BROADER MODEL SETS AND RAINFALL - COULD WE SEE A LARGER SHIFT IN RAINFALL SPREAD IN THE MEDIUM TERM?

That is the question that is gaining more traction tonight in the medium-term models, some strong signals for Winter to burst through at the end of the run, but how does that idea on one model stack up against the other agencies?


As we move through towards June, these events start to show up and they are not without cause, but they are suggesting that we could be seeing colder air moving into the south of the nation.


How we get from the above average temperatures from this week to the colder air of the following week remains to be seen. It could be accompanied by widespread rainfall sweeping the nation from northwest to southeast with a cloud band. It could also come through in drier fashion.


I am leaning for more dynamic weather to spread through the country for the end of the month and into June, with hopefully the rainfall focus shifting out of the east and into the south.


The only issue I have with that idea is that the Southern Annular Mode is set to remain positive and that leads to more easterly winds and showers over the eastern parts of the nation and keeps the south and southwest mostly dry.


What the positive SAM essentially does, takes the moisture from the east and places it over QLD and NSW leading to more rainfall events. This was a graphic I used months ago and does not represent the forecast for the medium term, just what a positive SAM does.

DATA AND ANALYSIS

00Z Euro - Rainfall Next 2 Weeks - 51 Members - MODERATE CHANCE

We have seen an uptick in the amount of rainfall being expressed by members for the eastern event later this week and that is continuing push further west in every update. The western interior seeing the bulk of the heaviest rainfall through the coming 2 days and again through the weekend with a strong cold front. About 4 frontal passages over the SWLD should each bring light to moderate rainfall, but some areas could sit in between the fronts and the cloud bands to the north which is normal, so the Central West and Goldfields/Wheatbelt could see less. Rainfall numbers come up over the southern and southeast coastal areas in the medium term with frontal weather moving through with light to moderate rainfall dominating the end of the month and a cooler windy shift.



00Z GFS - Rainfall Next 2 Weeks - 35 Members - MODERATE CHANCE

Rainfall numbers are coming up across the nation as a whole, especially over the southern third of the country as this model starts to shift the pattern to focus rainfall through the westerly wind belt with the better chances of rainfall via westerly winds since early March. The rainfall coming in via the Indian Ocean looks to increase through the period with a burst in the short term and the medium term. Rainfall numbers heaviest in the short term over QLD but then conditions starting to dry out for the northern and eastern areas as the westerly wind belt takes over.

00Z CMC - Rainfall Next 2 Weeks - 30 Members - LOW CHANCE

Showing the rainfall being rather split amongst the members tonight, with the members not well aligned and it shows in the median of all the members tonight. So, I am grading this a low chance with rainfall to become a little more organised in the days ahead as it starts to pick up on the influence of the Indian Ocean and whether we see a stronger westerly wind belt moving through.

00Z CFS - Rainfall Next 6 Weeks - 4 Members

Rainfall numbers also coming up right across southern Australia in line with the modelling supporting a northward movement of the westerly wind belt, the strengthening of the jet stream and the moisture meeting the colder and unstable air over the south. The east coast possibly wet in the next 10 days before drying out a bit and numbers should come down in coming updates I would think, based on climate averages, but this year has been a strange one. There is a chance we could see another 1-3 east coast lows as well.

More coming up in the early bird edition from around 530am EST and the next video and broader update from 8am EST and then climate for the next 6 weeks coming up from 11am EST. Lots on as always, trying to keep you informed!

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