Australia Winter 2018 Seasonal Outlook

Hello, it’s the Snowy Hibbo back for another Australian snow season. I’m getting excited myself, I cannot wait to finally get the skis on for the first time since September last year. Another year, and another outlook. Last year, I spanned this process into a three part series. I decided this year that I am going to complete it in one big post. It’s a big read, so let’s get started with the climate models.

Climate Models

First the EUROSIPS models, or the Met Office, Meteo France and ECMWF models combined. This ensemble of models all individually and collectively show a troughing anomaly over SE Australia and the Australian Alps, encouraging snowfall. It’s collective temperature and precipitation outlooks for winter look fairly neutral at the moment.

CanSIPS shows mild troughing anomalies across the Australian Alps, indicating more potential for snowfall. It’s precipitation and temperature forecasts are also neutral.

CFS shows mild troughing anomalies just to the north of the Alps, covering most of NSW. It forecasts the temperatures to be average, but the precipitation forecast to be fairly dry for the Alps, particularly in Victoria.

NMME, which is a multi model ensemble of most major US and Canadian seasonal models including CFS and CanSIPS, shows the temperatures to be slightly warmer than average in the Alps during winter.

Now onto the main section, where we dissect the climate drivers and put that into numbers. I will start with the 2007-2016 10 year dataset of approx 173cm, mainly because last year was a mathematical outlier. The dataset involved is the Spencer Creek snow depth measure

Climate Change: I am not using this, because it skewed data last year, when drivers also show the changing climate like ENSO and especially the SAM.

PDO: There is a weak correlation between a negative PDO and higher rainfall in our region. This increases moisture for snowfall, supported by this graph created by Gerg. We are currently in a negative PDO phase, so I am going to add two centimetres. 173+2 = 175cm

SAM: There is a fairly strong correlation between negative SAM and more snowfall for the Alps. I talked about the seasonal prediction of SAM here. El Niño Modoki (the only seasonal prediction factor of SAM, other than a weaker correlation to Eastern Pacific Nino) is at a Neutral phase, so no forecasted effect on SAM(on either JMA or POAMA). Adding in climate change(that increases chance of positive SAM), I am going to cut off 3cm. 175-3 = 172cm.

IOD: There is a correlation between the Australian snowfall and the IOD. There is a Negative IOD forecast for this winter by some models, others are just cool neutral, which in my opinion is just as good, if not better than a proper -IOD. This is good for our snow. I am going to add 7cm here. 172+7 = 179cm

ENSO: There is a correlation between ENSO and Australian snowfall. The current model predictions show a fairly neutral forecast. I feel this will help a little bit with our snow, looking at model projections from CFS and EC. I will add 5cm, based on what it could do to our neighbouring climate drivers. 179+5 = 184cm

MJO: Australian snowfall and MJO have a very strong correlation. There’s been work done on the relationship between ENSO and OLR anomalies (related to MJO). OLR anomaly forecasts are not usually given to the public. There is a 200hPa CHI anomaly forecast from CFS on Tropical Tidbits. This shows a Phase 7-8 MJO setup, which isn’t particularly helpful for Australia. During El Nino(which is probably not going to happen in our season), the MJO is typically suppressed, but the months leading up to one (like it could be now) typically have much more of a MJO presence, which is good for our snowfall. The current results with the global wind Oscillation and the effects of the Walker Cell(ENSO) show potential for this to occur. I am going to add 3cm, because these are encouraging, but not strong or absolute results. 184+3 = 187cm.

Sunspots There is a weak correlation between a higher amount of sunspots and more snow, as found by Francisco Sánchez-Bayo and Ken Green. We are heading towards a solar minimum(pretty close now), so I am going to cut off 3cm. 187-3 = 184cm

Volcanoes If a large stratospheric volcano explosion occurs, Australian snowfall substantially increases for that winter. None have occurred in the last year, so our forecast won’t be affected. 184-0 = 184cm.

SST anomalies: Based on current charts, the Bight is forecast to be pretty neutral this winter. Examples of this are ECMWF and CanSIPS. CFS disagrees showing cold elements in the Bight. In addition all models show warm to very warm anomalies in the Tasman, which increases moisture, but reduces cold rapidly in a double edged sword scenario. Gerg has a graph for this(Tasman SST). I think it is in our better interests to get this moisture from the NW of Australia through MJO or other wave activity. This is improved with higher than normal SSTs north and northwest of Australia. Because of these poor SSTs in the Tasman and the neutral Bight and the good NW Aus SSTs, I will decrease only two centimetres from the forecast. 184-2 = 182cm.

So my final maximum Spencer’s Creek Snow Depth for this year is 182cm. This number has came around from hours of analysis, tinkering and changing. The models in my opinion, are pretty good, despite CFS and NMME showing slight dryness and warmness respectively. The 182cm figure is higher than both the 10 Year figure from 2007-2016 that this is based upon, and the actual 10 year figure from 2008-2017, which is 180.9cm. So the forecast is for a slightly above average snow season in my opinion. I hope you enjoyed this analysis, and I will see you for a before the season long Range outlook.

Disclaimer: Remember seasonal prediction isn’t a very accurate tool, so be careful when basing any major decision on any seasonal forecast, including my own.

Thanks again for reading this Australian snow season outlook, follow me on Twitter @longrangesnow and subscribe to my email list by clicking on the tab on the main header above.

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