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Sunday storm on track for Ontario and Quebec

Some areas buried by lake-effect snow squalls this past week can now expect more snow from a winter-like storm
Some areas buried by lake-effect snow squalls this past week can now expect more snow from a winter-like storm

December 11, 2010 — The Weather Network is tracking a messy storm that will bring snow to Ontario and Quebec on Sunday.

Forecast snowfall totals. Click to enlarge.
Forecast snowfall totals. Click to enlarge.

Chris Scott, meteorologist

Get it done Saturday – with a stormy Sunday on the way for Southern and Northeastern Ontario into Southern Quebec, Saturday is by far the best day of the weekend for travelling. If you have a long distance drive to make on Sunday, especially in areas north of a line from Grand Bend to Toronto, you might want to reconsider.

Here is the latest on the forecast of this major winter storm as of Saturday morning:

  • The heaviest precipitation will hit Southern Ontario Sunday morning and move into Eastern Ontario and Southern Quebec Sunday afternoon.
  • Areas north and west of a line from Kincardine to Barrie to Pembroke will see primarily snow. This includes most of the highway 11 and 17 corridors in Northeastern Ontario where amounts in excess of 15 cm are likely with the possibility of localized amounts close to 30 cm.
  • Areas along the north shore of Lake Erie through the Niagara Peninsula will see some rain-snow mix, but the heaviest precipitation will likely fall as rain, limiting snowfall amounts to less than 5 cm.
  • In between these two zones, this is still a very tricky forecast in terms of the amount of snow and as luck would have it, the toughest forecast is for the area with 7 million people.
  • The latest trending in our forecast is that the storm should produce even more precipitation for the Greater Toronto area and areas east through Peterborough to Kingston where 20-30 mm of precipitation will fall. How much of this falls as rain vs snow is the question. There may be a huge difference in snowfall amounts across the GTA, and potentially even the city of Toronto where areas along and north of the 401 will receive more accumulating snow before a changeover to some rain Sunday afternoon.
  • Expect a burst of heavy wet snow with this storm along the 401 corridor through Southwestern Ontario as the precipitation becomes intense Sunday morning. It looks like the rain-snow line during the heaviest precipitation Sunday morning will be along the 403-QEW corridor. In areas where the precipitation stays as snow for more than 3 hours before changing to a mix, significant accumulations greater than 10 cm are likely. This will be the ultimate packing snow, and we’ll have to keep an eye on places along and north of the 401 if the precipitation stays as snow longer than anticipated before changing to rain as this heavy wet snow could start weighing on tree branches and potentially cause problems.
  • Eastern Ontario, including Ottawa, and into Southern Quebec have the greatest potential for a number of hours of ice pellets or freezing rain after an initial shot of snow. While this will not be a major ice storm, some ice accretion is possible. A change over to rain is likely along the St. Lawrence by Sunday evening.
  • Some good advice (that I don’t always follow) – if you live in one of these areas that receives a slushy mix, make sure to clear your steps and driveway Sunday afternoon or evening before the cold air moves in early Monday morning and turns the slush to ice.
  • Snow squalls are a guarantee for Monday. The latest computer model guidance delays the onset of the strong squalls slightly, with squalls strengthening off Lake Huron late Sunday night and off Georgian Bay Monday mid-morning. Significant accumulations and whiteouts are likely into Tuesday with areas like London and the 400 between Vaughan and Barrie being impacted.
  • On the warm side of this storm, heavy rain is still on track for the Maritimes Sunday night through Monday night. Amounts exceeding 50 mm, and locally up to 100 mm, are possible by Tuesday which could cause flooding.

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