A storm system that blanketed Ontario and Quebec with upwards of 25 centimetres of snow continues to track eastward toward the Maritimes, grounding dozens of flights and keeping motorists on high alert.
The dumping of fresh snow, along with chilly temperatures, created traffic troubles both on the ground and in the air in Central Canada.
East of Toronto on Sunday morning, three people were taken to hospital after a vehicle they were travelling in crashed into a cement barrier before being hit by a tractor trailer on Highway 401 in Mississauga.
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The Ontario Provincial Police said two female passengers in the Toyota RAV4 were airlifted to a Toronto hospital, one in life-threatening condition and the other in critical. The male driver of the vehicle was transported with minor injuries.
There were many accidents on snowy roads around the region, including a 20-car pileup on the Queen Elizabeth Highway in Mississauga just west of Toronto on Saturday.
The weather may have also been a factor in a head-on collision that killed two people near Barrie, north of Toronto, according to the OPP.
The provincial police tweeted that, as of 1: 20 p.m. ET on Sunday, they have responded to 255 collisions in Toronto and nearby communities since 7 a.m. 1761 calls for service were received since Saturday morning.
OPP have responded to 255 collisions in the GTA since 7:00 am this morning. A total of 1761 calls for service since 11:00 am yesterday— Ontario Prov Police (@OPP_GTATraffic) December 15, 2013
To the east, Winter storm warnings are in effect with snowfall amounts of between 30 and 40 centimetres forecast for southern New Brunswick, and slightly lesser amounts for parts of Nova Scotia and Prince Edward Island.
The storm is expected to hit the region later this afternoon before moving north toward Newfoundland and Labrador overnight.
"It's a large storm that's affecting probably 80 or 90 per cent of the Maritime provinces," Environment Canada meteorologist Jean-Marc Couturier said in an interview on Sunday. "It's a large storm with a lot of punch, a lot of vigour."
Couturier said up to 30 centimetres of snow was expected for parts of Nova Scotia, with the snow changing to a mixture of ice pellets and freezing rain Sunday afternoon.
Montreal's Trudeau airport is also reporting some flight delays and cancellations Sunday morning and has advised people to check the Aéroports de Montréal ahead of time.
Sunday is also the first day throughout Quebec that all motorists are required to have winter tires on their vehicles, or face a fine.
City officials estimate that the cost of snow removal in Montreal alone could surpass $20 million, which is the average cost of cleaning up a 15-centimetre snowfall.
The majority of flights at the Halifax Stanfield International Airport, the Fredericton International Airport and the Charlottetown Airport were cancelled as the provinces grappled with winds up to 90 km/h.
"With the high winds, we are expecting a lot of blowing snow," said Couturier from Halifax. "Large snow drifts will form in certain areas and there's poor visibility."
Winter storm warnings and the subsequent wind warnings for Halifax were lifted late Sunday afternoon.
The ferries that usually make the crossings between P.E.I. and Nova Scotia, Cape Breton and Newfoundland and Digby and Saint John are all tied up Sunday.
Dozens of flights through Toronto's Pearson and Montreal's Trudeau airports were delayed or cancelled yesterday.
Both Air Canada and WestJet are waiving fees for select travellers who wish to reschedule flights before the snow hits.