Here's when Ottawa will see 15 to 20 cm of snow

Ottawa is set to receive another blast of snowy weather tonight and Thursday, as a storm brings up to 20 cm of snow and threatens to disrupt travel over the next 24 hours.

A snowfall warning remains in effect for the city of Ottawa, with Environment Canada calling for "significant snowfall” beginning around 11 p.m.

"Snow, heavy at times, will develop this evening," Environment Canada said in a statement. The heavy snow will continue overnight.

"Snow will become light Thursday morning and may become mixed with freezing drizzle. Another round of snow, possibly mixed with ice pellets, will affect the area Thursday afternoon and evening."

The same system is expected to bring heavy snow, ice pellets and freezing rain to Toronto and southern Ontario today.  Environment Canada says Toronto could see 5 to 10 cm of snow and ice pellets overnight.

More than a dozen flights have already been cancelled out of the Ottawa Airport to Toronto today and Thursday due to the storm. Officials are advising travellers to check their flight status before going to the airport.

In Ottawa, city officials say all available resources will be deployed to deal with the storm.

"All available resources will be deployed, and will be working around the clock; because of the duration, intensity and colder temperatures of this storm, operations will take longer than usual to complete," the city said on its website.

"Our focus will be on clearing and treating priority sidewalks, roads, and the winter cycling network."

Ottawa has already received more than 239 cm of snow this winter. More than 96 cm fell in January.

Snow at times heavy beginning late Wednesday evening. Local amount 10 to 20 cm. Low -13 C.

Periods of snow with a risk of freezing drizzle on Thursday. Amount 2 to 4 cm of snow. High -9 C.

The outlook for Friday calls for a mix of sun and cloud with a 30 per cent chance of flurries. High -11 C.

Cloudy with a chance of flurries on both Saturday and Sunday.

DAYTIME WINTER WEATHER PARKING BAN

The city of Ottawa has issued a daytime winter weather parking ban on Thursday due to the heavy snow.

Only vehicles with on-street parking permits will be permitted to park on city streets between 10 a.m. and 7 p.m.

Vehicles parked on the street during the ban may be ticketed and towed.

WHITEOUTS TUESDAY

A band of heavy snow moved across eastern Ontario Tuesday causing some brief whiteout conditions for drivers.

A winter weather travel advisory was in effect for part of the afternoon because of the heavy flurries that were moving across the region.

"Brief but intense flurries could affect road conditions and will result in significantly reduced visibility at times," the advisory said.

The snow was heaviest in Ottawa around 2 p.m. but quickly moved east.