Lindsey Jacobellis launches off a jump during the World Cup women's snowboardcross event at Cypress Mountain last February. (Jonathan Hayward/Canadian Press)Vancouver's ski season is officially launching early this weekend, after a series of chilly storms dumped more half a metre of snow on the North Shore Mountains this week.

Concerns remain, however, about how an El Nino climate pattern may affect the ski season, and it is still not clear what the conditions will be like on when the Olympics come to town.

The Cypress Mountain resort, which is hosting the half-pipe and freestyle ski events during the coming 2010 Winter Olympic Games in February, was reporting one lift open with a 45-centimetre base on Friday morning, the third earliest opening in the resort's history.

'Generally El Nino means less snow.'—CBC meteorologist Claire Martin

Nearby Grouse Mountain, was planning to open one operating on Friday afternoon, with a 65-centimetre base of snow.

Earlier in the week, Whistler-Blackcomb announced it was also preparing for opening day on Saturday, when four lifts are expected to be open on the Whistler side of the dual-mountain resort.

In the interior earlier this week, the Big White resort near Kelowna and the Sun Peaks resort near Kamloops also announced plans to open this weekend.

The El Nino effect

CBC meteorologist Claire Martin said the West Coast is still in the midst of the same El Nino climate pattern that led to a record-setting heat wave across much of B.C. this summer.

And while the pattern is weakening as surface temperatures in the Pacific Ocean continue to slowly return to normal, it will be months before the El Nino pattern is over, said Martin.

Ski runs at Whistler Mountain are expected to open this weekend. (Doug McFarlane)And it is not clear what that will mean for B.C. slopes.

"The link between El Nino and milder temperatures is very strong. The link between the El Nino event and snowfalls is way tougher to forecast and tie together," she said.

"Generally El Nino means less snow," said Martin, but she notes there are exceptions.

During the winter of 1998, there was one of the strongest El Nino patterns on record. But during the last two weeks of February that year — right when the Olympics will be held — Whistler received one of its largest snowfalls ever recorded for that period — 205 centimetres.

Bigger threat at lower elevations

The bigger threat from an El Nino will be for ski operations at the lower elevations, such as the Cypress Mountain resort, or the Callaghan Valley, which is hosting the Olympic Nordic events.

That's because during an El Nino event, the freezing level rises just enough to make the difference between rain and snow for those locations.

While the top of Whistler is well above the winter freezing level at 2,000 metres, Cypress Mountain resort at just over 1,000 metres and the Callaghan Valley at just under 900 metres are both right in the critical transition zone.

The hills on the North Shore are known for having deep powder one week, only to have it disappear under a wave of rain the next, even in the depths of winter.

"At Whistler, it's almost irrelevant. They made their base. They can make all the snow they need at the higher elevations," said Martin.

"But at the Callaghan Valley and Cypress, they could see five to seven days of rain. It could become a race against time to get off all their events in 14 days," said Martin.