JMA doesn't handle the Greenland 850's well I'm afraid - there's a cold bias for some reason or another. It sometimes causes errors in the synoptic charts too, as an excessive thermal gradient causes sudden or enhanced storm development.
Anyway, it seems clear that there will be a marked LP to the SW of the UK next week, and a ridge of some form across us, but with no firm idea as to how that ridge aligns itself and hence what surface cloud amounts and temperatures we experience.
Curiously, while the majority of the models are persistent in modelling a 'dartboard low' to the SW, GFS keeps on coming up with elongated troughs. On the 12z run, the elongation occurs as a result of a second LP system interacting with the one to our SW, and happens to produce a trough elongated north to south, which pulls hot air up from a long way south days 9-11, producing a run of days hitting the mid-20's in England.
This favourable alignment is absent from the other model runs so is considered a wildcard at this time - but the behaviour of that second LP system, present on the ECM and GEM runs as well as GFS, needs to be watched in case it does have more of an impact on the trough to the SW. As far as I can tell, it's the same weak storm system that's been bringing excessive rain N/NE of Florida today, and has the potential to be warm-core in nature (i.e. a tropical cyclone, albiet a weak one) if it tracks over the nearshore waters along the East US Coast in the near future.
That makes it a highly uncertain feature and, for me, the one source of much interest in next week's model output
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