UPDATE: Snow squall warning in effect

File photo courtesy of © Can Stock Photo / wallbanger.

Londoners are bracing for what could prove to be their first significant snowfall of the season.

A snow squall watch issued by Environment Canada for London and Middlesex County was upgraded to a snow squall warning Thursday morning, with up to 40 centimetres possible in some areas by Friday night.

The national weather agency expects the squalls to develop off of southern Lake Huron Thursday night and intensify overnight with as much as 25 centimetres of snow possible by Friday morning.

Another 10-15 centimetres of snow could potentially fall throughout the day Friday before squalls weaken in the evening hours.

“Travel may be hazardous due to sudden changes in the weather. Visibility may be suddenly reduced at times in heavy snow,” Environment Canada warned in a statement.

Environment Canada has also issued similar snow warnings for eastern Lambton County, Perth County and northern Huron County. A winter weather travel advisory has been issued for St. Thomas and Elgin County, which could see five-15 centimetres of snowfall due to squalls by Friday night.