This NEG EPO was the driving force for last Winter's Cold and overall storm track. As we know, a strong NEG EPO signal ruled for much of last winter.
The Atlantic signal was a flop, with a Neutral to Positive NAO. With a strong NEG EPO during last Winter, the Cold and Arctic air flooded the Central and Eastern CONUS for a good part of the winter.
The Pacific signal IMO, can over-rule the Atlantic signal in a heartbeat. A bad Pacific signal (POS EPO) will in most cases negate a NEG NAO signal.
Such as last winter a POS NAO would in most case bring a milder and less stormy pattern to the East Coast, which was not the case due too a NEG EPO from the Pacific. Thus the PAC signal rules.
Here's a good illustration of a - EPO (top) vs. + EPO (bottom)