Update 2010-02-02: As this major storm continues to track northeast, snow accumulations in southern Ontario will generally be less than anticipated in some areas due to the high ice, rain and sleet content of the precipitation from the warm sector of this massive extra-tropical cyclone. The cold front associated with the low will continue to produce cold snow over the Great Lakes region for the next 12-24 hours as the storm continues to feed moisture from the south into the circulation. Strong winds across the frontal boundaries will contribute to significant blowing snow and and lake effect snow in the lee areas of the Great Lakes for most of Wednesday, and as the snow pack chills, ground level whiteouts may be frequent in open areas.

A major storm system is expected to develop out of the central US and extend across southern Ontario and the US Northeast through Wednesday, February 3, 2011, bringing possible snowfall amounts to the lower Great Lakes basin in excess of 20 in. (50cm), with possible amounts to 18 in. (45cm). Forecast models are in good agreement as to the severity of the storm. This storm will be the first major storm for the GH-GTA; southwestern Ontario has already had record multi-day lake effect storms this winter.

This should be considered a dangerous winter storm. Heavy and blowing snow combined with a temperature of approximately -10C create a dangerous and life-threatening exposure risk.

The first panel below is the GFS model snow accumulation forecast through February 3, 2011,

and the following panel is the NAM 84hr forecast snow accumulation model. Both project anywhere from 30-45cm of snow for southwestern Ontario and the GH-GTA, and some lake effect enhancement is expected.