Environment Canada is now saying snow accumulations in southwestern Ontario could near 10 cm (4 in) by Saturday night.
The national weather agency updated its special weather statement for Sarnia-Lambton late Saturday morning.
In the Sarnia and Windsor regions forecasters say rain or wet snow will continue through the day with accumulations by late Saturday evening ranging from 2 cm to 8 cm.
There was still considerable uncertainty, however, as to the exact snowfall amounts in the southwest, with temperatures very near the freezing mark.
Across the Bruce Peninsula and portions of central Ontario the Texas low could dump snowfall amounts ranging from 5 cm to 15 cm (6 in) by Sunday morning.
A snowfall warning was in effect for areas east of Georgian Bay including the higher terrain of Barrie-Orillia-Midland as well as the Dundalk Highlands.
The U.S. National Weather Service posted a Winter Storm Warning for parts of Michigan including Port Huron and St. Clair County with snow accumulations forecast to range from 6 in to 10 in Saturday.
