This winter could be one of the coldest in 20 years in Western Canada, but Newfoundland and Labrador is expected to see above-normal temperatures, according to Accu Weather senior meteorologist Brett Anderson.
He’s also predicting much of Newfoundland and southern Labrador will experience slightly drier than normal winter conditions this year, but a couple of significant snowstorms in the first two months of 2012 will increase the precipitation on the Avalon Peninsula, bringing it to normal or above-normal.
Anderson, who’s based in State College, Pennsylvania, writes a blog on www.accuweather.com about weather forecasts for Canada.
In a telephone interview, he said he believes temperatures will be warmer than normal throughout much of Atlantic Canada from December to February and most of March.
In Newfoundland, Anderson said, temperatures will likely average close to two degrees above normal. “In January, for instance, the normal high in St. John’s is about -1 C and the normal low is about -8 C,” he said, but the predicted temperatures will be more like 1 to 2 C during the day and -5 to -6 C at night.
One reason for this, Anderson said, is the position of the jet stream, “which we believe is going to be taking a big dip across Western Canada and, when it usually does that, it’s cold in Western Canada, but it’s not that cold across Eastern and Atlantic Canada. When the jet stream takes a dip in the West, it usually starts coming back up northward into the East, which keeps the cold air away from Atlantic Canada.”
Anderson said there is a moderate La Nina this winter, which has “a big impact” on the jet stream position during winter across Canada.
La Nina is a phenomenon that occurs when sea surface temperatures across the equatorial central and eastern Pacific are below normal. It produces extreme cold outbreaks across Western Canada during the winter due to its influence on the jet stream. Snowfall tends to be greater across Ontario and Quebec during La Nina winters, while there’s almost always unusually dry winter weather along the West Coast during weak and moderate La Ninas.
“Strong La Ninas can lead to wet winters along the West Coast, but I am predicting a moderate La Nina this winter,” Anderson said.
He’s predicting several Arctic air masses will come down through British Columbia and Alberta, giving Vancouver, Victoria and Edmonton one of the Top 3 coldest winters in the past 20 years.
“I’m pretty confident that the real part of the coldest weather is going to be out in Western Canada and that’s going to get pushed down into the northern plains of the United States,” Anderson said. “Based on what I’m looking at now, I think the amount of cold outbreaks across Newfoundland are going to be less than normal this year, which I don’t think many people are going to be upset about.”
Anderson said the slow return of sea ice — which has been well below normal again this year, similar to last year across much of northern Canada — combined with warmer sea surface temperatures, will also contribute to a milder winter throughout northeastern Canada.
When predicting snowfall and rainfall in long-range forecasts, he said, the margin of error is a little bit greater because precipitation is much more variable, whereas temperatures are much more uniform.
Regardless, Anderson said, Newfoundland is expected to have a slightly drier than normal winter. He’s predicting it will be drier than normal in Newfoundland and southern parts of Labrador and most of the Prairies will also get less snow than normal. Because the Great Lakes are running warmer than normal, the areas around it will have a greater amount of lake-effect snowfall as very cold air wraps in behind the Colorado lows.
As noted above, the exception to the dry winter weather could be the Avalon Peninsula, because it’s expected to get at least two significant snowstorms around January and February.
Anderson said the remainder of the island up to southern Labrador is “probably going to be a little bit too far north to be affected by those storms.”
Anderson said Newfoundland’s east coast will get its typical freezing and thawing cycles this winter, but added that nighttime temperatures won’t be as extreme as in normal winters.
He said there will probably be a lot more cloudy conditions, as well, because the warmer waters and lack of sea ice is expected to create more fog and more low clouds.
“The big key is whether or not we get a big, blocking high pressure system over northern Quebec. That’s uncertain at this point in time,” Anderson said.
“If that does happen again, I’m very confident that at least a good part of the winter will be warmer and drier than normal because that forces the coldest air down into Ontario and also forces the storm track much further south, so it kind of keeps all the nasty weather away.”
Accu Weather will have an updated winter forecast Dec. 1.