Welcome back to this season’s long term outlooks for the Australian snow season. First we will look at the modelling for dates, and then the climate drivers.
GEFS and EPS both show a trough peaking over Western Australia and falling down into Southeastern Australia and Tasmania starting either over the 14th and 15th, and pushing through the 16th of June, which may bring little for the Alps, could also be a signal for a warm and wet front, and it also could possibly mean a chance of some snowfall, which has been flirted with by GFS at times.
EPS shows more of a cut-off low scenario, and GEFS has a more trough-based scenario, and both have been slowly improving the prospects with this period.
EC Monthly Control shows dual troughs on the 23rd of June and 26th of June, both bringing snowfall to the Australian Alps. The ensemble mean doesn’t really connect with these ideas however, showing primarily ridging during this period.
On the North American model ensemble side, this period is forecast to feature ridging for SE Australia, but shows troughing over Western Australia.
You can see the LWT node for the date period above is relatively weak on the chart below south of Madagascar. But there may be something more interesting on the next cycle after that on the 2nd-7th July.
The AAO is forecasted to stay positive over the next two weeks for the most part, and it is clear that we are in a positive AAO state of play for a while indeed. The brief more neutral reprieve may be a catalyst for the WA peaking system as it aligns well with this event on the charts.
As for when we will see a more solid negative phase of the AAO, it is looking possible that we will see an easing of the positive state in the 15th-25th June timeline, per EC guidance, but it is very possible the models are showing us a false end to this state as well. But looking relatively good of heading towards a more negative phase in the later stages of the month or possibly in early July. AAO states typically cycle around a month or so, which means these timelines generally go with that flow.
The tropical base state is looking like it will benefit the Phases 1-3 of the MJO in the Indian Ocean. This is possibly a reason for the consistent progs for a WA peaker pattern for the rest of the month.
For Australian snowfall, we would prefer the negative cool coloured signal to be over Phase 5 and 6 within our region.
There may be a possibility for the MJO to enter our region in the last few days of the month into July, but this is only a possibility at this point.
As to be expected, the Global Wind Oscillation is largely acting in the mold of the MJO staying around the Phase 1 zone, however also similar to the MJO it is being generally kept in the neutral influence area.
The negative phase around the 13th of June may assist the medium-term system around that time down here, but a general more positive trend would increase the zonal flow in our region, that may serve to get rid of the dominant ridging blocks, but also weakens the chance for cut-off lows that bring good snowfalls.
Disclaimer: There is lower skill associated with using long range model forecasts to find snow systems.
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