AUTUMN OUTLOOK - REFRESHED RAINFALL AND TEMPERATURE OUTLOOKS

Well as I had been mentioning at nauseum through February, it would be a wet end to Summer and start of Autumn for the east and north of the nation. That has verified pretty much as advertised, with the drier weather back through the interior parts of the nation, especially over SA and WA.


The tropical weather over the northwest also introducing rainfall for the end of Summer has now verified with Anika passing through as I do this update. That will feature again before we see Easter and the end of the wet season proper.


For the remainder of the nation, we are likely to see another 4-6 weeks of positive SAM weather, onshore winds and rainfall above the average probably taking us through to around Easter at this stage.


This will mean that much of SA and parts of WA will remain drier which is somewhat normal for early Autumn (hence the term Autumn break) with things breaking around mid Autumn as the pattern shifts and the influence of La Nina wanes as we move through the season.


The lingering La Nina could see another wave of monsoonal weather across the north of the nation through late March into early April which can spawn late season cyclone activity as well which act to enhance any Autumn Break for the country as we see that moisture (as we are seeing with Anika right now) pass through from northwest to southeast.


FORECAST

Autumn Rainfall Outlook

% chance of exceeding median rainfall for Autumn 2022

Many areas of the east have already exceeded the seasonal averages for Autumn so it is really about how much more rainfall is to come, and there looks to be more above average rainfall for the season ahead. This will spill over into the eastern inland of QLD, NSW through the ACT and over eastern and northern VIC (once again some areas of seen above average rainfall for March and April. The weather over the northwest nearer to the coast also running above average with significant chances of 1-2 more late season cyclones. Some of these can be strong to severe cyclones, even if they are small. So will watch closely. The interior of the nation leaning slightly towards the wetter signal now, so I have paired back the risk of above average rainfall for now. The rainfall chances also leaning above normal for the season through southern WA, through SA and into western VIC, this connected to a wetter May coming up as we see the weather transition earlier to the cooler season westerly flow. Overall the wetter signal clearly lay in the early parts of Autumn and I do think we dry out somewhat as we go through the season, in line with the La Nina waning and then concluding. Remember the La Nina impacts from ocean observation to the practical influence on weather in Australia is about 4 weeks so the impacts of La Nina (which is the main climate driver through this period) is likely until the end of April.

Autumn Temperature Outlook

% chance of exceeding median temperatures for Autumn 2022

The cooler bias continues for the east with the onshore persistence thanks to the positive SAM and increased rainfall and cloud cover. We are observing that right now and I do suspect we will see more of that as we go along. Increased moisture over the north of the nation will lead to above average overnight and daytime temperatures, a prolonged wet season will see temperatures a few degrees above normal. The weather over southwest and southern parts of the nation near to above normal with persistent easterly winds but conditions likely to turn cooler once we see the westerly winds emerge as the seasonal shift get underway. That will result in the conditions over the east and north also seeing temperatures moving away from the what we are seeing now, so warmer days possibly increasing in frequency for the east coast of NSW and QLD and cooler days coming into the north of the nation with drier air surging northwards to kick off the build down and then dry season in May.

Key Notes

These are the refreshed key points for the period ahead. Refer to the outlook for April for more details on the coming 6-8 weeks and refer to the 6 week outlooks that refreshed here 2 times a week.

More to come on the next 6 weeks from tomorrow but for now some slight shifts in the guidance, we now can see the impact of the La Nina peaking and the phase waning over the course of the next 6 weeks will clearly be felt heavily over the east coast and adjacent inland through NSW and QLD.