El Nino Southern Oscillation (ENSO)
Observations done in August 2016 showed Nino3.4 Sea Surface Temperatures (SSTs) anomalies at weak La Nina (-0.54). The probabilities for La Nina are between 50% and 70% from September-November through to December-February 2016-17, then drops into the 40s during the latter and below 25% from March-May 2017 onwards. The probability for neutral conditions rises to 50% for November-January and December-February, and still higher thereafter.
Expected Impacts
Average circulation patterns during La Nina periods may contribute to increased frequency of developing tropical storms which can contribute to higher rainfall totals.
Climate conditions in the Tropical North Atlantic and Caribbean
Recent observations showed SSTs 0.5oC above-average within the Caribbean and the Tropical North Atlantic. Trade winds were calmer than usual.
Expected Conditions: Slightly positive SST anomalies are expected throughout the Tropical North Atlantic by October – December 2016. Tradewind strengths are hardly predictable at seasonal time scales.
Expected impacts: Warm Atlantic temperatures increases evaporation and local deep atmospheric convection, potentially increasing precipitation.
Regional Overview on Seasonal Forecasts for October to December 2016
Rainfall Outlook
There is a low predictability for rainfall amounts for Dominica for the period October- November-December 2016. Chances are that rainfall totals will most likely be that of climatological averages.
Probability:
- 33% chance of above normal
- 33% chance normal
- 33% chance of below normal
Wet Days and Wet Spells Outlook
Wet Days
Station | Climatology (Wet days) | Forecast (Wet days) |
---|---|---|
Canefield Airport | 58 to 69 | 61 to 78 |
Douglas-Charles | 25 to 35 | 27 to 46 |
Forecast: More wet days than normal (high confidence).
Implication: Increased disruptions of outdoor activities due to increase rainfall days.
7-Day Wet Spells
Station | Climatology (7 day wet spell) | Forecast (7 day wet spell) |
---|---|---|
Canefield Airport | 3.0 to 5.8 | 3.7 to 7.1 |
Douglas-Charles | 2.6 to 4.9 | 2.8 to 5.9 |
Forecast: More 7-day wet spells and very wet spells (medium confidence).
3-Day Wet Spells
Station | Climatology (3 day extreme wet spell) | Forecast (3 day extreme wet spell) |
---|---|---|
Canefield Airport | 0 to 1.2 | 0 to 1.5 |
Douglas-Charles | 0 to 2 | 0 to 1.3 |
Forecast: No significant shift in the amount of 3-day extreme wet spells (medium confidence).
Implication: Flash flood potential developing.
Drought Outlook
There are no drought concerns for Dominica both at the short term (July - December 2016) and long term (December 2015 – November 2016).
Temperature Outlook
Air temperatures are expected to be above to normal. Night and day-time temperatures are expected to be warmer.
Maximum/day-time temperature Probability
- 70% chance of above normal
- 20% chance normal
- 10% chance of below normal
Minimum/night-time temperature Probability
- 50% chance of above normal
- 30% chance normal
- 20% chance of below normal