© Weather Underground/Associated PressThis U.S. National Oceanic and Atmospheric Administration satellite image taken Tuesday at 12:45 a.m. ET shows a storm system over Texas and the central U.S. The front is expected to hit southwestern Ontario Tuesday evening with heavy snow and high winds
Environment Canada has upgraded a warning about a snowstorm expected to hit Ontario late Tuesday, saying there will be blizzard conditions in certain areas of southwestern Ontario.
"This major winter storm is quite large in size and will have a major impact on travel, especially tonight and on Wednesday," Environment Canada said in a warning issued Tuesday.
It will be "the strongest storm of the season" for urbanized areas like Toronto that are outside the Ontario snowbelt.
The weather agency had upgraded a winter storm watch in southern Ontario, stretching from Windsor to Kingston, to a winter storm warning.
Environment Canada added the blizzard warning for London, St. Catharines, Sarnia and Hamilton just after 3:30 p.m. ET on Tuesday.
A warning is typically issued between six and 24 hours before the start of severe weather.
By the time the storm finishes Wednesday, large swaths of southern Ontario could have snowfall accumulations of between 20 and 30 centimetres, the agency predicted.
Heavy snow is expected to hit southwestern Ontario on Tuesday evening and the Toronto area around midnight. It is then predicted to move into eastern Ontario on Wednesday morning.
The snow will be accompanied by gusting winds of 50 to 70 km/h at their strongest, Environment Canada said. The high in Toronto is forecast to be - 5 C on Wednesday, and the low will dip to - 9 C.
Plenty of people in Toronto were dashing out to stores on Tuesday to stock up on storm supplies.
Fraser Perkin was doing a brisk trade in salt and shovels at the Home Hardware location he manages at Highway 7 and Woodbine Avenue in Markham, Ont., Tuesday afternoon.