Here is the weather video for the analysis across Summer - and you can refer to the forecast notes below this video once again - which were posted yesterday.
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The broader outlook for Summer is really just a trend-based forecast, looking at the elements such as climate drivers and their potential impacts on the nation as we move through from what could be a wetter Spring into somewhat of a wetter Summer.
But as I keep saying, the further out you go in the space of weather forecasting, the poorer the accuracy and so this is why I am broad with my approach, and I will become more specific as we get closer with state-based updates and forecast rain and temperature outlooks as we move through Spring.
SUMMER OUTLOOK VIDEO
The pattern is set to resolve in the Indian Ocean where we are expecting the negative IOD to return to neutral values as the season shifts over the course of late Spring and into early Summer.
The longer the Indian Ocean Dipole continues to retain a negative status through Spring, the longer the wet bias will continue to emerge from this driver
For the ENSO region, the modelling as highlighted here, is leaning towards a weak La Nina more than neutral at this stage, but this will become clearer as we move through next 6 weeks so stay close to the updates. I am basing my forecast on the basis that the ENSO will be in La Nina and that we will likely see significant pooling of those warmer waters and likely strengthening of the warmer waters around northern and eastern Australia through Summer before they mix out during February at the earliest. I am not anticipating at this time that we see the La Nina linger as long as it did this year. But you cannot rule it out either. So, watching closely.
%Chance of exceeding or not exceeding the median rainfall for Summer 2022/23
The signals for widespread above average rainfall as mentioned in the video are running pretty high as we track a strong negative phase of the Indian Ocean Dipole waning through the November, and this could wash into December (like last year) leading to excessive rainfall and storm outbreaks over much of the country leading to flooding and damage/destruction of crops. There is some chance that December could have some places over the southeast and east of the nation record near record rainfall. The rainfall spread will continue to be above average through January and February, but more likely the further north and east that you go, the chance of exceeding the average in relation to rainfall increases drastically. This is the theme we have seen in previous La Nina Summers but also off the back of a waning negative IOD. So, it would be remiss for me to not to draw in the rainfall spread as outlined here. A seasonal expectation does exist for much of WA as they move into the drier part of the year for this area, but could follow a productive and drawn out Spring.
%Chance of exceeding or not exceeding the median temperatures for Summer 2022/23
The season looks to be once again below average for many areas over the southeast and eastern inland as well as coastal areas under the current climate guidance. The forecast is of low to moderate confidence based on the signals of the La NIna redeveloping over the ENSO but also, the lagging impacts of the negative IOD that is set to project a lot of moisture through November and December. I will outline once again, that it does not mean cold weather, it means more humid, cloudy and wet weather that stifles the drier and hotter spells that our country is known for through Summer. Does it mean it will not get scorching hot? No, but it will be more difficult under the current guidance, which may still evolve. With the elevated SSTs over northern and northwest Australia and developing along the east coast, it could work out that December may be warmer than normal in some of the areas shaded in blue but overall moderation in the temperature spread is expected to unfold as we move into 2023. The forecast confidence is low to moderate and based off the signals that the La Nina returns which carries as mentioned in many areas - a 59% chance of occurring at this time.
GOING THIS FAR OUT!
There is a lot of risk going this far out if you are far too specific in relation to an environmental science, and weather always will make you look foolish if you throw all your eggs in one basket.
The purpose of sharing this information with you is to show you trends, percentages of the scenarios on the table and then formulate a forecast for you that makes sense and that covers off all bases but includes the impacts to you and the bottom line of your operation or business or enjoyment of the warmer weather.
Weather means different things to different people so, understand that you need to put your expectations into context and understand that this is not a fortune telling service or just shooting wild theory from the hip, it is considered information based of data, analogues and what one would reasonably expect in the current climatic environment and guidance.
CLIMATE DRIVERS - FURTHER INFORMATION
The Indian Ocean should settle back down to seasonal expectations with the Indian Ocean Dipole remaining neutral for the most part of Summer 2022/23, but the lag impacts of the large negative expression we are likely to see play out through Spring, will mean we have excessive moisture to work with through this period.
For the ENSO, the modelling and chatter out there about it being another La Niña Summer is premature and caution is advised, however modelling is robust and sees another cooling phase for the Pacific Ocean that could support another La Niña, but it does remain to be seen.
If the ENSO remains neutral, this will promote and more typical SAM phase for the Southern Ocean with more variability from negative to positive phase with modest impacts. If we see the ENSO tend La Niña, then it is more likely we see another wet Summer for the east coast with a more positive than not SAM phase. It is unlikely we will be dealing with El Niño for this year and into early 2023, but our fortunes are likely to shift from next year into 2023/24.
ENSO FOR THE REMAINDER OF THE YEAR - INTERNATIONAL MODEL SET - WEAK LA NINA PERSISTS THROUGH SUMMER, BUT COULD EASILY STRENGTHEN.
DATA - MORE IN THE VIDEO TOMORROW.
Euro Seasonal Outlook Rainfall Summer 2022/23
The Euro is indeed looking very damp for large areas of the nation but refer to the video for more context on this outlook period for your region.
CANSIPS Seasonal Outlook Rainfall Summer 2022/23
We see the nation also quite wet with the seasonal outlook from the other longer range climate model but the skill score with this product is worse than the Euro.
Euro Seasonal Outlook Temperature Summer 2022/23
A stronger colder signal from some of the data sets allow us to understand that conditions may be dominated by humidity and cloudy skies with areas of rain remaining widespread from the Spring. More details in the video tomorrow
CANSIPS Seasonal Outlook Temperature Summer 2022/23
Also leaning colder in many areas, but the skill score is not great from this product. More can be found in the video tomorrow
IRI/CPC Seasonal Outlook November through January 2022/23 - Rainfall
More elaboration on this in the video tomorrow morning.
IRI/CPC Seasonal Outlook November through January 2022/23 - Temperatures
More elaboration on this during the video tomorrow morning.
This forecast will continue to evolve and the next update I will have on this is in about 4-6 weeks. Next update will be another look at Spring 2022 coming up later in the weekend.