Thursday, 29 November 2012

Southern Ontario First Significant Snowfall

The GTA and the golden horseshoe will experience its first significant snowfall of the season tomorrow. Light flurries will begin tonight with light bands of snow moving through the area after the midnight hour. As the night wears on, the snow will begin to pick up in intensity around 9 AM with more consistent bands of snow around the west end of lake ontario in particular which could pick up some precipitation enhancement from the lake. By 11 am the heaviest bands of precipitation will move through SW ontario first with a light burst of snow/freezing rain and sleet before moving northwards and effecting the GTA around noon. This band of snow will slowly move eastwards allowing for light snow to fall from orangeville, through the GTA, niagara, hamilton and the NW shores of lake erie between 10am and the late evening hours. This band of snow will be nothing special for southern ontario but it will promote an ENE to ESE wind off of lake ontario which may work to enhance snow totals. This has been advertised on the RAP, NMM and ARW high resolution models showing enhanced precipitation from hamilton to oakville and even the GTA to a lesser extent. Right now it is hard to tell if and where these bands will set up but my hunch tells me based on wind shear values, light easterly winds and a small temperature inversion that snow will stay light under this system causing 2-5cm amounts across the golden horseshoe. This will be enough snow to coat many cooler surfaces but will not present major problems for road travel. If under the event that lake enhancement does take place these amount can easily double with some areas picking up 5-10+cm of snow. I remember waking up one morning in january of 2011 with a surprise 15-25cm of snow due to lake effect bands off of lake ontario which can pack a quick punch if the correct setup presents itself including heavy snow rates.

NMM Similated Radar:
850mb Temperatures are supportive of snow:
Sounding for mid day friday:

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