La Niña To Bring Rainfall To T&T
La Niña is ongoing across the Eastern Pacific Ocean, and is only forecast to intensify over the next three months. La Niña is the cool phase of the El Niño-Southern Oscillation and has historically brought wet conditions to T&T. The last La Niña event occurred during 2017 into 2018, where several significant flood events were recorded.
The ongoing La Niña event is forecast to peak between December through February, with La Niña conditions continuing at least through April 2021.
Wet Conditions Forecast Through 2021 Dry Season
According to the Trinidad and Tobago Meteorological Service, there are “moderate enhanced chances” for wetter than usual conditions from January through May 2021, with above normal rainfall totals likely.
In a typical dry season, the country receives an average of 412 mm of rainfall, with 434 mm recorded in Trinidad and 334 mm recorded in Tobago, based on 1981-2010 averages. For the 2021 Dry Season, rainfall totals between 435-920 mm are likely, with higher rainfall totals expected across the eastern half of Trinidad.
During the first half of the dry season, there are strong probabilities for a wetter than usual January through March with above-normal rainfall totals likely. Similar conditions are expected during the second half of the 2021 Dry Season, with “moderately enhanced chances” for wetter than usual March through May.
Even with the anticipated wetter than average dry season, sunny spells and days with little to no rainfall are still expected. An average dry season records 109 dry days (days with less than 1.0 millimeters of rainfall), but the 2021 Dry Season is expected to have 90. While March is usually the dry season’s driest month, the TTMS forecasts April 2021 to be the driest month for the season.
Warmer Than Average Temperatures Also Expected
In keeping with the trends of 2020, the 2021 Dry Season is forecast to be warmer than average for both day and night temperatures. During April and May, temperatures may peak near 34°C, leading to excessive heat events and one or two short-duration hot spells.
What Does This Mean For T&T?
Above average dry season rainfall may not always lead to large amounts of rainfall on the monthly scale. Hence, the public is still advised to continue water conservation practices, store and manage water safely, and use water-smart farming practices for the dry season.
Enhanced rainfall may provide adequate water for the farming community but may also elevate the flooding risk for flood prone areas, including farmland. Stagnant water may enhance opportunities for mosquito breeding and the risk of mosquito-bourne diseases.
Elevated daytime and nighttime temperatures during the second half of the dry season may negatively impact heat-vulnerable individuals and animals, as well as increase water evaporation rates. Wet and warm conditions may allow agricultural pests, diseases, and fungi to thrive.
Climatologically, Saharan Dust events may also increase by late February into May, reducing air quality.