A tropical wave is forecast to move across Trinidad and Tobago this weekend, bringing showers and thunderstorms to both islands. However, wind shear is forecast to limit widespread activity, keeping most of the heavy rainfall offshore of eastern Trinidad and Tobago.
What you need to know
— Rainfall: Over the next five days, through Wednesday, between 5 and 15 millimeters of rainfall are forecast across most of Trinidad, with overall totals nearing 50 millimeters possible across the southern and eastern halves of Trinidad and isolated western coastal areas. Across Tobago, generally, up to 25 millimeters of rainfall is forecast, with isolated higher totals in eastern areas. Between Saturday afternoon and Sunday night, when most rainfall is forecast, highly isolated totals of up to 75 millimeters are possible, mainly in areas of isolated heavy showers/thunderstorms.
— Saharan Dust: Moderate to high concentrations of Saharan Dust are forecast from Sunday afternoon, lingering into the upcoming week.
— Hazards: Mainly Saturday and Sunday, the main hazards will be localized street/flash flooding in heavy showers/thunderstorms, which may be accompanied by gusty winds exceeding 45 KM/H, as well as lightning in thunderstorm activity. From late Sunday, Saharan Dust is forecast to reduce air quality.
— Marine: Seas are forecast to be slight to moderate over the next five days, with waves in open waters generally up to 1.5 and 2.0 meters. In sheltered areas, waves are forecast to be up to 1.0 meters and choppy in showers/rain and thunderstorms.
Latest Alert
Adverse Weather 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
Saturday
SaturdaySunday
SundayMonday
MondayTuesday
TuesdayWednesday
WednesdayMarine Forecast
Sea Forecast: Increasing Winds To Agitate Seas Into Weekend
Temperatures
Saturday
Low: 25-27°C
High: 30-33°C
Sunday
Low: 23-24°C
High: 28-31°C
Monday
Low: 25-27°C
High: 30-32°C
Tuesday
Low: 25-27°C
High: 32-34°C
Wednesday
Low: 25-27°C
High: 32-34°C
Forecast Impacts
Flooding
FloodingForecast Rainfall Totals
- Saturday: Most areas receive less than 5 millimeters of rainfall, with localized totals of up to 15 millimeters across eastern and southern areas of Trinidad and along western coastal Trinidad.
- Sunday: Between 10 and 25 millimeters of rainfall across both islands, with isolated totals between 25 and 50 millimeters favoring the southern and eastern halves of Trinidad as well as parts of Tobago. In isolated areas of western coastal Trinidad, locally higher amounts are possible.
- Monday: Little to no rainfall across most of the country, with isolated totals up to 5 millimeters along eastern coastal areas of both islands.
- Tuesday: Little to no rainfall across most of the country, with isolated totals up to 5 millimeters along eastern coastal areas of both islands.
- Wednesday: Between 5 and 10 millimeters of rainfall are forecast across Tobago, northern and eastern Trinidad, and less than 5 millimeters elsewhere.
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 50 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.
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.
Saturday afternoon through Sunday afternoon, isolated to scattered rainfall is forecast. Outside of this period, highly isolated rainfall is possible.
Forecast Discussion
Tropical Update
Tropical Update: Tracking Two Tropical Waves, Area of Interest East of Lesser Antilles
The first tropical wave analyzed by the National Hurricane Center (but not the first by the Trinidad and Tobago Meteorological Service or the Barbados Meteorological Service) is set to move across Trinidad and Tobago this weekend.
As with nearly all tropical waves, we see a leading edge of showers associated with the moisture surge and upper-level divergence ahead of the wave axis, which is set to move across T&T tonight through Saturday. The bulk of activity usually trails the wave axis, and this is forecast to occur Saturday night through Sunday afternoon, where there is favorable low-level convergence. This tropical wave is bringing abundant, deep tropical moisture and is coupled with a break in prevailing strong westerly wind shear, which should allow for heavy convection (showers/thunderstorms) to develop, particularly Saturday night through Sunday.
However, the wild cards will be how strong the wind shear remains at this time (models still showing moderate westerly shear, resulting in most of the heavy rainfall remaining east) and how quickly Saharan Dust moves in that is trailing the wave. Regardless, model guidance supports heavy showers and thunderstorms for T&T, primarily on Sunday, from the wee hours of the day.
As the wave moves west, a surface-to-low-level ridge is forecast to regain dominance across Trinidad and Tobago. In tandem, a moderate to high-concentration surge of Saharan Dust will remain present across T&T and the Windward Islands, leading to fairly dry low- to mid-levels of the atmosphere.
By Wednesday into Thursday, a southeasterly flow of wind is forecast to advect deep tropical moisture again across the country, with favorable low-level conditions and moderate wind shear, which will increase cloudiness, showers, and thunderstorms again. However, with Saharan Dust still present, this may be the limiting factor on widespread activity.
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.
