OTTAWA -- Environment Canada's winter storm warning for Ottawa has clawed back the centimeters of snow, but added rain and freezing rain to the mix.

Warning Preparedness Meteorologist Peter Kimbell spoke with CTV News Ottawa as the flurries began falling Wednesday afternoon.

“We’ve had a lot of warm weather lately and unfortunately it’s payback time,” said Kimbell.

The latest forecast, issued late Wednesday evening, calls for snow changing to freezing rain late Wednesday, then possibly into rain overnight, then back into heavy snow by Thursday morning.

Total snowfall amounts of 15 to 25 cm are now expected.

A previous forecast warned of up to 40 cm of snow.

"Light to moderate snow currently over the area is expected to change to freezing rain late this evening or after midnight," Environment Canada said in its warning late Wednesday. "Several hours of freezing rain are expected. The freezing rain may change to rain overnight for a brief period. The precipitation will then change back to heavy snow Thursday morning."

The City of Ottawa is warning motorists the Thursday morning commute will be slow.

Area Manager, Core Roads Bryden Denyes says over 500 pieces of equipment will be deployed to clear roads and sidewalks.

“Staff will be out all night treating the roads, sidewalks and the winter cycling network,” Denyes said Wednesday afternoon.

This is expected to be the largest storm of the year. The largest single day snowfall this winter was 18.8 centimetres of snow on Feb. 7.

Denyes says “we’re well prepared for this. So, we’ve been preparing for this the past couple of days.  Equipment, materials, staff are ready.”

Ottawa has received 163 centiemtres of snow so far this winter. During the same period last winter, Ottawa had received 269 centimetres of snow.

Kimbell warns that after the storm moves out of the region, strongly westerly winds will bring colder temperatures into Ottawa and eastern Ontario.

Environment Canada’s forecast calls for temperatures to drop to minus 12°C Thursday night, and minus 13°C Friday night.