Model Output Discussion - cold spell to end Autumn

[swfc]

29 minutes ago, West is Best said:

Pretty predictable though tbh. I'm fairly confident this will be the trend. This is a seriously cold airmass and the low isn't particularly intense. I think the low will continue to be moved south.

With all respect do these posts have to be in here !!! Je wiz

Yes mwb looks about correct there.I think a" less cold" spell has been showing and tbh isnt unusual during any december

Looking forward hopefully a stronger build of heights to the nne of Europe will show its hand later in the month-new year

 

Edited December 8, 2017 by swfc

[Singularity]

6 minutes ago, Man With Beard said:

With the EC clusters showing the odd doubtful outcome at the moment, I've looked through the EC ensembles this morning and made my own rudimentary clusters:

D10: 

Westerly/Southerly influence over UK: 70% of runs

Northerly: 10%

Easterly: 5%

Unclear/battleground: 15%

D15:

Westerly/Southerly: 45%

Northerly: 25%

Easterly: 15%

UK High: 5%

Unclear: 10%

In a nutshell, better longer-term than last night's ensembles, but westerly influence between D10 and D15 still in the ascendancy, in my opinion.

Thanks for this - it shows the tendency back toward HLB scenarios (of sorts) that I was talking about last night as something to look out for as a sign of the models seeing the other side of the more zonal spell. Hopefully a stronger signal will emerge over the coming few days, and with the zonal period as short as it can be.

I know it's setting the bar kind of high, but I feel we're in a rare situation where it's justified. 

Quite possible that we'll see the westerly influence but with complications in the flow and some shallow ridge versus split-off (from polar vortex) LP action (with the usual wins and losses; cold boundary could still depart the UK entirely for a time), in which case it may take a while for much to become apparent even in the clusters.

[Daniel*]

17 minutes ago, CK1981 said:

Is it just me, or does the EURO4 have the low even further south than the ECM at +48? When comparing both, EURO4 definitely looks a little further south. What are your thoughts?

Indeed it is!

Here is EURO4, GFS & ECM at T+48 dare it looks like a good angle for south of the M4 to come into it.

Edited December 8, 2017 by Daniel*

[Frosty.]

20 minutes ago, snowbob said:

That looks more promising than previous post frosty

was wondering if Sunday’s event would help bring temps down for further attempts as we go forward into next week.

surely lying snow in the centre of the country will help with temps as it’s blown further down.

 

Yes snowbob you're still in the game, i expect further adjustments, hopefully south to include all my mates in the s / se. Fascinating model viewing and great to be talking about realistic chances of snow for a change!

[West is Best]

19 minutes ago, swfc said:

With all respect do these posts have to be in here !!! Je wiz

 

 

 

Erm, discussing the prospect of the low sliding in a north-west to south-east direction? It is a model discussion thread   My sense is that the LP isn't intense enough, the airmass ahead is deeply cold, and the trajectory is insufficiently west-east for the fronts to advance as much as was being shown over the past 48 hours. The overnight 0z's reflect this from UKMO to ECM. The Fax charts are also showing this, which at short range we disregard at our peril. If that trend continues, which seems quite possible, the centre of Sunday's LP (not talking about the secondary Monday event) could move along the M4 corridor, or as I suggest even more likely, entering around the Severn estuary and exiting around Eastbourne.

Whilst some might be irritated at the GFS if it does continue to shunt the low southwards, I think we should remember that on the general picture it has been brilliant over the past 10 days.

They say that 'the trend is your friend.' All eyes on the 6z and Fax charts then.

Edited December 8, 2017 by West is Best

[stodge]

Morning all

Twas Christmas Eve on the Control Run:

And all through the Suite

Only one creature was stirring

A Beast From the East

Apologies but it's an evolution we could well see. The orientation of the ridge is more WNW but could we see the Atlantic regime pushed back westwards from this ?

It's not entirely without support as others have stated and the most extreme example probably P5:

Fans of cold would love it.

[ukpaul]

3 minutes ago, Nick123 said:

It looks like the north east is out of the game re Sundays event. Good luck to those who are in it - could be a memorable day!

I don't think so at all, the system appears to pivot once it gets north on Sunday afternoon and inland north east areas, at least, are in the frame. After that it moves from the Pennines down to Midlands and switches to a more southerly track (dew points and surface temps may have a say there though).

[Summer Sun]

UKMO looks to be a little bit isolated at this morning on its extended run with pressure beginning to rise from the south changing winds around to a north westerly

[Mike Poole]

An idea of the uncertainty on snow for Sunday and Monday from the GEFS probability plots on Meteociel:

Probability of snow 24hrs of Sunday:

Probability of snow 24hrs of Monday:

[carinthian]

8 minutes ago, stodge said:

Morning all

Twas Christmas Eve on the Control Run:

And all through the Suite

Only one creature was stirring

A Beast From the East

Apologies but it's an evolution we could well see. The orientation of the ridge is more WNW but could we see the Atlantic regime pushed back westwards from this ?

It's not entirely without support as others have stated and the most extreme example probably P5:

Fans of cold would love it.

Certainly not without support . Many milder clusters for Christmas week , about 60/40 in favour of milder westerly flow. However,no prolonged zonality is being shown to break through the Russian High block to allow a deeper penetration of the westerlies. Indeed, its this stubborn block that continues to support the Scandinavian trough. This trough cannot go anywhere in the medium term, so much of Western Europe to be cold for next 7 days or so at least. I have a inkling that this Russian block is not going to retreat/collapse and may even start to flex its might on proceedings as we move towards New Year.

[sparky71a]

11 minutes ago, ukpaul said:

I don't think so at all, the system appears to pivot once it gets north on Sunday afternoon and inland north east areas, at least, are in the frame. After that it moves from the Pennines down to Midlands and switches to a more southerly track (dew points and surface temps may have a say there though).

Indeed,only someone who doesn't live here in the N.E could think we would miss snow when it's near us ?

[radiohead]

Looks like a slight south shift on the 06Z GFS at T48

[shaky]

Gfs further south at 48 hours compared to 00z run!!

[karlos1983]

GFS has moved the Sunday fun-day low a bit further south. This can clearly be seen on the Precip chart. N Ireland was in the game and now isnt (at that particular time frame) 

That's a sizeable shift in 6 hours!

 

Edited December 8, 2017 by karlos1983

[MKN]

06z pushed the slider further south.

[Duane S.]

Emotions running high this morning I see...

Overall southerly corrections continue on the slider as we near the T-0. Still nowhere near finalised this though, anybody who thinks otherwise is deluding themselves. A few days back I mooted there was a 30% chance that this slider (or at least, the bulk of the associated PPN)  would all but miss the UK altogether, perhaps clip Cornwall/Devon. Even at this late stage, with no OPs showing this outcome, it still could happen.

As for further ahead to around the 7 - 10 day mark, I wouldn't be surprised to see a spell of more Atlantic derived weather than we've had for a little while. However, I do not see it as any more than a transitory mild(er) spell, before the next batch of fun and games commence later in the month (further HLB and the consequences of)

[SMU]

Epic snowstorm for someone...

[Man With Beard]

19 minutes ago, Mike Poole said:

An idea of the uncertainty on snow for Sunday and Monday from the GEFS probability plots on Meteociel:

Probability of snow 24hrs of Sunday:

Probability of snow 24hrs of Monday:

An excellent chart to highlight the uncertainty, and to show everyone (except Knocker) is in with a chance of seeing snow! (edit: though latest GFS puts Cornwall in the game too!)

Edited December 8, 2017 by Man With Beard

[feb1991blizzard]

The GFS 6z gives some ridiculous snowfall intensity for the London area Monday lunchtime.

[shaky]

3 minutes ago, Steve Murr said:

Epic snowstorm for someone...

All snow event for midlands on this run!!a snowstorm more like for about 18 hours!!and now you guys in the south east starting to get into the act aswell!!

[easton888]

Steve when is that chart for?

[❄️❄️❄️❄️❄️❄️❄️❄️❄️]

The Monday snow event is creeping south

 

[phil nw.]

One or 2 posts have been removed.Please all read the guide from Paul at the top and only post about the models in here.

If your post has views on the charts that's for here otherwise for general chat about snow please head over to the regionals or the general winter threads.

Thanks.

Edited December 8, 2017 by phil nw.

[snowbob]

1 minute ago, feb1991blizzard said:

The GFS 6z gives some ridiculous snowfall intensity for the London area Monday lunchtime.

That will deffo change next run I would have thought

as Sunday’s situation is no where near resolved

great model watching this much better than previous years

[ACCOUNT DELETED]

Lots of talk about snow potential Sunday but the wind accompanying the rain is worth mentioning across the south because there could well be a period of inland gale to severe gale force westerly gusts around the Bristol Channel & English Channel coasts and hills. Despite this it will be much milder with possible highs of 11-12C in Plymouth, 10C in Swansea. Wind & rain should ease from the west during the afternoon as the low quickly moves SE into France with drier, brighter weather following.