18th-22nd of August
We see a new long wave trough come through the region around this period, which shows potential for snow-bearing cold fronts. We see a proper cold trough come up on the Tuesday and Wednesday next week, as indicated by the cold air seen on the ensembles.
We see it squeezed between a ridge over NZ and the ridge SW of the trough towards Antarctic. This brings a longer trough trailing the main cold node, which brings a westerly theme to this particular system.
GEFS has a very similar setup, featuring all the same key components, with a slightly enlarged upper level cold node.
GEPS shows a zonal pattern from the Indian Ocean, with troughing anomalies stretching from WA to SE Australia, with the cold node nonetheless centred on the Southeast
Zooming in on the deterministic point of view, we have ECMWF here:
As one can see the front comes over SE Australia early on Tuesday, and pushes through to the Alps during the day.
We see stronger snowfalls associated with the cold airmass on Wednesday afternoon into Thursday morning. Then we see the main node push into the Tasman on Thursday, but we see a backdoor low coming up from the south during Thursday night into Friday, pushing up into NSW throughout Friday and bringing snow to low levels further north.
GFS shows a similar system coming down from the West on the Tues/Weds, and collapsing into the Tasman as a large-scale cold air mass. We then see the polarisation of a sharp deep low coming from the south, similar in timing to EC on Thursday night into Friday, but stronger, colder and it doesn’t shift as far north as EC.
So overall we have a great opportunity here, looking like a 30-50cm system at the moment, even more is possible with that follow-up low from the back. Certainly looks like a more traditional system, compared to some of the Tasman-based systems of recent.
Looks like we will have potential for another cold and snow-bearing system around the 27th August to the 31st of August, per the rotation of the Long Wave Trough.
Beyond that, perhaps a possibility for a system around the 4th-9th of September, EC Monthly is willing to play ball with it.
EC Monthly is showing a stronger signal for the 17th-23rd of September as well for a cold front through SE Australia.
We are currently in the best MJO phases for snowfall (and it hasn’t delivered a lot), but we may see it’s lingering effects on our region with the system next week.
You see the strong phase over Australia/Maritime Continent, and then it weakens and skips the Western Pacific, and strengthens within two weeks over the American continent. This serves to weaken any push away from a La Niña, and generally helps to lean towards a negative AAM state in the next few weeks. This is certainly something that could potentially help our snowfall chances.
Phase 8/1 are certainly highlighted by both EC and GFS ensembles, passing up expansion into the Western Pacific phases, which would spike momentum in the tropics. While the MJO will no longer be favourable in a week or so, the base-state might be improving for us.
We are currently heading towards a -AAO state for the next week or so.
As you can see the phase is strong, but quite likely to be temporary, with some more +AAO spikes later in the month. But hopefully we can push towards a few more -AAO moments.
Also worth noting that the stratospheric polar vortex in the Antarctic remains largely stable, with only minor disturbances and relative maintenance of strength at the moment.
EC concurs with the GFS model point of view below….
Thanks again for reading this Australian long range snow forecast, follow me on Twitter @longrangesnow and subscribe to my email list by clicking on the tab on the main header above.