Agata Imielska drops the latest on the seasonal outlook.
There has been a lot of speculation on whether ski resorts, or parks for that matter, will be open for the 2020 ski season. One thing we haven't talked about much is what the snow season itself might be like… Well, one thing is for certain, it won't be like the last 3 seasons we've had in 2017, 2018 and 2019. In fact it might a bit more like 2016.
How can we be so certain? Especially given that Australian snow seasons are as variable as they can get. Well for one, we can't be 100% certain, but climate models are slowly cranking up the likelihood of a negative Indian Ocean Dipole for this winter. This is a climate driver that brings tropical moisture from the northwest of Australia bringing wetter conditions to much of Australia during winter and spring.
Historically the most reliable snow seasons have been during 'neutral' years where neither the Pacific or Indian Ocean climate drivers (ENSO & IOD) have been active. While dry phases (such as El Niño or positive IOD), bring less moisture overall, also don't bring the risk of the moisture falling as rain rather than snow, helping the snow last longer and accumulate through the season. It also tends to be better for snow making conditions. Wet phases (such as La Niña or negative IOD), bring more moisture, but more risk of that falling as rain not snow, washing the existing snow cover away and making for some pretty dreary conditions on the slopes. However, if the conditions are right, it can also mean lots of moisture converting to lots of snow (if it's cold enough).This is more likely in isolated events as opposed to consistently throughout the whole season.The wet and dry phases are both double edged swords, which is why the neutral years have brought more reliable conditions in the past. There's also another climate driver, the Southern Annular Mode (SAM), that can increase or decrease the chances of cold fronts being able to bring that winter rain or snow. If you want to know more about the role of these climate drivers on our snow check out this article and BOM’s info on ENSO, IOD, SAM and their impacts on Australian climate.
Now enter climate change, warmer temperatures and decreasing snow and rainfall during our cool season – both important changes that need to be taken into account. Both factors are not good news when it comes to snow, but it certainly doesn't mean that Australian snow seasons are doomed. Think about the last three years, which were some of the worst drought conditions experienced for parts of Australia, and yet the snow has been well, pretty great (all things considered). A part of the reason why this is the case is in the mechanics behind these trends. High pressure systems have been sitting further south over Australia during winter in our warmer world. This has meant that you need a strong cold front to be able to push that high pressure system along. That's not always the case, but the overall trend has been that the usual winter storm tracks, that come from the south, don't make it as far north into our continent as they used to, and the result has been less rain which might also contribute to a lower snow accumulation (but temperature and rainfall plays a role there too).
We also know that it’s the low and moderate snowfall events that are reducing, not the big snow dumps, which lines up with the changes we have observed in our winter rain (and snow) bearing systems. If you love getting into the detail here's a great science paper to check out on just that.
What that might mean for Australia is increased avalanche risk in the snow season as these snow dumps are often interspersed with dry warm spells which drive melt freeze cycles in the snowpack with possible frost (surface hoar). This then creates very unstable snow layers once the snow starts to fall and then boom, avalanche. These are the weather conditions that lead up to size 2 avalanche at Ethridge Ridge Last year (read about the experience here).
Avalanches aside, there is plenty of other things that can go wrong in the Snowy Alpine regions. Ski resorts do a fantastic job of providing a safe environment in the snow, managing the risks they can, to make it easier for skiers and snowboarders alike to focus more on having fun. Once outside the ski resort patrol boundaries, you now need to ensure you manage that risk yourself. Do you know what the weather is going to do? What are the snow conditions like? Remember no one is grooming runs for you in the backcountry! How will you find your way if you lose visibility? Do you know how to manage icy conditions and if you slip and lose your footing? Do you have a first aid kit? A personal locator beacon? And does someone know where you are going, when you're expected back and what to do when you're not?
To help out any newbies thinking of heading out into the backcountry we will be doing a series of blogs that will help to demystify how to get started, but also raise awareness of the things you really need be aware of to reduce your risks and maximise your fun while in the backcountry.