I mean, I think it's all linked? The shortwave coming out will pump heights out ahead of it, but the strength of the trop PV (and associated HP at the surface) is trying to squash it. If you look at 12z Friday as a point in time, yes, the GFS has the upper low farther west off the California coast, but Euro/EuroAI aren't *that* much farther east. But the GFS has the height field over the eastern 2/3rds of the CONUS much lower.