The La Nina summer continues with little indication of significant change in the foreseeable future. In fact, some international models predict the current La Nina event will persist well into autumn, although weakening at that time.
Different probability forecasts averaged out show there is a greater than 66 per cent chance (two chances out of three so quite strong) that the La Nina will be the dominant Pacific basin in the three-month period of March to May 2022. After that a neutral pattern is favoured to become dominant to at least August.
In the longer term, the chances of a neutral pattern persisting for the rest of the year remains the most likely scenario but the chance of a La Nina continue to be a little higher than those for an El Nino even at the end of the year.
For the more immediate future, in early to mid-January, the sea surface temperature anomalies in the tropical Pacific remained at the level of a weak to moderate La Nina. The water temperatures in the subsurface were also in the La Nina range and indicate a continuation of La Nina until autumn more than anything else. It is then expected to transition to ENSO-neutral during the following six months with probabilities close to or slightly above 50pc.
It still seems likely that another Madden-Julian Oscillation could develop near tropical Australia in late January or early February, which will be another period of interest for increased rainfall potential as the monsoon trough strengthens once again. In many past a Nina years, the monsoon trough tends to remain active throughout summer anyway. This indicates that there is further potential for above average rainfall to occur across eastern Australia during the next four to six weeks, possibly tailing off a little in late February or early March, but even then, below average rainfall is unlikely.
So, average to slightly above average rainfall will remain a reasonably likely scenario well into autumn. Patterns to monitor will be the extent of tropical (or sub-tropical) systems that often can be a source of moisture for more southward locations. Given the increased chance of easterly winds across eastern NSW, maximum temperatures should generally sit close to average for the next three-month period.
This does not mean there will be no hot periods (hot temperatures still occur in a La Nina summer), just the potential for extended heatwaves is below average in all of south east Australia.
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