Excellent analysis, 805! You've captured many/most of the contributing signals for a significant change both in the near and far term patterns as compared to what we've seen in recent years. If I may, here's a couple of additional comments to ponder:
1. The NPO is finally shifting negative, while the PNA is moving positive. Both are good/classic signs of a Winter pattern setting up.
2. The re-curving tracks of several recent (and powerful) hurricanes off Baja is defining where the "Baja Ridge" may be setting up for at least the early Winter. Notably, the continental ridge seems further east than in past years, and there has been a relative "weakness" in the atmosphere off the Cent/SoCal coast sandwiched between HP in the NPac and HP over the continental SW where troughs and CoL's seem to be periodically recurring (not just one-and-done's). In past years, these quasi-permanent twin highs have been bridging, which essentially/effectively cut off juicy sub-tropical moisture feeds into NPac lows/storms...but now with the two highs becoming increasingly discrete, relative troughs extending from the tropical SW towards California are gradually becoming more frequent.
3. IMHO, this may also be a sign of a developing El Nino pattern that could be quite favorable for Central and SoCal, especially if lows continue to drop down the coast within the relative troughs and start tapping into progressively juicier sub-tropical air flowing NE out of the ITCZ.
4. The recent hurricanes off Baja have significantly cooled the local ocean temps over much of the Baja coast all the way to the Calif. border, thus (edit: reflecting) the weakening of the overlying H.P. anti-cyclonic circulation(s). Eventually (~ Oct. wk4), the eastern flank of the continental high should be shifting gradually east and moisture will increasingly be directed NE...perhaps even forming a series of weak AR's by mid-November provided there is enough energy up in the GoA to progressively drive the jet into California.
5. And lastly, we need to keep an eye on the split-flow of the SPJ..and whether or not a southern jet starts to evolve. Right now, we've seen brief glimpses of a split flow, but mostly in conjunction with the aforementioned blocking pattern's, and not a true STJ taking shape...but with other atmospheric signals suggesting El Nino-ish flows, we just may indeed see a STJ taking shape in the next few weeks that might eventually direct some serious energy our way, most likely in the form of an AR?