One snow, and three temperature records fall

This morning's official record-low reading of 4 above Fahrenheit at the airport marked the third daily temperature record of the winter of 2013-14.

Record highs were reached on the first day of winter, 67, followed by a 68 on Dec. 22. In fact it wasn't that long ago that the temperature hit 60 in Philly; actually, about 28 hours ago.

As our online story noted, the two-day temperature difference of 56 – that's 60 to 4 – the second-biggest spread in the period of record, just one behind Jan. 8-9, 1978.

What's happened with the temperature the last four days has been nothing short of incredible: The low on Saturday was 8, and the official high Sunday, 53.

You might have heard so much about the "polar vortex" that you think it rode in on a UFO with Elvis.

The swirling cold air mass of the polar vortex is always up there in the Arctic and has made frequent incursions into the United States.

But the recent invasions have been particularly vigorous, and, yes, these temperature contrasts are legitimately amazing.

As for snow, Philadelphia already has received 20.2 inches, quite close to the average for an entire season.

We've observed that having two snowfalls of over 8 inches in the same winter is a rarity. And never in the period of record has Philadelphia had two such snowfalls so early.