CLIMATE OUTLOOK - NEXT 6 WEEKS COULD SEE THE BEGINNING OF THE END OF LA NINA.

We have been battered by the impacts of the La Nina which I may add was forecast here by this agency back in last August. Any mention of no one knowing the risks of what would occur in the Summer and Autumn which is 3 days old, needs a subscription. The pattern was clear.


That said, some areas have missed out in recent months too, that being Central QLD, parts of tropical QLD as well have seen reduced rainfall in what you would assume should be above average rainfall with La Nina, but not one La Nina is ever the same.


In this case we have seen the peak of La Nina and that has influenced the performance of the Southern Annular Mode. The SAM tends to be more positive than neutral through La Nina and negative than usual in an El Nino phase. So all the ingredients that come with La Nina have been there and produced those above average rainfall events for the eastern and northern parts of the nation.


But as the La Nina wanes in the coming 6 weeks, the rainfall should begin to reduce, that is mainly appearing in April. You can refer to the April Outlook at the front blog page or look in the climate section for that.


I suspect that the pattern we have seen during the past week, will be repeated 1-2 more times across the nation with the wettest weather in the east and the drier weather over the south and west of the country, typical for this time of year. The monsoon may have one more go at the north of the nation as well. This could see some late season activity. Some indications that the MJO will rotate through the Indian Ocean in the coming weeks and likely pass just north of the continent at the end of the month.


The SSTs are also above average for many locations around Australia so we are still seeing increased risk of low pressure systems being fairly productive rainfall producers throughout the coming few weeks.


Lets take a look

FORECAST

% chance of exceeding or not exceeding the median rainfall for the coming 6 weeks

The wet signal unfortunately continues for the eastern seaboard with no shift in the signal for above average rainfall. The flood risk remains high to very high. The quantity above the average may be lower than what we have seen in previous weeks but above average none the less. The risk of above average rainfall for eastern inland parts of QLD, NSW, ACT and through eastern VIC remains elevated but tapers off the further west you go, where values are leaning above, but not a strong signal through the remainder of southern Australia. Moderate risk of above average rainfall for much of interior parts of WA with more tropical moisture working south, I do expect one or two more cyclones to form in the Indian Ocean and these could shear off moisture as we have seen with Anika, and drag rainfall southwards. The Top End looking wetter as we go through the month and parts of Cape York, but the FNQ coast could see marginally above average rainfall with the trade winds continuing. As we move into April, a prolonged period of more neutral SAM conditions, could allow for westerly winds to return for southern Australia lifting more rainfall events towards WA through southern SA and into the southeast. The SSTs being elevated means that the systems passing through could be more productive.

% chance of exceeding or not exceeding the median temperatures for the coming 6 weeks

Temperatures are expected to be below average through the period as a whole over the eastern parts of QLD through NSW and east of the ACT with a persistent easterly flow and low cloud, showers and rain above average. That should be a feature for atleast 4 out of the 6 weeks during this time. The remainder of the east neither above or below average at this time so more variability in temperatures but coming in seasonal. The further west we go, the persistence of easterly winds will see heat build up under sunny skies from SA and points west. The heat values could become excessive at times through southern WA in the absence of persistent tropical moisture and I am leaning on that solution for now. The moisture over the north of the nation will be higher than normal leading to above average day and night temperastures.

Key Points

These are the key points covered off in the video, where you can find more context behind the images above.

I am travelling to the Central West of NSW so I will try and get a small update out this evening covering off the weather risks across the nation into the weekend. Remain weather aware!!


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