Tropical Wave 25 moved across T&T without much fanfare, producing some isolated thunderstorms across the country with localized street flooding. As the ITCZ lingers on Thursday, isolated thunderstorms remain forecast, but with an approaching high-pressure system and increasing Saharan Dust, a mostly dry weekend is ahead.
What you need to know
— Rainfall: Over the next five days, between 5 and 25 millimeters are forecast across Trinidad and Tobago. In isolated areas across western and eastern coastal Trinidad, locally higher amounts are possible.
— Saharan Dust: Elevated Saharan Dust concentrations are forecast across T&T through the next five days, with a moderate to high concentration surge likely by Thursday, July 19th into 20th.
— Hazards: Over the next five days, the main hazards will be reduced air quality and increasing temperatures. Air quality through the forecast period will be reduced, particularly from Thursday. Heat indices will also reach levels that require extreme caution from Thursday into the weekend.
— Marine: Seas are forecast to be slight to moderate, with waves in open waters ranging between 1.0 and 1.5 meters, while in sheltered areas, waves are forecast to remain below 0.5 meters.
Latest Alerts
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
Wednesday Night
Wednesday NightThursday
ThursdayFriday
FridaySaturday
SaturdaySunday
SundayMonday
MondayMarine Forecast
Seas Forecast: Moderate Seas, Reduced Visibility
Temperatures
Thursday
Low: 24-26°C
High: 31-33°C
Friday – Caution due to high temperatures!
Low: 24-26°C
High: 32-35°C
Saturday – Caution due to high temperatures!
Low: 24-26°C
High: 32-35°C
Sunday – Caution due to high temperatures!
Low: 24-26°C
High: 32-35°C
Monday
Low: 24-26°C
High: 32-34°C
Over the next five days, maximum high temperatures are forecast to be hot, ranging from 32°C to 35°C, with higher temperatures across urbanized areas of Trinidad, where in built-up areas, maximum high temperatures are likely to exceed 34°C. Minimum lows are forecast to remain mild, ranging between 24°C and 26°C in Trinidad and Tobago, trending marginally cooler in interior areas. The heat index will generally be above 35°C through the forecast period.
Forecast Impacts
Flooding
FloodingForecast Rainfall Totals
- Thursday: Little to no rainfall across most of Trinidad and Tobago, with up to 10 millimeters across western coastal areas of Trinidad and up to 20 millimeters in isolated areas of southwestern Trinidad.
- Friday Little to no rainfall across T&T, with isolated totals less than 5 millimeters.
- Saturday: Little to no rainfall across T&T, with isolated totals less than 5 millimeters.
- Sunday: Between 0 and 5 millimeters of rain across Trinidad and Tobago, with isolated totals nearing 10 millimeters across eastern areas of both islands.
- Monday: Between 0 and 5 millimeters of rain across Trinidad and Tobago, with isolated totals nearing 10 millimeters across eastern areas of both islands.
Understanding Rainfall Rates
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 WindsOther 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.
On Thursday, isolated rainfall is forecast. From Friday through Monday, highly isolated rainfall is possible, with mostly dry days ahead.
Forecast Discussion
The Intertropical Convergence Zone (ITCZ) interacted with Tropical Wave 25 on Wednesday, with isolated to scattered showers and isolated thunderstorms across Trinidad and, to a lesser extent, Tobago.
Instability and moisture trailing Tropical Wave 25 are forecast to remain across T&T through Thursday, with a high-pressure ridge forecast to rebuild across the Windwards, pushing the ITCZ southward and bringing in an influx of Saharan Dust. Saharan Dust will limit any widespread or even scattered convection from developing.
The atmosphere is forecast to be fairly dry from late Thursday through Saturday, with occasional pockets of moisture moving in by Sunday. Additionally, forecast models indicate the high-pressure system that is forecast to be in place will be anomalously strong, about two standard deviations above what is expected for mid to late July. This sinking air, combined with light winds and relatively high humidity, although dry air will be in place just above the surface levels, will result in warmer-than-usual temperatures.
By late Monday into Tuesday, Tropical Wave 26 is forecast to move across the region, with forecast models keeping the highest total precipitable moisture and stronger winds well north of T&T, tracking across the central and northern Windwards, French Antilles, and Leewards. The National Hurricane Center has tagged this wave for tropical cyclone development, giving it a low chance over the next seven days. However, a significant amount of dry air and moderate wind shear will limit any major short-term development.
