Polar vortex collapse leads to cold polar air mass moving south over the course of the next few weeks. At least where I am, this article is coinciding within a day or so of the end of "fake spring".
In fact, this might help explain the concept of fake spring in general. The final collapse of the vortex is ultimately caused by warming of the northern hemisphere as spring kicks in. This implies that the pattern of "get pretty warm, then the polar vortex collapses, then you get one more surge of winter weather, and then you get real spring" is actually typical.