In the upper reaches of the Southern Ocean, just below the Great Australian Bight, an enormous, spiralling stream of icy air churns eastward.

Before sun-up in a lounge room in suburban Wollongong, a man known as The Frog pores over satellite charts and data sets, plotting the path of this meteorological beast.

On a hunch, he can accurately predict when the monster highs will deliver the next major dump over the nation's ski fields - although not always so precisely how much snow will arrive.

Snow forecasting is at once an exact and inexact science, says Pete Taylor.

Regarded as Australia's best at what he does, he should know.

He's also probably the only expert in this obscure field who still does his work based on personal observations rather than sophisticated computation.

"I'm probably the only human forecaster left," he tells AAP.

"These days, everyone else is using some kind of algorithm. I'm the only one who seems to go on actually seeing something I think is going to happen."

This winter, the southern hemisphere oscillations have gifted skiers and snowboarders the best opening to a season in more than 20 years.

At Australia's largest resort, Perisher, a metre of snow - or يلا لايف يوتيوب half a good season's worth - prompted a limited early opening.

At Thredbo, falls have totalled 125cm, with lifts operating since Saturday.

The story is similar further south. Mt Bullah (76cm), Mt Hotham (94cm) and Falls Creek (95cm) are also up and running.

"Everything is looking good because the high-pressure systems involved have shifted a lot further south than they normally would," Mr Taylor says.

"We're really lucky. The La Nina pattern, with so much moisture around, meant it looked like we were going to see a lot of rain.

"But because the highs have shifted down, they're spiralling a lot of cold air up from the south and it's all mixing together."

He reckons the good times will roll on for at least two or three weeks, with the next big dump due on June 22.

For it to be the best ski season ever, the snow depth would need to exceed 3.5m between mid-June and October, as it did in 1981, according to Snowy Hydro records that date back to the 1950s.

The further into the future forecasters look, however, the more difficult the prospect of accurate prediction becomes. Projections are also complicated by the prospect of precipitation falling at lower altitudes manifesting as rain.

"Sometimes in the early days, I'd see something and I'd get a bit excited, think it was going to be 40cm or 50cm of snow and it would turn out to be 20cm and people would be disappointed," Mr Taylor says.

"So I go on the lower side and then as things get closer, if I'm really confident with it, I ramp it up."

It's a fine line. There could be a single degree between a big dump and powder washing away, while falls from the same weather system can also vary greatly between resorts.

The Frog's forecasts for NSW and Victoria are published at snowatch.com.au over five, 10 and 15 days. He then offers general long-range observations and a seven-day report for New Zealand's south.

It takes around 90 minutes of analysis every morning before Mr Taylor sets off for his 'real job' as graphic designer. The forecaster graduated from art school and has no formal scientific background.

After joining an online forum in the 90s, he began chatting with other snow enthusiasts about how to make the most of the ski season and got interested in studying meteorological charts.

When his self-taught predictions began attracting notice, people started emailing for advice on when to best head for the mountains. A trickle became a flood, so he set up his own free website.

He initially used "The Frog" pseudonym to remain anonymous but dispensed with it as his confidence grew.

"I just look at the data and type out what I see," he says of his method. "That's pretty much it."

It was good enough to convince organisers to postpone World Cup aerial skiing events at Mt Buller in the early 2000s in order to catch more favourable conditions.

Over the years, the process has become more involved, with the addition of wind strengths and the likelihood of conditions allowing for artificial snowmaking to supplement natural falls.

"I've fine-tuned things and found a few more resources," Mr Taylor says.

"There's a lot more to look at on the internet than there was when I started out."

Although travel companies advertise on his site, he doesn't charge clients for forecasts.

"I couldn't in all honesty guarantee what I was telling them was going to be a hundred per cent correct so ...

I couldn't do that," he says.