormsWhat 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 63 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 WindsWith wind gusts exceeding 50 KM/H, whole trees can be in motion, with larger trees and weaker branches falling. Light outdoor objects can topple or become airborne, such as garbage cans, loose galvanize, construction material, and outdoor furniture. Tents may also jump.
Other Hazards
Significant Saharan Dust is forecast for Monday, with levels expected to diminish to mild or moderate by Tuesday.
Saharan Dust Forecast
Saharan Dust Concentrations Forecast To Fluctuate Across T&T Over Next 7 Days
Why I May Not/Will Not See Rainfall?
A frequent complaint is that 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.
While isolated showers are forecast on Monday, scattered to widespread rainfall is forecast for the remainder of the week.
Forecast Discussion
A back-to-back tropical wave and a low-level trough are forecast to trigger a prolonged rainfall event across Trinidad and Tobago this week, amid generally favorable background conditions.
On Monday, the axis of Tropical Wave 04 is forecast to move across the country without much fanfare due to significant Saharan Dust concentrations in the region. Ahead of tropical waves, conditions are usually calmer, with active weather following the wave axis. This tropical wave is forecast to be no different, with showers and thunderstorms from Tuesday morning.
Generally, throughout this forecast period, wind shear is forecast to remain low to moderate, with upper-level winds generally from the west. Nevertheless, a favorable upper-level divergent pattern is forecasted, which will enhance the generally favorable low-level convergent pattern already in place.
Abundant, deep-layered atmospheric moisture will also be flowing through the region from equatorial regions, and a mid-week low-level trough will further enhance activity from Wednesday.
The combination of these factors is likely to result in daily rainfall accumulations exceeding 25 millimeters in many locations. In some isolated areas, places may even experience daily rainfall totals between 50 and 75 millimeters. Based solely on the potential for flooding, an Adverse Weather Alert is expected to be issued for this week, primarily from Tuesday onward, with a significant possibility of riverine flooding across the central and southern river basins in Trinidad, even if it is short-lived. However, longer-range modeling suggests that rainfall will continue into the weekend. A reminder that alerts, watches, and warnings for T&T are entirely the prerogative of the forecasters at the Trinidad and Tobago Meteorological Service.
Compounding this flood threat are spring tides that began on Sunday, June 8th, and will persist through Saturday, June 14th. These higher-than-normal high tides will slow runoff, while the lower-than-normal low tides will lead to quicker runoff. The issue arises when heavy rainfall coincides with high tide periods, and when upstream runoff reaches the lower river basins simultaneously with high tides, leading to flooding in both scenarios.
Additionally, low-level winds are forecast to be elevated on Monday through Wednesday, and again from Friday into the weekend. In heavy showers and thunderstorms, wind gusts are likely to exceed 50 km/h, with the potential for gusts exceeding 60 km/h, particularly in elevated and coastal areas. As soils become increasingly saturated, falling trees and resulting downed utility poles and power outages are likely to occur as the week progresses.
The takeaway: A multi-day, heavy rainfall event is likely this week, starting on Tuesday. As a result, multiple periods of heavy rainfall will lead to flooding, resulting in traffic delays (street and flash flooding), and for those in low-lying areas, particularly near watercourses, impacts on homes, lives, and livelihoods. However, this is notexpected to be a Greenvale (October 2018) level event, which saw upwards of 250 millimeters of widespread rainfall in three days. Those living in elevated areas, as well as those in low-lying areas near watercourses, should pay close attention to rivers, wider surroundings, as well as the latest weather forecast and conditions in the coming days.
