Notice how this wind circulation is largely cut off from the overall flow of upper-level wind circulating from W. to E. around the world.
Once such an air mass is cut off from the overall circulation it tends to linger in place for several days until it is again caught up in the upper-level wind pattern. Hence the term Cut-Off Low for this type of airmass.
Often a Cut-Off Low will induce a counter-clockwise spinning surface low at the surface.
You can see this happening in the second image. Due to the presence of Northern California and the coast range, the low pressure looks more like an elongated eddy running parallel to the coast.