Environment Canada has issued a snow squall watch for a large portion of southern Ontario, inlcuding the GTA.
West to east snow bands are expected to develop early Thursday evening off Lake Huron and Georgian Bay then shift and reform into a more northwest to southeast orientation for Friday.
The westerly bands this evening will affect portions of Grey and Bruce as well as the area from Honey Harbour to near Muskoka. The Muskoka area will only be affected during the evening hours.
The main squalls Friday are expected off Georgian Bay toward the Barrie area and off Lake Huron toward the London and Woodstock areas.
Snow squalls cause weather conditions to vary considerably; changes from clear skies to heavy snow within just a few kilometres are common. Visibility may be suddenly reduced at times in heavy snow. Surfaces such as highways, roads, walkways and parking lots may become difficult to navigate due to accumulating snow.
Snow squall watches are issued when conditions are favourable for the formation of bands of snow that could produce intense accumulating snow or near zero visibilities.
Areas covered by the watch are: London - Parkhill - Eastern Middlesex County, Woodstock - Tillsonburg - Oxford County, Uxbridge - Beaverton - Northern Durham Region, Newmarket - Georgina - Northern York Region, Midland - Coldwater - Orr Lake, Orillia - Lagoon City - Washago, Barrie - Collingwood - Hillsdale, Port Carling - Port Severn, Bracebridge - Gravenhurst, Fenelon Falls - Balsam Lake Park - Northern Kawartha Lakes, Lindsay - Southern Kawartha Lakes, Bruce Peninsula - Sauble Beach - Tobermory, Owen Sound - Blue Mountains - Northern Grey County, Saugeen Shores - Kincardine - Southern Bruce County, Hanover - Dundalk - Southern Grey County, Wingham - Blyth - Northern Huron County, Listowel - Milverton - Northern Perth County, Goderich - Bluewater - Southern Huron County, Stratford - Mitchell - Southern Perth County, Mount Forest - Arthur - Northern Wellington County, Innisfil - New Tecumseth - Angus, Shelburne - Mansfield - Northern Dufferin County, Orangeville - Grand Valley - Southern Dufferin County, Caledon