Good stuff Ralph. Don't take this as a post trying to steal your spotlight. Just trying to share some thoughts. Anyway, I would think a PV split is most likely to occur later on in the winter, as the QBO would have descended enough into the easterly phases which support such a thing occurring. It could still occur even without a favorable QBO, however. But the progression of the QBO is admittedly not occurring as fast as I had hoped. Save for a miraculous uptick (which is very much possible), the QBO might not be too much of a factor this year. That's fine though. Last year it's something that helped kill us. The ENSO is in an overall favorable look - Cooler ENSO regions 1.2 and 3. Regions 3.4 and 4 much warmer. It's very much a Modoki look. A warm Atlantic/AMO is still evident in the data sets and SST maps. The PDO is actually cooling off a bit with the NP warm blob starting to regress to the west a bit south of the Aleutians. What I fear the most this winter is actually what we've got potentially in store for us next week. The ridge out west is just a bit too far west, aided by the warmer SST's a bit further west. We've actually been stuck in a +TNH pattern for a while now which supports my analog set as well. Cold dumps into the central states and Great Lakes, the SE ridge tries to pop, and you get cold before and after each storm, but as the storm comes in the trough axis is just a bit too far west.
Now, I've been delving into this upcoming winter since July/August and have stuck with this SST composite and 500mb composite since September. I don't see any reason to change now.
As I mentioned above, the cold will be there I believe with the mean trough centered across the central states and Great Lakes. The question is how does it modulate when storms come through? With no HL blocking, you can bet App runners and coastal screamers will be a real threat. Kinda like this upcoming Tuesday/Wednesday storm. It's a battle between the Ridge/Trough orientations, WAR, and incoming cold press. If HL blocking does commence this winter, I truly believe it's off to the races. The Pacific is favorable enough for there to be some hope.