First off, I can't remember seeing the SOI ever going this POSITIVE....
19-Dec-2003-- 1010.96 / 1004.90 / 12.10 / 1.77 / -1.80
20-Dec-2003-- 1012.01 / 1003.20 / 26.40 / 2.83 / -1.29
21-Dec-2003-- 1012.76 / 1001.60 / 38.60 / 4.71 / -0.76
22-Dec-2003-- 1012.06 / 999.80 / 44.30 / 6.99 / -0.21
Signals are pointing towards significant blocking ... and here we go ...
The Day 8-10 three day average of the EURO maybe implying such blocking ...
ECMWF 3 day average - days 8-10
the NAO signs of going NEG along with a 50/50 low...as well as the AO tanking. Did you notice the cutoff SSW of HAWAII? That's a significant rex-blocking signature with the high north of Alaska ... wild setup ... however, the one thing that bothers me is no ridging in Japan, which would help bump heights in Eastern Russia and help induce a little more in the way of cross-polar ... but it's a clear cut start in the right direction.
Anyway, the NAO Ensemble forecast means are unanimous in tanking the NAO. The AO is forecast to go positive in the short term with an ensemble spread from slightly neg to tanking neg.


The EPO is also forecasted to go negative as well, though the PNA is up in the air with the forecast spread after going NEG in the short term ...


The ECMWF's depiction are supporting towards a much colder scenario, possibly just after the onset of the New Year.
SF