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Updated: Wed, 26 Mar 2014 12:09:14 GMT | By CBC News, cbc.ca

More cold weather to come, Environment Canada warns



A man walks a dog along a street during an early spring snowstorm near Montreal, Saturday, March 22, 2014. THE CANADIAN PRESS/Graham Hughes The Canadian Press

A man walks a dog along a street during an early spring snowstorm near Montreal, Saturday, March 22, 2014. THE CANADIAN PRESS/Graham Hughes The Canadian Press

As Atlantic Canada braces for a massive spring storm that is expected to bring high winds and heavy rain and snowfall Wednesday, people in other parts of the country can take heart that they'll be spared this wallop of winter.

But they shouldn't get too comfortable: the cold weather is not behind us yet.

While forecasts beyond five to seven days are difficult to make with any accuracy, Environment Canada's monthly and seasonal forecasts are suggesting that the unseasonably cold weather will continue off and on at least into the first half of April pretty much everywhere but the West Coast, says Environment Canada meteorologist Matt MacDonald.

"We may get a little teaser — mainly on the weekend — of sun and near seasonal temperatures, but the long range, unfortunately, there is no good news there. It's continued cool and below-seasonal temperatures," he said.

The normal seasonal high for the Toronto area is 7 C, but temperatures in the city Tuesday rose only as high as 1 C. In Montreal, temperature highs were also about six degrees below normal while in the Prairies they were as much as 13 degrees below what they usually are at this time of year.

Calgary saw highs of –6 C on Tuesday, a good 12 degrees below normal. In Winnipeg, where lows usually dip down to –8 C this time of year, temperatures dropped to –21 C in the early morning.

Lake ice cover keeping temperatures low

Most of the country east of the Rockies has remained stuck in the jet stream trough — often referred to, somewhat erroneously, in the media as the polar vortex — that has been responsible for the especially harsh winter we've had. This trough within the jet stream, the system of air currents that move weather from west to east, has pushed cold arctic air south and prevented the warm air from the Gulf of Mexico from circulating north as much as it usually would.

The result has been the coldest winter since 1978-79.

"It's not people’s imagination; it has actually been a really cold and snowy winter," said MacDonald.

The cold temperatures have left the Great Lakes covered with more ice than they've had since 1979, with some lakes more than 90 per cent covered.

Large dumps of snow as late as last week in Quebec and parts of Ontario have left significant snow cover on the ground, which is also helping winter maintain its grip past the official start of spring, which this year fell on March 20.

"The biggest weather drivers this year are the fact that most of the country is still covered in snow, which reflects most of the incoming solar radiation back to space and therefore prevents the ground from heating up, and the fact that the Great Lakes and Gulf of St. Lawrence are still mostly covered in ice, which prevents these massive bodies of water from warming the adjacent atmosphere," MacDonald said.

Sunny, warm weekend ahead

Residents of Ontario, Quebec and Atlantic Canada will get a bit of a reprieve this coming weekend, which will bring warm temperatures — as high as 10 C in Toronto and 11 C in Halifax — and sunny skies that will help melt some of that snow and ice, but long-range models are forecasting a continuation of below-seasonal temperatures, meaning it will be a while before we get a sustained stretch of sunny days and temperatures of 10 C and above.

"We’ve seen snowy springs before in the Prairies and the eastern half of the country, but given the prolonged, difficult, cold winter they’ve had, I think a lot of Canadians are just fed up of winter, and it doesn't want to end," MacDonald said.

"Looking into next week, we're still going to be stuck in these below-seasonal temperatures."

The West Coast has largely been spared the harsh weather experienced east of the Rocky Mountains. It has been under the influence of a ridge within the jet stream, which facilitates warmer and calmer weather, and has sprung into spring with gusto.

"Anything west of the Rockies, we've already had our first tease of spring," MacDonald said from Vancouver. "We've had several sunny days and temperatures between 10 and 15 C, so we've had it quite good."

The region will be hit by a lot of rain next week, MacDonald said, but temperatures will remain mild and within or above the seasonal range of highs of 12 C and lows of 5 C.

Storm will hit Atlantic provinces hard

On Tuesday, it wasn't spring that was on the mind of most meteorologists in Canada, but the massive storm headed toward the East Coast.

The storm is travelling north over the Atlantic seaboard and will be far enough from the east coast of the U.S. to bypass its coastal cities but will hit Nova Scotia hard early Wednesday morning, dumping 20 to 30 centimetres of snow and causing wind gusts of more than 100 km/h. As it moves north and east over the other Atlantic provinces, the barometric pressure (measured in units called bars and millibars) at the centre of the storm system will drop quickly as the storm grows in intensity.

"In the world of meteorology, we talk about weather bombs, and a weather bomb is when a low-pressure system deepens by more than 24 millibars in 24 hours, and in this case, it's almost a double bomb. It's actually deepening by [about] 40 millibars in 24 hours, which is incredible from a meteorological perspective," MacDonald said.

"It's quite exciting. We rarely see storms this vigorous."

CBC meteorologist Michelle Leslie said the storm will bring a mix of snow, rain and high winds.

"For Cape Breton, after heavy snowfall, ice pellets and rain are forecast," she said Tuesday. "But for the majority of Nova Scotia and New Brunswick, this will be a snowfall event.

"As the storm moves into Newfoundland on Wednesday, expect it to start as snowfall, but by Wednesday evening, the Avalon and Burin peninsulas should start to see a change over to mixing and, eventually, rainfall."

Temperatures will hover around the zero degree mark, she said.

"It won't be the cold that's the big story. The heavy snow and high winds will work together to give blizzard conditions and whiteouts. Expect travel, air and ground, to be disrupted," Leslie said.

Leslie said it's not unusual to see strong storms in March.

"Think of March as a transitional month where you have a good clash in air masses," she said. "You still have cold arctic air moving down from the north and warm air from the south and this clash of air masses is one ingredient in setting up good storms."

The fact that the storm is not coinciding with high tides should reduce the intensity of storm surges and flooding and the strong winds it's bringing should help break up the ice along the coasts of the Atlantic provinces — without pushing too much of it onto the shore, MacDonald hopes. 

"They had quite impressive ice coverage last week, but I think that storm will break up a lot of that ice, and as it opens up the waterways, the waterways will be able to start warming the atmosphere slightly."

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