Southern Ontario - 7 days 'til Christmas! The big question is, will Southern Ontarians experience a white Christmas? We had unpleasant experiences before with green Christmases, like last year, we had a warm-up right before Christmas Eve, melting majority of the snow, making Christmas - a green Christmas. As far as I recall, I don't think we had a white Christmas in a very long time.

Well good news is here! It looks like by Christmas Day, some parts of Ontario can have as much as 40 cm on the ground, and maybe even more with lake enhancement snow beginning next week. Good opportunities for skiers, but messy driving / commute conditions for drivers / commuters for the rest of the workweek before Christmas. This is the second winter storm in a week. Winter Storm Watch is already issued and in effect for areas south and west of Toronto (including Toronto).

A series of winter storms are making its way into the Southern Ontario area throughout next week. Right now, the most urgent one has just formed back in the Four Corners last night, moving rapidly aiming at Southern Ontario, and subsequently it will make its way into Southern Quebec and into Atlantic Canada.

The storm is forecasted to intensify as it finds its way up to Eastern Canada, and moving very rapidly. Current forecasts suggest by 7AM EST tomorrow morning, places west of London, Ontario will start seeing light flurries and snow. By this time in Windsor, 3 cm may have already accmulated. In the GTA however, snow is not expected to start until at least 8AM.

By 11 AM, heavier bands of snow will move in from the south, and depending on the track (whether the system will move more northerly or more southerly than current suggestion), the GTA can see various amounts of snow. Winds will be at north-easterlies, and with this cold north-easterly strong winds gusting up to 60 km/h, areas such as Oakville, Burlington, Hamilton, and the Niagara Peninsula could see much heavier snow due to lake effect. In other words, lake effect snow will combine with the system snow forming a blizzard like condition. By this time, the GTA will be seeing periods of moderate snow and at times heavy, with occasional blowing snow.

At 1PM, the snow will start in and around the Ottawa Valley, at this time, there might be as much as 5 to 8 cm on the ground for the GTA, and about 12 to 15 cm for Windsor.

Snow for Montréal and possible Trois-Rivière will start by 4 pm. Due to the blocking high to the north, the system cannot penetrate very far north, hence it does not look like Quebec City and the Gaspé Peninsula will see any snow.

The heavier bands of snow for much of Southern Ontario will move out by 7 pm. At 7pm, Southern Ontario can still experience light snow and at times at moderate intensity. Snow for Windsor will be ending by this time with close to 18 cm on the ground.

By 1 AM, the snow will move out all of Canada, but snow is still possible for Nova Scotia and New Brunswick and possibly P.E.I.. Lingering snow will continue to fall for some eastern parts of GTA, and Niagara Peninsula. The snow band can stretch as far as to the Ottawa Valley and into Montreal. This can accumulate as much as 2 more additional cm overnight.

Another possible system is coming into Southern Ontario on Sunday, currently forecasting 5 to 15 cm for GTA on Sunday, but the forecast can change as the temperature is 0C for much of GTA. If the temperature goes higher, the precipitation can switch into rain/snow mix which may drastically reduce storm total amount.

Lingering lake effect flurries and brief clippers is in store through Monday and Tuesday, up to 3 cm expected, followed by another system on Christmas Eve, which can dump as much as 10 cm of snow just in time for Christmas.

Some forecasting models are calling for an upwards of 27 cm for Toronto, and 23 cm here in the HQ in Markham, Ontario, but I'm strongly disagreeing it. Here is my snowfall forecast for Friday Morning through Friday Overnight.

Ontario

Essex County (Windsor; La Salle; Tecumseh) - 12 to 18 cm 
Lambton County; Chatham-Kent - 12 to 18 cm
Perth County; Huron County (Stratford) - 14 to 21 cm
Waterloo Region (Kitchener; Cambridge) - 15 to 22 cm
Middlesex County; London - 18 to 25 cm
Brant County; Oxford County (Brantford) - 15 to 20 cm
Hamilton (Stoney Creek; Dundas; Ancaster) - 18 to 28 cm
Niagara Region; Haldimand County; Norfolk County (St. Catharines; Niagara Falls) - 20 to 25 cm
Halton Region; Peel Region (Burlington; Mississauga) - 12 to 18 cm
Toronto (North York; Etobicoke; Scarborough) - 8 to 18 cm
York Region (Markham; Vaughan; Newmarket) - 8 to 15 cm
Simcoe County (Barrie; Collingwood; Midland) - 5 to 12 cm
Muskoka (Huntsville; Gravenhurst) - 4 to 10 cm
Sudbury (Chelmsford; Nickel Centre) - No Accumulation to 1 cm
North Bay - No Accumulation to 1 cm
Durham Region; Northumberland, Prince Edward, Hastings Counties (Belleville; Oshawa) - 7 to 13 cm
Frontenac, Stormont-Dundas-Glengarry Counties (Brockville; Kingston; Cornwall) - 2 to 6 cm
Ottawa (Kanata; Nepean; Gluocester) - 2 to 6 cm
Renfrew County; Haliburton - 7 to 17 cm

Peterborough County (Peterborough); Hastings County - 7 to 15 cm

Québec

Vaudreil - Dorion - 4 to 9 cm
Mont Tremblant - 2 to 5 cm
Gatineau (Hull; Chelsea) - 2 to 6 cm
Montréal - 3 to 8 cm
Terrebonne - 2 to 4 cm
Laval - 2 to 5 cm
Trois-Rivières (Cap-de-la-Magdaleine) - 1 to 3 cm 
Shawanigan - Trace to 2 cm
Sherbrooke; Drummondville - 5 to 10 cm
La Ville de Québec (Lévis; Ste-Foy) - No Snowfall

New Brunswick

St. John - No Accumulation to 3 cm

Prince Edward Island

Entire Island (Charlottetown; Summerside; Souris) - Trace to 4 cm

Nova Scotia

Cape Breton (Sydney; North Sydney) - No accmulation to 1 cm 
Glace Bay ; Picton - Trace to 2 cm
Annapolis; Kent - No Snowfall to No Accumulation
Halifax; Dartmouth - Trace to 3 cm
Yarmouth - Trace to 2 cm