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



ISSUED AT: 12:33 PM

Date: Saturday 20th of August 2022

Dryness Indicator for April to June 2022 & 3-month Dryness Outlook for July to September 2022

Key Message

Trinidad and Tobago received beneficial rainfall during April and May, with high rainfall amounts in June. Piarco, Trinidad monthly totals for April-May-June range from about 61.1mm, 68.1mm and 415.8mm respectively, while Crown Point, Tobago monthly totals April-May-June range from about 27.4mm, 71.1mm and 230.3mm respectively. There is no concern for dryness at this time. The outlook for the next three months, July-August-September 2022 shows all areas are likely to be free from dryness in the short-term.

Dryness Indicator for April to June 2022

During April, normal rainfall...


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



ISSUED AT: 12:33 PM

Date: Saturday 20th of August 2022

Dryness Indicator for April to June 2022 & 3-month Dryness Outlook for July to September 2022

Key Message

Trinidad and Tobago received beneficial rainfall during April and May, with high rainfall amounts in June. Piarco, Trinidad monthly totals for April-May-June range from about 61.1mm, 68.1mm and 415.8mm respectively, while Crown Point, Tobago monthly totals April-May-June range from about 27.4mm, 71.1mm and 230.3mm respectively. There is no concern for dryness at this time. The outlook for the next three months, July-August-September 2022 shows all areas are likely to be free from dryness in the short-term.

Dryness Indicator for April to June 2022

During April, normal rainfall occurred, with five relatively wet days (>1.0 mm) and two wet days (>10.0 mm) occurred with monthly totals ranging from 27.4 mm to 94.8 mm or more in other parts of the country. A drier period than normal ensued in May, where only three wet days (>10.0 mm) and five relatively wet days (>1.0 mm) happened, while relatively dry days occurred with rainfall amounts less than 1.0 mm. May’s monthly totals ranged from 59.5 mm to 132.1 mm. The month of June experienced above-normal rainfall amounts, five relatively wet days (>1.0 mm), six wet days (>10.0 mm) and one excessively wet day (>50.0 mm), with monthly totals ranging between 230.3 mm and 489.0 mm across the country. The 3-month dryness indicator for April to June shows dryness indicator values that ranged from +0.2 to +1.2, which is within the no concern for impactful dryness category (see Figure 1).

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

Figure 1. 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 April to June 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 July to September 2022:

The accumulated rainfall received nationwide, since 2022 began, together with the predicted volume of rainfall July-August-September 2022 has definitely removed the chances of dryness witnessed up to the end of May. Frequent rainfall events and wet conditions are expected to continue into August and September. The Dryness Outlook shows dryness indicator values between -0.08 and +0.15 are likely to develop across the vast majority of Trinidad and Tobago by September 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 July to September 2022.  It is based on the difference between standardized accumulated rainfall (observed and predicted) from July to September 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 are 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.