Flood risk on the rise this week in southern Quebec

Heavy rain, record warmth and melting snow will increase the risk of flooding this week in southern Ontario and Quebec. (AccuWeather.com)

Near record breaking warmth is forecast this week across southern Ontario and Quebec. A large ridge of high pressure located off the southeast US coast, will pump unseasonably warm and humid air northward. A frontal boundary will become established along the northern periphery of the high pressure. Along this boundary, several waves of low pressure are expected to bring significant rainfall through late Wednesday. Conditions in Montreal will start off dry and mild on Monday, with daytime highs approaching 5C (41F). Clouds will thicken late in the day, along with rain developing by evening. Intermittent rain is expected in the St. Lawrence Valley through Wednesday evening, with 20 to 40mm (0.5-1.5 inches) possible. The combination of above freezing temperature, rapid snowmelt and potential ice jams, will increase the risk of flooding across the entire region. Widespread flood watches are in effect south of the border across New York and New England, with a special weather statement covering the flood risk here in southern Quebec.

As far as daytime high temperatures go, Tuesday and Wednesday will be the warmest days of the week, potentially challenging the record highs. We have a decent shot at the record set Tuesday in Montreal, which was 10C (50F) set in 1994. Wednesday and Thursday may be a little more difficult, with the current records dating back to a very warm February in 1981, at 13.9C (56F) and 15C (59F) respectively. The current forecast calls for highs of 8 to 12C (45F to 54F) both days. The overnight lows Monday through Wednesday should remain above freezing as well, near 5C (41F).

A cold front arrives late Wednesday, accompanied by flurries and cooler temperatures.