A slug of rain moved up over us this morning, with just a bit of freezing on cold pavements, though the temperatures were above freezing at 36. I suppose the stones remembered the cold. The rain swiftly swept north and is gone, and now we are seeing a gray sun, with temperatures pushing 40. I suppose this is the long-awaited “warm-up.”
The rain-snow line has been pushed well to the north, but I am going to call this “Winter Storm #10” all the same. (We had some icy pavement, after all.) (I’ll never match the 26 winter storms of the 1600’s if I don’t cheat a little.) Also a little snow may be swept around the backside, and give us a backlash tomorrow.
The map shows the warm front never made it here. It zipped up into an occlusion, and a weak coastal low has formed where the zipper is zipping, and the cold front separates from the warm front. It seems that nearly the entire mild air-mass, full of Chinook kindness, was lifted before it got east. We got gypped. It all passed over head, as down on the ground we got a case of the shivers. (Click maps to clarify and enlarge)
That coastal low will likely blow up into a gale up over the Canadian Maritimes, and we will get north winds and some moderated arctic air. Somehow the cold always seems to manage to sneak down our way. Here’s the latest temperature map: (Click and then click again to fully enlarge.)
Besides the chill hanging tough over New Hampshire, the map shows some grey coloring south of Hudson Bay, indicative of temperatures dipping below zero Fahrenheit ( -18 Celsius). That is some home-brewed Canadian cold that was prepared for us during the long nights the air sat over the snow-covered Canadian prairies. When nights are at their shortest Canadians don’t need to import air from Siberia to freeze our socks off. The irony is that where the subzero air now sits is the exact location where the friendly Chinook air lay, last week. It seemed so sure to sweep east and warm us.
I’ve been doing a lot of thinking about what happens to the warm air when it is occluded upwards. What happens to the heat it holds? There is a surprising amount of argument about whether it is radiated to outer space or not.
Another thing that kept the warm air from reaching us was all the snow-cover it had to melt away, as it came east. It takes a lot of heat top melt snow, as the available heat turns into latent heat as water goes through the phase changes from solid to liquid, and from liquid to gas. (The opposite occurs when the phase changes reverse. A storm actually releases a lot of heat as vapor turns to liquid and liquid to snow.)
The snow-cover was at record levels at the end of November, and had advanced down to Texas, but the “warm-up” chased it north to Canada by December 13:
It has made a comeback behind Storm #10:
You can see the snow is hanging stubborn, in New Hampshire, but it is not the pretty snow you see in Christmas cards. It is inferior, dingy stuff, with patches of bare ground showing on the south slopes. We could do with a touch-up, though preferably not until Christmas Eve.
I am going to add to this post later, as there is a lot of gossip about a storm this weekend, but I have chores to do before I can delve into that.
UPDATE —“Santabomb” storm?—
As usual Weatherbell and “Whats Up With That” have beaten me to the punch, as Ryan Maue has tweeted the news about various Christmas blizzards the models are seeing. The news can be read at http://wattsupwiththat.com/2014/12/17/santabomb-winter-storm-predicted-for-northeastern-u-s-at-christmas/#comment-1816610
The GFS computer was cranking out a 956 mb low over the Great Lakes: (Click to clarify and enlarge.)
First, this is a modeled storm, and models change their so-called “minds”, especially about events a week away.
Second, some sort of big storm is likely, as the very cold air returns and runs into the “warm-up” air in place over the USA. The question is, where they will form and where they will move. In the winter of 1978 there were three big storms, two of which gave blizzards to New England, and which sandwiched a warm storm that sank my shack on the coast of Maine.
Here are some comments from the post over at WUWT: