Record breaking warmth to be replaced by snow across southern Quebec and Ontario

It did feel like spring had arrived, but Montrealers know better. Despite the rain and record warmth this week, snow is forecast to fall Thursday night across southern Quebec. The snow may mix with freezing rain at times, with 10 to 15cm forecast by noon Friday.

Montrealers witnessed a 141 year-old temperature record fall on Wednesday evening, when the mercury hit 9.1C (49F) at Trudeau Airport and 10.5C (51F) downtown. The previous benchmark for the day was 7.2C (45F) set at McGill University downtown in 1882. We also surpassed the Trudeau Airport record of 6.8C (44F) established in 2006. The surge of warm air impacted a large swath of eastern North America, with over 200 new daily temperature records established including Toronto and Ottawa.

Temperatures will remain above normal, but we have a significant change in the weather over the next 24 hours as a quick moving winter storm moves just south of the international border. The path of the low pressure has changed somewhat over the last 24 hours and so has the weather accompanying the system. Colder air is filtering into the St. Lawrence Valley, with Thursday's high of 7C (45F) reached at midnight, that was just shy of the 7.7C record for the date set in 1981. The updated track will result in more snow than rain for Montreal.

Thursday evening into Friday the strengthening storm system will move from Oklahoma to just south of Montreal and into Atlantic Canada on Friday. The storm will push a swath of deep moisture into the colder air across our region, with rain and freezing rain beginning after 6pm and changing to all snow this evening. The snow will end Friday morning for metro Montreal. Between 10-15cm of snow and perhaps a few millimetres of freezing rain are possible for the St Lawrence Valley. The temperature in Montreal will fall to -5C (23F) by morning, with a high of -3C (27F) Friday.

Widespread winter weather advisories have been posted along either side of the St. Lawrence Valley in Ontario and New York. In Quebec, freezing rain warnings are now in effect for the Richelieu Valley, with snowfall warnings posted in the Eastern Townships and Beauce regions for 15-25cm.

Skies will slowly clear Friday afternoon, followed by a cold night, down to -15C (5F).  The weekend is expected to be dry and mild at this time, with temperatures rebounding to near the freezing point or even above by Sunday.