look at this. block decays and sits over the Davis Strait, low heights out west retrograde, heights over the Rockies rise, and the low heights from the TPV move into the 50/50 region. you thinking what I'm thinking? lmao
those kinds of -PNA/-EPO/-NAO patterns can deliver good overrunning while the block is in place and the TPV is close. likely have Arctic air over the top
at the same time, i think the lack of retrogression on the GFS is due to the fact that it buries everything out west and you don’t have that final wave break
i think the GFS just buries it. doesn’t mean that it’s correct. even if it is correct, it just delays the cold air outbreak for a few days, it wouldn’t be disastrous or anything