Trinidad and Tobago Dryness/Drought Indicator, Monitor and Outlook By End of April 2022



ISSUED AT: 02:10 PM

Date: Tuesday 19th of April 2022

Key Message

Much of Trinidad and Tobago received beneficial rainfall during March with monthly totals ranging from about 40.0 mm to 180.0 or more in parts of the country. This maintained 3-month dryness levels across the country. The outlook for the next three months, April-May-June 2022 shows the vast majority of the country is likely to become borderline dry to slightly dry, but abnormal dryness is unlikely to develop.

Dryness Indicator f...


Trinidad and Tobago Dry/Wet Spell Monitor and Outlook by End of April 2022



ISSUED AT: 02:10 PM

Date: Tuesday 19th of April 2022

Key Message

Much of Trinidad and Tobago received beneficial rainfall during March with monthly totals ranging from about 40.0 mm to 180.0 or more in parts of the country. This maintained 3-month dryness levels across the country. The outlook for the next three months, April-May-June 2022 shows the vast majority of the country is likely to become borderline dry to slightly dry, but abnormal dryness is unlikely to develop.

Dryness Indicator for January to March 2022

During March, light to moderate rainfall was common with much of the country receiving beneficial rainfall as monthly totals ranged from 40.0 mm to 180.0 or more in parts of the country. Moderate rainfall totals ranging from 5.0 mm to 19.0 mm on five (5) to eight (8) days of the month contributed mostly to the easing of dryness, leaving 3-month dryness levels mostly unchanged, compared to the previous month. The 3-month dryness indicator for January to March shows dryness indicator values that ranged from +0.7 to -0.5, which is within the no concern for impactful dryness to slightly dry categories (see Figure 1).

The colour-coded dryness indicator map showing observed level of dryness is based solely on rainfall and can be used for decision making or for heightening awareness on dryness.

Figure 1.0 The colours on this map show observed dryness levels based on the rainfall differences from average, which have been standardized and expressed as the number of standard deviations less than average. The period used to compute the dryness is  the  3-month period January to March 2022 compared to the historical average for the same 3-month period. The yellow to red colours on the map are used to indicate areas with borderline-dry to extremely-dry levels of dryness. The grey colour indicates areas where there is no significant dryness concerns.

Dryness Outlook for April to June 2022:

The accumulated rainfall received nationwide, since 2022 began, together with the predicted volume of rainfall for April-May-June 2022 are unlikely to sustain the erosion of dryness witnessed up to the end of March. Borderline to slightly dry conditions are expected to develop and short-term dryness is likely to become entrenched at least, by the end of May. The Dryness Outlook shows dryness indicator values between -0.5 and -0.75 are likely to develop across the vast majority of Trinidad and Tobago by June month end (see Figure 2). The outlook is based solely on rainfall and should be used only as a guidance tool.

Figure 2. The colours on this map show the predicted levels of dryness for the period April  to June 2022.  It is based on the difference between standardized accumulated rainfall (observed and predicted) from January  to June 2022  and the historical average rainfall for the same period. The yellow to red colours indicate borderline dry to extremely dry levels of dryness. The grey colour indicates areas where there is no significant dryness concerns.

Standardized Precipitation Index   

The Standardized Precipitation Index (SPI) is an index showing the severity and rarity of dryness or wetness of an area. Negative values of SPI indicate less than median rainfall and drier conditions; positive values indicate greater than median rainfall and wetter conditions. In general, dryness impacts are expected when the value of the 3-month SPI lies near -1.0. As the negative SPI value becomes larger in amount than -1.0, the severity of impacts increases. For Trinidad and Tobago, extreme dryness occurs in the dry season when negative SPIs are larger than -1.25.