Rainfall and Temperature Outlook for Trinidad and Tobago, April to June 2019



ISSUED AT: 09:59 AM

Date: Saturday 30th of March 2019

Overall Drier Than Average Conditions Are Likely During April - June 2019   

Key messages

  • Rainfall occurrences are likely to increase during April to June 2019;
  • April is likely to be drier than usual. Weak El Niño conditions have strengthened slightly during March and increases the chance for drier than usual conditions for April.
  • April to June (2019) is likely to be drier than average overall with below normal accumulated rainfall totals likely over both islands (medium confidence);
  • There is a 60-70% chance for at least three 7-day dry spells during April to June;
  • Near-average (just as wet as usual) accumulated rainfall totals are likely for July to September 2019 (low confidence)
  • Warmer than average days and nights are likely for the three months (AMJ). Enhanced chance for hot days (maximum temperature greater than 34.0 degrees Celcius)  and short duration hot-spells during April and May;
  • Drier than usual April to June is likely due to weak El Niño conditions.
 

 

Likely Impacts

  • Drier and hotter than usual conditions normally mean the potential for high levels of surface water evaporation is enhanced.
  • Drier than average conditions tend to negatively affect ground water recharge, surface water flow and faster depletion of large reservoirs;
  • Drier and hotter than average conditions usually mean bush, forest and landfill fire potential is enhanced;
  • Reduced air quality possible during bush, forest and landfill fires;
  • Drier than average conditions enhance the chance for some agricultural pests and diseases to thrive;
  • Periods of excessive heat can increase heat stress for persons with heat-sensitive ailments, as well as for heat-exposed livestock, pets and other animals.
 

 


Rainfall and Temperature Outlook for Trinidad and Tobago, April to June 2019



ISSUED AT: 09:59 AM

Date: Saturday 30th of March 2019

Overall Drier Than Average Conditions Are Likely During April - June 2019   

Key messages

  • Rainfall occurrences are likely to increase during April to June 2019;
  • April is likely to be drier than usual. Weak El Niño conditions have strengthened slightly during March and increases the chance for drier than usual conditions for April.
  • April to June (2019) is likely to be drier than average overall with below normal accumulated rainfall totals likely over both islands (medium confidence);
  • There is a 60-70% chance for at least three 7-day dry spells during April to June;
  • Near-average (just as wet as usual) accumulated rainfall totals are likely for July to September 2019 (low confidence);
  • Warmer than average days and nights are likely for the three months (AMJ). Enhanced chance for hot days (maximum temperature greater than 34.0 degrees Celcius) and short duration hot-spells during April and May;
  • Drier than usual April to June is likely due to weak El Niño conditions.

Likely Impacts

  • Drier than usual and hotter than usual conditions normally mean the potential for high levels of surface water evaporation is enhanced;
  • Drier than average conditions tend to negatively affect ground water recharge, surface water flow and faster depletion of large reservoirs;
  • Drier and hotter than average conditions usually mean bush, forest and landfill fire potential are enhanced;
  • Reduced air quality possible during bush, forest and landfill fires;
  • Drier than average conditions enhance the chance for some agricultural pests and diseases to thrive;
  • Periods of excessive heat can increase heat stress for persons with heat-sensitive ailments, as well as for heat-exposed livestock, pets and other animals.
 

 

Figure 1: Category of rainfall likely for April to June 2019 (AMJ) with the highest chance of occurrence expressed as probabilities and colour coded on the map. Blues indicate that it is more likely for above normal rainfall to occur than for below normal or near normal. Browns indicate it is more likely for below normal rainfall, while greens indicate it is more likely for near normal rainfall. Normal is defined by the rainfall totals that were observed in middle one-third of AMJ rainfall totals during the historical period used to produce the outlook.

 

  • The April to June 2019 rainfall outlook indicates a good enough chance for drier than usual conditions across the country with rainfall totals most likely in the below normal rainfall category (medium confidence) ;
  • Below normal rainfall totals mean less than 75% of the long term average rainfall for the AMJ. At Piarco this means an AMJ accumulated rainfall total less than 327.0 mm and at Crown Point, less than 222.0 mm;
  • There is a 60-70% chance for at least three 7-day dry spells during April to June.
 

 

Figure 2: The map shows the chances for extremely dry conditions over the three months ending June 2019. Extreme refers to the lowest 10% of April to June accumulated rainfall in the historical record.

 

  • There is a 12-15% chance for AMJ 2019 accumulated rainfall totals to be in the lowest 10% of all past AMJ rainfall totals on record;
  • This means the chance for AMJ 2019 to be extremely dry is moderate (medium confidence).
 

  Figure 3: Possible accumulated rainfall totals with the highest chance of occurring during April to June 2019.

 

  • All areas in Trinidad and Tobago are likely to receive accumulated rainfall totals that are less than 500.0 mm over the three months (AMJ);
  • Rainfall totals are likely to range between 220.0 mm and 485.0 mm in Trinidad with the lowest totals likely in south-western areas. Tobago totals are likely to range between 205.0 mm and 360.0 mm.
 

 

              

Figure 4: Possible rainfall totals with the highest chance of occurring during April 2019.

 

  • April 2019 rainfall totals are likely to be slightly below average with greater than 40% chance for this to occur (medium confidence);
  • Possible rainfall totals range between 20.0 mm and 78.0 mm.
 

Figure 5:  Category of rainfall likely for July to September (JAS) 2019 with the highest chance of occurrence expressed as probabilities and colour coded on the map. Blues indicate that it is more likely for above normal rainfall to occur than for below normal or near normal. Browns indicate it is more likely for below normal rainfall, while greens indicate it is more likely for near normal rainfall. Normal is defined by the rainfall totals that were observed in middle one-third of JAS rainfall totals during the historical period used to produce the outlook.

 

  • The early outlook for July to September 2019 shows the most likely chance is for near average accumulated rainfall totals;
  • This means JAS 2019 is likely to be as wet as usual, while the chance for much wetter or much drier than average is less likely.
 

Temperature Outlook:

  • The months of April and May are usually two of the hottest months and are part of the heat seasons in Trinidad and Tobago;

 

  • April to June average daytime temperatures are very likely to be warmer than average for all of Trinidad and Tobago;

 

  • The chance for warmer than usual maximum daytime temperatures and warmer than usual minimum night temperatures during April and May is greater than 80% for Trinidad and greater than 70% for Tobago;

 

  • There are increased chances for the occurrence of hot days (days with maximum temperatures reaching or exceeding 34.0oC in Trinidad and 32.0oC in Tobago) and short duration hot spells (periods of consecutive hot days).

Likely Implications

  • The potential for high levels of surface water evaporation is enhanced;
  • Ground water recharge rates, surface water flows and rain-fed water availability are likely to be negatively impacted;
  • Drier than average conditions can increase the need to collect and store water in containers which can increase breeding areas for mosquitoes;
  • Drier and hotter conditions will increase the chance for bush, landfill and forest fires;
  • Bush, landfill and forest fires are likely to reduce air quality;
  • Periods of excessive heat can increase heat-stressfor persons with heat- sensitive ailments and for heat-exposed livestock and other animals;
  • Increased heat may increase the need to access cooling, which requires energy;
  • Drier than average conditions can lead to late development of some agricultural crops;
  • Drier than average conditions and warmer than average temperatures tend to favour better quality in some fruits;
  • Drier than average conditions may favour some outdoor activities such as those in the Tourism industry.
 

Sectorial Early Action That Can Be Taken To Reduce Possible Disaster Effects!                

Water and Energy sector

  • Escalate water conservation and energy efficiency awareness messages;
  • Revisit contingency plans for efficient production and flood management for the upcoming wet season.

Disaster Risk Management Sector

  • Sensitize communities and citizens on the forecast, its negative impacts and early actions to be taken early;
  • Consider who may be most affected by therainfall forecast and alert accordingly;
  • Review your contingency plans and early warning information dissemination channels.

Drainage

  • Use drier conditions to conduct routine de-silting, cleaning and upgrading of drainage systems, water channels and river mouths in preparation for the rainy season.

Waste Management Sector

  • Ramp-up contingency plans to mitigate landfill fire occurrence;

Health Sector

  • Clear bushes, open drainage systems, fumigate in and around residences;
  • Revisit contingency plans to manage spikes in respiratory, heat-related and vector-borne ailments.

Agriculture & Food Security Sector

  • Raise awareness on the risk of increase in bushfires;
  • Initiate contingency planning for drier than usual conditions.

General Public

  • Continue preparation especially for persons at risk. Stock up on water and emergency supplies for 3-7 days;
  • Conserve, store and manage water in a safe and adequate manner;
  • Take measures to lessen impacts from drier than usual conditions. Be dry season ready;
  • Be vigilant and visit the Met. Service website at www.metoffice.gov.tt regularly to keep up to date with local weather changes and follow us on social media.
 

  Climatic Influencers and Context of the Outlook

  • Waters in, and around Trinidad and Tobago currently show sea surface temperatures(SSTs ) that range fromnear averagetocooler than average but SSTs are forecasted to warm and become near average to slightly warmer than average by the end of June;
  • SSTs in the equatorial Pacific Ocean increased within the weak El Niño category during February and early March and further strengthened slightly from mid-March to present, while subsurface waters became more strongly warmer than average. Patterns in the atmosphere now show evidence of El Niño conditions present.
  • Assessment of environmental conditions, collective model forecasts and guidance suggest weak El Niño are likely to continue through the rest of the local dry season and the start of the 2019 wet season. However, these are viewed with some caution since these model-based outlooks have less skill for forecast period.
  • Weak El Niño conditions during the late half of the local dry season tend to tilt the odds in favour of rainfall suppression in Trinidad and Tobago;
  • The closest historical years with similar in appearance to the evolving El Nino SST anomalies are 1987 and 2015. During these years, AMJ rainfall totals at both Piarco and Crown Point were below average.
  • The North Atlantic Oscillation (NAO) continued in its positive phase during February and March and is expected to remain in its positive phase during most of April. A positive NAO tends to aid in cooling SSTs in waters around Trinidad and Tobago. This can negatively affect rainfall potential.
  • The Madden Julian Oscillation (MJO), a key influencer of rainfall at the sub-seasonal scale enhanced rainfall over the southern Caribbean during mid-March. It is expected to be weak to none-existent in the region during April 2019, as models suggest that it will not be active near Trinidad and Tobago’s region during the next four to six weeks.