The afternoon rush home is expected to be a tricky one as commuters deal with the third snowstorm in Toronto in a week.

Forecasters predicted about 15 centimetres of slippery slush on the roads.

Motorists were warned to stay off the roads and take public transit.

Environment Canada issued a snowfall warning Tuesday morning as heavy snow fell over the city, hampering efforts of clean-up crews still trying to clear out the mess from last Wednesday's storm.

The agency said on its website that between 15 and 20 centimetres of snow would fall today and tonight.

Police said there haven't been any serious collisions on local roadways though there were about 160 accidents reported on the 400-series highway.

The warning said visibility on the roads could drop suddenly to less than one kilometre because of blowing snow and a heavy snowfall. Motorists were being advised to exercise extreme caution.

A deep freeze plus fresh snow on the ground is making streets and sidewalks slippery for all commuters.

A snowfall warning has also been issued for Mississauga, Brampton, Burlington and Oakville. Those areas are also expected to be hit with 20 centimetres of snow.

At Pearson International Airport, about 100 flights were delayed or cancelled. Officials warned travellers to call ahead before making their way out to the airport.

GO Transit warned commuters all GO buses were experiencing a 45 minute delay because of the weather.

Centennial College has cancelled their continuing education classes because of the weather.

However, classes at York University, Ryerson University and the University of Toronto are going ahead as scheduled. The schools said they are monitoring the weather and would be posting changes to the schedule on their websites.

In total, more than 130 centimetres of snow has fallen in the Greater Toronto Area this winter.

City crews have been scooping up some of the snow that fell last week and dumping it at a special snow-melting site on the grounds of Ontario Place. Another melting site has been set up near the Leslie Spit.

Drivers are finding it nearly impossible to drive through many side streets as they have become too crowded with mounting snow banks to allow for traffic.

Snow removal trucks are also finding it difficult to make their way through these streets to clear them up.

With a report from CTV Toronto's John Musselman