The GFSP 18z is strangely consistent with the 12z in terms of both the mid-month super-storm and the general pattern evolution thereafter - the first attempt to set up a blocking high falls, but background drivers push the next Atlantic trough quickly over to Scandinavia with high latitude blocking starting to materialise at the same time.
A good fit with the increasingly Pacific-centered MJO and other changes taking place on the other side of the hemisphere from us (for those familiar with the terms, how does a switch to positive AAM tendency, with positive frictional and then mountain torque events sound? Totally different to what's been going on these past few months).
The GFS 18z is also consistent with it's previous output to day 8, including having the storm that GFSP hammers us with develop further west to bring something wild and wet but not nearly as devastating.
Beyond that, the jet happens to split rather nicely in the western North Atlantic, with a slide of low pressure underneath the developing mid-Atlantic ridge giving it the support needed to build to Greenland and stick around there for a few days before transferring to Scandinavia.
A nice evolution to see, but unless GEFS turn out not to be overcooking the MJO after all (not out of the question but I would be pleasantly surprised), I have cause to lean in favour of the slower development of a cold and snowy UK weather pattern offered by GFSP... though obviously I'll take the far more dramatic 12z GFSP over the 18z
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T-Max: 30.2°C 9th Sep (...!) | T-Min: -7.1°C 22nd & 23rd Jan | Wettest Day: 25.9mm 2nd Nov | Ice Days: 1 (2nd Dec -1.3°C in freezing fog)
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