Thursday, December 20, 2012

Big winter storm for Quebec & Ontario

Our approaching storm has been dumping snow from Colorado to Wisconsin overnight and today. (AP Photo)
A snowfall warning has been issued by Environment Canada for southern Quebec as well as eastern Ontario. A strong winter storm over the Midwest this morning is forecast to move towards the St. Lawrence Valley and then east just to the south of Montreal. It is a very similar track to Monday's storm with rain forecast in much of New York and Vermont, and heavy wet snow here in Montreal and the Ottawa Valley. Montreal will be right on the rain/snow line for most of the event so a change in just a few kilometres will mean different weather. Ottawa should remain all snow as well as the regions just north of the city. Accumulations will be impressive with snowfall rates of 2-5cm per hour overnight as the first wave of moisture approaches. Look for storm totals of 10 to 25cm (4-10 inches) for Montreal with 20-40cm (8-16 inches) for points north and west of the city. The heavy wet snow on top of Monday's storm may pose a risk to structures, trees and power lines, especially in the Laurentians. Temperatures during the storm will hover around the 0C (32F) mark over most of the region. Winds will be another factor with this storm gusting between 30 and 50km/h out of the northeast and increasing behind the storm to 70km/h in northwest gusts. Temperatures will fall to very cold readings by late Saturday with more snow forecast. Roads across the region from Brockville to Quebec City and northwest to the Ottawa Valley will be snow covered and icy with very poor visibility in heavy wet snow for most of the overnight and Friday. If you are travelling south on Friday the snow should transition to rain before the US border.

All this is subject to modifications if the path of the storm alters in any way. In addition there may be some coastal development of a second low. If this happen the forecast will change as well. I will post another brief update this afternoon.

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