Here's how a wavy jet stream is screwing up weather all over the US this weekend

Apr 4, 2020
The article say there is a "low pressure air mass", but there is no such thing. The meteorological community has several categories of air masses, but none of them are defined using pressure! In fact, air masses often have a pressure gradient from one part to another (high pressure to low pressure).

An air mass is a wide-spread area of air sharing common characteristics generally associated with its area of origin and path of evolution. Since it may be evolving, particularly if it moves from its area of defining origin, the air mass might even be characterized as "modified".