LA NINA - IS SHE STAYING OR IS SHE GOING....WILL SHE ACTUALLY GO AT ALL?

That is the question at the moment among some very excitable weather weeny pages out there and some of the discussions I have had with colleagues at different networks internationally. Right now, the sequence is for La Nina to wane, but more slowly, in line with the climate guidance.


We can actually see the impacts of this persisting La Nina at the moment across the nation as a whole, with the wet weather bias in combination with the positive SAM phase (that is brought on by La Nina more frequently than normal). The moisture over the northern tropics is also above average with a more active end to the wet season continuing.


Also the persistent below average temperatures over parts of the east is set to continue for another week but this should start to improve by this time next week.


HEADLINE

La Nina is beginning to wane and it will resolve to NEUTRAL ENSO conditions but the end of May. This will result in the tail end of the wet season continuing at above average thresholds for far northern tropical areas, especially QLD. The east coast wet season also running above average for NSW and QLD through to the end of June. La Nina may suppress the surge in the westerly wind belt through May into June for southern Australia with more positive phases unfolding. But what about through Winter and into Spring 2022?


DATA

Sea surface temperatures for the Pacific and in a state of slow transition with the warming waters over the western Pacific and surrounding northern and eastern Australia, a symptom of the La Nina event and the ongoing above average moisture and rainfall values a signal of that continuing. You can see in the top window the current sea surface temperatures. Under that are the anomalies and you can see those elevated values over northern and eastern Australia which is supporting the above average rainfall and then you can track the cool waters of the Eastern Pacific Ocean starting to warm as we see the back of the La Nina event through Pacific. So on that account, the waning of the La Nina is slower than last year's event leading to a protracted period of above average rainfall for the northern and eastern parts of the nation.

Here is a closer look at the current SSTs and the deviation from the average throughout the basin, with cooler than normal waters continuing for the Basin and warmer than normal waters surrounding Australia which is supporting the above average rainfall and moisture levels which we have been seeing for recent months. Also the elevated SSTs over the northern regions will also support the deepening of tropical activity across the northern areas of Australia.

Current Model Predictions for ENSO through the remainder of 2022.

Note that the models have softened the recovery out of the La Nina phase across Australia meaning that it is protracted through Autumn. Also noting that some of the members (more since the last update) are now keeping the ENSO region in La Nina throughout the remainder of the year which is of interest to me. Now I am not forecasting that, nor am I forecasting an El Nino, but the Neutral phase that is most likely to evolve, may be sitting on the cooler side throughout the year, opening the door for yet another La Nina event into the Spring of 2022 and Summer of 2022/23.

This is another great way of looking the forecast for the remainder of the year. Now as I mention constantly, the outlooks lose their confidence the further you go out and when dealing with ENSO, you usually have better confidence at this time of year for the forward 3 months into Winter, beyond that season, it becomes much more difficult to pin down the forecast. For now, you can see that a cool neutral is the likely outcome for the Winter into Spring, but there is some shifting towards the chance of another La Nina forming through the Spring and Summer. For now, El Nino is not likely at this time.

HOW WOULD IT IMPACT RAINFALL LATE WINTER INTO EARLY SPRING?

The weather over the course of late Winter into Spring could be excessive, but this chart is misleading if you are relating this to the ENSO region (as some publications are suggesting). This is likely picking up on the potential for a negative IOD phase forming and this leading to higher moisture values being dragged across the nation from northwest through to the southeast of the nation, leading to these excessive values. BUT IT IS CONDITIONAL. I am not forecasting nearly this type of rainfall through the period and I will have more on late Winter and Spring forecasting next week. But for now, the ENSO IS NOT bringing this rainfall to the nation. The give away? The higher values through Indonesia and northwest Australia, which suggests elevated SSTs and higher moisture content.

HOW WOULD IT IMPACT TEMPERATURES LATE WINTER INTO EARLY SPRING?

Temperatures once again would be above average for the remainder of Autumn through northern Australia but the impact from the ENSO as per the rainfall would be minimal. What you are seeing here is the impacts of the developing negative IOD. This is a conditional forecast for the nation and is of low confidence.

WHAT ABOUT LATER ON IN THE YEAR?

CANSIPS - Spring 2022 - Rainfall Anomalies

The ENSO turning cooler through Spring coupled with the negative IOD would result in a wetter Spring than last year across the nation as a whole. BUT, and it is a BIG BUT, this is one product that suggests we could see both of those phases in play, and other climate models are not quite going down this path. But it is an example of what would happen if La Nina returns in the Spring and into Summer later this year.

CANSIPS - Spring 2022 - Temperature Anomalies

A cooler Spring for much of Australia with the extra cloud cover from the negative IOD more than the impact of the developing potential La Nina being expressed by this model. The give away on this data is the warmer weather over northern Australia which is a direct result to the negative IOD phase.

CANSIPS - Summer 2022/23 - Rainfall Anomalies

Noting that we lose the impact of the IOD but seeing the ENSO turning cooler or into a La Nina, the wet season over northern Australia would be early onset and the risk of above average rainfall would be very high and then this moisture would spread throughout the nation where troughs set up over a warmer nation. But this again is a very low confidence forecast, and represents what would happen under a third La Nina phase in a row.

CANSIPS - Summer 2022/23 - Temperature Anomalies

The cooler bias continues for the south with the widespread above average rainfall expected under these climate forecasts from the modelling. Over northern Australia the increased moisture and elevated SSTs through the tropical waters keeps the temperatures above normal. This is in part from the departing negative IOD and through this period, the peaking La Nina phase which is why we see the increased chances of elevated SSTs over the Coral Sea.

I will have further information about the Indian Ocean in the coming weeks as we move away from the ENSO region, the influence from the ENSO will reduce over time but will keep one eye on that process. If it does bubble along at a cool neutral phase through to July, we may see another La Nina on the way, but confidence as mentioned at this time of year is poor.



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