A series of low-level to surface troughs have affected Trinidad, Tobago, and the Windward Islands from December 6th and is expected to continue through December 9th, bringing periods of rain, heavy showers, and thunderstorms. While heavier rainfall is forecast to remain offshore and affect eastern areas, street/flash flooding will be a concern, with gusty winds accompanying heavy/violent rainfall.
What you need to know
— Rainfall: Over the next five days, across the western half of Trinidad, between 15 and 35 millimeters are forecast, while across the eastern half of Trinidad and Tobago, between 30 and 75 millimeters of rainfall is forecast. In isolated areas across eastern Trinidad and eastern Tobago, five-day totals approaching 100 millimeters are possible. In highly isolated heavy showers and thunderstorms, 24-hour rainfall totals could exceed 50 millimeters. Over the last 40 hours (12 AM December 6th through 4 PM December 7th), up to 150 millimeters of rainfall has fallen across parts of T&T.
— Saharan Dust: Mild concentrations will be present through Sunday, with rainfall tempering air quality impacts.
— Hazards: The main hazards, primarily through Saturday, will originate from periods of rain, heavy showers, and thunderstorms, producing cloud-to-ground lightning, gusty winds that may occasionally exceed 55 KM/H, and periods of heavy/violent rainfall, which can trigger street/flash flooding. In elevated areas of northern Trinidad and eastern Tobago, landslides are also possible. Elevated winds are set to continue into the weekend.
— Marine: Seas are forecast to be moderate, with waves in open waters generally reaching as high as 2.0 meters and getting as high as 2.5 meters into the weekend. In sheltered areas, waves are forecast to be up to 1.5 meters and choppy in heavy showers and thunderstorms.
Latest Alert
Hazardous Seas Alert Discontinued For T&T
Trinidad and Tobago is NOT under any tropical storm or hurricane threat, watch, or warning at this time.
The Forecast
Thursday night
Thursday nightFriday
FridaySaturday
SaturdaySunday
SundayMonday
MondayTuesday
TuesdayMarine Forecast
Seas Forecast: Moderate Seas, Reduced Visibility
Temperatures
Friday
Low: 23-25°C
High: 28-30°C
Saturday
Low: 23-25°C
High: 29-32°C
Sunday
Low: 23-25°C
High: 30-32°C
Monday
Low: 24-26°C
High: 31-33°C
Tuesday
Low: 24-26°C
High: 32-34°C
Through Saturday, maximum high temperatures are forecast to remain near to below-average levels for December across Trinidad and Tobago due to forecast rainfall and cloudy skies. Warmer temperatures are forecast to return from Sunday. Across the country, mainly from Sunday, the heat index, or feels like temperature, is forecast to range between 34°C and 38°C, trending higher over the weekend. Minimum lows are forecast to range between 23°C and 26°C daily but can trend lower in interior areas of the country and across eastern Tobago, where rainfall persists.
Forecast Impacts
Flooding
Flooding
Forecast Rainfall Totals
- Thursday: Across the western half of Trinidad, between 5 and 20 millimeters of rainfall. Across the eastern half of Trinidad and Tobago, between 20 and 50 millimeters of rainfall is forecast with locally higher amounts nearing 75 millimeters. Higher totals are likely in northeastern areas.
- Friday: Across Trinidad and Tobago, rainfall totals between 5 and 25 millimeters are forecast, with isolated higher totals along Trinidad’s western and eastern coastal areas, as well as eastern coastal Tobago, nearing 50 millimeters.
- Saturday: Less than 5 millimeters across western areas of Trinidad, with eastern and southern Trinidad, as well as Tobago recording totals between 15 and 25 millimeters with isolated higher totals across eastern areas.
- Sunday: Less than 5 millimeters across most of Trinidad and Tobago, with higher totals across eastern areas.
- Monday: Little to no rainfall across T&T, with isolated totals up to 5 millimeters, and isolated higher totals possible across Tobago and eastern Trinidad.
- Tuesday: Between 5 and 15 millimeters of rainfall with locally higher totals in heavy/violent showers or thunderstorms.
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 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 WindsWith winds gusting to 55 KM/H and occasionally above, 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. Note these impacts are mainly possible ahead of and during heavy/violent showers and thunderstorms.
Other Hazards
Saharan Dust Forecast
Major Saharan Dust Surge Now Moving Across T&T
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 on Thursday and Friday, with isolated rainfall thereafter.
Forecast Discussion
A series of low-level troughs have been affecting the Windward Islands since December 6th, producing cloudiness with scattered showers, periods of rain and the odd offshore thunderstorm.
Another surface to low-level trough lies east of T&T and south of Barbados, moving toward the Windwards on Thursday evening and is forecast to affect the region on Friday. The lower half of the atmosphere (surface to mid-levels) has high levels of moisture, supporting rainfall and cloudiness, while the upper half of the atmosphere (mid to upper-levels) is supportive of showers and isolated strong convection (heavy/violent rainfall).
These conditions are forecast to persist through Saturday, leading to periods of rain, showers and isolated thunderstorms that will decrease by Saturday evening.
Flood watches have been issued for St. Vincent and the Grenadines and Barbados due to the potential for heavy rainfall up to 3 inches (75 millimeters) through Saturday. While up to 100 millimeters of additional rainfall, on top of the widespread 25-75 millimeters of rain that has fallen across T&T over the last 24-36 hours, there are no alerts, watches, or warnings from the TTMS for T&T at this time. All major rivers are contained, with the Cunupia River and Caroni River nearing or just above 60%, the highest across the country.
By Saturday night, a high-pressure system is forecasted to dominate across the region, leading to mostly settled conditions. By Tuesday, this ridge weakens slightly, with localized climatic effects coming into play, leading to the chance of isolated late morning through afternoon showers and the odd thunderstorm across western and hilly areas – a typical pattern during the wet season.
Note that as an extended forecast goes further into the future, it is normal for the certainty to be reduced relative to the extended period.
