PDO is meaningless other than the fact it’s reflective of the low frequency circulation over the previous 10-12 months.
Low frequency regimes by definition don’t change frequently, so a simple/linear correlation will indeed project a correlation between the pattern and the PDO.
However, that doesn’t offer any predictability whatsoever because the PDO lags the extratropical atmospheric response forced by changes in the tropics.
Ultimately, if you’re looking for long term predictability, the only variables of consequence are the structure of the Indo-Pacific Warm Pool (IPWP), QBO, and solar cycle.
The NH spatial response to MJO/tropical forcing over the lower-48 literally inverts from Oct to Jan.
Example: MJO/RMM Phase-4 (niña) forcing in mid-Oct vs mid-Jan. Near perfect diametric opposition.