I can still see some potential for a significant storm event even from the ECM version of events, though not as extreme as could occur via the GFS/GFSP route, as the temperature gradient reduces steadily with time and ECM takes a couple of days longer to bring the UK in the firing line for anything running up from the SW.
Now how about that U.S. low...
The ECM solution (right) has a negative tilt to the trough, and that in combination with the cut-off trough west of the Azores sets us well on course for a cold spell to reach the UK a some point within the following 4 or 5 days.
This is because the energy heads up to NW Greenland and breaks down there, which allows the Greenland block to hang on by shifting SW a bit rather than being blasted apart as happens from the GFS solution (left).
Just how well the blocking holds on comes down to the Atlantic shortwave behaviour; the slower progression on the ECM, GEM and JMA runs places the developing low in the right place to counteract the attempt by the U.S. low to push the ridge out of Greenland.
Having a faster Atlantic low progression is the reason why GFSP, despite having the negatively tilted low at day 5, ends up shoving the ridge out of Greenland and sinking it. At least GFSP was less progressive than GFS, having slowed the storm down from yesterday's runs.
In conclusion, now that ECM has started hammering the Euro High south from day 8 onward, it has become clearer that the ECM/JMA/GEM solution is far better for a longer-lived cold spell.
I read the U.S. NCEP discussion earlier and it speaks of a negatively tilted trough in 5 days time, suggesting that the GFS and UKMO solutions are being cast aside in favour of the ECM and GEM ones. This is encouraging.
This follows a morning discussion in which it was stated that ECM seemed to have a habit of 'crashing deep lows through obviously blocked patterns'.
Combine the two and you have to wonder if the trough will actually displace the Greenland High at all, after all it doesn't do so on the JMA and GEM runs:
...though it's true that JMA (left) is far from clear-cut.
It will be embarrassing for GFS and GFSP if this turns out to be the case... but far from unprecedented in the case of GFS, in fact it could be considered a very typical form of correction for that model.
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