How to predict the coming southern winter season snowfall…

Can’t decide where to book for the upcoming ski season? Have you asked the moon? How about your next door neighbours dog? Sam Pullos pulls a rabbit out of his forecast hat.

March may be too far out for any serious meteorologists for this southern winter, but our nagging desire to pin down powder days sends our search for weather insight to all corners of the species spectrum. No animal, celestial body or even month is safe from our incessant scrutiny and false correlation.

Red skies at night. The cows are laying down. Wasps making their nests higher up in trees. Moons with Halos. ‘Snow in May won’t stay’. Black cockatoos coming down from the mountains. These are just some of our most popular meteorological predictors.

To be fair, some more firmly based in reason than others, but still. I won’t be booking my accom in Thredbo based on what the cockatoos tell me. If I did, I’d be a bit of a galah.

Whilst we humans love to correlate unrelated events, a halo around moon is actually something to get excited about. If you live somewhere that snows. And it’s winter. And the temperature is right. The halo is caused by cirrostratus clouds which often form as precursors to storm fronts.

So, if the above conditions are all aligned you could be in for some snow within the next few days. Hardly a season prediction though.
moon-halo

La Nina or El Nino?

The truth is, the Australian and New Zealand snow season is at the mercy of numerous powerful weather systems/patterns. Our snow seasons are greatly effected by the ENSO cycle and whether or not it is a El Nino, La Nina or neutral year, with neutral years generally being the most reliable.

ENSO_schematic_large

Then there is the Sea Surface Temperature (SST). The warmer that is, the more likely rain will show up and ruin the party. Although, cold temperatures and high SSTs can result in big snow dumps. So it really depends. I know, I’m not helping.

Who could forget about the Indian Dipole Index? This looks at the difference in sea temp between the Arabian sea and the sea to the south of Indonesia. It is proposed that warmer temps in the Arabian Sea lead to greater precipitation in the south of Australia.

 

iod-negative

Last but not least, we can look at the Southern Annular Mode (SAM). This tracks north/south movement of a belt of westerly winds whipping around Antarctica. From what I can tell, a positive reading means dryer conditions in the south. This is why I’m not a meteorologist.

Southern Annular Mode

Combine all of that with the low altitude and warmer (relatively) temps of the Australian mountains and you have a very delicate snow ecosystem.

New Zealand relies on a combination of a lot of the same systems, plus a few more. Then there is the fact that the ski spots are much more spread out in Aus, meaning that different locations benefit from different weather cycles. The NZ season is just as hard to predict overall.

No wonder the cows get it wrong.

Who to call?

In the midst of all this cross-species speculation, two animals have shown themselves to have an authoritative and reliable voice in the world of snow prediction. The grasshopper and the frog.

Now, snow is not exactly what comes to mind when thinking of these biblical icons, I mean, some frogs just give up and freeze solid whilst grasshoppers tend to just, well, die. Don’t worry, I’m not going to tell you to go and count the croaks in your drainpipe or read the palms of hoppers eating your grandmother’s roses. No, I am talking about specific, bipedal, humanoid incarnations of their plague inducing namesakes.

frozenfrog
The Grasshopper and The Frog are the resident meteorological forecasters at Mountainwatch and Snowatch, respectively. They are also experts in making sense of the complex weather systems I atrociously under-explained earlier. The end result is impressively bang-on snow forecasts before any of us have even pulled out our ski gear.

The peak snow depth at Spencers Creek in NSW, acts as one of the primary snow-depth indicators for the snowy mountain region and is closely monitored by Snowy Hydro. Here is what the last 5 years have looked like:

Screen Shot 2017-03-29 at 3.41.26 pm
Let’s hope we get a 2012 repeat this year. In any case, in five years of pre-season predictions, The Grasshopper is on average, within 14.5cm of the actual seasonal season peak snow depth. That includes a bumper 2012 season where snowfall took everyone by surprise. Just to be clear, these predictions are made in April.

The Frog has a similarly stellar strike rate. Given the notorious difficulty of predicting snowfall, the long-range accuracy of these guys is incredible. Forget the moon, the wasps, the cockatoos and whoever else squawks prophetic snow predictions, these two guys are your go to.

Each give regular seasonal outlook updates both as the season draws closer and once the snow starts falling, so you’re always in the know.

Both animals extrapolate their readings to cover NZ, so if you are looking for some southern hemi skiing this winter, your best bet is to take their advice when booking your trip.

It is still too early for our leading meteorological animals to be making predictions about the coming season. However, winter is coming, as the Crows would say (Oh, I went there).

Keep on the lookout. We’ll have a detailed report from the best forecasters here on SnowsBest later in April.

Until then, you could always see if wombats work like their trans-pacific brethren, groundhogs: if they see their shadow and run back to their burrow, it’s going to be a long winter!

 

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