Southern Ontario braced for a second wave of heavy snow Wednesday from the same strong system that walloped the region in the early morning and wreaked havoc in the United States the day before.

In the southern U.S., the bottom end of the system caused storms and dozens of tornadoes across five states, uprooting trees, destroying homes and killing dozens of people.

Slushy Toronto streets were expected to turn icy later Wednesday.
(CBC)

The other end of the storm, meanwhile, piled soggy snow on southern Ontario overnight, with a mix of ice pellets and rain or freezing rain.

There was a lull for much of the daytime, but a second round of heavy snow from the same system was forecast to begin falling around 7 or 8 p.m. ET, said CBC meteorologist Nick Czernkovich.

In Toronto, claps of thunder were heard at least around 6 p.m., an uncommon occurrence during winter storms.

Winter storm and freezing rain warnings were in effect from Windsor to Kingston as the storm slowly tracked northeast.

The system is expected to graze Ottawa and Montreal before moving east and sweeping across the most southern parts of New Brunswick and Nova Scotia.

The storm's second blast could see 15 to 30 centimetres of snow fall on some parts of southern Ontario.

Pearson travellers face delays, cancellations

Throughout the day Pearson Airport reported numerous delays and cancellations, with passengers advised to call ahead to check their flight status.

By mid-afternoon Wednesday, Ontario Provincial Police had already reported more than 200 accidents on major highways around Toronto, most of them involving one vehicle.

Meanwhile, parts of Wisconsin, Iowa and Kansas were also blanketed with about 30 centimetres of snow from the same system, forcing airports to ground hundreds of flights and many schools and business to close their doors.

One traffic death in Wisconsin was blamed on slippery road conditions.

The death toll from the storm system in the southern part of the U.S. continued to rise throughout the day after tornadoes tore through Arkansas, Tennessee, Kentucky, Alabama and Mississippi.

By early evening, the number of dead had risen to at least 54. Hundreds of others were injured.

CNN reported that at least 69 tornadoes were spotted Tuesday, with at least 20 believed to have struck the ground.

With files from the Canadian Press