Have been watching the current charts with great interest. If the current pattern is to break, which inevitably it will at some point, the current output would provide a plausible mechanism for doing so. Of course when this happens, and exactly what we would end up with, is another matter entirely. A Sceuro high or a high over us are as likely as a high latitude block favourably positioned for cold. On past trends it will also likely take several attempts to achieve this. With so much energy going North in the jet to high latitudes, and large amounts of warm air advection, plus the current longer term output, in some ways this reminds me of early 2005 (and the various teases and let downs) before the major late winter pattern change. I recall Tom C mentioning back then how when the jet is progressively forced north then the pattern will eventually re-set itself. This would also tie in to the METO thinking re.the late winter period , at least when the contingency forecast was issued.
Against this must be measured the strength of this years' El Nino and the additional energy in the system compared to, say, 1983 which saw such a change also. As such these are uncharted waters, it will be fascinating to see how the later winter period will develop. FWIW if there is a severe freeze of any duration this year I would think it will probably more likely be of the intense but relatively brief 1991/1987 type than massive Northern blocking like 2010. Not that many would complain
On a final note would have to say I rate the METO 144 charts on a purely anecdotal basis, certainly in this type of situation. I could be wrong, but I cannot recall a significant cold spell that came to fruition without its support-regardless of GFS or ECM output at the same range.