And that news is spelling a very wet signal for Australia if indeed the La Nina does indeed develop through October to March next year!
It is not uncommon to have a rebound La Nina after a strong first season La Nina, the second sometimes is more productive in terms of impact than the first, given that the signal wanes through the winter months here before increasing in strength through our spring and summer.
That could increase the risk of flood events for eastern Australia and bring on an above average wet season - which we covered last week here.
Now the signals have continued to strengthen in the latest spread of data released overnight.
What El Nina vs La Nina looks like in the Pacific Ocean and it's impacts through the continents surrounding the driver.
El Nino drives cooler seas surface temperatures over eastern Australia with persistent westerly wind bursts over the central and eastern equatorial Pacific sending above average sea surface temperatures towards South America. The opposite occurs in La Nina, with persistent easterly winds, driving above SSTs towards Australia. Warmer waters, more moisture, more potential for rainfall with lower air pressure over Australia.
ENSO Multivariate - Observed anomalies through the basin. Valid July 9th 2021.
The basin has recovered from the previous La Nina to neutral thresholds, but note the back to back La Nina events in the past, the second event can quite often be more robust and deeper, not longer, but more intense, so will be watching trends.
BoM ENSO Forecast - July 6th 2021.
Note the dip towards La Nina but on the cusp
BoM ENSO Forecast - July 9th 2021.
Note the dip towards La Nina more possible with a dip towards thresholds by October and continue through summer.
The outlooks here in Australia remain neutral with no La Nina watch declared by the BoM. But climate agencies have started to declare a La Nina watch which I am now factoring into my forecasting down the track for Spring and Summer.
Finally this was the result of a negative Indian Ocean Dipole and La Nina coinciding, and the rainfall and temperatures were highly anomalous and triggered widespread flooding and severe weather events across the nation.
Remember not one event is ever the same, but the influence for above average rainfall and seasonal to below seasonal temperatures is high for the coming 6-12 months. I have posted below the last time we saw a negative IOD and La Nina somewhat coincide through a 2 year phase and this was the outcome.
Rainfall Deciles - 2010
Temperature Anomalies - 2011
Rainfall Deciles - 2011
Temperature Anomalies - 2011
So time to pay attention to climate forecasts and longer term forecasts. My next 6 week update coming up soon.
My outlook for the coming 3 months was published earlier this week.
Rainfall for the seasonal period - August through October 2021.
This product will be updated on Friday 23rd of July 2021.