Yes, exactly.  Without going through the 50 permutations I'd guess that very few will have the high pressure in the same place as the Op.

The polar vortex being split almost into three chunks is also notable.

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Taken from NW Peter

ECM ensembles watch

Looking at members with 850Hpa of minus 5 or below for large parts of the UK:

D11 36 yes, 15 no

D13 36 yes, 15 no (though different runs)

D15 36 yes, 15 no (again, some different runs)

Still remarkable consistency for cold for such a long way out

Edit: forgot to mention, probably half of the runs which failed to show minus 5 uppers at the precise time had very cold air very close by, either leaving or about to come in. 

 

ECM mean is encouragingly similar to GFSP which forces the AH to take a much needed holiday SW of the Azores - let's hope it's a long holiday.

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I always find my friend Jackie D and Irn Bru, is much better for a spot of positive model watching.😉😛

Mentions of similarities with Jan 2013 on here over past few days, that would suit me fine (IMBY). Whatever the outcome, these are very interesting Synoptics, which are not our usual winter fare. I get the feeling the vortex almost wants to dive down right over us, if only, but you never know. 

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Thanks, that's good to know.  At that range 70/30 is a decent signal, particularly if part of the 30% is just about timing.

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Your drunk …………….clearly Hic! 

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Tuesday's coming Richard, there's no getting away from it 

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Well the GFS 18z pub run is a bit of a damp squib. Follows the ECM 12z op to t240 to a degree with the Azores High exerting itself, but the run closes with no immediate route to prolonged cold. 

One run with all the usual caveats but this is beginning to look like jam tomorrow. Let's wait on the GFS P and the ensembles to see if the op has support.

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18z Op run ends the cold spell before it's even started?

Here with a slice of you know what?

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Yes how strange? maybe there is something wrong with these GFS models? and must be a reason why they can't get the cold persistently ? Para was showing us -10c isotherm at 850hpa with easterly followed by northerly on the 12z @ 384.

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GEM shows midday temps widely below freezing and highs of -7c in Birmingham by 22nd:

 

 

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Whereas the GFS(P) maintains the theme of a chunk of the polar vortex dropping SSE with a mid-Atlantic ridge building

Roughly how the ECM 12z might have evolved.

 

 

 

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ECM 12z ensemble suite for London confirms that the Op was at the top of the mild cluster at Day 10.  Essentially little change, with a strong signal for cold/very cold conditions and some ice days amongst the perturbations. Still a few options producing milder conditions, but very much the minority at this stage.

 

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Para 18z still has that Icelandic low pressure sinking southwards and then pulling in the easterly come 300hrs: Thus allows winds to turn easterly and HP to build to our north over Greenland & Iceland come +384 with daytime maxes barely getting above freezing and wind-chill combined with more persistent snow over eastern areas as the LP moves into the southern part of the North sea, come the end of the run @ +384! THE GFS 18z Para has a way more wintry and blocked ending compared with the GFS 18z Op run.

 

When will the GFS Op run follow the Parallel run and start being more consistent??

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Only a couple of weeks ago, the ECM op started showing the trend that HP would remain close by when the ENs continued to show otherwise, and was proved right in the end when the mean chart started backing away a couple of days later. Something to maybe keep in mind if the next few ECM runs show something similar to tonight's run. 

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The Town won today against all odds: I'm humming the Great Escape, so if the Town can win, the weather can verify cold - eventually! 

 

Can an anyone remember the roller coaster leading to the Beast? There was plenty of promise, followed by wrist slitting disappointment, followed by renewed optimism. This one is more uncertain true but it's the same roller coaster. 

I don't usually like the mean outputs. But right now they are a sanity check to the inconsistency. I think the UKMO is the one to watch with greater hope.

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18z ensembles chart  for London: -the OP run was a mild outlier:

 

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Tally, an outlier is a run without any support amongst the ensemble perturbations. The 18z was not in any way an outlier even towards the end.

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Yes and the 18z ens show the op to be in the milder cluster. Still strong signals for cold, but with the Azores High continuing to pose a threat it seems.

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What will tomorrow's runs bring I wonder?

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Maybe not put quite as I meant and late Feb is probably pushing it a bit John. I am saying that the uncertainty that is there now for 8-10 days should be resolved by next weekend if not before. If it isn't showing a consistent cold outlook and the cold isn't with us we will be starting to look at the first week of February onwards. That will be the last month of winter and the later it is the more special it will have to be to justify it as a cold second half to winter that has been widely predicted and more especially so since Christmas with the SSW event.

Whilst I personally think  there is enough evidence that it will be cold I think -5C 850's still might not make for severe cold and settling snow in  the South. I also do think that the mean is likely to fall to -7C though. 

This was and is not meant to be a "winters over" type post in any shape or form, just being a bit more measured. 

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The current situation with the model output reminds me of last February in a lot of ways as there was a lot of variation back then among the various operational runs before the models all came into line wrt the arrival of the Beast. My own feeling is that at the moment, the models are quite possibly still getting fully to grips with the effects in the troposphere of the SSW which took place over the festive season and they may not have this fully worked out yet.

Tomorrow's model runs will make for interesting viewing I suspect.

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Very likely David.

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No great change to the overall outlook yesterday evening, I see! The GFS(P) 18z yet again plastered the UK in snow, it was very consistent yesterday.

The ECM strat charts:

https://www.geo.fu-berlin.de/en/met/ag/strat/produkte/winterdiagnostics/index.html 

haven't changed much since Friday either. The SSW is still ongoing and is forecast to end on the 20th - the best part of three weeks after it started. It's shown to affect 30hPa, but 50hPa doesn't quite go negative on this run... the vortex is well and truly split, however.

The ECM ensemble means last night show a decent-sized cluster, perhaps even a majority cluster, for a low pressure, accompanied by a chunk of the polar vortex, to cross the UK. Now, where have we seen that before? Oh yes, the GFS(P)!

As has been mentioned in passing from the NW post, the ECM was a very cold suite last night with the majority cluster on the cold side. You can see this via the 10th/90th percentile charts quite nicely - there's more scatter on the warm side than the cold side:

https://weather.us/forecast/2639577-reading/ensemble/euro/temperatur850 

With ECM mean maxima for London pretty much matching the GEFS in the 10 day+ time frame, i.e. 2 or 3C, the signals for a noteworthy cold spell are the strongest they've been this winter. Another exciting day of model-watching beckons!

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A different parallel this morning, with the "bit of the vortex" heading east instead. Much of Scotland and northern England still gets hammered with snow, but for the southern and SE folks it's a series of slushy coverings instead of one big dump.

It's interesting though that even outside the deep upper low, on the "warm" side of it, it's still cold enough for snow at times.

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