While we’re certainly in a chilly pattern now, it’s been several weeks since we’ve had some serious Arctic air in North Texas. There’s still plenty of time for another Arctic invasion, especially considering February is historically one of the coldest months for DFW. (Coldest temperature ever recorded at DFW was -8 on February 12, 1899).
Even still, when we get an Arctic blast it typically only lasts for a couple days.
So why does Arctic air only stay for such a short visit here in North Texas? I know what you’re thinking, "Because we live in Texas, you dimwit." True. But aside from this obvious response, here’s a more detailed explanation.
The answer lies in the depth of the cold air. Since Arctic air originates near the North Pole, it’s much deeper (thicker) to the north. As it slides south, it maintains its dome-like, or bubble-like, characteristics.
Since this is a three-dimensional air mass, it’s thickest in the middle and much thinner along the edges. By the time the leading edge gets to Texas it’s typically quite thin (shallow).
It’s best to visual from a side angle.
Surprisingly, this shallow air can be quite frigid but may end up only being a couple hundred feet thick. This was the case just a few weeks ago when we had temperatures below freezing at ground level, but a few hundred feet up it was dramatically warmer (50s, 60s). For us meteorology enthusiasts we find this fascinating. There’s a special name for it too. When a layer of warmer air resides above cold air it’s called an "inversion." This is not normally the case of course, as the air temperature usually drops the higher you go (think Rocky Mountains). Oftentimes in winter, however, we get a temperature inversion when Arctic air moves into North Texas. This makes us especially prone to ice, not snow.
So, in answer to the initial question, due to the shallow nature of the cold air it usually retreats to the north after a short stay. All it takes is for a south wind to return for a day or two and it’s "Adios, Arctic outbreak."
Yet again, another good reason to live in Texas.