“We should expect significant school bus and school cancellations on Monday,” he said.
Farnell said a “disruptive winter storm” was already producing “severe weather” across the southern U.S. on Sunday.
“As the system lifts north, heavy snow will begin around the Niagara region this evening and just before midnight in the GTA,” he said.
According to Farnell, the snow will “quickly become heavy overnight,” with snowfall rates of up to five centimetres per hour.
He said by the Monday morning commute, there will already be around 15 to 20 centimetres of snow on the ground in Toronto.
Meanwhile, areas like St. Catharines and the Niagara region could receive “almost double that.”
Farnell said this is a “complicated storm” because of the “sharp snowfall gradient.”
He said the west end of the Greater Toronto Area will see less snow (15 to 20 centimetres) compared to the east end (20 to 30 centimetres) and closer to the lake.”
According to Farnell, southwest Ontario and the Bruce Peninsula will “barely see any snow from this storm.”
Meanwhile, eastern Ontario and the Niagara region could receive anywhere from 30 to 50 centimetres of snow.
What’s more, Farnell said winds will continue throughout the day on Monday, “reducing visibility in blowing snow.”
Environment Canada has issued winter storm and snowfall warnings for a large swath of the province.