Bureau of Meteorology (Australia) & NOAA ENSO Alert System Status: 25th March 2019
The El Niño–Southern Oscillation (ENSO) is currently neutral. The Bureau's ENSO Outlook has moved to El Niño ALERT.
Tropical Pacific sea surface temperatures have touched on El Niño thresholds for the past three weeks,
Equatorial sea surface temperatures (SSTs) are above average across most of the Pacific Ocean.
The pattern of anomalous convection and winds are consistent with El Niño.
Weak El Nino conditions are likely to continue through the Northern Hemisphere spring 2019 (~80% chance) and summer (~60% chance).
The latest weekly SST departures are:
Niño 4 0.9ºC
Niño 3.4 1.1ºC
Niño 3 0.9ºC
Niño 1+2 0.2ºC
During the last four weeks, equatorial SSTs were above average in the central and east-central Pacific Ocean. SSTs were below average around Indonesia.
In the last two months, positive subsurface temperature anomalies have persisted across most of the equatorial Pacific Ocean.
Negative subsurface temperature anomalies have weakened east of 100ºW.
The ONI is based on SST departures from average in the Niño 3.4 region, and is a principal measure for monitoring, assessing, and predicting ENSO. Defined as the three-month running-mean SST departures in the Niño 3.4 region.
El Niño: characterized by a positive ONI greater than or equal to +0.5ºC. La Niña:
characterized by a negative ONI less than or equal to -0.5ºC.
By historical standards, to be classified as a full-fledged El Niño or La Niña episode, these thresholds must be exceeded for a period of at least 5 consecutive overlapping 3-month seasons. CPC considers El Niño or La Niña conditions to occur when the monthly Niño3.4 OISST departures meet or exceed +/- 0.5ºC along with consistent atmospheric features. These anomalies must also be forecasted to persist for 3 consecutive months.
The most recent ONI value (December 2018 – February 2019) is +0.8ºC.
The 30-day Southern Oscillation Index (SOI) has been steady over the past two weeks, remaining within El Niño territory. The SOI value for the 30 days to 17 March was −13.3. However, the 90-day SOI is still well within neutral territory at −5.1.
Sustained negative values of the SOI below −7 typically indicate El Niño while sustained positive values above +7 typically indicate La Niña. Values between +7 and −7 generally indicate neutral conditions.