Don't really have much to add, because my oppinion hasn't changed, the catalyst that causes that spoiler low is a shot of cold air from the canadian high. However the ECM really has very little confidence in it (at least less than any other feature in the northern hemisphere). The low itself originates well south of the jet and is a surface feature (at least to start off with). I don't quite buy this massive development and sudden expansion of the PV into canada so I would still excpet a good 5 day cold spell. However, the northern blocking is going to weaken over the next 192 hours, so it doesnt look to hopeful that we will get any sort of reboot. The only possibility that remains to continue a cold spell beyond about 5 days, is ridging to scandanavia imo and that looks perhaps very tenous at this stage. I think the heights are simply too low. Looking further ahead it doesn't look good, models reform the PV and send us into full atlantic mode.
I mean, past about the 11th of December it looks truly awful. Really very zonal indeed, with no cold weather to speak of 
Originally Posted by: Quantum