From AccuWeather.com

Winter Storm Watch....Posted for Ontario

A possible record breaking snowstorm is on the horizon for Eastern Ontario and Quebec. Low pressure organizing over Texas will race along the spine of the Appalachians while intensifying to a 988mb low (barometric pressure). The March 3-4, 1971 east coast blizzard had a 966mb pressure reading by comparison and dumped 60cm on the area. This will place the current storm is some very close company.

I expect snow to begin across North Grenville and here in Kemptville late tomorrow afternoon and continue into Saturday. It is not outside of the realm of possibility that 50cm could be on the ground by late Saturday with lesser amounts to the north and west. A mix of precipitation is possible over New York state. The upper Ottawa Valley may see a little less snowfall along with the GTA. It is still in the formative stages so some deviations in the path of the storm may occur changing the type and quantity of precipitation.

Travel may become impossible Saturday in heavy snow and blowing snow. Another update will be posted by 11pm this evening.