Late season La Niña weather event a chance to develop

Does a late season La Niña automatically mean more rain over summer?
Does a late season La Niña automatically mean more rain over summer?

AFTER coming within a whisker of entering El Niño territory earlier in the year, the climate drivers in the Pacific Ocean have dramatically turned around, so much so that the Bureau of Meteorology (BOM) has said it is possible a late season La Niña event may form.

In its latest El Niño–Southern Oscillation (ENSO) report, the BOM said the Pacific Ocean remains neutral, however there is cool water below the surface.

The BOM reported that five of the eight international models it follows were predicting further cooling of the tropical Pacific sufficient to reach La Niña thresholds by December.

However, only three of the eight models saw cool waters persisting long enough to be classified as a bona fide La Niña event.

The BOM said it was unusual, but not unknown for a La Niña to occur this late in the year.

La Niña events are correlated to higher than average rainfall, but the BOM had a word of warning for summer croppers expecting to fill their boots this year saying the link between late season La Niñas and rain is mixed.

Some late events have led to widespread above-average falls across eastern Australia, and others have had only minimal effect.

Bearing this lack of certainty in mind, the BOM’s three month rainfall outlook has only got a 50pc likelihood of wetter conditions in many parts of the country, including the summer cropping zone.

On the other side of the continent, the Indian Ocean Dipole (IOD) remains neutral.

Three of the six climate models surveyed suggest positive IOD thresholds may be reached during spring, correlated with lower than average rainfall, but the BOM said these positive values would be short-lived as IOD events naturally decay by December.


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