El Nino Southern Oscillation (ENSO)

Recent Observations

In recent months, sea-surface temperature anomaly (SSTs) in the Equatorial Eastern Pacific (NINO3.4), increased slightly from -0.5^oC or borderline La Nina conditions, to near average or ENSO neutral.

Model Forecast and Guidance

Most models suggest ENSO neutral conditions by February 2017 (with 75% - 90% confidence) and continuing through the first half of 2017. Models also forecast the return of El Nino by the end of 2017.

Expected Impacts on Rainfall and Temperatures

ENSO neutral phase usually have little effect on rainfall and temperature in February-March-April.

Climate conditions in the Tropical North Atlantic and Caribbean

Recent observations showed SSTs up to 0.5^oC above-average within the Caribbean and the Tropical North Atlantic east of the islands. SSTs north of the Greater Antilles are now near-average due to usual trade wind activity in the region.

Expected Conditions Near normal SSTs are expected to return to the Caribbean Sea and further east by May-June-July 2017. Trade wind strengths are hardly predictable at seasonal time scales. Strength of trade winds is hardly predictable at seasonal time scales.

Expected impacts: A slight probability shift towards above- to normal rainfall is expected for February-March-April 2017 as positive SST anomalies in the Caribbean Sea and Tropical North Atlantic tend to increase humidity in the region, which in turn can lead to increased rainfall. This influence will tend to subside by May-June-July 2017.

Regional Overview on Seasonal Forecasts for February to April 2017

Rainfall Outlook

Forecast: Slightly above to normal rainfall totals can be expected for the season February-March-April 2017. (Normal range- approximately 139 - 403mm).

Probability:

• 40% chance of above normal
• 35% chance normal
• 25% chance of below normal

Wet Days and Wet Spells Outlook

Wet Days

Table 1: February - April 2017 Wet Days(>1.0mm) Frequency Shift

Station	Climatology (Wet days)	Forecast (Wet days)
Canefield Airport	23 to 35	20 to 44
Douglas-Charles	37 to 56	36 to 59

Forecast: There is little indication in the forecast of wet days.

7-Day Wet Spells

Table 2: February - April 2017, 7 Day Wet Spells Frequency Shift

Station	Climatology (7 day wet spell)	Forecast (7 day wet spell)
Canefield Airport	0 to 2.1	0.1 to 2.1
Douglas-Charles	0.4 to 2.6	0.7 to 2.9

Forecast: Small increase to the usual amount of 7-day wet spells.

Implication: Depletion of large reservoirs during the dry season would likely be slower than usual.

3-Day Wet Spells

Table 3: February - April 2017, 3 Day Extreme Wet Spells Frequency Shift

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 0.1	0 to 0.1

Forecast: Low chances for 3-day extreme wet spells (high confidence).

Implication: Flash flood potential is not a major concern until the end of April.

Drought Outlook

There are no drought concerns for Dominica both at the short term (November 2016- April 2017) and long term (June 2016 –May 2017).

Temperature Outlook

Forecast: Temperatures across the Caribbean are forecast to rise but gradually become uncomfortable beyond April, with the chance of heat waves appearing in May and June for many. (Maximum temperature normal range: 28-30^oC) (Mean temperature normal range: 25-27^oC) (Minimum temperature normal range: 22-23^oC).

Probability