Could Oz snow season be an El Nino bust?
With the start of the Australian ski season a little over three months away the combination of these words are about as welcome as Trump and presidency; Nickelback and concert and Kyrgios and Tomic.
Unfortunately in its glimpse to autumn and beyond this is exactly what the Bureau of Meteorology tends towards for the eastern part of Australia in 2017.
So, should you be putting extra storage wax on your skis or board after the northern hemisphere season? Well …
It’s complicated but here goes
First up, while suggesting caution at this time given autumn models tend to be the most variable this is what the BOM is saying:
“Recent changes in both the tropical Pacific Ocean and atmosphere, and climate model outlooks surveyed by the Bureau, suggest the likelihood of El Nino forming in 2017 has risen. As a result, the Bureau’s ENSO Outlook status has been upgraded to El Niño WATCH, meaning the likelihood of El Nino forming in 2017 is approximately 50%.
“Sea surface temperatures have been increasing in the eastern Pacific Ocean and are now warmer than average for the first time since June 2016, while the Southern Oscillation Index (SOI) has been trending downwards.
“Seven of eight international models surveyed by the Bureau indicate steady warming in the central tropical Pacific Ocean over the next six months. Six models suggest El Niño thresholds may be reached by July 2017.”
Enough already, tell me what it means for the snow season
Broadly speaking El Nino brings with it below average winter/spring rainfall over eastern Australia and warmer than average winter-spring maximum temperatures in southern states.
Obviously, not so good.
El Nino years often have lower snow depths at our snowfields. How much lower? Looking at El Nino seasons through to 2014 the BOM calculated on average a depth 35cm less than the overall average. Also the period of time with 1m of snow or more on the ground at Spencers Creek was 2.5 weeks shorter.
The four worst seasons were in El Nino years and two of them resulted in the 1m not being reached: 1982 (peak depth 91cm) and 2006 (peak depth: 85cm).
So far, so bad. But it may not be a complete shit sandwich
History has shown that El Nino years don’t always = bad season. Try for example 1972 (227cm) 1977 (227cm) and 1991 (285cm), El Nino years where the peak depth was well above average.
Also while the day time temperatures are higher (eeww, meltage) the night time ones are frequently lower due to the reduced cloud cover. In fact northern Victoria and southern NSW can experience an increase in frosts of between 15 to 30 per cent under such conditions.
That can also be a big help with snowmaking, and if the temps during the day don’t regularly get too out of control there’s a better chance of keeping what falls than say when you get a number of big rain events that occurred during season 2016.
A classic example of this was 1994, a year I remember fondly as I worked the season in Thredbo. It wasn’t a huge snow year (peak base: 168cm) but it still holds the coldest temperature ever record in Australia (Charlotte Pass – 23, June 29). My memory is of a good start, some nice cold storms, very little rain until September and then a quick tailing off of the season before a late dump.
So, what to conclude
Granted, early signs are not great but you’d be foolish to rule anything in or out just yet.
Less than two months out from the North American season plenty of experts actually had little to no idea about what was to come and in a number of areas it has turned out to be a cracker of a winter.
My less than scientific advice? Wait for a decent base and be prepared to strike when the weather and conditions allow shortly thereafter. It’s not ideal but it’s kinda how you have to roll in Australia.