ENSO is a big player in my outlook, the solar activity does not. I really do not believe there is enough of a difference in the solar activity to have a measurable effect on weather. I am willing to change my mind if a correlation is found though.
As for things like the AO, that is really a tail wagging the dog situation. While the AO is an actual thing and quantifiable, it is really just a term used to explain the current status of a pressure relationship in the Atlantic and is controlled by the jetstream and does not actually control it.
I have never heard of the SPV.
A number of things I use are actually my own tools I have developed over the years. None of them are strong correlations, but when used in conjunction with each other can give a hint as to what the winter will be like. I like to keep these personal tools private though.
-John
Stratospheric Polar Vortex.
Do you ever track the historical accuracy your seasonal forecasts, to see if you do better than NWS/NOAA or Farmer's Almanac? I think we all know by now that seasonal forecasts are basically for fun, and will never have a high degree of accuracy, but everyone seems to enjoy reading them.
I really believe that there is some correlation between our winter temperatures and solar cycles. It's never a guarantee, just like ENSO isn't. But remember that bitter cold winter of 2013-14? Near solar minimum. Remember the great winters of the mid-nineties, and the bitter cold of 1996, when Superior froze over? Near solar minimum.
Thanks for taking the time to answer.