"Full-fledged winter storm" to follow mild temps and thunderstorms Wednesday afternoon

Southwestern Ontario is in for a roller coaster ride of weather conditions throughout the day Wednesday. 

The early morning hours saw thunderstorms bear down on the London region combined with above-seasonal temperatures. The afternoon forecast is projecting a different story, with temperatures set to swiftly change course from mild to icy. 

"We're expecting temperatures to drop rapidly to about -3 C by mid-afternoon," said Geoff Coulson, a warning preparedness meteorologist with Environment Canada. "What that's going to mean is any lingering shower activity we're experiencing is going to change to flurries during the early afternoon hours." 

Up to 2 cm of snow is expected by the end of the day, said Coulson. As the cold front passes through it will bring moderate winds gusting between 40 to 60 km/h starting at around noon. There's a chance the area could see snow squall watches or warnings being issued if higher amounts of snow are expected. 

The risk of freezing rain is low, but wet roadways could ice up as the temperatures take a dip. 

"That's something for drivers and pedestrians to be aware of," said Coulson. "In most cases, the worst of the rain on the surface is probably going to be dried up by the time it gets really cold, but there's still going to be some icy patches around." 

There's also going to be poor visibility closer to Lake Huron, where flurries will mix with blowing winds. 

It's all part of the same system that brought periods of hail to parts of the city on Tuesday, along with reports of downpours and intense lighting.

"While we've dealt with summer-like severe weather yesterday and more winter-like conditions today, this is a full-fledged winter storm across much of central and Northern Ontario where they've experienced significant snowfalls and some freezing rain and ice pellets," said Coulson, adding that it's "pretty rare" to get summer-like thunderstorms at this time of year.

The cold air looks to be short-lived, said Coulson, following a low of -6 C, feeling more like -13 C with the windchill Wednesday night. On Thursday, temperatures will bounce back to above seasonal with a high of 0 C, followed by a high of 5 C by Friday.

Saturday's daytime high will reach 9 C, then 13 C on Sunday.