A shot of snow late Sunday in parts of southern Ontario will herald a more widespread fall at the beginning of the week, timed in some areas for the Monday evening commute.
Environment Canada has already issued a special weather statement for almost all of southern Ontario with the exception of eastern areas, and snow is forecast to fill in Monday afternoon across the southwest and into the evening for the the Niagara regions. The GTA is looking to see its first significant snowfall Monday night into Tuesday, with around 5-10 cm expected.
The latest forecast track brings the low along the north shore of Lake Erie — a notorious track for impactful snow for the Niagara-Hamilton corridor, as an easterly flow sets up along the Lake Ontario axis, enhancing snowfall amounts. And with the system lacking significant moisture initially, we will depend on the lakes to supply it.
As the system tries to depart to the east, the seducing warm waters of lakes Erie and Ontario will tempt the storm to linger over the region. If this scenario verifies, snow will continue into Tuesday morning for most areas across southern Ontario, but with higher impacts for Niagara-Hamilton (QEW) corridor, before departing through Tuesday.
At this point, widespread snowfall amounts are in the 5-10 cm range across the GTA, but this could be conservative. Higher ranges for the lake-enhanced regions to the east of Lake Huron and the north shore of Lake Erie could see 10-20 cm through Tuesday.
Temperatures will truly plummet into Wednesday as the coldest air of the season leaves daytime highs fighting to rise above the -10°C mark across southern Ontario.