One reason today's afternoon EPS was worse than 0z is due to the placement and strength of the Aleutian low. Comparing 12z to 0z, we see that the Aleutian low in 12z is weaker and further west. A stronger + further east Aleutian low allows for a more poleward western ridge to setup, and along with the -EPO and -NAO/-AO, allows for cold to press on the EC and gives us the great look.
Note: The 12z EPS today is certainly not bad at all, and is still a good look, just not as good as previous runs and not the "textbook" setup.