A mild Stratospheric warming is happening.

[AfewUniversesBelowNormal]

For the next ~10 days. 

There is really strong correlation with late October/early November Stratospheric warming, and -NAO 45-60 days later. I think it happened every single time going back to 1948. Some pretty awesome blocking Decembers (1983, 2000) occurred in this pattern. 

-NAO December. 

[40/70 Benchmark]

15 minutes ago, StormchaserChuck said:

For the next ~10 days. 

There is really strong correlation with late October/early November Stratospheric warming, and -NAO 45-60 days later. I think it happened every single time going back to 1948. Some pretty awesome blocking Decembers (1983 etc) occurred in this pattern. 

-NAO December. 

I'd watch March, too, if la nina weakens as some guidance indicates.

[AfewUniversesBelowNormal]

November is stronger Hemispheric pattern, October has a higher mathematic correlation to December. I agree that both are important, perhaps equally. One year had a Stratospheric warming in September,- because the anomalies aren't as great doesn't mean these events are less... I've found that earlier in the season actually has a higher % correlation using history. I doubt with the way the pattern is moving, the strengthening vortex after Nov 1 will have any weight, and models have it breaking up or displacing, quickly. 

[Planoclima]

No time no see this mid warming happenig in October

http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/gif/pole30_nh.gif 

[AfewUniversesBelowNormal]

Good call... pattern completely retrograding on models. Nothing special about this time, likely MJO related. 

 

It would still be interesting to see of a -NAO happens the first few weeks of December. Although this is only a ~7day event, it probably still does have predictive value.