After some brief respite from inclement weather on Tuesday, showers and thunderstorms are set to return across Trinidad and Tobago later today (Wednesday) as a result of Tropical Wave 12 and the Intertropical Convergence Zone (ITCZ) with a new hazard – gusty winds as a result of increased low-level winds.
What you need to know
— Rainfall: Over the next three days, rainfall accumulations will vary between 10 millimeters in northwestern areas, to as high as 50 millimeters across southern and eastern areas of Trinidad. Across eastern and southern areas of Trinidad, eastern Tobago, and western coastal Trinidad, totals may exceed this 50-millimeter mark on Wednesday evening into Thursday, during the wettest period of the next 72 hours.
— Saharan Dust: A surge of Saharan Dust is forecast to return to the area from today, Wednesday, but higher concentrations are forecast from Thursday evening.
— Hazards: Over the next three days, particularly through Thursday afternoon, street/flash flooding and gusty winds are forecast to be the main hazards with riverine flooding likely to continue across southern areas of Trinidad. In and ahead of heavy showers or thunderstorms, wind gusts are expected to exceed 45 KM/H with gusts exceeding 55 KM/H likely. There is the potential for landslides in elevated areas, particularly across the southern half of Trinidad.
— Marine: Seas are forecast to be moderate in open waters, with waves up to 2.5 meters and near 1.0 meter in sheltered areas. Seas may become locally choppy or rough in heavy showers or thunderstorms.
Latest Alerts
Adverse Weather Alert Discontinued For T&T
Adverse Weather Alert Issued For T&T Due To Gusty Wind Threat
Trinidad and Tobago is NOT under any tropical storm or hurricane threat, watch, or warning at this time.
The Forecast
Wednesday
WednesdayThursday
ThursdayFriday
FridayMarine Forecast
Sea Forecast: Increasing Winds To Agitate Seas Into Weekend
Temperatures
Generally, over the next three days, maximum highs and minimum lows are forecast to be near average.
Saturday through Wednesday
Low: 25-27°C
High: 29-32°C
Maximum high temperatures are forecast to range between 29°C to 32°C, trending cooler on Wednesday and higher across urbanized areas of Trinidad, where in built-up areas, maximum high temperatures could exceed 32°C. Overall hotter days are forecast from Friday. Minimum lows are forecast to remain mild, ranging between 25°C and 27°C in Trinidad and Tobago, trending cooler in interior areas. The heat index will generally be near or below 36°C.
Forecast Impacts
Flooding
FloodingForecast Rainfall Totals
- Wednesday: Between 10 and 15 millimeters of rainfall across both islands, with totals nearing 25 millimeters across the eastern and southern halves of Trinidad, as well as localized areas of western Trinidad where thunderstorms occur. In isolated areas, totals may exceed 25 millimeters.
- Thursday: Between 0 and 5 millimeters across both islands, with higher accumulations favoring the southern and eastern halves of Trinidad, where totals can near 15 millimeters.
- Friday: Between 0 and 5 millimeters across both islands, with higher accumulations favoring the southern and eastern halves of Trinidad, where totals can be near 15 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 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 55 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 WindsPossible impacts include localized wind damage to trees, power lines, and small structures. Small potted plants may blow over with light outdoor objects becoming airborne in stronger gusts. Tents may jump. Power outages are possible.
Other Hazards
Saharan Dust Forecast
Short-Lived Saharan Dust Surge From Thursday into Weekend
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.
On Wednesday, scattered rainfall is forecast with isolated rainfall forecast thereafter.
Forecast Discussion
On Wednesday, Tropical Wave 12 is forecast to move across Trinidad and Tobago. This tropical wave is well-defined and is forecast to bring the Intertropical Convergence Zone across the country.
As it moves across T&T, favorable low-level convergence, upper-level divergence, deep tropical moisture, and moderate vertical wind shear are forecast to support scattered showers and thunderstorms. However, in showers and thunderstorms that do form, while heavy to violent rainfall rates are likely, low-level winds are elevated and are forecast to create fast-moving convection, leading to a lower potential for high rainfall accumulations.
Still, there is the potential for street, flash, and exacerbated riverine flooding on Wednesday through Thursday. These elevated low-level winds are also forecast to make it to the surface ahead of and during heavy showers and thunderstorms, hence the High Wind Alert that goes into effect for Trinidad, Tobago, and offshore marine areas from 8 AM Wednesday.
By Thursday morning, moderate concentrations of Saharan Dust are forecast to follow TW12’s passage, but forecast models indicate sufficient moisture and instability for the isolated afternoon and overnight thunderstorms near Trinidad into Friday. Some upper-level enhancement is possible due to a favorably positioned upper-level trough, but this same feature will cause wind shear to dramatically increase on Thursday through the weekend, leading to these thunderstorms or showers being short-lived.
Through the next 72 hours, as wind shear remains generally from the west to northwest, heavier rainfall accumulations are forecast to remain southeast of Trinidad and Tobago.
Note that with the ITCZ near T&T today through Friday, based on research, the ITCZ in the Tropical Atlantic has its strongest activity occurring between 12:00 AM and 6:00 AM local time, with another peak during the Northern Hemisphere summer months between 12:00 PM to 3:00 PM. Minimum activity occurs between 5:00 PM to 8:00 PM.
