The problem is we are in the critical stage when upgrades or downgrades really matter. We need a major pattern adjustment to avoid milder air coming in next Tuesday. In 24 hours from now it will be basically too late for that major pattern adjustment to occur. If we do go for the mild solution the cold ensembles I'd expect to disappear over the next day too. Its not impossible to come back from a downgrade on the 12zs but it nearly is I think.

Sadly ECM will probably fall into line this evening.  And then its goodnight Eileen. Roll on some spring warmth and longer nights.  I've had it with winter now, forever!

I know major pattern changes are sometimes needed to reverse outcomes, but this set up as Sarah KL said only yesterday is so battleground that the dividing zone between the dominant air masses is incredibly difficult to judge over the UK at the moment.

We definitely need to be seeing something else on the GFS.

Like you I don't put a major emphasis on the Op run but wait until I can see it in context.  But right now it feels like 1 step forward then 2 steps back, even with the Ens charts.

Everything I wish to happen in the States never happens. And I don't just mean weather wise!

EDIT: nevermind its now further NE. Probably a bad sign.

EDIT2: maybe not. The problem is the LP is eventually picked up by a very weak easterly branch of the jetstream (not the main westerly jet). The weak steering flow is causing difficulty in predicting where things end up.

Both the EPS and the  GEFS have had a quite a few members showing such a solution for next week.  Ive maintained all along that the models are finding this situation challenging and that Thursday morning would be one of the crunch points the charts coming into the semi reliable at around t96.   It remains the case.  The models are not as good as sometimes they are given credit for.

EDIT: OK I'm calling it GFS12Z is an upgrade on the GFS6Z.

Thursday's low and next week's low are heavily influenced by tiny movements in the main jet stream and the easterly subarctic jet to the north. The cold air advection from the continent is strongly dependent on the shape of Thursday's low which still hasn't been decided.

Thursday's low pushed north on the UKMO though, even if the 120h chart looks similar the GFS is in the cold airmass, the UKMO is not.

In the GEM12Z, the ECM6Z the main jet merges with the subarctic jet prior to next week's low moving in. This results in a stall across the main atlantic and heights are able to build to the north of the UK.

Keep in mind this is a big difference at the 300hpa level, its a bit unusual; the models are mostly good at these higher levels.

Anyway we want a stronger subarctic jet for that merger to occur. 

Key moment is at around 96h. At that point we actually paradoxically want next week's low further north to facilitate that merger. If it is further south the merger doesn't happen.

AI picked up this cold incursion well in advance compared to other models is my opinion, though it has lost favour now it seems . 

"AI" just pattern matches the past climate, not the current one, so is of limited use in situations like this. We saw a run of several days of simply stonking charts from both the "AI" models, but in the last couple of days they have - of course - veered away from such. No surprise whatsoever, but it's interesting I guess that this setup would have led to a classic easterly blast in previous decades. 

The BBC app isn't worth relying on either, of course; a week ago it showed lots of sleet here for this weekend coming, then over the next few days it switched to a whole day of light snow, then back to sleet, and now it just shows rain every single day for the next 2 weeks.

Not much excitement in the models through today (aside from perhaps the 6z ECM, which got down to an earth-shattering -7 at 850 here at one point, the others struggling to reach -2 in the next week), but fans of rain will be delighted. Indeed, I continue to expect news stories about flooding by this time next week... some of the totals being churned out for the next week, especially in the southwest, are eyebrow-raising, especially given the sodden nature of the ground already.

In GEM we trust... 

In all seriousness though, I've just watched the latest 10 day trend on the Met Office YT and they highlighted these key subtle differences. For example it only takes the cold coming out of Canada to be slightly less cold for it to have a positive knock on effect for us.

Sadly, we are left in the worst case scenario of cold flooding rain.  

I do wonder again ....

Is this because it is incredibly cold in the NE of USA/Canada?? Never a shortage of cold there..