We are tracking a large bomb-cyclone which is expected to move over New York State and up the Northeastern United States affecting both Atlantic Canada and Quebec alongside the United States. This system appears to be clipping portions of Far Eastern Ontario bringing a widespread 5 to 15cm of snow with local amounts towards 20cm or even higher. Widespread flurries are expected across South Central and Southwestern Ontario alongside a front which will pass into Southern Ontario. Localized moderate or even heavy pockets of snow can't be ruled out in these frontal snow squalls. Widespread wind gusts between 50 and 70km/h are possible, which will certainly cause blowing snow inside the snow pockets.
Blue or '1':
Areas in the blue or marked with a '1' can expect less than 5cm of snow. This includes all of the Extreme South, Golden Horseshoe, GTA, South Central Ontario, most of Southwestern Ontario, excluding the southern shores of Georgian Bay as well as much of Eastern Ontario including Algonquin, Bancroft, Pembroke, and Tamworth. Most areas should see between 1 and 3cm of snow although local amounts towards 5cm are possible.
Disclaimer: As the system is working with temperatures near 0C for Eastern Ontario, any switch over to rain will lower these snowfall totals and limited rain with slightly lower temperatures could boost these snowfall totals. As of now, the models are disagreeing on the amount of rain, if any for Eastern Ontario.
Green or '2':
Areas in the green or marked with a '2' can expect between 5 and 10cm of snow.
This includes much of Far Eastern Ontario extending from Cobden and Calabogie eastward through Ottawa and Hawkesbury as well as southward towards Perth and Kingston. This area could see local amounts between 10 and 20cm if limited to no rain occurs. If rain occurs, snowfall totals could drop from 5 to 10cm to 3 to 7cm of snow.
There is some higher confidence over the Dundalk Highlands between Meaford and Collingwood that some locally enhanced snow squalls may produce snowfall amounts between 4 and 8cm, locally 12cm.
Yellow or '3':
Areas in the yellow or marked with a '3' can expect between 10 and 20cm of snow. This includes much of the Canada-United States border in Far Eastern Ontario extending from Gananoque to Quebec reaching areas as far north as Kemptville and Alexandria. This includes Brockville and Cornwall. This area could see local amounts between 20 and 35cm if limited to no rain occurs. We have included an 'Area of Interest' where 25 to 35cm appears most likely if limited to no rain occurs. If rain occurs, snowfall totals could drop from 10 to 20cm to 5 to 15cm of snow.
At this point, we are working with the higher possible totals in this forecast for Eastern Ontario. It does appear that a switch over to rain is likely, therefore, the mentioned lower totals are increasingly likely. Just a reminder that the models are still disagreeing on this, hence, the addition to the higher possible totals in the forecast.