Friday 7 December 2012

Lake Effect Snow Setup Dec 11-12th


I can see some LES setting up late monday night into tuesday morning after this storm passes through the area. With a NW surface flow as well as low and mid level flow the setup will be there for significant lake effect snows in areas downwind of lake huron and georgian bay. Delta-T values between lake and 850mb temperatures will be in the range of 15-20C. This temperature inversion with limited wind shear values will be conductive for a LES setup. Cold air advection will be enhanced behind the cold front passing through the area because of the late time of day. Right now I see this as a minor set up that will not last as long and setting up in traditional areas that get hit during NW and NNW flow events. The winds will be originated out of the NW for most of the time before a shift to the NNW during the morning hours of tuesday. I expect areas from barrie south to alliston and NW to collingwood to get in on the action off of georgian bay while areas from Goderich to london and south to the lambton shores get hit with the snows off of lake huron. With more favourable upper level dynamics I think we will see stronger bands off of lake huron but with georgian bay water temperatures running above normal bands will be significant there as well. In general i am expecting a pretty minor 2-8cm event that will not last for very long but areas outlined in my forecast map should be prepared for this monday night into tuesday. The GTA may feel a few convective flurries under the passing upper level low but no significant LES is expected.

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