I have often noticed that the 06z has the tendency (in cold or mild situations) to have everything further south than other runs. The 06z run seems to be living up to that...and if it gets rids of the easterly muck sooner then it's good with me. 

I see the 6z run seems to want to live up to it's overly progressive reputation (well, I always tend to think it's the most progressive one anyway!).

Sinks the block readily and fires energy North.

I suspect the ens will be similar to yesterday in terms of a step back from the 00z albeit not a disaster in the short to mid term. Given the other GFS Op runs, the other ens sets and ECM/UKMO I'd guess at this evolution being a little suspect but you never know

Good post. Hope the GFS is wrong. Other output suggests it is. We are getting nearer to the easterly cold. From what I learned watching BBC magnetic charts of the past and experience from the expertise on here I thought the marginal situations like the possible up and coming spell were best for notable snow fall? StuH

---

Thurlstone
South Yorkshire
230m AMSL

And even then, until we get to all that "potential" cold stuff later on in the week, it does look like four or five days of dreary dull cool overcast damp conditions faces me as weather fronts grind to a halt and decay over us.

At least winds will be light for most of the time, though.

84h fax shows cold fronts making progress west.

GFS ens are not entirely unexpected:-

As with yesterdays set more runs on the milder side (850s) and less on the colder side. More unsettled runs later too.

Aberdeen ens nicely show the expected hit from the colder pool that never really gets to us down here:-

Given the 6z yesterday trod a similar path I'll wait till this evenings 12zs before getting too bothered by things.

I think to many people on here are govern their thoughts by the GFS

If we look at the 06z JMA @ 84 ( just updated ) its a lot sharper & perfect allignment....

There's always been a GFS bias here because there are four runs each day and each run has about 10 times the data. Not to mention that it runs out five days further than ECM and GEM and nine days further than UKMO (eight if you go count the North America view at T+168).

ECM 00z ensemble for London:

http://www.weathercast.co.uk/meteo/eps/ensemble-tt6-london.gif

solid agreement on 3-4 days of very cold weather, with maxima 2-3C. Some very cold overnight minima as well, presumably where a drier airflow reduces cloud cover.

The precipitation chart shows perhaps a centimetre or two of snow

http://www.weathercast.co.uk/meteo/eps/ensemble-rrrcum-london.gif

Some cold days and frosty nights coming over the next 7-10 days, for MBY its been a very good winter for frosts

84h fax shows cold fronts making progress west.

Not being picky, but that is a stationary occlusion.

Exeter have skewed towards ECM/GFS and changed the orientation/axis of the high to more NW/SE, 

As much as it pains me to say it, the chances of something more than a 'basic' shallow cold spell for more than the E coast between Scarborough and Whitby, in this particular attempt at least, are fading. 

I think to many people on here are govern their thoughts by the GFS

If we look at the 06z JMA @ 84 ( just updated ) its a lot sharper & perfect allignment....

Yes, its the curse of data that is too frequent.  JMA is a decent model and may well have a better handle on this than the GFS.  Certainly it should be considered.

ECM 00z ensemble for London:

http://www.weathercast.co.uk/meteo/eps/ensemble-tt6-london.gif

solid agreement on 3-4 days of very cold weather, with maxima 2-3C. Some very cold overnight minima as well, presumably where a drier airflow reduces cloud cover.

Coldest set of ensembles so far for down here - narrowly pipping yesterday's 12z.

The number of members showing an ice day is remarkable. I wouldn't be at all surprised to see an even colder 12z operational tonight, as this morning's run was one of the mildest 20% or so for the 9th and 10th!

It's a very valid point Doc, one which I think you have mentioned before.

We are dealing with a very rare beast here, i would hazard a guess that we don't know the likely outcome of any output with confidence in general until say 72 hours out. Most current output are variations on a theme, that of a large Scandy block. I think the tipping point is Tuesday/ Wednesday, I've a nagging feeling the AZ HP may get involved and cut off any easterly. All we need now is some luck.

All the main models have some energy sliding south as the jet comes up against the block; at around day 5-6.  If that evolution is being modelled correctly then the Azores high is prevented from rigging NE, at least for a couple of days.  After that you're right but T+168 and more is FI: it is conceivable that a surge of WAA may reinforce the block, although I agree it could work to flatten the pattern as per GFS.

W COUNTRY OUTLOOK: Shift to colder conditions (E/SE flow) later next week remains strongly signalled; a low (10%) chance of milder SW flow >

W COUNTRY CONTD... A minority (20%) of model solutions present a risk of much colder air moving W across UK, bringing heavier snow showers >

W COUNTRY Into 10-15d period, thro mid-Feb, continuation of below avg temps looks most likely; low (20%) chance W'ly/zonal weather by then

From IF in the last hour

Ironic that as the model outlook turns less cold the MetO issues its coldest and wintriest 5-15 day MRF of the winter!

MetO short range MRF has been excellent this winter so I think they have a handle on the developing cold spell as indicated by Ian F. above.

Expect up grades all round on tonight's models.

Andy

Indeed ^^^^

So off we go then - The 12z is under starters orders....

In respect to everything available at the moment inc the 06z runs & known bias from models we cannot 'expect' The GFS poor solution to be correct- however based on history & the aforementioned bias / weaknesses of this model I would forecast the 12z + 18z & 00z to move to the more Easterly flow as per the JMA 06z-

GFS is also poor with euro heights between around 114-144 in these scenarios often being around 8 dam to heigh- so all if this Should change & manifest in the next 24-36 hours....

S

GFS is not friendly to the UK - has us under mild SW winds on Monday - just the wrong side of the good stuff.