12/11/2014 05:58 EST | Updated 02/10/2015 05:59 EST

Toronto weather: Snowfall warning issued, school buses cancelled

Environment Canada has issued a snowfall warning for the city of Toronto and surrounding areas, with an additional 10 to 15 centimetres of snow expected on top of the approximately five centimetres that fell overnight. 

Shortly after 8:30 a.m., the federal weather agency said a snowfall warning was in place for a vast swath of southern Ontario, including for Halton, Peel, York, Durham, Vaughan, Richmond Hill, Markham, Newmarket, Georgina, Northern York Region, Dufferin-Innisfil and Caledon.

At 9:30 a.m., that warning was updated to include Toronto and Burlington, as well as several other locations. Those areas can expect between 15 and 20 centimetres of snow to fall today. 

The snow, the result of a low pressure system that moved northwest from Cape Cod yesterday, is expected to taper off later this afternoon in the eastern parts of southern Ontario and in the evening over central and southwestern Ontario. 

OPP are warning commuters to leave extra time this morning to allow extra time to get to work, as accumulated and blowing snow is causing significant problems for drivers, and snow plow caravans will also likely cause delays. "It is not a good situation on the highways," said OPP Sgt. Kerry Schmidt. "I cannot see the lane markings, the roads are snow covered, and it is very busy."

"Traffic is building and there are reports of collisions all throughout the Toronto region."

The south-central Ontario branch of the CAA said that it has received more than 600 calls for service already today, while Toronto police Const. Clint Stibbe told CBC News that the department is receiving a traffic incident report every three and a half minutes this morning. 

In the city, the TTC is set to experience some delays. The service ran storm trains on subway and streetcar tracks last night to prevent snow and ice from building up along the routes.

TTC spokesman Brad Ross said riders must allow for slowdowns in service if the snow continues throughout the day.

"Buses and streetcars can only operate as quickly as the traffic and weather conditions allow. So leave yourself extra time if the roads are quite messy this morning," he said. 

GO Transit riders can also expect longer trips this morning, with a 45-minute system-wide delay currently being reported. 

Toronto deployed salt trucks to treat roads as early as Tuesday night in preparation for this snowfall, and road operations and transportation services chief Hector Moreno said crews are prepared.

"The trucks will be stationed at specific locations throughout the city and they can deployed within five minutes once the snow starts to hit the pavement," he said. 

Moreno said he expects all major highway routes to be plowed by about 11 a.m., with the focus shifting to collector lanes after rush hour. Plows will hit local roads throughout the city between 10 a.m. and noon — a job that could take up to 18 hours to fully complete, Moreno said. 

School buses cancelled, flights delayed

As a result of the snow, school buses have been cancelled by the following GTA school boards:

- York Region District School Board; schools remain open. 

- York Catholic District School Board; schools remain open.

- Peel District School Board; schools remain open.

- Dufferin-Peel Catholic District School Board; schools remain open.

- Durham District School Board in zones one, two and three; schools remain open.

- Durham Catholic District School Board in zones one, two and three; schools remain open.

The Toronto public and Catholic school boards have not cancelled any bus service, but said to expect significant delays throughout the morning, while the Toronto Waldorf School has cancelled all classes for the day.

At Pearson airport, about 80 flights have been delayed due to weather, mainly incoming flights from the eastern U.S. and the Maritimes. Airport officials are asking passengers to please check flight statuses before arriving. 

Porter Airlines at Billy Bishop city airport is warning travellers of possible delays for flights in Toronto and several parts of Quebec and eastern Canada.