Our weather has been fairly typical of early winter over the past week, which means that temperatures have been riding a roller coaster. Last Tuesday and Wednesday were mild with highs in the 60s.

Then on Thursday a cold front passed through ushering in a colder air mass. Highs Thursday through Saturday stayed in the 50s and most locations in the county saw lows near or slightly below freezing Saturday and Sunday mornings.

Meanwhile temperatures across the northern Rockies and Great Plains and the Great Lakes have been downright frigid since last week. Last Thursday morning the thermometer at Casper, Wyoming, read 33 degrees below zero.

Regardless, given that 33 degrees above zero feels pretty cold to me, I can’t imagine what it must have been like to walk outside last Thursday morning in Casper .

The cool air over us (I hesitate to call it cold after mentioning Casper) began to moderate on Sunday. Yesterday our high was back in the 70s, and that should be the case today also.

Another surge of bitterly cold air has plunged out of Canada into the Northern Great Plains and will be spreading mostly eastward the rest of this week into the upper Midwest, Great Lakes, and Northeast.

By Friday, Boston’s temperature is forecast to stay in the teens all day.

The source region for the cold air affecting the U.S. last week and this week has been northern Alaska and northwestern and central Canada.

You might be tempted to infer that one thousand miles north of Alaska at the North Pole and the surrounding frozen Arctic Ocean it would be even colder.

It is cold there. It’s December in the Arctic. But, it has been abnormally warm in those far northern regions for much of the last two months. According to the National Snow and Ice Data Center, “Average Arctic sea ice extent for November set a record low, reflecting unusually high air temperatures, winds from the south, and a warm ocean.”

Even this week near the North Pole models predict that temperatures will be well above zero, which is 10 to 20 degrees above average. There will be times this week that it is colder in North Dakota than at the North Pole! Maybe Santa is still in his summer shorts and t-shirt.

Those of us in the Gulf South will get a glancing blow from this week’s invasion of cold air into the U.S. There’s a good chance of showers and thunderstorms today and tonight as it approaches. After the cold front passes us on Wednesday, our temperatures will remain in the 60s most of the day. Thursday will be a fair, breezy, and cool day beginning with lows in the 30s warming to 50s in the afternoon.

The roller coaster bottoms out on Friday morning with lows near freezing, and then starts climbing upward. By Saturday afternoon southerly winds and the 70s will return to town. By Sunday in the mild, humid air ahead of yet another cold front, showers are forecast to return.

By Skip Rigney