Mostly Near Normal Rainfall for September to November: Flooding Potential remains Moderate
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Figure 1: Category of rainfall likely for SON (September to November) 2023 with the highest chance of occurrence expressed as probabilities represented on the map. Blue areas indicate places with an increased chance for above-normal rainfall, brown areas show an increased chance for below-normal rainfall, while green areas show an increased chance for near-normal rainfall. Normal is defined by the rainfall that was observed in the middle one-third of the SON period rainfall totals during the historical period used to produce the outlook.
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- A moderate probability exists for near-normal rainfall totals over most parts of Trinidad and Tobago during SON;
- Chances are moderate (65%) for a lower-than-usual number of extremely wet days (> 25.0 mm) for SON; i.e. expect between 2 – 5 extremely wet days in Trinidad and 2-5 in Tobago during the period.
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Figure 2: Risk of the SON 2023 being extremely drier than normal (within the lowest 10% on record).
- The risk of extremely drier than normal conditions is moderate (14-50%) over Trinidad;
- The risk of extremely drier than normal conditions is moderate (13-44%) over Tobago;
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Figure 3: Outlook of possible rainfall accumulated totals for September to November, with the highest chance of occurring.
- The largest rainfall accumulated totals for SON are likely to be as high as 905 mm in areas such as North Oropouche, Valencia, Sangre Grande and Plum Mitan in Northeast and east Trinidad; and near 639 mm in Goodwood, Mt. Saint George and environs in southeast Tobago.
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Figure 4: Possible rainfall totals for September 2023.
- September has a moderate (65%) chance for near-normal to below-normal rainfall across most of Trinidad and Tobago;
- September’s rainfall with the highest chance of occurring ranges from about 84-251 mm in Trinidad and 126-179 mm in Tobago.

Figure 5: Percentage of Average Rainfall Totals for September to November 2023.
- September to November (SON) rainfall totals are likely to be near-normal over most of Trinidad and a small part of Tobago;
- Few small drier than usual pockets are likely to occur over central and northern Trinidad and most of Tobago;
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Figure 6: Category of rainfall likely for December to February (DJF) 2023/4 with the highest chance of occurrence expressed as probabilities represented on the map. Blue areas indicate places with an increased chance for above-normal rainfall, brown areas show an increased chance for below-normal rainfall, while green areas show an increased chance for near-normal rainfall. Normal is defined by the rainfall that was observed in the middle one-third of the DJF seasons during the historical period used to produce the outlook.
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- Mostly near-normal rainfall totals are expected during the period December to February 2024 over most of Trinidad and Tobago.
- Pockets of below-normal rainfall totals are likely in the southwest peninsula of Trinidad and northeast eastern parts of Tobago.

Figure 7: The map shows the colour-coded category (below-normal, above-normal, and near-normal) of maximum and maximum temperatures that are most likely to occur across Trinidad and Tobago for the September to November (SON) period 2023. The colour-coded bar-graph with the numbers to the right gives the likelihood for each forecast category to occur.
The Temperature Outlook Favours Above Normal Temperatures for September to November 2023.
- Both daytime and night temperatures are likely to be warmer than average over both islands;
- There is a high (80%) chance of warmer-than-average days in urban and built-up areas in Trinidad and Tobago;
- Chances of warmer than average nights are highest in Trinidad where there is 68% chance, while Tobago has a 64% chance;
- A moderate chance (65%) exists for short-duration hot spells during SON with maximum temperatures greater than and equal to 34.0oC in Trinidad, greater than and equal to 33.0oC in Tobago;
Climatic Influencers and Context of the Outlook
- Currently, sea surface temperatures (SSTs) in waters surrounding Trinidad and Tobago and further east of the islands are above average. Most climate models surveyed favour above-average conditions to persist throughout the period September to November;
- El Niño conditions will continue to develop during SON 2023 and strengthen to moderate El Niño conditions by the end of the year. El Niño conditions generally have been associated with the reduction of local cloudiness and local rainfall, but not always;
- The North Atlantic Oscillation (NAO) was observed in a moderate negative phase throughout August and is forecast to continue into September. The overall influence should be a negative impact on local wind speeds. This will enhance surface heating during the rest of the heat season (September and October);
- Observations of the Madden Julian Oscillation (MJO) signal have shown that the (MJO) is not existent over Trinidad and Tobago in August and the beginning of September, and is not likely to reside over the region for the next two-week period. This will have a negative influence on the first half of September’s rainfall.
How Should You Respond? Take Early Action!
Health Sector:
- Clear bushes, open drainage systems, fumigate in and around residences;
- Revisit contingency plans to manage spike in vector borne incidences and rainfall related infections.
Disaster Risk Management Sector:
- Sensitize communities on the forecast and its negative impacts;
- Revisit early warning information dissemination channels;
- Alert communities in low-lying areas (flood-prone) to act early;
- Alert at-risk residents and communities that are still prone to landslide and slip.
Agriculture & Food Security Sector
- Practice soil moisture conservation like mulching and trenches;
- Clear vegetation from crop beds and drains to ease waterlogged soils.
- Put in place disease control measures.
Water, Drainage and Energy sector
- Implement water harvesting, storage and proper usage;
- Conduct routine de-silting of water channels, canals and reservoirs;
- Remove dry branches, trees and overhangs near electrical wires.
General Public
- Proper preparation especially for persons in at-risk areas;
- Clean drains and surrounding areas of debris, be sand-bag ready;
- Conserve, store and manage water in a safe and adequate manner;
- Be watchful for extreme rainfall events especially on extremely hot days;
- Take measures to lessen the potential impacts of the expected decreased rainfall and warmer-than-average temperatures.
Be vigilant and visit the Met Service website regularly to keep up to date on local weather changes daily at www.metoffice.gov.tt or download our mobile app on Google Play Store or Apple iStore.
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