Some very intriguing systems and climatic conditions to talk about, which should hopefully bring us more snowfall in the next few weeks!
But I don’t think we can go without acknowledging today’s snowfall for the Snowies, and the good potential for more snowfall over the next few days.
Something that was called in our last outlook a little more than 2 weeks back is becoming clearer to see now.
There are a number of schools of thoughts from the modelling about this period:
- EPS (above) is looking for a peaking trough through the 2nd-4th of July, with this being on trend in terms of timeline from previous runs (albeit it has significantly strengthened in nature since)
- GEFS (below) delivers us a more muted affair trying to come up over the 4th all the way through to the 7th, not as grand or strong as the EPS effort. This has been on for about two runs, succeeding a less bountiful collapsing trough to clip SE Australia, so the system is improving on trend on GEFS.
- GEPS (not pictured) offers a more meagre scenario with a break between the ridges during the 3rd to 5th of July, being the less exciting of the models for this period. The Canadian ensemble has bucked the timeline of previous runs, pushing forward from the 1st-3rd July.
EPS is certainly the keen one and certainly has decent trend and reputation to back it. Beyond the modelling solutions, looking at the projected long wave node on GFS:
The LWT is aligned roughly around the 3rd of July. The best systems typically occur just after the long wave node, so it implies that the best possible period of favourability for the SE Australia region would be from the 3rd to the 6th. But as Deterministic GFS has appointed itself upon in the most recent run, we could always have a curtain-raiser just as the node begins to pass.
And the better main system which the first trough has cleared for gets to pass through on the 3rd-7th of July.
EC also has a massive node in the Bight, that is due to land in SE Australia’s doorstep around the 3rd of July. It is yet to be seen if this peaks over SA, or the ridge leans over it and pushes the conveyor belt right into the Australian Alps. It also might be pushed a little later as this system forecast matures, but it’s certainly the stage on what could very well be the season starter for 2020.
We are looking at another potential system period in a little while, shown by the LWT south of Madagascar that should be in our region around the 10th-14th of July.
EC Monthly Control certainly agrees with a scenario that is set-up to deliver moderate-heavy snowfall for the Australian Alps. It’s certainly potentially a big fish.
Should we want to go even further with the forecast, I can see the next LWT node in our region around about this time next month.
EC Monthly Control is certainly trying for it.
We are currently outside of the tropical signal, but by the end of the month and into July, we should see the tropical signal move into our region, which is beneficial for our snowfall, and should really help the 1st-7th July period come to fruition IMO.
We have a number of conflicting takes from the models on the all important long range forecast of the AAO.
EC shows a great setup for the rest of the month, as we see a strong negative decline, heading towards that potential in the first week of July. However of course it is uncertain how long it will stay like that once in July, but noting the model trend and the gravity of this switch, there is potential for it to be a while.
It’s worth discussing the GEFS, which shows a decline in the AAO now, but struggles to hold that into July. It could be said that it has a bias towards potentially strengthening the Southern Hemisphere polar vortex in the upper stratosphere, but only time will tell, but it certainly doesn’t look amazing.
But it’s American compatriot in the GEOS (NASA model), shows a solution more like EC, and shows a potential for a longer term dip of the -AAO.
We see a trend over the month for a positive AAM to grow, which may be bad news come mid-late July, but for the next few weeks we see:
- A pre-existing negative AAM base state which is good for Australian snowfall.
- And potential for positive mountain torques that would help to disrupt the stratospheric polar vortex.
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Charts courtesy of Tropical Tidbits, Weatherzone, Weathermodels, Accuweather, Michael Ventrice, Stratobserve and Victor Gensini
Image courtesy of Charlotte Pass.