An unstable atmosphere with multiple weather features, including an active Intertropical Convergence Zone (ITCZ), particularly by the end of the week, and a tropical wave by Wednesday, are forecast to produce additional rainfall over the next five days.
What you need to know
— Rainfall: Through Friday, a combination of partly to mostly cloudy skies, periods of rain, isolated to scattered showers, and thunderstorms are forecast across the country. Over the next five days, between 25 and 75 millimeters of rainfall is forecast across both islands, with totals nearing 125 millimeters, favoring eastern and southern areas of Trinidad. In isolated areas across both islands, totals may reach or exceed 125 millimeters.
— Hazards: Over the next five days, the main hazards will be street/flash flooding, localized gusty winds, and landslides. Wind gusts up to 45 KM/H are very likely, mainly through Wednesday, with gusts up to or over 55 KM/H possible in heavy showers or thunderstorms possible. Lightning will accompany thunderstorms. Riverine flooding is very likely through Tuesday and again from Thursday into Friday.
Latest Alerts
Riverine Flood Alert Discontinued For South Trinidad
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
Monday
MondayTuesday
TuesdayWednesday
WednesdayThursday
ThursdayFriday
FridayMarine: Through Thursday, moderate seas are forecast in open waters with waves up to 2.0 meters. In sheltered areas, waves are forecast to be less than 1.0 meter. However, long-period swells through Wednesday may cause larger, battering waves along northern coastlines. Sheltered areas may also occasionally become choppy during showers and thunderstorms. Winds drop off on Friday, with seas becoming slight in open waters (up to 1.25 meters) and near calm in sheltered areas.
Temperatures
Generally, over the next five days, with increased cloud cover, maximum highs and minimum lows are forecast to be cooler than usual. However, marginally increased sunshine over the weekend could lead to warmer days.
Monday through Friday
Low: 23-25°C
High: 29-32°C
With mostly cloudy skies over the next five days, maximum high temperatures are forecast to struggle to reach 30°C, with minimum lows remaining near 23°C to 24°C in Trinidad and near 24°C to 25°C in Tobago. The heat index will generally remain below 35°C.
Forecast Impacts
Flooding
FloodingStreet/flash flooding is very likely across both islands through the next five days. Riverine flooding is also very likely across the North Oropouche, Ortoire, Caparo, Nariva, South Oropouche, and Caroni River Basins. Smaller watercourses of the Caroni and South Oropouche Rivers are already outside of their banks following the last six days of heavy rainfall.
Forecast Rainfall Totals
- Monday: Between 5 and 15 millimeters of rainfall across both islands. Higher totals of up to 25 millimeters are forecast, trending across the eastern and southern halves of Trinidad and along the western coastal areas of Trinidad.
- Tuesday: Between 5 and 15 millimeters of rainfall across both islands. Isolated higher totals are possible.
- Wednesday: Between 5 and 15 millimeters of rainfall across both islands. Higher totals of up to 35 millimeters are forecast, trending across the eastern and southern halves of Trinidad and along the western coastal areas of Trinidad. Isolated higher totals are possible.
- Thursday: Between 15 and 35 millimeters across both islands, with isolated totals exceeding 50 millimeters across Trinidad, particularly southern areas, in persisting heavy shower/thunderstorm activity.
- Friday: Between 15 and 35 millimeters across both islands, with isolated totals exceeding 50 millimeters across Tobago in persisting heavy shower/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 ThunderstormsStrong thunderstorms can produce frequent lightning, gusty winds, and violent rainfall rates. Short-lived funnel cloud development is possible, particularly on Friday when low-level winds weaken. 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
With forecast rainfall accumulations and already saturated soils, landslides are likely across both islands over the next five days.
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.
Over the next five days, isolated to scattered rainfall is forecast.
Forecast Discussion
Tropical Waves (and other notable weather features) near and east of T&T: Based on the Tropical Analysis and Forecast Branch’s 18Z surface analysis on October 30th, 2022, as well as the latest satellite and model guidance:
- The 49th tropical wave for 2022 (TW49) is along 53°W, south of 18°N, moving west at 10-15 knots (18-27 KM/H). Scattered moderate convection has been noted with this wave where the axis interacts with the ITCZ. This wave is forecast to interact with the ITCZ as it moves across T&T on Tuesday night into Wednesday.
- Potential Tropical Cyclone Fifteen (PTC15): The National Hurricane Center has designated Invest 95L as PTC15, with tropical storm watches in effect for Jamaica and Grand Cayman Island. This system is still not yet a fully-fledged tropical storm, with high chances of tropical cyclone formation over the next 48 hours and five days. The NHC notes this could become a tropical storm tonight, nearing hurricane intensity by Tuesday night. It poses no direct threat to T&T.
Over the last six days, Trinidad and Tobago has been affected by a tropical wave, a series of different troughs, and a persistent Intertropical Convergence Zone. As seen above, widespread rainfall totals between 100 and 150 millimeters have been recorded across the country, with isolated totals exceeding 200 millimeters and, in fewer areas, exceeding 250 millimeters. These six-day rainfall totals have led to multiple rivers and tributaries breaking their banks and landslides across both islands, particularly on October 27th and October 30th. Over the next five days, additional rainfall at realtively lover overall totals are forecast.
Presently, the ITCZ is present across T&T but instability remains mild to moderate. Over the next 24-48 hours, a surge in Saharan Dust will marginally dry the mid to lower levels of the atmosphere, reducing widespread rainfall. However, the ITCZ is forecast to remain near and across the country over the next five days, with the passage of a tropical wave (TW49) on Tuesday into Wednesday and trailing convergence on Thursday into Friday, supporting additional rainfall.
Generally, after Tuesday, a very moist and unstable atmosphere is forecast to remain across T&T through the next five days. Wind shear, however, is forecast to remain at moderate levels between 10-25 knots from the west to west-northwest, keeping stronger convection (showers and thunderstorms) east of T&T. This will result in with overall heavier rainfall favoring southern and eastern areas of Trinidad and across Tobago. Latest model guidance is in fairly well agreement with this outcome.
By Thursday, forecast models diverge on what may occur across T&T. The GFS, which is far more agressive with rainfall, shows a very active ITCZ across the country under minimal wind shear and abundantly moist atmosphere. This particular model shows southwesterly winds (quite rare) as a cold surge aloft (850 millibar level) moves off the South American Coast. This cold surge from the south amplifies the ITCZ, pushing it northward towards the Leewards (also quite rare), with widespread rainfall across the Windwards and T&T.
The ECMWF, another top global model, shows a lesser amplified and active ITCZ by the end of the week. However, both models agree with a deep-layered low pressure developing over the southwestern Atlantic (near Florida), which allows for southerly to southeasternly wind flow across the eastern Caribbean. This flow is forecast to bring copious levels of moisutre across the region into the weekend, setting up a fairly wet pattern by Thursday through the second week of November.
The Larger-Scale Cause Of Our Prolonged Rainy Spell
Overarching the next five days will be a series of larger-scale features supporting shower and thunderstorm development. The convectively active phase of a Convectively-Coupled Kelvin Wave (CCKW) is forecast to remain across the region through the end of the month. CCKWs are huge impulses spanning thousands of miles, moving west to east through the stratosphere, typically rolling along at about 30 to 40 mph. Like a giant chimney, each CCKW has a broad zone of rising air at its heart, tilted toward the west as you move up. As low-level air converges, the resulting circulation favors the development of showers and thunderstorms ahead of the CCKW.
Another factor aiding shower and thunderstorm development will be the convectively active phase of the Madden-Julian Oscillation (MJO). Like the CCKW, the MJO is a large-scale rising air area promoting shower and thunderstorm development. This convectively active phase of the MJO is also forecast to remain across T&T and the Caribbean region through the next two weeks, promoting rainfall activity.
