La Niña has ended - ENSO now neutral. El Niño WATCH issued.
La Niña has ended in the tropical Pacific Ocean. The El Niño–Southern Oscillation (ENSO) is now neutral (neither La Niña nor El Niño) with oceanic and atmospheric indicators having returned to neutral ENSO levels.
International climate models suggest neutral ENSO conditions are likely to persist through the southern autumn (March to May). However, there are some signs that El Niño could form later in the year. There is around a 50% chance of an El Niño in 2023.
Bulletin March 2023 - El Nino Oscillation
The 2022–23 La Niña has ended, having been declared in September 2022. Oceanic and atmospheric indicators have returned to ENSO-neutral (neither El Niño nor La Niña) values.
El Niño Southern Oscillation (ENSO) is a single climate feature that has three states: El Niño, La Niña, and Neutral.
During an El Niño, sea surface temperatures in the Tropical Pacific Ocean, both at the surface and the sub-surface tends to WARM. Surface pressure changes across the Pacific; higher in the west, and lower in the east. Trade winds weaken and sometimes reverse. Cloudiness increases near the Date Line. El Niño events tend to develop in Autumn to Winter (March - August), and starts to decay in Summer (December - February). In Vanuatu, extreme below normal rainfall which results in drier conditions with warmer daytime temperatures are associated with El Niño.
During a La Niña, sea temperatures in the tropical Pacific Ocean, both at the surface and the sub-surface tends to COOL. Surface pressure changes across the Pacific; higher in the east, and lower in the west. Trade winds are much stronger than normal. Cloudiness decreases near the Date Line. La Niña events also tend to develop in Autumn to Winter (March - August), and finishes the following Autumn (March - May). In Vanuatu, above normal rainfall which results in extreme wetter conditions with cooler temperatures are associated with La Niña.
During a Neutral phase, all ENSO indicators (Sea surface temperatures, Southern Oscillation Index (SOI), trade winds, and cloudiness near the Date Line) in the tropical Pacific Ocean, remain within the neutral range. Normal climate conditions are experienced over Vanuatu during Neutral ENSO phase.
Bulletin March 2023 - MJO
What is an MJO (Madden-Julian Oscillation)? An MJO is a group of cloud and rain that circulates the globe near the equator, and usually occurs every 30-60 days. When an MJO passes over an area, it brings heavy rain with varying wind speed. During cyclone season, an MJO can help develop tropical cyclones by fueling any overlying low pressure systems.
The diagram below shows the track of the MJO for the past 40 days (coloured lines). [Click to enlarge the diagram]. When the lines are within the circle, MJO is weak and has no influence on rainfall. Outside the circle, the MJO is active and will usually move in an anti-clockwise direction. Vanuatu will most likely experience rainfall related to an MJO event when it moves over the Maritime Continent on the diagram.
Note: Due to frequent images update from source provider, the quoted Sources might not give the same images as shown
Bulletin March 2023 - Cloud
The above maps show regions experiencing more or less cloudiness. The top map is the total outgoing long-wave radiation (OLR), and the bottom map is the cloud anomaly. Outgoing longwave radiation (OLR) is often used as a way to identify tall, thick, convective rain clouds. This means, a region which experiences lower outgoing radiation is an indication of more cloudiness over the area.
The purple shading indicates higher than normal, active or enhanced tropical weather (above normal cloudiness), while brown shading indicates lower than normal cloud or suppressed conditions.
Equatorial cloudiness near the Date Line typically increases during El Niño (negative OLR anomalies) and decreases during La Niña (positive OLR anomalies).
Note: Due to frequent images update from source provider, the quoted Sources might not give the same images as shown
Bulletin March 2023 - SST
For the five days ending 12 March 2023, sub-surface temperatures were significantly warmer than average across the western to central equatorial Pacific between about 100 m depth and 250 m depth, reaching more than 4 °C warmer than average west of the Date Line. Weak cool anomalies were present between 140°W and 120°W at depths between 100 m and 150m depth.
Compared to two weeks ago, warm anomalies in the western Pacific sub-surface have increased in strength and extent
Note: Due to frequent images update from source provider, the quoted Sources might not give the same images as shown
Bulletin March 2023 - MSLP
Regions of HIGH pressure anomalies (brown shades) are associated with lower rainfall, while higher rainfall are associated with regions of LOW pressure anomalies (purple shades).
Note: Due to frequent images update from source provider, the quoted Sources might not give the same images as shown
Bulletin March 2023 - Model Outlooks
Most of the international climate models shows that the central Pacific sea-surface temperatures will remain at ENSO neutral throughout March to May.
Several models suggest that El Nino may develop later this year, however model accuracy at this time of the year is lower than other times, and outlooks should be viewed with caution.
The ENSO Outlook has been moved to El Nino WATCH. AN El Nino WATCH means there is around a 50% chance that an El Nino will develop. An El Nino WATCH is not a guarantee that El Nino will occur, rather it is an indication that some of the typical precursors of an event are currently observed.
Bulletin March 2023 - SPCZ
The Intertropical Convergence Zone (ITCZ) was more active in the eastern Pacific around 150°W, while the South Pacific Convergence Zone (SPCZ) displaced southwest over Solomon Islands, Vanuatu, Fiji and Tonga, indicating the La Niña event.
