Monday, 14 April 2014

Classic battle between winter and spring in southern Quebec

Flooding has started in Laval from the Mille Iles River. (CTV Montreal)
You have to love Canada in April with every weather possible in the next 48 hours across portions of Ontario and Quebec. We have a stubborn cold air mass stuck in the St. Lawrence Valley right now. As is typical with a warm front to our south, northeast winds are keeping the temperature in check in Montreal as we sit at 3C (38F) while just to our south, Potsdam, New York is 18C (65F) and Malone is 16C (61F). That warm air should surge into Montreal by midday as the low clouds and fog begin to burn off and we reach a high of 21 to 24C (70-75F).

We were treated to our first thunderstorm of the season last night here on L'Ile Perrot. Thunder with heavy rain, about 9mm, occured around 9pm last evening. The rain was not as bad Sunday in metro Montreal as expected but that did not stop area rivers from rising. Flooding from rapid snow melt continues across the region and especially south of Montreal. Flooding has also reached the metro region with Laval reporting water on the rise from the Mille Iles and des Prairies Rivers. A flood watch remain in effect for the entire area from eastern Ontario across southern Quebec and into New York and Vermont.

A slow moving cold front will approach Montreal this afternoon with showers and thunderstorms developing by late today and becoming a steady rain on Tuesday. Anywhere from 15-30mm of rain is likely, which will increase the threat for flooding. The warm temperatures today will begin to fall into the low teens by Tuesday morning and then rapidly down towards freezing by late Tuesday. This drop in temperatures will allow precipitation to change from rain to freezing rain, sleet and wet snow across the Ottawa Valley, southern Ontario and eventually southern Quebec. A quick 5-10cm of slushy snow is not out of the question for many locations by the time the snow ends overnight into Wednesday morning. Temperatures will plummet to lows as cold as -9C in many areas of the province. There will be lots of icy spots around late Tuesday so be aware if you have travel plans. It all clears out Wednesday with a cold day but sunny, highs near 1C (33F).

The amount of snowfall will be very dependent on how fast the cold air filters into the region behind the cold front. This will be updated over the next 24 hours so check back often as well as my Twitter feed.

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