C-c-c-cold

We had a blizzard of electronic and voice communications last night.  It started about 8 pm, when my wife and I received both text and email messages from our local high school district that school would be closed today because of predicted snowfall overnight (expected to be 6-10", with heavy snowfall during morning rush hour).  A few minutes later, our land line (yes, I still haven't cut the cord) rang with a prerecorded call with the same info.  Then, a bit after 10 pm, the phone rang again, this time from the Catholic school where one of my daughters teaches, another prerecorded call announcing that it also had caved to impending snow doom.  Finally, at 5 o'clock this morning, the land line and my wife's cell phone, both at her bedside nightstand, each rang simultaneously, causing both of us to hit the ceiling, with a prerecorded call announcing that her office has a delayed start.  (As I work from home, and my employer's US operations are based in Texas, it has no official interest in Chicago weather.)

I am writing this just a few minutes after my wife handed me a plastic 12-inch ruler from the kids' elementary school days.  I stepped out onto our stoop in my sneakers and plunged the ruler into the snow on the walk.  Three inches, which far from spelling doom is practically yawn-worthy around here.  Supposedly the heavy bands now have moved out across Lake Michigan and Indiana.  Our street is plowed.  I'll shovel during lunchtime today.  Doom averted, apparently - and in fact, I've driven my children to school many times in worse conditions.

But wait.

Those of you from snowy climes are well aware that the usual pattern is: a round of snow, followed by a temperature drop (and often clear skies).  Well, the temperature drop following this storm is going to be more like an anvil falling from an airplane and crashing through the floor.  The high temperature around here on Wednesday is going to be something like -14 degrees F, with the low sinking to -27 F.  Add in the wind chill, and it will feel like -47 F, with Thursday not much better.

According to Tony Briscoe in the Chicago Tribune:

The wintry onslaught will be driven by the Northern Hemisphere's polar vortex, the pocket of cold air sitting atop the North Pole.  When temperatures rise in the Arctic, the polar jet stream - the torrent of westerly winds that hold the polar vortex in place - can weaken and dip into parts of North America ... A destabilized polar vortex typically splits over Canada and Russia, and has the potential to move farther south.  As the cold front bore down on northern Minnesota Sunday morning, the border city of International Falls set a record low of minus 44 degrees, shattering the previous record by 8 degrees.

What accounts for this extreme weather?  As we might have guessed, it's that pesky climate change problem:

... scientists say winters like these could become more common in the future due to climate change.  The Arctic is warming twice as fast compared with the rest of the planet, partly because there's less ice cover, [climate research scientist Jennifer] Francis said.  Instead of ice reflecting sunlight away, the water is absorbing this heat.  A growing body of evidence suggests another warming trend in the Pacific Ocean is believed to be causing the jet stream that confines the polar vortex to warp further, with warm air penetrating near the Pacific Northwest and a lobe of cold air sinking into the Midwest and Northeast.

We're also seeing some big temperature swings over the next few days.  My children and I shoveled snow during lunchtime today, and the temperature was in the low 30s F, which will be today's high temperature.  As mentioned above, the high temperature on Wednesday is expected to be -14 F, a downward slide of nearly 50 degrees.  By Sunday, the high temperature may be as high as 48 degrees F, which would be a "real feel" differential of 100 degrees or more from the -50ish degree wind chills expected on Wednesday.