Extremely dumbed down and simplified, but follow the streamline (green arrow) around the EPO ridge. Not a true CPF but a better look to get 'some' negative temp anomalies down into the US.
And we better hope that EPO look is even remotely close, because if that PAC firehose into the West Coast verifies per that map without some AO/NAO blocking holding which would allow the PJ to dip South into the GL and Northeast, then we are in trouble.