Rainfall and Temperature Outlook for Trinidad and Tobago, June to December 2022



ISSUED AT: 11:20 PM

Date: Monday 23rd of May 2022

Key Messages

  • A slow onset to the 2022 wet season is likely with June expected to receive less rainfall than usual (below-normal).
  • The first half of the 2022 wet season, June-July-August is likely to be as wet as usual, while the rest of the season is likely to be wetter than usual with above-normal rainfall expected. Potential for flooding is elevated.
  • Overall, the 2022 wet season is likely to be volatile and erratic with wetter than usual (above -normal) conditions predicted.
  • Above-normal number of heavy and extremely heavy rainfall days, 3-day and 5-day wet spells are likely.
  • Flood potential is much higher than normal for known and emerging flood prone areas. Citizens are urged to accelerate preparations.
  • Both day and night temperatures are expected to be much warmer than average.
  • A few hot days (maximum temperatures ≥34.0oC) and one or two short duration hot spells (5 or more consecutive hot days) and heat surges (3 consecutive hot days) are likely. Cities and urban areas are likely to get the most intense heat.
  • The Madden Julian Oscillation (MJO) is likely to enhance local rainfall during the 2nd and 3rd weeks of June.
 

Likely Impact

 

An outlook with increased chances for drier than usual conditions can still have:

  • Heavy rainfall days that are high risk enough to cause severe flooding.
  • Heightened concerns for persons in flood prone areas remain, especially for June and July.

Hotter than average maximum day and night temperatures during May suggests:

  • Heightened concerns for persons with heat-sensitive ailments, vulnerable persons exposed to excessive heat, and heat-stress in livestock and other animals, as well as, in young and transplanted crops.
 


Rainfall and Temperature Outlook for Trinidad and Tobago, June to December 2022



ISSUED AT: 11:20 PM

Date: Monday 23rd of May 2022

2022 Wet Season Likely to be Volatile and Erratic with Wetter Than Usual Conditions Favoured  

Much Higher Than Normal Flood Potential

 
 
Key Messages
  • A slow onset to the 2022 wet season is likely with June expected to receive less rainfall than usual (below-normal).
  • The first half of the 2022 wet season, June-July-August is likely to be as wet as usual, while the rest of the season is likely to be wetter than usual with above-normal rainfall expected. Potential for flooding is elevated.
  • Overall, the 2022 wet season is likely to be volatile and erratic with wetter than usual (above -normal) conditions predicted.
  • Above-normal number of heavy and extremely heavy rainfall days, 3-day and 5-day wet spells are likely.
  • Flood potential is much higher than normal for known and emerging flood prone areas. Citizens are urged to accelerate preparations.
  • Both day and night temperatures are expected to be much warmer than average.
  • A few hot days (maximum temperatures ≥34.0oC) and one or two short duration hot spells (5 or more consecutive hot days) and heat surges (3 consecutive hot days) are likely. Cities and urban areas are likely to get the most intense heat.
  • The Madden Julian Oscillation (MJO) is likely to enhance local rainfall during the 2nd and 3rd weeks of June.
Likely Impact

An outlook with increased chances for wetter than usual conditions suggest:

  • Elevated risks of heavy rainfall days and prolonged wet periods.
  • Heightened concerns exist for persons in occasionally flooded and flood prone areas.

Hotter than average maximum day and night temperatures during May suggests:

  • Heightened concerns for persons with heat-sensitive ailments, vulnerable persons exposed to excessive heat, and heat-stress in livestock and other animals, as well as, in young and transplanted crops.

 

Early  Actions & Preparedness

  • Strengthen community coordination with disaster management personnel;
  • Persons living in flood risk areas should quicken their flood planning and preparedness efforts;
  • Purchase emergency supplies and pack a grab and go-bag with clothes and essentials and have these on standby;
  • Get acquainted with your flood prone areas, shelter locations and become sand-bag ready;
  • Develop an evacuation plan that outlines the safety of family members and pets;

Update contact information for the local disaster officials and other emergency services.

 

Figure 1: Category of rainfall likely for June 2022 with the highest chance of occurrence expressed as probabilities and is 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 that was observed in middle one-third of the June period rainfall totals during the historical period used to produce the outlook.

  • The outlook favours a drier than usual start to the 2022 wet season, with below-average rainfall totals having the best chance of occurring in June.
  • The outlook suggests a 40 to 50% chance for below-normal rainfall in June across Trinidad and Tobago. 

 

Figure 2: Category of rainfall likely for June to August 2022 (JJA) with the highest chance of occurrence expressed as probabilities and is 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 that was observed in middle one-third of the JJA period rainfall totals during the historical period used to produce the outlook.

  • The first half of the 2022 wet season, June-July-August is likely to be as wet as usual, with near normal rainfall totals more likely than drier than usual or wetter than usual.
  • There is a greater than 45% chance for near-normal rainfall totals to occur.
  • Concerns remain for flash flooding during heavy and prolonged rainfall events.

        

Figure 3: The map shows the chances for extremely dry conditions over the May-June-July 2022 Season. Extremely dry conditions refer to the lowest 10% of MJJ Season total rainfall amounts in the historical record.

  • The three (3) months July to September are likely to get near normal rainfall totals with the chance greater than 40% across all areas.
  • The country is likely to see a shift in the rainfall pattern, with August to October favoured to be wetter than usual, with greater than 50% chance for above normal rainfall totals.
 
 

Figure 4:  Category of rainfall likely for September to November 2022 (SON) with the highest chance of occurrence expressed as probabilities and is 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 that was observed in middle one-third of the SON period rainfall totals during the historical period used to produce the outlook.

  • The outlook maintains a likely upsurge in rainfall during September to November (SON) and favours wetter than usual conditions with much higher chances for above normal rainfall totals during SON.
  • August, October and November are likely to be the wettest months as the season progresses.

Figure 5. Category of rainfall most likely for the Wet Season 2022 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 that was observed in middle one-third of the Wet Season rainfall totals during the historical period used to produce the outlook.

  • Overall, the 2022 wet season is likely to be slightly wetter than usual with accumulated rainfall totals likely to be in the above-normal  category.
  • Probabilities are greater than 40% for above normal accumulated rainfall totals across the entire Republic of Trinidad and Tobago for the 2022 wet season.
  • There is 58% chance for above normal number of heavy rainfall days (days with rainfall equal to or exceeding 25 mm). The country is likely to get 16-20 heavy rainfall days during the season.
  • A 37% chance exists for above-normal, extremely heavy rainfall days. These are days with rainfall reaching or exceeding 50.0 mm.
  • The country is likely to get 4 to 10 extremely heavy rainfall days, with at least two likely to produce in excess of 3 inches or 75 mm of rainfall.

 

Figure 6: Possible accumulated rainfall totals with the highest chance of occurring during the 2022 wet season.

  • Possible rainfall volumes for the 2022 wet season are likely to range from 1300 mm in most areas of Tobago and areas along the west coast of Trinidad, with higher volumes that are closer to 3000 mm in northeast Trinidad, in the vicinity of Sangre Grande, Vega De Oropouche, Plum Mitan and environs.
  • The wet season usually produces 102 to 106 wet days (days with rainfall > 1.0mm).
  • The 2022 wet season is likely to get a slight increase in the number of wet days, with 110 to 122 wet days  most likely.
  • The outlook favours at least four, 5-day wet spells, with  5-day totals exceeding 80 mm of rainfall.  At least two of the 5-day wet spells are likely to exceed 100 mm.
  • There is also a high chance for at least six, 3-day wet spells, with 3-day totals exceeding 50 mm and at least three of these wet spells are likely to produce above 80 mm of rainfall.

Figure 7: Chance of exceeding 250 mm of rainfall during August 2022.

  • The chance of exceeding 250 mm of rainfall during August, the wettest month of the year, is relatively high.
  • The outlook shows there is a 20 to 50% chance of reaching and exceeding 250 mm during August 2022, which is more than the average for the month in most areas.
  • The outlook shows that Sangre Grande and environs have the highest chance for rainfall to exceed 250 mm in August.

Figure 8: Chance of exceeding 250 mm of rainfall during October 2022.

  • The chance of exceeding 250 mm of rainfall during October (the known flood-prone and high-impact flood month), is relatively high.
  • The outlook shows there is a 15% to 40% chance for October’s rainfall to reach or exceed 250 mm, across most areas, with the higher chances occurring in northeast Trinidad, which is usually the wettest part of the country.
  • These results have implications for flooding across the country.

 

Figure 9: The 2022 wet season flood risk potential outlook with categories of flood potential colour coded on the map. Blue indicates much higher than normal flood potential. Brown indicates it is more likely for moderately higher normal flood potentiaal. Yellow indicates slightly higher than normal flood potential. Green indicates near normal flood potential.

Seasonal Flood Potential Outlook:

  • Overall, enhanced flood risk potential exists across the whole wet season. The areas of greatest risk for flooding include the Caroni, North Oropouche and South Oropouche river basins. The local flood season is likely to expand and worsen, as the season progresses. 
  • There is much elevated flood potential, with much higher than normal flood potential in northeast Trinidad, near Valencia, Sangre Grande, including Vega de Oropouche, Fishing Pond, Sangre Chiquito and environs. Similar elevated potentials exist in the South Oropouche River Basin, Penal, Debe, Princes Town and parts of Couva.
  • Flood potential is moderately higher than normal for St Helena and environs, Plum Mitan and environs, parts of Mayaro, the city of Port of Spain, Maraval and lower Diego Martin.
  • Tobago has slightly higher than usual flood potential in the western half of the island.
  • Areas which are not colour-coded also have flood risks, but not as high as those colour-coded.

Saharan Dust Haze Season Outlook:

The 2022 Saharan Dust Haze Season is likely to peak during JJA with the number of Saharan dust haze days expected to increase significantly in frequency. The duration of plumes of Saharan dust haze visiting both islands are also likely to be more prolonged than earlier in the year, with increased odds for higher dust haze concentration during plumes visitation.

Temperature Outlook:

  • The 2022 wet season temperature outlook favours warmer than average temperatures.  There is a greater than 45% chance for maximum day temperatures and minimum night temperatures to be above normal.
  • The month of August is favoured to get slightly cooler than usual temperatures with the odds tilted towards near normal temperatures.
  • The excessive heat season usually peaks in during August to October. There are elevated chances for maximum temperatures to reach or exceed 34.0oC during the season.
  • Chances are also elevated for 5-day short-duration hot spells and 3-day heat surges (maximum temperatures ≥34.0oC) to develop during September, and early October.
  • Cities and urban areas have the highest chance for warmer than average temperatures and are likely to get the most intense heat, with temperatures likely to reach or exceed 35.0oC.

Figure 10: The map shows the colour-coded category (below-normal, above-normal, and near-normal) of maximum and maximum temperatures that is most likely to occur across Trinidad and Tobago for the Wet Season 2022.  The colour-coded bar-graph with the numbers to the right gives the likelihood for each forecast category to occur.

Likely Implications

  • Drier than usual conditions in June can still have sufficient heavy rainfall days that are high risk enough to cause flooding. Flash flood risk remains elevated in occasional and well-known flood prone areas;
  • An enhanced likelihood for near-normal and above-normal rainfall during the 2022 wet season suggests increased chances for flooding and increased flood-risks in flood-prone areas;
  • Localized moderate to heavy rainfall days and prolonged wet spells could trigger flash-flooding in high-risk/flood-prone areas and within watersheds with narrow valleys and steep hill-sides;
  • Expect an increase in recharge rates, surface water flows and river levels;
  • Possible increased turbidity and degraded water quality on heavy rainfall days;
  • More reliable rains for agriculture but the excess rainfall can lead to water logging of agricultural fields.
  • Increased rainfall, mixed with warm and humid conditions tend to promote rapid multiplication of some agricultural pests, diseases and fungal growth;
  • Increased rainfall could lead to reduced traffic flows, disruptions in localized travel, and longer travelling times, which may require earlier commute start-times;
  • An increase in surface water ponding can promote mosquito breeding, which can lead to higher risks for spikes in vector-borne diseases;
  • Higher than usual and extreme temperatures can lead to relatively excessive heat for Trinidad and Tobago during the peak of the local heat season, which can amplify existing health conditions in vulnerable persons and worsen chronic health conditions in others;
  • Increased heat may increase the need to access cooling, which requires energy;
  • Hot days and spells can cause heat stress in livestock and wilting in newly transplanted and younger crops;
  • Warmer than usual temperatures can lead to warmer than usual water-temperatures, which are particularly important for the health of aquaponic fishes  and plants;
  • Water temperatures much warmer than 30.0oC can affect warm-water fishes such as tilapia.
 

Sectorial Early Actions  and Preparedness That Can Be Taken To Reduce Possible Impacts

General Public

  • Strengthen community coordination with disaster management personnel;
  • Persons living in flood risk areas should quicken their flood planning and preparedness efforts;
  • Purchase emergency supplies and pack a grab and go-bag with clothes and essentials and have these on standby;
  • Get acquainted with your flood prone areas, shelter locations and become sand-bag ready;
  • Develop an evacuation plan that outlines the safety of family members and pets;
  • Update contact information for the local disaster officials and other emergency services.

Disaster Risk Management Sector

  • Put  in place the necessary measures to ensure communities are sensitized;
  • Start preparedness for the expected increase in rainfall and the associated negative impacts;
  • Review contingency plans and early warning information dissemination channels;
  • Revisit and review emergency plans and communication  strategies;
  • Refresh media training and distribute appropriate advice on the outlook through the media.

Water and Energy Sector

  • Update flood action plans and continue water conservation awareness messaging
  • Revisit contingency plans and ramp-up de-silting of major rivers and reservoirs;
  • Remove dry branches and tree-overhang near electrical wires, especially in landslip prone areas.

Drainage & Infrastructure

  • Ramp-up de-silting and cleaning of drainage systems, water channels, outlets and river mouths;
  • Pay attention to areas of rock fall which may be indicative of potential future landslides.

Agriculture & Food Security Sector

  • Raise awareness on agriculture pest and disease control measures. Revisit flood action plans.

Waste Management Sector

  • Review contingency plans and operational practices (such as diverting rainfall water-flows away from waste heaps) used for preventing leachate and contamination of ground/surface water.

Health Sector

  • Revisit contingency plans to manage spikes in vector-borne and excessive heat ailments;
  • Review fumigation plan and programme.

Be vigilant and visit the Met. Service website at www.metoffice.gov.tt regularly and follow us on social media to keep up to date. Download our mobile app on Google Play Store or Apple iStore.

Climatic Influencers and Context of the Outlook

  • Currently, sea surface temperatures (SSTs) in waters surrounding Trinidad and Tobago including waters to the east of the eastern Caribbean all the way to the West Coast of Northern Africa are mostly near average with pockets of warmer than average temperatures. There is however, a noticeable cooler than average cold tongue near the West Coast of Africa, where there is ongoing upwelling of cooler water.
  • This may come into play with the strength of the tropical waves and fluctuation of the ITCZ northward, or not.
  • A key factor, with this influencer is that a much warmer than average Area of Interest favours an expansion of the rainy season at both ends, the onset and cessation of the season.
  • La Niña conditions exist in the central-eastern equatorial Pacific Ocean. Over the last four (4) weeks sea surface temperatures remained below-average but strengthened slightly in the central-eastern equatorial Pacific with the main oceanic and atmospheric variables remaining consistent with La Niña conditions.
  • A large majority of the models forecast SSTs to remain below-normal at the level of a weak La Niña until Jun-Aug 2022 with decreased probability, afterward.
  • La Niña tends to influence favourable conditions for increased cloudiness and rainfall in Trinidad and Tobago. However, so far the ongoing La Niña has influenced the local climate in an unusual way.
  • The  north/south sea surface temperature gradients, well known as the Atlantic Meridional Mode, which is a key facilitator of local rainfall during the season is currently in negative mode but is likely to transition to its positive phase during the wet season.
  • A positive phase of the AMM is associated with enhanced ITCZ activity shift farther north and reducing upper-level westerly winds throughout the Atlantic MDR.
  • The North Atlantic Oscillation (NAO) has alternated been phases since April and is forecast to move to negative phase during June.
  • The rainfall enhancement phase of the Madden Julian Oscillation (MJO) is expected to track across Trinidad and Tobago’s vicinity during week 2 and 3 of June.

The rainfall and temperature outlook is based on statistical and dynamical seasonal climate models outputs and known seasonal climate influencers. The outlook is in reasonable agreement with several of the global climate models.

The rainfall and temperature outlooks are based on CCA-canonical correlation analysis, which linearly predicts the evolution of patterns local temperature and rainfall based upon patterns of global SST, other statistical and dynamical seasonal climate models outputs and historical relationships between a known seasonal climate influencer and the local climate.

The forecasts in the outlooks are expressed as the probabilities of the observation of the rainfall totals or temperature occurring in the most likely of three categories (above-normal, near-normal or below-normal). The categories are defined by boundaries that split the 1991-2020 climatological spread of rainfall totals or temperature, into thirds. Climatologically, each category has a climatological chance of occurrence of 33.3%.