BURSTMore heavy snow forecast for north-east this week, while South Africa endures third heatwave of summer
Winter is well underway across the pond in North America with two distinct lake-effect snow events taking place since Thanksgiving. Lake-effect snow is common across the Great Lakes region, and happens when cold air originating from Canada passes over the relatively warm waters of the lakes, causing the layer of air near to the surface to absorb heat and moisture. Warmer than the air above it, this layer of air then starts to rise, cooling and condensing into clouds which deposit snow on the windward side of the lakes.
In this particular event, an area of low pressure centred across eastern Canada dragged very cold Arctic air in from the north and plunged it into the north-east of the US. The dry, arctic air blew in from the north-west across the relatively warmer Lake Erie through Thanksgiving, picked up moisture and deposited snow across areas to the south and east of the lake. A dominant band of snow brought rates of 2.5cm to 7.6cm (1in to 3in) an hour to the Erie and Crawford counties. Within the first 12 hours, approximately 30cm of snow fell in Ashtabula County, Ohio, and by Saturday morning, there were reports of more than 90cm of snow in the far north-east of Ohio and north-west of Pennsylvania. As a result of this heavy snowfall, parts of the Interstate 86 and 90 were shut on Friday 29 November.
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