Possibly, but it was largely absent from this country in the vast majority of summers from 2007 through to and including 2017.

The latest GFS Para though is good 240h+  . it's the 6z coming out now.

Nice 276h + though again from GFS 

12z looks fine to me?  I mentioned earlier that GFS had changed the way it handled the key LP exiting the Eastern Seaboard: on this run it has gone back to pushing a deep LP north up the west coast of Greenland and that promotes a surge of WAA and throws up a mid-Atlantic block again. Beyond that it looks like perhaps the SSW might be having an effect, looking at the way the next pulse of energy gets squeezed and thrown SSE.

Signs are there finally to our north as the Azores HP retreats westwards???

So the GFS op is good then Ally?

Unsettled from (a bit before mid month) with cold shots following on then possibly something more. The first shot of -10°C t850s into the north is on the 16th (next Wed) on this op run and the trend is the same as it has been.

LOL.  yes definitely good after 280h . I was too hasty 6z para also very good. Obviously we want to see the glory charts get closer though.

The End of FI finally presents a very very wintry tone.  But its so far away its almost pointless to get excited about.  Bare in mind we had similar charts a week ago for a few days time, and we find ourselves still a slave to the atlantic HP.

If we get to 10.45pm tonight and we see some modicum of consistency then i think Ill be a bit more interested.

We didn’t really. The change to more unsettled conditions was always in the 14th to 17th period and that has not changed. There has been no delay except in isolated charts or people’s perceptions. I have all the charts saved and the details have changed a little, not much, the timescale is amazingly almost totally unchanged to within a day from the beginning of the year. 

Ill admit - slight exageration.  But we were anticipating a cold northerly and wintry showers 7 days ago for today.  Also for this weekend about 10 days ago was expecting to be rather wintry (one of those cold shots that fail to materialise) I know this becuase Im in spain for a few days from Friday and have been monitoring Fridays weather like a hawk.

Today's "Ensemble Watch" update. Despite the initial appearance, very little has changed in the last 24 hours with roughly 1 in 5 members showing deep cold (-10C 850s or lower) affecting London.

All these pages & pages of comments on the GFS -
The UKMO@144 is superb with upstream amplification out of the states which blends nicely into the ICON -

The GFS mean @-6 for days 7 into 8 will probably end up closer to -8c as the resolution allows it to step west...

There has been an occasional op or GFSP run that has taken things to extremes but in terms of the overall picture no real cold was expected any sooner than is being shown currently. Here are the ensembles from one week ago and the second chart from today’s 12z GEFS set (both for this location):

Looking at the timescales the consistency is very good. Note in the first examplethe “rogue GFSP run”. There have a been one or two in the same way there has been one or two that showed little if any cold.

12z ensembles for London: - A few more colder runs in Deep FI now starting to appear! (about time too).

I agree with Michael's posts on the consistency; this has, bar a few blips, been reasonably stable since the timing first appeared.  I'm also noting that more members are maintaining the cold for longer, so we get the "flatlining" at lower temps showing sustained cold:

Am liking those  The trends are consistent and as each day goes by as late Jan and early Feb come into range I would expect the ens to continue to trend down. I noted the ECM ens today were solid too so all in all a good day.

A question about the ensemble members... I was led to believe that the ensemble members were lower resolution and run with slightly changed initial values, while the control run was run with the exact same initial values as the op run, but at the lower resolution.

However, looking at the tabulated figures on Meteociel, that appears not to be the case. The control run (run 0) has different initial values than the op run (GFS run at right hand side). Any thoughts?

http://www.meteociel.fr/modeles/gefs_table.php?x=0&y=0&lat=51.5085&lon=-0.12574&run=12&ext=fr&mode=0&sort=0

And by the way, run 12 is astonishing... SE dioving low pressure in -10C air, yes please.

I've only really been scanning the postage stamps for the GFS but from what I've seen of the FI portion (of the 12z and preceding runs) there's good agreement for cold air hitting the UK at times but little or no consistency on the set up.

I'd tend to read this as encouraging for cold air to make it - all roads (almost) are leading to a chilly or cold destination but not so encouraging if it's a prolonged cold spell you're after. (Down south anyway, see next comment!).

In some ways it reminds me of some of the 80's winters - cold enough for some snow almost anywhere at times but the south always at risk of rain and milder weather whilst the North stays more consistently cold.

It's a good place to be though IMO if it does come off as disrupted jet and cold air around that's easier to tap in to does mean any Northern blocking that does set up could stick for a while and lead to a more prolonged cold spell.

All in all though worth just remembering that the GFS FI signal isn't one for rampant Northern blocking at the moment so expecting a rerun of Dec 2010 or Feb/March's easterly is going to lead to disappointment. Not to say it won't happen I guess, just it's not really being shown at the moment so would want to see a decent signal in the GFS ens (or other model output) before getting too carried away.

For me the longer term outlook is currently cold, unsettled, snow for some, possibly many at times but with the possibility of milder air encroaching, particularly for the southern 3rd of the UK.

I think that is a pretty accurate summary.

On a different note the 12z ECM op run is very similar to 00z run (and is out to day 8 at time of writing).

Haven't looked into it but it will be related to resolution. When talking about resolution there is a lot of confusion because it can apply to two different things:

1) The vertical and horizontal resolution the computer resolves at 

2) The data sets output by the model. For example, NCEP provide 0.25 deg, 0.5 deg and 1 deg data sets from the same GFS run. The lower resolution sets are smaller, so are cheaper and quicker to download. For example, I believe MC plot the 1 deg GFS data set as standard. On TWO I run the 0.25 out to 96, 0.5 from 96 to 180 and 1 from 183 to 384.  

Both points are applicable to the GEFS too.

Therefore the issue you raise is almost certainly related to resolution. 

I think that's a very optimistic outlook with the Azores High so close, 

ECM rolling out, strongly zonal at T216.