Southern Ontario: Snowfall Outlook for Tuesday, December 21 to Wednesday, December 22, 2021

Forecast Discussion

A weak system will move into northern parts of Southern Ontario late Tuesday evening bringing the potential for some light to moderate snowfall continuing into Wednesday. This will mainly affect Northeastern Ontario and into some parts of Central Ontario to the northeast of Georgian Bay. Total snowfall accumulation will generally range from 6-12cm, but a few locations along the northern shoreline of Georgian Bay could see up to 15-20cm due to lake enhancement helping to boost totals. The system will move out by Wednesday afternoon, however, lake effect snow is expected to develop off Lake Huron and Georgian Bay in the wake of the system.

Current indications suggest one main squall will set up off Lake Huron affecting the northern Grey and Bruce counties throughout the afternoon and into the evening. A few locations may approach 15-20cm by the end of Wednesday due to these squalls with more general amounts ranging from 5-10cm. For Georgian Bay, some heavier lake effect snow could result in accumulation between 6-12cm and locally up to 16cm in parts of Simcoe County.

The lake effect snow may linger into Thursday, but there is low confidence on intensity and location so that will be covered in a future forecast.