Friday, February 24, 2012

Storm update

12PM UPDATE: At noon, snow is advancing northeast across Ontario and into southwest Quebec. The snow will start out very light this afternoon but become much heavier as low pressure deepens and moves south of Montreal by evening. Heavy wet snow and strong winds will continue into Saturday morning with 15-25cm forecast for southern Quebec by the storms end. Up to 15cm is expected in eastern Ontario and none now in the GTA with perhaps just a few flurries. Visibility will lower and travel become difficult in southern Quebec by the evening rush hour. 

7am Friday UPDATE: Snowfall Warnings have been extended to the metro Montreal region this morning for 15-25cm of snow over the next 18 to 24 hours. We have a deepening low pressure area over Lake Erie this morning that is forecast to move down the St. Lawrence Valley. A second low is forecast to develop off the Maine coast and deepen rapidly. This will result in precipitation across New England and Quebec for the next 24 hours.  Radar returns over Ontario at this time are not overly impressive, but there is some rain and snow being observed. Winds are also beginning to increase in eastern Ontario out of the east and northeast. For southern Quebec the snow will not get in here much before noon with the heaviest expected during the evening hours. Winds will also increase to between 30 and 50km/h. The temperatures will be right around the freezing point.

Previous Discussion
I had chosen not to call our upcoming weather a storm this morning but it seems the 15cm threshold may be reached after all in southern Quebec and possibly exceeded. At this time we have low pressure over Illinois that is expected to work its way across western New York and just south of Montreal by late Friday. Snow is expected to overspread the area beginning in southern Ontario tonight and reaching Montreal by mid morning on Friday. It appears the heaviest snow will fall across the region between the city and the US border as well as the higher elevations of the Laurentians, Adirondacks and Eastern Townships. Presently snowfall warnings are in effect from the GTA north and east into the Ottawa Valley as well as the area north of Montreal and from my region here on L'Ile Perrot south to the US border and east towards Sherbrooke. Amounts will generally be in the 10-15cm (4-6 inches) range with upwards of 20 to 25cm (6-10 inches) in the Adirondacks and Green Mountains of Vermont. Winds with this system will be gutsy out of the northeast 30-50km/h primarily in the St. Lawrence Valley, before backing to the northwest late Friday night. Temperatures will cool to -4C tonight and remain around 0C for the duration of the storm. Roads will become snow covered on Friday with low visibility in heavy wet snow which may fall at the rate of 2cm an hour or more for a time tomorrow.

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