2nd July Australia on the long term

Welcome back to another long term update for the Australian Alps on the matter of when our next snowfalls will be, via looking at the long term modelling and the climate drivers.

The day to day modelling outlook

The next major snowfall looks to be around the 11-15th July system period.

EPS here shows the deep anomaly of cold air in this period. Guidance from GFS LWT charts shows significant support from a long wave trough for this period. This shows a potential dump risk for this period. However the weak moisture drivers will prevent a very large one unfortunately.  Preliminary thoughts are for a system on the 11th/12th as indicated by EC(below) and GFS.

And some sort of system on the 13th and 14th also indicated by both EC and GFS. This is certainly the kind of period where there is a large potential for a solid streak of snowfall days in a row. And this is increased, because of the deep and prolonged anomaly that is involved with this period.

Beyond that period, we have a ensemble pronged high moving in over the 15th through to the 17th. The interesting period after this is the 18th to the 21st of July. The period has some old RRWT support, but the LWT factors look weak for this period, with the succeeding long wave after the 11-15th LWT pass stalled south of Africa. However the main reason I bring it up, is some support from GEFS(below) and GEPS… (annotation: mine)

The 24-28th of July period also intrigues me, because of this chart below from the EC Monthly run, and the parameters the period has that allows it to be potentially conclusive to a LWT pass, if the stagnation of the LWT wave south of Africa on the 10th moves towards us, after a few more days being stuck.

Climate Drivers

The MJO is looking like it is going to be around Phase 2/3 by the 15th of July per GEFS and EPS (below).

We could see the Phase 4/5/6 MJO pass we are looking for, could occur in late July and Early August. That would mean we see more moisture later in the month.

The AAO or Antarctic Oscillation also looks like it is improving as well, although the latest GFS run looks like the -AAO values neutralise around the 11th and 12th of July. These are all better signs for our snowfall. There is also a sign of some weakening in the Stratospheric Polar Vortex, which would help us to strengthen the LWT and therefore make the AAO more negative.

The AAM or Atmospheric Angular Momentum is currently close to neutral, and the closest it has been to negative values for a long time. It is currently forecasted by CFS to remain neutral for the rest of the month.

However GFS (bias-corrected) has flung the other direction and is deeply negative in it’s forecast. All of this means that July should be a better month than June, because there should be more of a meridional setup, which helps to bring coldfronts to SE Australia. Add in the negative anomaly at our latitude and there is a lot of potential for snowfall bearing conditions in this outlook. The AAO is improving, the AAM is improving, all we need is the MJO to help out with moisture later in the month. Given the +IOD, you won’t really be able to deliver a solid big dump without MJO and Equatorial wave support.

Disclaimer: There is lower skill associated with using long range model forecasts to find snow systems.

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(Courtesy to Victor Gensini, weathermodels.com, the CPC, Levi Cowan and Accuweather for the graphics)