Climate Driver Update 19/02/25
ENSO and SOI
The ENSO remains Neutral as it has since April last year, the value has dipped in to La Nina thresholds 3 times but it has not remained there for longer then 2 weeks. As Fig 1a shows the current value is -0.54 below the average SST for the Nino3.4 region. Outlooks from the BoM (Fig 1b) are predicting that the ENSO index will remain within Neutral thresholds until at least July. This means the index should be neither El Nino or La Nina over the next few months at the very least. Although that being said, some Ensembles are showing a chance of El Nino thresholds being reached this winter. However these are a long way out so caution should be used when looking beyond a couple months as actual obs can change rapidly in some instances. So look out for updates in the future.
Once again the 30 day SOI index (fig 1c) is well above +7. This is typically seen during La Nina or times where the pressure difference between Tahiti and Darwin is large. since the 1st Feb the 90 day reading has been over +7 as well. However the coupling of the Atmosphere and ocean is not being observed.
IOD
The IOD index is neutral as it typical for this time of year. It has reached positive thresholds (Fig 2a) however at this time of year, the IOD has little effect on Australian climate. Outlooks (Fig 2b) are showing a similar scenario to last year, with mostly neutral outlooks for the start of Winter, as the outlooks reach July, the uncertainty is bigger with ensembles spread almost evenly between positive, neutral and negative outlooks, although the mean is trending towards cool neutral. So definitely something to watch in the coming months, that being said we are almost in the period where IOD and ENSO outlooks become less accurate, autumn is always problematic for outlooks.
MJO
The MJO is in the western hemisphere. Outlooks have it hanging around the western hemisphere until mid March.
SAM
The SAM is currently positive but is expected to drop to neutral, Neutral has little influence on the Australian climate.