From late afternoon saturday into early the evening hours it looks like cells set up in a WNW fashion(collingwood/wasaga band south towards stayner, angus and Bradford/Newmarket) before shifting further to the SW once the flow shifts to the NNW by late evening into the overnight. This squall should be able to briefly move through the GTA/hamilton area's as well before building back to the West. These squalls should sit in this type of position through sunday morning with a band extending through meaford/collingwood and down towards shelbourne and perhaps as far east as alliston. Don't think areas east of barrie see very significant accumulations with this outbreak besides some weaker squalls after the immediate passage of the cold front saturday evening/afternoon. Barrie is in the 5-10cm zone. The squalls should build back to the NE sunday afternoon with the flow lining up in a more NW direction as the high moves through, but this will only last for a few hours before shear starts to rebuild.
BL lapse rates should remain rather steep throughout tomorrow evening into the overnight and through sunday morning with some wavering of the band from more of a goderich, st mary's, tillsonburg position before shifting further south into the london/strathroy/lambton shores areas. Going to see this band waver considerably throughout the duration of the event as winds shift between these two positions. Thinking thundersnow is possible especially in areas North of London, may even get into the city, where 10-25cm is likely IMO.
Here is my Forecast Map. Thinking a trace-5cm is possible outside the blue zone with the area shaded in pink, including the GTA and hamilton.