Wetter, Warmer Conditions To Continue Through June 2021

In Trinidad and Tobago Meteorological Service’s rainfall and temperature outlook for April through June 2021, the Service is calling for above-normal rainfall and temperatures.

What you need to know

  • After a relatively wet March, the month of April is likely to transition to drier than usual conditions across most areas.
  • However, the remainder of the 2021 Dry Season and the beginning of the 2021 Wet Season through June 2021 is likely to be wetter than usual, with above-normal rainfall totals most likely.
  • Many sunny days with typical dry season weather are expected in April and May, including periodic Saharan Dust events.
  • The TTMS is also calling for both day and night average temperatures are very likely to be warmer than average over Trinidad and Tobago.
  • There are increased chances for hot days and short-duration hot spells when maximum day-time temperatures are likely to reach or exceed 34.0°C in Trinidad and 33.0°C in Tobago.
  • The week of April 19–25 (week 3 ahead) is very likely to be dry for both islands. The week of 26-03 April-May (week 4) is likely to be dry.
  • La Niña conditions in the tropical Pacific Ocean continue to decline and are likely to reach neutral conditions by the end of the local dry season. The Madden Julian Oscillation (MJO) will probably influence the suppression of local rainfall during the second half of April.

Likely Impacts

  • Above-normal rainfall totals during March through May may not be significantly large rainfall totals but can still reduce some of the usual drying expected during the season.
  • Wetter than average conditions suggest increased chances for heavy rainfall days, triggering street/flash flooding as well as heightened concerns for persons in flood-prone areas, particularly during May and June.
  • Hotter than average temperatures during April and May means there will be heightened concerns for persons with heat-sensitive ailments, vulnerable persons exposed to excessive heat, and heat-stress in livestock and other animals, as well as, in young and transplanted crops.

April 2021 To June 2021 Rainfall Outlook

A map showing the percentage probabilities for the most likely category of rainfall from April 2021 through June 2021. For both Trinidad and Tobago, above normal rainfall is likely with percentage probabilities showing varying shades of blue, ranging from 45% to 60%.
Category of rainfall likely for April 2021 to June 2021 (Trinidad and Tobago Meteorological Service)

From April 2021 to June 2021, most areas of Trinidad are likely to experience wetter than usual conditions.

In their outlook, the odds are tilted towards above-normal rainfall over the three months across all of Trinidad and Tobago. The TTMS notes these above-normal rainfall totals may more likely be due to May and June rainfall totals.

Across Trinidad, between 100% and 114% of the rainfall long-term average is likely, while closer to 111% is likely across Tobago.

The TTMS also notes that drying is still likely even though wetter than usual conditions are favored. Dryness will still occur as days with moderate to heavy rainfall will be sparse, at least through April. These heavy rainfall days will push rainfall totals to above average.

A map showing the percentage of average rainfall from April 2021 through June 2021. For Tobago, shaded in a deeper blue, between 111% and 125% of the average rainfall is forecast, while across Trinidad, most areas show between 100% and 114% of average rainfall is forecast, indicated in grey and varying shades of blue respectively.
Percentage of average rainfall totals likely for April 2021 to June 2021 (Trinidad and Tobago Meteorological Service)

As we progress through one of T&T’s drier months (April 2021), the TTMS is advising that the population continue water conservation programs and revisit contingency plans to take advantage of the expected increase in rainfall. Rainwater harvesting should also be encouraged to boost residential water availability.

However, as we also near the transitionary month of May and head into the 2021 Wet Season in June, above-normal rainfall totals increase the likelihood for flooding in flood-prone areas on heavy rainfall days, especially during May and June. People living in flood risk areas should start their flood planning and preparedness efforts by taking early action by cleaning drains, canals, and guttering. It is not too early to become sand-bag ready.

A map showing the risk of extremely low rainfall for Trinidad and Tobago, with all areas across Tobago and most areas across Trinidad at a low chance, <10%, shaded tan. Areas of southwestern Trinidad and along the north-central coast of Trinidad have a moderate chance, 10-30%, of extremely low rainfall according to the Trinidad and Tobago Meteorological Service.
Chance for extremely dry conditions over the three months, ending June 2021. (Trinidad and Tobago Meteorological Service)

The TTMS has given the period between April 2021 to June 2021 a low of the period being extremely dry. An extremely dry period would be where recorded rainfall totals are within the lowest 10% of all totals in the historical record.

Even though above normal rainfall is favored, there is still a very small chance for AMJ 2021 to be extremely dry (i.e., rainfall totals within the lowest 10% of all totals in the historical record for AMJ). The percent chance for this to occur is between 4% and 10%. Very low but still probable. The outlook indicates a 60-62% chance for at least one 7-day dry spells during AMJ 2021.

Possible accumulated rainfall totals with the highest chance of occurring during April 2021 through June 2021. (Trinidad and Tobago Meteorological Service)
Possible accumulated rainfall totals with the highest chance of occurring during April 2021 through June 2021. (Trinidad and Tobago Meteorological Service)

Based on their outlook, areas in the northeast and eastern half of Trinidad are likely to receive the largest accumulated rainfall totals. This is typical during the dry season.

During April 2021 through June 2021, wetter conditions in northeast Trinidad stretching from Plum Mitan to Valencia are likely to lead to the largest accumulated totals for the period, which could range between 590 mm and 720 mm in these areas. Tobago and the rest of Trinidad can experience possible accumulated totals between 340 mm and 540 mm. The least rainfall totals are expected near Port of Spain and environs in Trinidad and southwest Tobago.

Above-normal rainfall increases surface water ponding, which can promote mosquito breeding. According to the TTMS, this can lead to higher risks for spikes in vector-borne diseases. Increased rainfall, mixed with warm and humid conditions, promotes rapid multiplication of some agricultural pests, diseases, and fungal growth. Above-average rainfall in April through June 2021 raises pest infestation risks and the likelihood of an increased prevalence of crop pests and crop and animal diseases.

Possible rainfall totals with the highest chance of occurring during April 2021 (Trinidad and Tobago Meteorological Service)
Possible rainfall totals with the highest chance of occurring during April 2021 (Trinidad and Tobago Meteorological Service)

Trinidad experienced moderate to considerable rainfall totals across most areas during March, leading to much wetter than usual conditions when compared with average rainfall. Tobago was less wet with rainfall totals closer to average or just above average.

A drier than average pattern is expected to develop for most of April 2021 across both islands. Rainfall totals are likely to range between 22.0 mm and 72.0 mm in Trinidad and between 27.0 mm and 45.0 mm in Tobago, mainly from a few rainfall days early and late in the month. The chance for these totals to occur is greater than 40%, which is larger than the chance for above-average or near-average totals.

April 2021 – June 2021 Temperature Outlook

Category of maximum and maximum temperatures that is most likely to occur across Trinidad and Tobago through June 2021. (Trinidad and Tobago Meteorological Service)
Category of maximum and maximum temperatures that is most likely to occur across Trinidad and Tobago through June 2021. (Trinidad and Tobago Meteorological Service)

Following the trend of the last several years, from April 2021 to June 2021, daytime temperatures are very likely to be warmer than average for most of Trinidad and Tobago according to the TTMS’ outlook.

April to May is usually two of the warmest months of the local heat season, with April typically the warmest in some locations. April 2021 is forecast to be particularly hotter than usual. From April 2021 to June 2021, day and nighttime temperatures are very likely to be warmer than average over the country but are expected to be warmest in cities and urban areas.

The chance for warmer than average maximum day and minimum night temperatures increase to 80% for both islands. High chances continue to exist for the occurrence of hot days (days with maximum temperatures reaching or exceeding 34.0°C in Trinidad and 33.0°C in Tobago) and short duration hot spells (periods of at least 5 consecutive hot days) during late April and May.

Warmer than usual temperatures on hot and very hot days can lead to warmer than usual water temperatures, which can cause heat stress such as wilting in aquaponic crops. The TTMS urges to take action ahead of time to support crop production and livestock health to prevent agriculture production losses.

Periods of excessive heat can increase heat stress for persons with heat-sensitive ailments, amplify existing health conditions in vulnerable persons and worsen chronic health conditions in others. The TTMS also advises that higher than usual temperatures are likely to be high enough to impact heat-exposed livestock, other animals, and crops.

Further agricultural impacts are possible as hot days and spells can cause heat stress in livestock and wilting in newly transplanted and younger crops. Warmer than usual temperatures can lead to warmer than usual water temperatures, which are particularly important for aquaponic fishes and plants’ health. Water temperatures much warmer than 30.0°C can affect warm-water fishes such as tilapia.

The TTMS is advising “taking action ahead of time to support crop production and livestock health could prevent agriculture production loses.”

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