Looking back at the January - March 2017 Season
The dry season runs from December to May when the seas are cooler and thunderstorms and rainfall activities are relatively low. Rainfall accumulated at both the Canefield and Douglas-Charles Airports for the season January - March 2017 was above normal. Above to normal maximum and mean temperatures were recorded with the Douglas-Charles Airport recording cooler than normal night time temperatures.
Rainfall
|
||
Canefield Airport | Douglas-Charles Airport | |
---|---|---|
Normal |
179.3 to 259.1 mm
|
301.0 to 397.3 mm
|
JFM 2017 Total |
300.3 mm (above normal)
|
426.9 mm (above normal)
|
Temperature
|
||
Average Maximum Normal |
29.5oC to 30.1oC
|
28.1oC to 28.6oC
|
JFM 2017 Average Maximum |
30.3oC (above normal)
|
28.6oC (normal)
|
Average Mean Normal |
25.8oC to 26.3oC
|
25.0oC to 25.6oC
|
JFM 2017 Average Mean |
26.5oC (above normal)
|
26.2oC (above normal)
|
Average Minimum Normal |
21.7oC to 21.9oC
|
22.0oC to 22.3oC
|
JFM 2017 Average Minimum |
21.8oC (normal)
|
21.6oC (below normal)
|
El Nino Southern Oscillation (ENSO)
Recent Observations
ENSO-neutral conditions continued during February, with near-average sea surface temperatures (SSTs) across the central equatorial Pacific and above-average SSTs in the eastern Pacific.
Model Forecast and Guidance
Most models predict the continuation of ENSO-neutral (3-month average Nino-3.4 index between -0.5oC and 0.5oC) through the Northern Hemisphere summer. However, some dynamical models anticipate an onset of El Nino towards the end of the dry season into the wet season (dry season-December to May, wet season-June to November).
Expected Impacts on Rainfall and Temperatures
ENSO neutral conditions have little effect on rainfall or temperatures. However, if El Nino manifests during the first half of the wet season, odds are in favour of drier weather with less extreme rainfall than usual for that part of the wet season.
Climate conditions in the Tropical North Atlantic and Caribbean
Recent observations: Recent observations showed SSTs up to 0.5oC above-average in the eastern part of the Caribbean Sea. Although recently cooling, SSTs in the far northwest of the region remained above average. Elsewhere, SSTs have been close to average. Trade winds have been slightly stronger than usual over the Tropical North Atlantic.
Expected Conditions: SSTs are expected to warm in the Tropical North Atlantic until September 2017, but the warm anomalies are forecast to be less extreme than in previous years. Note also that episodes of Saharan dust blowing into the region are likely at least until July 2017, increasing the likelihood of reduced rainfall but they are hardly predictable at this time.
Expected impacts: A slight probability shift towards above to normal rainfall is expected as positive SST anomalies in the Caribbean Sea and Tropical North Atlantic tends to increase humidity over the region which in turn can lead to increased rainfall. This influence may subside by June-July-August.
Regional Overview on Seasonal Forecasts for October to December 2016
Rainfall Outlook
Forecast: There are uncertainties at this time for the expected rainfall for the season April to June 2017. However, beyond June with the anticipation of a transition to El. Nino phase, below normal rainfall are forecast. (Normal range for April to June- approximately 250 to 400mm) (Normal range for July to September- approximately 600 to 900mm).
Probability for April - June 2017:
- 33% chance of above normal
- 33% chance normal
- 33% chance of below normal
Probability for July - September 2017:
- 20% chance of above normal
- 30% chance normal
- 50% chance of below normal
Wet Days and Wet Spells Outlook
Wet Days
Station | Climatology (Wet days) | Forecast (Wet days) |
---|---|---|
Canefield Airport | 27 to 45 | 28 to 51 |
Douglas-Charles | 41 to 63 | 43 to 69 |
Forecast: An increase in the amount of wet days (low to medium confidence) is expected.
Implication:
- Disruptions of outdoor activities will become more frequent
- Decreasing surface dryness across the region, especially after April
7-Day Wet Spells
Station | Climatology (7 day wet spell) | Forecast (7 day wet spell) |
---|---|---|
Canefield Airport | 0.9 to 3.4 | 1.3 to 5.5 |
Douglas-Charles | 0.9 to 4.7 | 1.7 to 5.9 |
Forecast: An increase in 7-day wet and very wet spells frequency (medium to high confidence).
Implication: The build-up of usual dry season impacts on water availability should be slower than usual.
3-Day Wet Spells
Station | Climatology (3 day extreme wet spell) | Forecast (3 day extreme wet spell) |
---|---|---|
Canefield Airport | 0 to 0 | 0 to 0 |
Douglas-Charles | 0 to 2 | 0 to 1.2 |
Forecast: There is little indication of change in frequency for 3-day extreme wet spells (low confidence).
Implication: Flash flood potential is becoming a concern mostly after April.
Drought Outlook
Forecast: A short term (January to June 2017) drought watch has been issued for Dominica. This means that drought conditions are possible within the next 3 months. Continue to monitor the situation and conserve water.
Temperature Outlook
Forecast: Temperatures across the Caribbean are forecast to gradually rise and become more uncomfortable throughout the period. Heat discomfort will probably grow more slowly in the Windward than at this time in the past couple of years. The chances of heat waves are appearing in May and June for many islands. (Maximum temperature normal range: 30-32oC) (Mean temperature normal range: 27-28oC) (Minimum temperature normal range: 23-24oC).
Probability
Maximum/day-time temperature Probability
- 40% chance of above normal
- 35% chance normal
- 25% chance of below normal
Minimum/night-time temperature Probability
- 40% chance of above normal
- 35% chance normal
- 25% chance of below normal