The Ottawa area is now under a winter storm warning for Tuesday night and Wednesday morning as the season's first storm could bring close to 20 cm centimetres of snow.

The storm, which will bring the first significant snowfall of the season to much of eastern Ontario, is the result of a low pressure system from the Gulf of Mexico.

As well, "some brief freezing rain is possible in the Cornwall and Prescott-Russell areas overnight into Wednesday morning," Environment Canada warned Tuesday morning.

"Driving conditions are expected to deteriorate quickly beginning this evening as the snow moves in. Motorists should be prepared for hazardous winter driving conditions due to very low visibility in snow and local blowing snow and rapidly accumulating snow on untreated roads. Travel plans should be adjusted accordingly."

The weather agency said 15 centimetres of snow or more are expected in most places, with up to 25 cm possible in the Ottawa area.

CBC climatologist Ian Black said Tuesday evening the city was more likely to get anywhere from 15 to 19 cm. But road conditions will still be poor, he said.

"Here in Ottawa mainly just snow overnight and through the day tomorrow, you are going to have to give yourself plenty of time to get around, the wind really picks up in the afternoon," said Black.

An overnight parking restriction is in effect for Ottawa city streets for the first time this season. During the restriction, vehicles without an on-street parking permit are banned from parking on city streets from 1 a.m. to 7 a.m. so that street crews can clear streets. Vehicles that remain parked will be ticketed.

The forecast in Ottawa Tuesday night calls for 10 to 15 cm of snow and a low temperature of -2 C.

Wednesday calls for another five to 10 centimetres of snow with winds becoming northwest at 30 km/h gusting to 50 km/h early in the afternoon, then becoming light late in the evening with the temperature steady near -1 C.

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