Eastern pacific oscillation is a variation of the atmospheric flow across the eastern pacific.
Here is the epo index pattern in its +phase for h5 and surface temps (negative would be the opposite of map)
When in the + phase mild air flows onto the west coast and as it crosses the Rocky Mountains it dries out and becomes temperate and sinks. In the east we would rather the epo be negative, as would be the opposite of the above +phase depiction. A ridge would be in place over the east pacific off the west coast and high pressure would force the air up into Alaska and the artic. The ridge would displace the colder air down into the central and nothern US which would then modify our temperatures here in the northeast as well also indicated on the above index pattern.
The stronger the -epo the more cold that can be displaced, the longer the epo stays negative the longer the temperatures in the central and nothern reaches of the US will stay modified.
So no the hugely +epo upcoming is not good for snows in the east which makes the current model depictions of a snowstorm so difficult.
However bombogenesis can create its own dynamics as we well know. Fascinating to watch the battle on the models for this period.