Over the last several days, the Intertropical Convergence Zone has remained north of Trinidad and Tobago, with deep-layered moisture and generally favorable conditions allowing for showers and thunderstorms to affect both islands. Similar conditions are forecast through the end of the week.
What you need to know
— Rainfall: Isolated to scattered showers and thunderstorms are forecast through Friday, with isolated activity on Saturday. Over the next three days, rainfall accumulations between 25 and 50 millimeters are forecast with isolated high totals exceeding 75 millimeters across Trinidad.
— Hazards: Street/flash flooding is likely in heavy showers/thunderstorms. Chances for riverine flooding remain low at this time as rivers remain contained. Gusty winds in excess of 45 KM/H accompanying heavy showers or thunderstorms are likely. Lightning will accompany thunderstorms. Landslides are possible in elevated areas.
— Alerts/Watches/Warnings: There are no alerts, watches, or warnings in effect for T&T from the Trinidad and Tobago Meteorological Service. There are no tropical storm or hurricane watches or warnings in effect for T&T at this time.
— Saharan Dust: Dust concentrations are forecast to remain negligible into the weekend.
The Forecast
Thursday
ThursdayFriday
FridaySaturday
SaturdayMarine: Generally moderate seas in open waters with waves up to 1.5 meters and smooth to near calm in sheltered areas with waves less than 0.5 meters.
Temperatures
Thursday
Low: 23-25°C
High: 29-31°C
Increased cloud cover will keep temperatures relatively cool across the country, with heat indices (or feels like temperatures) forecast to be up to 34°C.
Friday
Low: 24-26°C
High: 30-33°C
After a fairly cool Thursday, minimum lows are forecast to be similar. Decreased cloud cover will allow for temperatures to warm across the country, with cloudiness returning by late morning. Heat indices (or feels like temperatures) are forecast to be up to 42°C.
Saturday
Low: 24-26°C
High: 32-34°C
As sunshine returns to T&T, heat indices are forecast to be between 35°C and 45°C across the country, with higher temperatures possible across western and urbanized areas of Trinidad.
Forecast Impacts
Flooding
FloodingStreet and flash flooding chances are high across Trinidad and Tobago over the next 72 hours due to the saturated nature of soils, particularly across the western and southern halves of Trinidad. Chances for riverine flooding remain low at this time as rivers remain contained.
Forecast Rainfall Totals
- Thursday: Between 10 and 25 millimeters of rainfall is forecast across the country, with higher totals generally across Trinidad.
- Friday: Across Tobago, less than 10 millimeters of rainfall is forecast. Between 10 and 25 millimeters of rainfall is forecast across Trinidad with isolated higher totals favoring western and southern Trinidad.
- Saturday: Less than 10 millimeters across the country trending higher towards western coastal Trinidad.
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 ThunderstormsThe chances of strong thunderstorms are medium to high as an unstable atmosphere associated with the passage of a low-level trough, a favorable upper-level pattern, and abundant moisture.
Funnel cloud development is possible through Friday. 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
Abundant frequent cloud-to-ground lightning is possible in strong thunderstorm activity.
With the forecast rainfall and already saturated soils, landslides, mudslides, and rockfalls are possible across elevated areas of Trinidad and Tobago.
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, becoming more isolated on Friday and highly isolated on Saturday.
Forecast Discussion
Tropical Waves (and other notable weather features) near and east of T&T: Based on the Tropical Analysis and Forecast Branch’s 00Z surface analysis on September 28th, 2022, as well as the latest satellite and model guidance:
- Hurricane Ian remains a powerful hurricane across interior central Florida, moving to the north-northeast. It poses no threat to Trinidad and Tobago.
- Tropical Depression Eleven remains well out in the open Atlantic Ocean at 17.2°N, 35.6°W, posing no threat to any landmasses, including Trinidad and Tobago.
- The 40th tropical wave for 2022 (TW40) is along 29°W, south of 22°N, moving west at 10 knots (18 KM/H). This wave is forecast to move across T&T and the Lesser Antilles by Tuesday, October 4th, 2022, into Wednesday, October 5th, 2022. Little to no shower activity has been noted with this wave, though a surge of moisture has been noted on Total Precipitable Water imagery.
- A new tropical wave that has yet to be analyzed is moving off the African Coast, interacting with the Monsoon Trough (similar to the Intertropical Convergence Zone).
Over the past week, an unstable atmosphere has remained in place due to the Intertropical Convergence Zone north of Trinidad and Tobago with favorable upper-level conditions. On Wednesday, a low-level trough also moved across the Windwards, aiding low-level moisture and instability.
Through Friday afternoon, the overall pattern is forecast to remain unchanged. gentle to moderate low-level winds (less than 25 KM/H) are forecast with favorable low-level confluence and convergence, favorable upper-level conditions, and abundant moisture throughout the atmosphere are forecast to fuel and support cloudiness, showers, and thunderstorms.
Across Trinidad, with winds remaining fairly light, sea-breeze convergence, daytime heating, and orographic effects may trigger shower/thunderstorm activity or enhance already present showers/thunderstorms across the country.
Wind shear is forecast to remain moderate through the next 72 hours from the northeast. Wind shear will increase cloudiness across the country for stronger showers and thunderstorms that develop north or west of Trinidad and Tobago.
By Saturday, a surface to mid-level ridge rebuilds across the Windwards, including Trinidad and Tobago leading to overall settled and sunny conditions across the region. Low-level cloud patches still could bring some isolated showers, interrupting a mostly sunny weekend.
