Beware of slick road conditions in Ontario, with more snow, high winds

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We’re in the thick of it in southern Ontario as heavy snow and whipping winds spread across the region through the overnight hours.

Blizzard-like conditions will threaten dangerous—if not impossible—travel overnight through Saturday morning. Snowfall rates of 3-5+ cm per hour are possible at times. Blustery winds will lead to blowing and drifting snow.

Thundersnow is likely for some communities from Windsor through the Greater Toronto and Hamilton Area (GTHA), as well. Multiple lightning strikes were reported in downtown Toronto in the 7:00 p.m. hour.

Flight delays and cancellations are mounting at Toronto-area airports. Localized wind damage and power outages are also possible.

MUST-SEE PHOTOS: Thundersnow, blizzard-like conditions hit Ontario

Through Saturday: Heavy snow, whiteouts, even rumbles of thunder

You know we’re dealing with a formidable winter storm when the term ‘thundersnow’ pops up.

A strong low-pressure system lumbering across the Great Lakes is responsible for this latest bout of foul weather. Folks across the province should take this storm seriously and avoid travel if possible.

Going somewhere? Check out the current highway conditions before heading out!

Snow will continue spreading across southern Ontario through the overnight hours, eventually reaching Ottawa where hazardous conditions will linger into early Saturday morning.

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Heavy snow will be accompanied by 60-80 km/h wind gusts, significantly reducing visibility for all roads in southern Ontario through the overnight hours. Gusts of 90-100+ km/h are possible along the shores of Lake Huron, Lake Erie, Lake Ontario, and Georgian Bay.

These bursts of heavy snow will come on quickly, so it’s important to remain vigilant if you have to travel during the storm. Blizzard conditions are possible across well north of the 401, though the potential for whiteout conditions will be widespread throughout the region.

Snowfall rates could reach 3-5+ cm per hour, allowing wet snow to accumulate in a hurry.

STAY SAFE: Be aware of your heart while shovelling heavy snow

The combination of a fast-strengthening storm and lake enhancement will create a risk for intense snow bands complete with thundersnow across parts of southern Ontario on Friday evening. Locally heavier snowfall totals are possible beneath these bands, making for a tricky forecast.

WATCH: Winter storm brings thundersnow to the GTA

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We’ll see a bit of warm air nudge into southwestern Ontario as the heart of the low-pressure system passes to the west overnight Friday into Saturday.

Forecasters expect some changeover to rain across the Lake Erie shores, the GTA and the Niagara Peninsula during the overnight hours and spread east through early Saturday. This will result in waking up to much lower snowfall totals where the rain forces some snowmelt.

Overall, a widespread swath of 10-20+ cm of snow is possible across southern Ontario through Saturday morning. Locally higher totals are possible along the Dundalk Highlands, with 20-30 cm possible around Orangeville. A swath of heavier snow is also possible toward Bancroft east into Ottawa, where forecasters see the potential for 20-25 cm of snow.

Areas that transition over to rain will likely see less than 5 cm of snow from this system.

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A razor-thin line cuts through the GTHA as only a short distance will separate significant snows from lower totals as the warmer lake forces rain to mix with snow. Snowfall totals across the GTHA are a bit uncertain as a result of this setup, complicated further by whether those bands of heavier snow can overwhelm the lake-influenced warmup.

Beyond: Arctic air switches on the lake-effect snow

A surge of cold air flooding in behind this storm will crank up the lake-effect snow machine across the region. We’ll see a multi-day lake-effect snow setup unfold across the traditional snowbelts, which could add to Friday's snow totals.

Northwesterly winds late Saturday will give rise to bands of snow along the Saugeen Shores, Wasaga Beach, Barrie, and the surrounding areas.

Shifting winds will blow from the west by Sunday into Monday, forcing lake-effect snow to pile up on the Bruce Peninsula and communities east of Georgian Bay, including Parry Sound, Huntsville, Bracebridge, and Gravenhurst.

Stay with The Weather Network for the latest on this high-impact storm across Ontario.

WATCH: Do you know these 'common sense' winter driving tips?

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