It's 5.30 p.m. on Sunday, and the dog and I have just been out for a walk in the storm. Probably 20 cm. has fallen already and it's still falling steadilly, though there's no sign of a snowplow anywhere near here. Presumably they're busy trying to keep the main roads open. But the dog loves it, romping through the deep snow in the ditch at the end of her long leash, and shoving her face in the snow to chase the sounds or the smells of mice.
Then I blew out the laneway, blasting 8 inches of soft snow in the air, so I won't be faced with an overwhelming depth tomorrow morning. With a gentle slope to our lane, we can't afford to let it get snowed in.
The cause of this snow is completely different than the lake effect snow some of southern Ontario got last week. This is a mid-latitude low pressure system passing across the continent, what meteorologists would call a cyclonic storm. It formed where the cold arctic air sweeping out of the north was meeting warmer air from the Gulf of Mexico over the western states.
As the whole package moves to the east, it spirals, so the first part of the storm actually has southern winds, blowing moist air northwards - you can see the pattern clearly on the radar. The moist air coming from the south rises over the cold air from the north, and starts crystalizing as snow; in a big system like this the snow can continue for hours. The southern part of this system usually brings rain, while the snow occurs further north, just as it did today.
All in all it's a great winter storm! The world will be white tomorrow.