Winter Storm Warning

We have another rather difficult forecast as deepening low pressure over the Great Lakes is forecast to move towards Ottawa and east across southern Quebec today and tonight. A warm front remains draped over the border region keeping warm air to our south and cold air at the surface in the St. Lawrence Valley. This is a very similar setup to last week. What this means weather wise is a whole mix of precipitation ranging from snow to sleet to freezing rain and just some old plain rain, especially south of Montreal toward the US border. The first batch of precip brought a trace of snow to Montreal overnight along with some patchy freezing rain. It was enough to slow the morning commute. The next batch will lift out of southern Ontario and across the region by afternoon. Winter storm warnings are in effect for all of eastern Ontario as well as southern and central Quebec. The mix will accumulate 10-15cm across the southern regions with 15-25cm further north. Ottawa can expect about 20cm with Montreal closer to 10cm. South of the St. Lawrence, rain and mixed precipitation will limit amounts to under 5cm, the same is true for the GTA where temperatures are already well above freezing at 4C, rain with warm highs near 8C is forecast today.

The other factor with this strengthening storm will be an increase in surface winds. Winds are forecast out of the northeast at 20 to 40km/h most of the day here in Montreal, keeping the valley cold enough for snow and freezing rain. They will back to the northwest tonight and increase to between 50 and 80km/h. Temperatures will slowly warm from where they are now at -8C, up to 0C and perhaps a degree or two above overnight and then drop during the day on Wednesday as colder air moves in behind the storm with some flurries as well.