The week is set to end with a messy mix of heavy rain and snow for central and southern Ontario.
A low pressure system will develop south of the border and make its way toward Ontario and Quebec Wednesday night as another, weaker low pressure system makes its way to northeastern Ontario and southern Quebec from northwestern Ontario. Both systems are set to merge as they move into southern Quebec, leaving behind a messy trail of snow.
Previously, there was uncertainty about whether or not Ontario would be significantly impacted by this storm. Now, there is high confidence that central and parts of southern Ontario will, in fact, bear the impacts of the heavy snow and rain associated with the system.
Some uncertainty does remain, however, in the amount of snow the southwestern region of the province and the Greater Toronto Area (GTA) will receive.
The southern low pressure system is expected to move into the province early Thursday. Precipitation will begin as rain before transitioning to snow Thursday afternoon for areas south of Georgian Bay, or through Thursday evening and overnight for the GTA as cold air gets pulled into the region.
How much snow falls in southwestern Ontario and the GTA is ultimately dependent on how fast the transition from rain to snow is and how much moisture is left in the atmosphere as the cold air moves in. Currently, snowfall amounts of 5-10+ cm of snow are forecast for regions between the lakeshores and north end of the GTA.
Areas between Brantford and Ottawa will bear the brunt of the snowfall, with amounts between 25-35 cm expected by Saturday morning as the system makes its way into southern Quebec. The heaviest period of snow will be overnight Thursday through Friday morning.
Rain will persist in Kingston until transitioning to snow by Friday morning.
Regions north of the shores of Lake Erie and Lake Ontario will see between 20-40 mm of rain between Thursday and Friday morning, with amounts drastically reducing northward until reaching the central regions of the province, where there will be only snow.
The system will move out of the province and into Quebec by Friday afternoon, with all snow departing with it by Friday evening.
For more forecast information and updates, keep checking back to The Weather Netowork.