Roller coaster ride

11am UPDATE: A Flash Freeze Warning has been posted for most of Ontario including Kemptville, Ottawa and Cornwall. A strong cold front will rapidly drop temperatures from well above freezing to -10C starting around noon and reaching Montreal by early evening. Any rain will change to snow with rapidly dropping temperatures, strong southwest to northwest winds, blowing snow and icy roads. It will drop to -18C overnight. Travel with care this afternoon or adjust your plans. Warnings may be extended into Quebec later today.

Stubborn temperatures below freezing on the island of Montreal at 8am have allowed for the falling rain to freeze on contact on all surfaces. Roads and sidewalks are very icy. The freezing rain should change to rain my mid morning and snow this afternoon. It will be a messy drive today with rapidly changing road conditions.

The temperature will be the big weather story this week with big jumps and falls anticipated. This morning low pressure near Ottawa is expected to slide along the international border and well east of the region by late today. This morning temperatures are all over the place across the region. Montreal Trudeau Airport is currently -4C with freezing rain and a northeast wind. South of the city St. Hubert is all the way up to plus 3C with light rain. Meanwhile up Highway 20 in Quebec City it is -7C with snow. Down the 401 in Cornwall they are plus 1C. Overnight over 10cm of heavy wet snow fell on the city making for a messy commute. That puts the snowfall for Montreal for February near 60cm, or double that of January with half the month to go.

So now the roller coaster ride begins. We may nudge above the freezing mark for a few hours this morning, but it will be short lived. A strong and breezy cold front is moving across Ontario this morning with gusty winds over 90km/h, a burst of steady snow and rapidly dropping temperatures. Despite highs in southern Quebec and the Ottawa Valley of plus 1 to 3C today, the temperature will plummet tonight to -18C with wind chills near -30C. Tuesday will be a cold day with the mercury struggling to reach -10C. After that from Wednesday to Friday a major warming trend will bring the warmest air of 2011 into the region. Highs could approach plus 8 to 10C across southern Quebec, Ontario and New England, assuming we can chase this arctic air out of the valley. Skies will be partly cloudy with an increase in clouds by Friday, and rain possible. The rain will change to a period of snow late Friday into early Saturday as another cold front allows the temperature to take a dive.

It will be quite a ride from winter to spring and back to winter this week. Keep this in mind while travelling as the weather will be changeable with lots of icy surfaces around.