We are tracking a dangerous Colorado Low expected to move throughout Southern and Northeastern Ontario beginning Tuesday morning lasting until the later hours on Wednesday. A swath of 20-40cm of snow is likely with 8-12mm of freezing rain. Widespread power outages from damaging winds alongside blizzard conditions are expected. Bus cancellations and school closures are likely alongside road closures.
* This forecast includes both snowfall and ice pellets.
* If at all, more freezing rain or even rain moves into the heavier expected snow regions, snowfall amounts will be less but freezing rain amounts will increase by a trace to 2 or 3mm of ice accretion.
Blue or '1':
Areas in the blue or marked with a '1' can expect less than 10cm of snow. This includes Windsor, Chatham, Long Point, and Rodney. Snowfall totals between 2-4cm appear to be possible across the southern portions of Essex County with totals between 4 and 8cm north of there, including the southern shores of Lake St. Clair and areas north. This also includes much of Northern Ontario north of a line between Agawa Bay, Chapleau, Timmins, and Matheson.
Green or '2':
Areas in the green or marked with a '2' can expect between 10 to 20cm of snow. This includes much of the Extreme South and Golden Horseshoe regions including Sarnia, London, Grand Bend, Port Dover, Niagara Falls, and Dunnville. Snowfall totals between 8 and 12cm are possible along the shores of Lake Erie extending towards Newbury and Sarnia. Areas north of this including London, Dunnville and Niagara may see between 10 to 15cm with local amounts towards 20cm, especially towards the north and for areas between Port Dover and Grimsby. In Northern Ontario, snowfall totals between 10 and 15cm appear likely Sault Ste. Marie extending northeast towards Elliott Lake, Ruel, and Temiskaming Shores. Local amounts towards 20cm will be possible for areas furthest south towards Sudbury and Manitoulin Island.
Yellow or '3':
Areas in the yellow or marked with a '3' can expect between 15 and 30cm of snow. This includes much of the GTA and Southwestern Ontario. Areas expected to see near 15cm with local amounts towards 13 or 18cm include Goderich, Stratford, Woodstock, Brantford, and Cambridge. Areas expect to see between 15 and 20cm include Hamilton, Oakville, Kitchener, Waterloo, Listowel, Wingham, Kincardine, Hanover, and Arthur. Local amounts towards 13cm or even as high as 25cm may be possible depending on if freezing rain and/or rain move into the region, which, would limit the snowfall totals. Areas likely to see between 20 and 30cm of snow include Toronto, Brampton, Newmarket, Barrie, Collingwood, Markdale, and Shelburne. Local amounts towards 35cm may be possible depending on if freezing rain moves into the region, which would limit snowfall totals. Localized lake-enhancement bands off of Lake Ontario may impact portions of Toronto extending down to Oakville. In Northern Ontario, a general 20 to 30cm is possible over Manitoulin Island extending northeast to include Sudbury, West Nipissing, Espanola, and Killarney.
Orange or '4':
Areas in the orange or marked with a '4' can expect between 20 to 40cm of snow. This includes portions of Central Ontario and the Bruce Peninsula. Over the Bruce Peninsula extending down into Owen Sound and Meaford, snowfall totals between 20 and 30cm are possible with amounts as high as 35 to 40cm in places. In Northeastern Ontario including the southeastern side of Manitoulin Island and North Bay can expect between 25 and 35cm of snow with local amounts towards 20cm for areas towards the north and amounts towards 40cm for areas near the south, such as Powassan. In Central Ontario, totals between 25 and 35cm are possible for Midland, Orillia, Minden, Lindsay, and Peterborough. Local pockets of 40cm may be possible.
Red of '5':
Areas in the red or marked with a '5' can expect between 25 and 45cm of snow. Areas over Prince Edward County extending north towards Aspley, Bancroft, and Kaladar as well as Algonquin, Haliburton and Muskoka (Huntsville, Parry Sound, etc) can expect snowfall totals between 25 and 35cm of snow with local amounts towards 40 and 45cm. In the Far Eastern including portions of Eastern Algonquin along the Ottawa River including Renfrew County, Sharbot Lake, and Brockville and everything east can expect between 30 to 40cm of snow with local amounts towards 45cm and even 50cm. There is the potential for snowfall amounts to overachieve above 50cm although the risk is low.
* If at all, more freezing rain or even rain moves into the heavier expected snow regions, snowfall amounts will be less but freezing rain amounts will increase by a trace to 2 or 3mm of ice accretion.
Blue or '1':
Areas in the blue or marked with a '1' can expect less than 2mm of ice accretion. This includes Kincardine, Goderich, Wingham extending inland to Arthur, Guelph, and Toronto. Local freezing rain amounts towards 3 or 4mm may be possible but unlikely given the current model guidance. There is the risk of this freezing rain to push even further north towards Hanover, Shelburne, Barrie, and Newmarket although the risk is too low to put onto the map. If freezing rain does impact that area, a trace can be expected. For areas between and including Kitchener, Oakville, Hamilton, and St. Catharines, freezing rain amounts towards 2mm look to be possible although isolated totals closer to 5mm are possible.
Green or '2':
Areas in the green or marked with a '2' can expect between 2 and 5mm of ice. This includes Grand Bend, Sarnia, London, Rodney, Long Point, Stratford, Woodstock, and Brantford. This region may push further east towards Dunnville and further north towards Wingham, Listowel, Goderich and Kitchener depending on how far north the freezing rain pushes. As of now, we have gone with the trace to 2mm for these regions although it certainly is possible for 2 to 5mm as well.
Yellow or '3':
Areas in the yellow or marked with a '3' can expect between 5 and 10mm of ice accretion. This includes Windsor, Leamington, and Chatham. Freezing rain totals towards 15mm may also be possible. Due to the strong and gust winds, widespread power outages are possible. The National Weather Service has issued Ice Storm Warnings to the southwest of Essex County. Based on the forecasted winds and ice, the criteria for a classified ice storm may be met.
Windy: Alongside the snow and ice, we are also tracking the peak winds which will be gusting between 60 and 80km/h across Southern Ontario. This will likely create widespread blizzard conditions for areas which receive snow and widespread power outages for areas which receive freezing rain. Areas closer to the west including Kitchener, Waterloo, Toronto, Barrie, Haliburton, Peterborough, Parry Sound, Manitoulin Island, North Bay, Sudbury, Sault Ste. Marie, Batchawana Bay, and Wawa, winds may be locally strong with gusts between 70 and 90km/h. Finally, areas east of Lake Huron over Huron, Perth, Bruce, and Grey Counties, including the Dundalk Highlands and higher terrain in Wellington County, wind gusts will peak between 75 and 95km/h. Widespread blizzard conditions and ice storm conditions may be possible depending on the timing of the winds and the precipitation type at the time.
On Wednesday, the winds will shift from an east flow into a west and northwest flow with pockets of southwest and south winds depending on your location. Widespread wind gusts between 40 to 70km/h are possible with gusts between 70 to 90km/h along the lake shores of Erie, Ontario, and Huron. Localized snow squalls will develop off of Lake Huron and will create near-blizzard conditions from system snow and lake-effect snow.
Timeline:
Tuesday Morning:
Into the early morning hours between 12 and 3am, light to moderate snow will move into the Extreme South over Essex County and the Chatham region. Following this, a quick change over to a long period of freezing rain is expected. By the dawn hours between 6 and 8am, widespread freezing rain will be possible for Essex County, Chatham-Kent and portions of Lambton County. Widespread moderate to at times heavy snow will push across the Golden Horseshoe, Extreme South and begin to impact the Toronto region. Blizzard conditions over Huron, Perth, Wellington, Waterloo, and the GTA are possible. By the late morning (11am-1pm), snow will have pushed into Eastern Ontario impacting Kingston, Bancroft, Parry Sound and Manitoulin Island. Snow continues for the GTA. Ice pellets will be possible across much of Southwestern Ontario including Hanover, Wingham, Kitchener and possibly Toronto. Freezing rain will continue for Niagara and the shores of Lake Huron as well as extending into Huron and Perth Counties, near the south. Freezing rain will change to rain over Middlesex, Elgin, Lambton, Essex, and Chatham.
Tuesday Afternoon + Evening:
In the mid-afternoon, moderate to heavy continue will be impacting all of Eastern Ontario extending towards North Bay, Timmins, Wawa and Chapleau and much of Northeastern Ontario. Ice pellets may mix with snow across the GTA extending towards Barrie and Owen Sound. Freezing rain and snow continue for Southwestern Ontario while rain dominates the Extreme South and the Niagara region. By the mid-evening (7 to 9pm), snow continues for Northeastern, Eastern and Central Ontario. Snow mixed with freezing rain continues for the GTA and the northeastern portions of Southwestern Ontario. Freezing rain is possible in the GTA extending west to Lake Huron. Rain continues in the south. The low will move through the center of the region with moderate to heavy snow switching over for Sarnia and Windsor. By the late evening (9 to 11pm), heavy snowfall is possible in Central and Eastern Ontario with moderate to heavy snow in Southwestern Ontario and the Extreme South. Widespread blizzard conditions may be possible across all of Southern Ontario. Hazardous driving is expected.
Wednesday Morning:
In the early morning hours (1 to 3am), light to moderate snow will fill in across Southwestern Ontario and moderate snow will continue in Eastern and Central Ontario, as well as Northeastern Ontario. The snow will begin to become patchy across the Extreme South and GTA extending into Central Ontario. Localized pockets of heavy snow will be possible. Widespread whiteout conditions from blowing snow are possible. In the near dawn hours (6 to 8am), widely scattered light to moderate snow will be possible with some moderate snow lingering around along the Ottawa river. Localized lake-enhancement bands of Lake Huron will boost totals over Huron and Bruce Counties. Road closures are possible.
Wednesday Afternoon + Evening:
By the afternoon, widespread pockets of moderate snow with patches of heavy snow will continue across all of Southern Ontario. Blowing snow is possible. Heavier snow will be possible over areas east of Lake Huron. By the evening, most of the snow has ended with some lingering localized lake-effect bands of Lake Huron and Georgian Bay.
Road closures will be highly possible over the next few days across Southern Ontario. A list of road closures can be found on the page here.
Alongside road closures, widespread school cancellations will be possible both Tuesday and Wednesday. You can find a list of closures and a snow day forecast here.