2023 Wet Season: Another Year With Elevated Flood Potential

The 2023 Wet Season is forecast to have near-normal rainfall overall, but several communities are under threat of flooding, according to the Trinidad and Tobago Meteorological Service (TTMS).

This year would be the second they have issued flood guidance within their “Flood Potential Outlook” as part of their overall Wet Season climate outlook.

Through the next six months, they are forecasting accumulated rainfall totals from 887 millimeters in most areas of Tobago and areas along the west coast of Trinidad. Higher rainfall accumulations near 2076 millimeters in northeast Trinidad, in the vicinity of Sangre Grande, Vega De Oropouche, Plum Mitan, and environs, are also forecast.

Though in their headline, they state “flooding potential remains high,” for the 2023 Rainfall and Temperature Outlook for Trinidad and Tobago’s Wet Season, there are no high-risk areas in their Flood Potential Outlook compared to last year, where 21 communities were placed under high flood potential compared to normal.

The Met Office notes, “Overall, flood risk potential exists across the whole wet season. The areas of greatest risk for flooding include the Caroni, North Oropouche, and South Oropouche River basins. The local flood season is likely to expand as the season progresses.”

According to the TTMS, overall, higher risks of flooding exists across the western half of Trinidad and northeastern Trinidad. Areas not indicated in the following maps also have flood risks, according to the TTMS, but not as high as the ones singled out.

Moderate Flood Risk Potential – 55 Communities

Based on the Met Office’s analysis, the following communities have a moderately higher than normal flood potential:

In Tobago, there are no communities highlighted by the TTMS that has a moderately higher-than-normal potential for flooding.

Slight Flood Risk Potential – 71 Communities

Based on the Met Office’s analysis, the following 54 communities have a slightly higher than normal flood potential in Trinidad:

In Tobago, the TTMS has highlighted 17 communities exclusively in west Tobago that have a slightly higher than normal flood potential:

Near-Normal Flood Risk Potential – 47 Communities

Across Trinidad, 28 communities met the Met Office’s threshold for a slightly higher-than-normal flood potential, all of which fall in northern Trinidad:

In Tobago, 18 communities with slightly above-normal flood potential were indicated by the TTMS:

When can we expect to see most floods?

August is the wettest month of the year, climatologically for Trinidad. For 2023, the chances of rainfall exceeding the monthly threshold for flooding (250 millimeters of rainfall accumulation) are low to moderate, according to the TTMS.

Their outlook shows a 20% to 60% chance of rainfall accumulation reaching and exceeding 250 millimeters across Trinidad and Tobago, which is above average for most areas. These chances were between 20% and 50% for 2022, and it was exceeded by a large margin in Tobago, which experienced its wettest August on record. For 2023, the highest chances for exceeding the August average rainfall totals exist near Sangre Grande, Navet, and Rio Claro, according to the TTMS.

Meanwhile, October is the most flood-prone month with high-impact flood events. Like August this year, the chances of monthly accumulated rainfall exceeding the flood threshold are low to moderate, according to the TTMS.

There is a 4% to 60% chance for October’s rainfall to reach or exceed 250 millimeters across most areas of the country, with the higher chances to occur in pockets across northern, northeast, and central Trinidad. Northeastern Trinidad is generally the wettest area of the country.

Comparing 2023 to 2022’s Flood Potential Outlook

For 2023, the TTMS introduced the near-normal category that captured a substantial number of communities, while no communities were placed under a high risk of flooding or “much higher than normal.”

Last year, 81 communities were highlighted for their above-normal potential for flooding. This year, that total stands at 126, with 47 communities having near-normal chances.

Unlike last year, the potential for flooding has significantly expanded across the western halves of both Trinidad and Tobago.

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