Here's the timeline of Toronto's potentially biggest snowstorm of the season

Snow clearing continues after winter storm Ottawa has now received more than 300 centimetres of snow this winter. CTV's Jackie Perez on the city's snow clearing efforts.

A winter storm anticipated to be the biggest snowfall in Toronto this season is now expected to bring even more snow than initially forecasted across southern Ontario.

Environment Canada upgraded its storm warning early on Friday morning to forecast up to 30 cm of snow in Toronto. Originally, up to 25 cm was expected.

By early afternoon, the weather agency bumped up the expected hourly snowfall rate to 5 to 8 cm per hour.

The storm is expected to “rapidly” accumulate and become heavy, creating “hazardous travel conditions” beginning on Friday night into Saturday morning.

The most dangerous conditions are expected to peak between about 9 p.m. and midnight, according to the weather agency.

Air Canada has issued a travel alert for weather delays and possible cancellations in Toronto, along with Montreal, Ottawa, Quebec City and Halifax. VIA Rail is also alerting customers in southern Ontario that the storm could impact their operations.

A Texas low is expected to bring heavy snow and strong winds to a large swath of southern Ontario where winter storm warnings span most of the region.

Locally, that includes Toronto, York Region, Durham Region, Halton Region, Peel Region and Hamilton. Winter storm warnings have also been issued in Barrie, Kingston, London, Waterloo, Windsor and Niagara.

The combination of heavy snow and strong easterly winds will result in significantly reduced visibility, according to the weather agency.

“Prepare for quickly changing and deteriorating travel conditions. Visibility will be suddenly reduced to near zero at times in heavy snow and blowing snow,” Environment Canada said on Friday morning.

According to The Weather Network, the upcoming storm has the potential to be the biggest of the season for the Greater Toronto Area.