El Nino Southern Oscillation (ENSO)

Recent observations: A now moderate El Nino is rapidly weakening after reaching peak strength in November 2015. Sea-surface temperatures (SSTs) are 1.1oC above average in the Equatorial Eastern Pacific (NINO3.4).

Model forecast and guidance: Models indicate further return to ENSO neutral conditions for May-June-July 2016 (55-75% confidence) and a possible transition to La Nina conditions by August-September-October (50-65% confidence).

Expected impacts on rainfall and temperatures: Shift towards above-normal rainfall is noted for the Caribbean due to reduced winds in the upper atmosphere which allows for stronger local showers to develop. Higher temperatures are probable for the region which may also add to increased moisture uptake and lead to increase precipitation.

Climate conditions in the Tropical North Atlantic and Caribbean

Recent observations: Sea Surface temperatures are 0-1oC above-average north of the Caribbean and near average elsewhere. Trade wind speeds are stronger than average.

Expected conditions: Positive Sea Surface temperature anomalies are expected towards the Eastern Atlantic by May - June 2016, but cooler than average waters may develop along the equator and off the Western African coast. Trade winds are hardly predictable at seasonal time scales. Upper level winds are expected to weaken.

Expected impacts: Warm Atlantic temperatures results in an increase in evaporation, local deep atmospheric convection and potentially increasing precipitation. However, cooler waters off West Africa and around the Equatorial Atlantic may reduce the formation of rain-producing weather systems that are carried into the Eastern Caribbean by the trade winds during May-July.

Regional Overview on Seasonal Forecasts for May - July 2016

Rainfall Outlook

Rainfall Outlook

There is low predictability for rainfall totals for Dominica at this time.

Probability:

  • 30% chance of above normal
  • 35% chance normal and
  • 35% chance of below normal

Wet Days and Wet Spells Outlook

Wet days and wet spells outlook

Forecast and Implications

  • Many wet days: greater occurrence of outdoor activity disruptions; decreasing surface dryness
  • Several wet spells: effective recharge of water reservoirs expected
  • Up to 2 extremely wet spells: serious flash flood potential developing

Drought Outlook

Drought outlook

There are no drought concerns for Dominica up to July 2016

Temperature Outlook

Temperature outlook

Air temperatures are expected to be above to normal.

Probability:

  • 60% chance of above normal
  • 25% chance normal
  • 15% chance of below normal