|Another low pressure area and cold front will bring a reinforcing shot of cold air to southern Quebec late Tuesday with perhaps 5cm of snow. (AccuWeather)|
A strengthening low pressure area will move across the Ohio Valley and into the eastern Great Lakes today. East of the storm, mild air along with a surge of moisture will affect southern Quebec and Montreal. Steady rain will start shortly in southern Quebec and last most of the day. Heavy rain warnings have been posted for regions north and west of the city including Ottawa where 30-40mm may occur. Along with the rain will be strong southerly winds. These winds will shift to the southwest this evening in Montreal as a cold front associated with the storm sweeps across southern Quebec. The wind will increase to 60-90km/h with higher gusts likely in some locations. Environment Canada has issued a high wind warning for Montreal and the St. Lawrence Valley.
The temperature will be very mild today, reaching 8C (47F) by early this evening. However, behind the cold front, it will rapidly turn colder with a low of -5C (23F) expected by Monday morning in Montreal, colder elsewhere. The rain will change to snow overnight with a dusting in Montreal but perhaps a few centimetres across eastern Ontario. Any standing water will freeze making roads and sidewalks very icy. Monday will be blustery and much colder with snow showers and temperatures nearly steady or even falling. It will be much colder this week with lots of clouds and flurries and temperatures remaining well below freezing for Montreal.
Strong winds blowing across the Great Lakes will generate snow squalls this week. The squalls will affect western New York and portions of Ontario. In the most persistent bands of snow 30-60cm (1-2 feet) are possible. Keep this in mind if you are travelling Highway 401 or Interstate 81 and 90.