LA NINA CHANCES GOING UP THIS SUMMER!

As promised I have been working on the data sets coming in off the latest modelling for the past week and now will share with you what you need to know and how it will impact the next 4-6 months across the nation. A more detailed post will be made on the seasonal outlook in about a week's time with my charts so this is further information that is not really spelt out with any skill, anywhere, until there is an event unfolding.


I have heard people say in the industry say they would eat their hat if there was another La Nina declared or develop - well get the knife and fork ready, because the weather will do what it will do and here we are. It does not care about personal bias and feelings, it is weather. So how does this event appear to be impacting you this Summer?


CHANCE ACROSS THE DATA SETS AFTER RENDERING



HEADLINES


  • Wetter than average conditions expected for large parts of the NT, QLD, NSW, VIC and northern parts of WA through SA.

  • Near normal rainfall expectations for the remainder of SA and WA.

  • Very little of the nation expected to be under below average rainfall predictions at this time.

  • Temperatures, above average for parts of the west and south, with higher humidity values being infused into the heat.

  • An uncomfortable Summer ahead with above average humidity values expected. This was pointed out in the tropical outlook from back in August and that is playing out through the nation as we go through spring.

  • That humidity will lead to issues for the fruit and food bowl this Summer with a higher risk of brown rot, mildew issues and fungal conditions.

  • There is also a higher risk of inland flooding continuing on from Spring and coastal areas through the Summer into next year.

  • The monsoon to be early, heavier and more productive this season with that monsoonal trough generally further south across the continent in La Nina years.

DATA SETS AS OF OCTOBER.


IRI ENSO PROBABILISTIC FORECASTS - OCTOBER 2021

This has seen a dramatic increase in the likelihood but also the duration of a La Nina event this summer. There is now a 91% chance across all of the climate models, again remember that these are some of the most robust climate models globally, and last year we did not have such strong values at this time of year - we went into a decent La Nina event which brought wild weather. So this is of considerable importance for the outlook period. Note that by the time we get to Autumn, the event is concluded and neutral values resume. The GREAT news - the likelihood of El Nino conditions developing next year are being offset for now - BUT we will know more on that by December. For now - the takeaway is a VERY HIGH chance of La Nina conditions developing throughout the back of November into December.

Dataset breakdown in table format

This particular product lift the chances to 92-93% in the latter part of November - I am rendering the forecast down slightly but overall, when you have values above 70% which this model has had since July, it is really inconsequential at what percentage we are dealing with.

SEPTEMER DATA TO COMPARE.

You can see the shift in conditions from 4 weeks ago and as advised, the shift towards La Nina or Neutral conditions for the Summer would be made in this time and now we know which way the coin has landed.

SSTs Anomalies.

Note the year 2000-2002 and the 2012-14 period where we had a significant double dip La Nina. But also lets go back to 1985-1987 where many can remember the significant flooding that occurred through that season after the severe drought. That double dip La Nina in the 1985-87 period was in step with a negative IOD and produced significant rainfall. This also occurred in the 2012-14 period too. So the signals for a lot of humidity, rain and storms continues to be strong.

FORECAST - RAW DATA - NOT A CURATED FORECAST!


RAINFALL ANOMALIES

Seasonal Rainfall Outlook - Raw Data

November through January

Seasonal Rainfall Outlook - Raw Data

December through February

Seasonal Rainfall Outlook - Raw Data

January through March

Seasonal Rainfall Outlook - Raw Data

February through April

MY SUMMER RAINFALL OUTLOOK

%chance of exceeding median rainfall for Summer 2021/22 - December 2021-February 2022.

The residual impact of the weakening IOD through December will offer more widespread rainfall chances over inland areas from northwest through southeast and keep the increased build up conditions going from Spring into Summer. The weather over the east will begin to get more humid and wetter through November, we have seen the storm season potential this year and I suspect that will continue onwards into December and January. But the real widespread rainfall is expected to kick off nationwide in line with the monsoon getting underway up north. We saw that as the trigger for widespread rainfall events over the nation earlier this year, the moisture from the north being drawn south into a persistent easterly flow and this lifting rainfall over central and eastern parts of the nation. The rainfall bias again, like for much of this year, over northern and eastern areas of the continent, but areas over the south can also expect widespread rainfall from time to time. This will be helped along by cyclone activity decaying over the continent. As we saw with earlier this year, the wettest part of the Summer for the nation likely to be January through February with the peak of humidity values through this time, the lowest air pressure over the nation is from January to February, this leading to widespread inland rainfall. For coastal areas of NSW and QLD, every time we go into a positive SAM phase, expect an absolute bucket load. This was experienced earlier in the year under the weak La NIna phase and under the current guide this is to be expected again. The wet bias continues for much of the nation into Autumn. The forecast confidence is MODERATE at this time.


TEMPERATURES ANOMALIES

Seasonal Temperature Outlook - Raw Data

November through January

Seasonal Temperature Outlook - Raw Data

December through February

Seasonal Temperature Outlook - Raw Data

January through March

Seasonal Temperature Outlook - Raw Data

February through April

MY SUMMER TEMPERATURE OUTLOOK

%chance of exceeding median temperatures for Summer 2021/22 - December 2021-February 2022

The cooler bias is expected persist through much of the nation with widespread cloud cover, higher humidity values and significant rainfall potential to exist through much of the season. The blues on this chart does not mean it won't be hot at times. Heatwaves will still occur, there will be 40C days in the capitals, but the overall trend for the season is cooler than normal, especially through outback areas and across the tropics, which are expecting an active wet season (through tropical outlooks are very poor as they use a different set of parameters and data sets - too complicated to go into here). The continent is expected to continue the cooler bias into Autumn at this stage but we are going out 5-6 months now, however all models do see the cooler bias continuing.

So that is the update for now - there is certainly a lot to digest on this information alone if you are on the land, got a good orchard of fruit or vines full of grapes etc. There is a risk to your produce under such guidance.


For those crop farmers, a lot rainfall the further north and east you go through the nation may prove helpful for some and not so good for others. Flooding is also a risk.


Severe weather will also be running high, we have experienced that and it will continue for the next few months.


I will have another severe weather outlook and tropical outlook coming up later this week as well looking at the Summer impacts.




0 views0 comments