The Trinidad and Tobago Meteorological Service (TTMS) is forecasting below-average rainfall totals across much of the country for April and May in their updated outlook, issued on March 29th, 2023. By June, according to the TTMS, there is a moderate chance for near-normal rainfall.
Rainfall Outlook for April 2023
For April 2023, the Met Office is forecasting anywhere from 32 to 140 millimeters of rainfall accumulation across Trinidad, trending higher across northeastern Trinidad, while the forecast range is between 26 and 160 millimeters across Tobago, trending higher across the eastern half of the island.
According to the Met Office, while a strong negative phase of the North Atlantic Oscillation (NAO) is forecast to transition to a weak negative phase that will have a small positive impact on rainfall, a strong negative Madden Julian Oscillation (MJO) and ENSO neutral conditions, transitioning into an El Niño, will negatively influence rainfall across T&T.
2nd Half of 2023 Dry Season Rainfall Outlook
The TTMS is forecasting a moderate chance for below-average rainfall across parts of Trinidad and Tobago from April through June 2023. According to their climate outlook, there is also a moderate chance for a lower-than-normal number of extremely wet (24-hour rainfall totals exceeding 25 millimeters) during the same period. The Met Office is explicitly forecasting between four and seven extremely wet days for Trinidad and three to five extremely wet days for Tobago between April and June 2023.
Over the next three months, the Met Office is forecasting the highest rainfall accumulations to occur across northeastern Trinidad and parts of south-central Tobago. Explicitly, the TTMS says rainfall between April and June 2023 can reach as high as 706 millimeters in areas such as North Oropouche, Valencia, Sangre Grande, and Plum Mitan in Northeast and east Trinidad while rainfall accumulations may near 483 millimeters in Goodwood, Mt. Saint George, and environs in southeast Tobago.
June is generally the first month of the annual Wet Season in Trinidad and Tobago. Early-season tropical waves commonly affect the country every five to seven days. Rainfall may occasionally be influenced by the Intertropical Convergence Zone or an early-season Atlantic tropical cyclone.
Drought Concerns?
In the latest dryness and drought indicator, issued by the TTMS on February 10th, 2023, there is a concern for short-term dryness developing by the end of this month. Piarco recorded its 4th driest March on record since 1981 last month, with only 6.8 millimeters of rainfall recorded. Meanwhile, Tobago fared marginally better, with the 11th driest March on record with 17.7 millimeters recorded at Crown Point.
Climate Context
April is the third driest month of the year for Trinidad, and the second driest month for Tobago, with an average (1991-2020) monthly rainfall of 51.6 millimeters at Piarco, Trinidad, and 47.9 millimeters at Crown Point, Tobago.
The driest April recorded 1.6 millimeters at Piarco (1946-2021) and 3.9 millimeters at Crown Point (1969-2021). The wettest April in the same period recorded 376 millimeters at Piarco in 1981 and 194.4 millimeters at Crown Point in 2013.
