Over the next 72 hours, showers and thunderstorms are forecast to affect Trinidad and Tobago due to the passage of a tropical disturbance, Invest 91L, and a trailing Intertropical Convergence Zone. T&T is set to experience periods of heavy rainfall and occasional gusty winds from this system, while the strongest winds and heaviest rains generally remain north of the country.
What you need to know
— Rainfall: Broad areas of rain, periods of showers, and thunderstorms are forecast through Saturday, with isolated strong showers and thunderstorms through Friday. Updated (as of 2:00 AM Wednesday): Overall rainfall totals of up to 150 millimeters are forecast across both islands over the next five days. Isolated totals of up to 200 millimeters are forecast across the southern and eastern areas of both islands.
— Hazards: Street/flash flooding and localized ponding is expected. Chances for riverine flooding will increase by Thursday, though the risk is low to medium. Wind gusts in excess of 55 KM/H accompanying heavy showers or thunderstorms are likely, with wind gusts in excess of 45 KM/H expected. Stronger winds are forecast to remain well north of Trinidad and Tobago. Lightning will accompany thunderstorms. Landslides are possible across both islands. Seas are forecast to become agitated.
— Alerts/Watches/Warnings: The Trinidad and Tobago Meteorological Service issued an Adverse Weather Alert (Yellow Level) for Trinidad and Tobago from 12:00 AM Wednesday, October 5th, 2022, and remains in effect through 12:00 PM Friday, October 7th, 2022. There are no tropical storm or hurricane watches or warnings in effect for T&T at this time.
— Saharan Dust: Dust concentrations are forecast briefly increase by early Thursday across Trinidad and Tobago, with higher dust levels north of the country.
The Forecast
Wednesday
WednesdayThursday
ThursdayFriday
FridaySaturday
SaturdaySunday
SundayMarine: Through Thursday, moderate seas are forecast in T&T’s open waters, particularly north of the country. There is a high risk of rip currents along the country’s northern and eastern coastlines with agitated seas initially, with agitated seas in the Gulf of Paria by Wednesday afternoon. Seas are forecast to return to slight to moderate in open waters by Friday, but spring tides begin.
Temperatures
Wednesday
Low: 24-25°C
High: 28°C
Increased cloud cover will keep temperatures relatively cool across the country, with heat indices (or feels like temperatures) forecast to be up to 30°C.
Thursday
Low: 23-24°C
High: 28-29°C
Increased cloud cover will keep temperatures relatively cool across the country, with heat indices (or feels like temperatures) forecast to be up to 30°C.
Friday
Low: 23-24°C
High: 29-30°C
Increased cloud cover will keep temperatures relatively cool across the country though some sunshine may allow for warmer temperatures in some areas, with heat indices (or feels like temperatures) forecast to be up to 35°C.
Saturday
Low: 23-25°C
High: 29-31°C
Increased cloud cover will keep temperatures relatively cool across the country though some sunshine may allow for warmer temperatures in some areas, with heat indices (or feels like temperatures) forecast to be up to 35°C.
Sunday
Low: 23-25°C
High: 29-32°C
As the sunshine begins to return to T&T, heat indices are forecast to be between 30°C and 38°C across the country, with higher temperatures possible across western and urbanized areas of Trinidad.
Forecast Impacts
Flooding
FloodingStreet and flash flooding is expected across Trinidad and Tobago over the next five days, with the highest chances between Wednesday and Thursday. There are increasing chances for riverine flooding across all major river basins of Trinidad from Thursday morning.
Forecast Rainfall Totals
- Wednesday: Across both islands, between 35 and 75 millimeters of rainfall is forecast. Across Tobago, 24-hour rainfall totals could reach 150 millimeters favoring eastern areas. Generally higher rainfall totals are forecast across the eastern and southern halves of the island. In highly isolated areas, rainfall totals up to 150 millimeters are possible. If these rainfall totals materialize, there is a significant threat of street, flash and riverine flooding across T&T
- Thursday: Across both islands, between 25 and 50 millimeters of rainfall is forecast. In isolated areas across both islands, rainfall totals could exceed 50 millimeters.
- Friday: Between 15 and 25 millimeters of rainfall is forecast across both islands, with isolated totals exceeding 25 millimeters in prolonged or persisting heavy showers and thunderstorms favoring western coastal Trinidad.
- Saturday: Between 5 and 15 millimeters across both islands, with higher totals towards 25 millimeters across western coastal Trinidad and eastern and northern areas of both islands.
- Sunday: Less than 15 millimeters of rainfall across both islands with locally higher totals in thunderstorm activity.
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 ThunderstormsThe chances of strong thunderstorms are high as a highly unstable atmosphere associated with Invest 91L moves across T&T. Though wind shear is forecast to be moderate, high moisture, high instability, and favorable upper-level conditions will support strong shower and thunderstorm activity.
Funnel cloud development is possible through Friday. If a funnel cloud touches down on a body of water, it becomes a waterspout; if it touches down on land, it becomes a tornado.
Gusty Winds
Gusty WindsPossible impacts include localized wind damage to trees, power lines, and small structures. 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
Abundant frequent cloud-to-ground lightning is possible in strong thunderstorm activity.
With the forecast rainfall accumulations, landslides, mudslides, and rockfalls are possible across elevated areas of Trinidad and Tobago.
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.
Widespread rainfall is forecast on Wednesday through Thursday, where activity becomes isolated to scattered through the remainder of the forecast period.
Forecast Discussion
Latest On Invest 91L
Live Updates: Aftermath of Invest 91L, ITCZ Activity Across T&T (Day 5)
On Tuesday, a combination of surface to low-level areas of convergence, deep-layered moisture, localized climatic effects, and favorable upper-level conditions allowed for the development of localized heavy showers and thunderstorms under partly cloudy to mostly cloudy skies.
By Tuesday night into Wednesday, as the ill-defined low-level center of Invest 91L tracks north of the country, a cluster of convection trailing the center is forecast to begin moving across Trinidad, Tobago, and the Windward Islands.
Invest 91L is bringing abundant moisture and instability to the region. A favorably positioned upper-level trough is also forecast to provide upper-level support for convective activity, leading to cloudy to overcast skies, broad areas of rain, scattered moderate to heavy showers, and isolated to scatted thunderstorms through Thursday.
By Friday, the Intertropical Convergence Zone trailing Tropical Wave 41/Invest 91L is forecast to remain present across the country, maintaining deep-layered moisture. Favorable conditions and as well as T&T’s localized climatic features (sea-breeze convergence, orographic effects, and daytime heating) are forecast to support isolated showers and thunderstorms into the weekend.
Wind shear is forecast to be moderate through the forecast period from the east, keeping heavier rainfall north and east of the country. Another wild card will be the moderate levels of dry mid-level air associated with a surge of Saharan Dust arriving across Trinidad and Tobago on Thursday, which can limit rainfall activity as we head into the weekend, hence reducing thunderstorm chances.
