I'm not so sure. If you compare 22z output of Hirlam to the Radar, they are pretty well aligned. A few differences, but that is always the case. I am very much a newbie though, so call me out if I am misinterpreting it. The northern extent looks pretty much bang on. Perhaps the radar shows the heavier PPN extending east off the coast more than the model, but to me it just looks like the model didn't get the west to east "width" of the PPN correct, rather than it moving through quicker ? though again, I may be looking at this wrong.