April 2023’s extremely dry weather is forecast to end in the coming days as Trinidad and Tobago enters a fairly unsettled weather pattern, with the potential of uncommon Dry Season thunderstorms by the weekend.
What you need to know
— Rainfall: Over the next five days, between 25 millimeters to 60 millimeters of rainfall is forecast, with isolated totals reaching just over 100 millimeters. The heaviest rainfall days are forecast to be Sunday, April 23rd, and Monday, April 24th, with overall higher rainfall accumulations favoring eastern and southern Trinidad, as well as eastern Tobago.
— Saharan Dust: A moderate concentration surge of Saharan Dust is present across T&T, with concentrations remaining elevated through Friday, with improvement by Sunday.
— Hazards: Over the next five days, the main hazard will be occasional wind gusts exceeding 45 KM/H, as well as localized street/flash flooding, generally accompanying heavy or persistent showers and isolated thunderstorms. Funnel cloud development is possible from Saturday through Monday. Air quality is forecast to be marginally reduced through Friday.
— Marine: Seas are forecast to be moderate, becoming slight, in open waters with waves up to 2.0 meters, becoming up to 1.25 meters by Saturday evening, and up to 1.0 meter by Sunday. Caution is still advised through Sunday as a result of Spring Tides.
Latest Alerts
Adverse Weather Alert Discontinued. Heavy Rainfall Still Possible
Trinidad and Tobago is NOT under any tropical storm or hurricane threat, watch, or warning at this time.
The Forecast
Thursday
ThursdayFriday
FridaySaturday
SaturdaySunday
SundayMonday
MondayMarine Forecast
Seas Forecast: Moderate Seas, Reduced Visibility
Temperatures
Generally, over the next five days, maximum highs and minimum lows are forecast to be fairly seasonal to below average.
Saturday through Tuesday
Low: 23-25°C
High: 29-32°C
Maximum high temperatures are forecast to range between 29°C to 32°C with slightly warmer temperatures on Thursday compared to the remainder of the forecast period, particularly in urbanized areas. From Friday through Monday, maximum highs are set to trend slightly cooler, though conditions are forecast to remain humid and warm. Minimum lows are forecast to remain near 23°C to 25°C in Trinidad and Tobago, trending cooler in interior areas. The heat index will generally remain below 35°C.
Forecast Impacts
Flooding
FloodingForecast Rainfall Totals
- Thursday: 5 to 10 millimeters across both islands, with locally higher across eastern Trinidad, as well as isolated areas of western coastal Trinidad.
- Friday: Most areas are forecast to see less than 5 millimeters of rainfall, with up to 15 millimeters across both islands. In heavy showers or a thunderstorm, accumulations could be near 25 millimeters in localized spots of southern and western coastal Trinidad.
- Saturday: Less than 5 millimeters of rainfall across Tobago and most of Trinidad, with isolated totals reaching 10 to 20 millimeters across southwestern and southern Trinidad.
- Sunday: Between 5 and 15 millimeters across both islands, with totals reaching 25 millimeters favoring the southern and eastern halves of Trinidad, localized areas of western Trinidad, as well as Tobago. Locally higher totals are possible in persisting heavy showers or isolated thunderstorms.
- Monday: Between 5 and 15 millimeters across both islands, with totals reaching 25 millimeters favoring the southern half of Trinidad, localized areas of western Trinidad, as well as Tobago. Locally higher totals are possible in persisting heavy showers or isolated thunderstorms.
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 ThunderstormsGusty 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
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.
Through the next five days, isolated to scattered showers and isolated thunderstorms are forecast, interrupting variably cloudy and decreasingly hazy skies.
Forecast Discussion
After a near-record dry April 2023, with 1.9 millimeters of rainfall recorded at Piarco as of April 19th, welcome rains are forecast for both islands through the next five days.
A westward-moving low-level trough traverses the area tonight through Thursday, but the air mass remains fairly dry until the late morning of Thursday. Convergence trailing the trough and increased low-level moisture and instability will support increased cloudiness, showers, and even the isolated afternoon thunderstorm across Trinidad and Tobago (see above forecast).
A modest surge of Saharan Dust is forecast to move in during the next 12-18 hours, with the low to upper (700 mb to 200 MB) levels remaining fairly dry until late Friday. This dry air will suppress any deep convection from developing, in addition to strong wind shear.
By Saturday, Trinidad and Tobago will exist on the western periphery of a high-pressure ridge anchored in the eastern Atlantic. A deep low-pressure system in the North Atlantic leaves a weak pressure gradient across T&T and the Windwards. The entire atmospheric column is forecast to become moister from Saturday. Abundant low-level moisture and modest instability are forecast to support shower and isolated thunderstorm activity into the weekend and the beginning of next week in the face of strong westerly shear.
Winds are forecast to be light and variable, at times coming from the south from Sunday into Monday, with the steering flow of showers/thunderstorms light and variable, which could result in both the development of funnel clouds across both islands, as well as near-stationary rainfall where heavier showers or thunderstorms do develop.
Compounding the Sunday/Monday heavy rainfall threat would be south-to-north moving rainfall, which is susceptible to orographic and sea-breeze enhancement. There is ample moisture present, with forecast PWAT values reaching up to 2.3 inches (58.4 mm), which is quite high generally and particularly for this time of year. However, the good news is that higher resolution model guidance generally keeps maximum 24-hour rainfall accumulations below 25-35 millimeters, likely as a result of moderate to strong wind shear preventing deep convection from persisting.
Larger-scale features like the Madden Julian Oscillation (MJO) and two convectively-coupled atmospheric Kelvin Waves are set to enhance convection (showers and thunderstorms) and are moving across the region. These features could enhance rainfall accumulations in the coming days.
For those looking even further ahead, a more potent trough is forecast to move across the region by the middle to end of next week. Top models indicate a continuation of our wetter-than-usual pattern to round out the exceptionally dry April. However, too much rain, too soon, could usher in new problems – from bushfires to floods.
