I don't see the point in caring so much whether PDX gets to 99 or 100. There is no perceptible difference between the two, it's a very hot day either way.
I remember a lot of the 500mb map comparisons are very similar. Like you said though Lower level dynamics and the marine layer is much less persistent than it was in the summer of 2010 so far. Marine layer is practically non existent this time around despite similarities in the upper levels.