By Andrew Mitchell
While no doubt some Canadians are welcoming the Meteorological Service of Canada’s forecast of a warm, dry winter, the impact on coastal mountain resorts like Whistler may not be as bad.
According to MSC weather forecaster Peter Jones, the main culprit behind the warmer temperatures is an El Niño developing over the eastern Pacific Ocean.
Warmer El Niño waters typically influence temperatures across Canada, to the extent that it has become one of the more reliable forecasting tools for meteorologists.
The connection between El Niño and precipitation is less certain, says Jones, and on the coast it can vary depending on the presence of an Aleutian low pressure system further north. While most of the country could experience lower precipitation because of El Niño, the coast could actually be a great deal wetter.
That, says Jones, is where freezing levels come in and higher temperatures will have the greatest impact.
“In the end, what we think we know and do know to some extent is that at lower elevations in the Coast Mountains, 1,200 metres and below, whatever precipitation falls will fall more as rain proportionally than in a normal winter,” said Jones. “When you look at Cypress Bowl at 350 metres you can see the snow at a fraction (of normal) during an El Niño, while at 1,900 metres at the Roundhouse (on Whistler) — where we have records back to 1973 — is more total snow.
“It might be wetter snow on average, because the freezing level is a little higher, but overall that’s what we’ve seen.”
Some of Whistler-Blackcomb’s best winter seasons, including 1997-98 and 1998-99 were El Niño years.
El Niño conditions in the Pacific so far are rated as weak, but according to MSC computer models will become moderate by December and the start of the winter season. As a result there is less likelihood of arctic outbreaks that last for any length of time, if the southern part of the province sees any arctic weather at all, and parts of the Lower Mainland will likely stay snowless throughout the winter.
“Personally I’m a skier so I’m always interested in the data, and I’m anticipating a lot of questions about this because of the huge economic impact it could have on the province, a lot of questions about the snow,” Jones said. “It’s only in rare years that I would take the time to explain what we know, every other year I would say we’re guessing, don’t waste you’re time on this even though we put out a seasonal forecast for every season.
“El Niño winters are different — only when El Niño is moderate or strong do we have any confidence in (the seasonal forecast).”
For December through the end of February, temperatures in the southern part of the province are expected to be about 1.5 degrees Celsius warmer on average, with parts of Ontario and Manitoba expecting temperatures almost three degrees warmer. Temperatures will be close to normal, about one degree warmer than average, for March, April and May.
In terms of precipitation, the Coast Mountains could see anywhere from 0.2 to 3.8 additional millimetres per day, averaged out over December, January and February, while the Interior of the province could see a drop of 0.3 mm per day on average — depending on the strength and position of the Aleutian Low.
Precipitation in March, April and May for the Coast Mountains is forecast to be close to normal, or about 0.1 mm per day above average.
Although there is no established link between El Niño and global warming, some evidence suggests that there’s an indirect link that amplifies the effect of the warmer waters on climate.
It’s interesting to note that Environment Canada’s predictions run against those of the Canadian Almanac, which is predicting temperatures that are one or two degrees colder on average and near normal precipitation. The Almanac also predicts that the most snow will fall in mid-to-late November, from early to mid-January and from mid-to-late February.
While the MSC uses computer models to predict weather, the Almanac uses a secret formula devised in 1792 and calculations based on solar activity and sunspots, as well as weather history.