It sounds like a "standing wave" in the winds over the mountains. Which could maintain pressure differences that extend much higher and remain for a time.
Such waves can even have their own internal circulation, such as a horizontal rolling wind that is like a "tube" downwind from the mountains. I have seen such things near where I live, and I have seen videos available online.
But when the wind at lower levels changes, the standing wave could dissipate quite quickly.
Have such waves been seen in earth's upper atmosphere levels, from the ISS?