Model output discussion - here comes the beast!

[Rob Walker]

15 minutes ago, stodge said:

...so for me UKMO is far superior to GFS and ECM this evening.

Erm I'm not so sure about that stodge.  I mean I do get your point about prolonged cold; but "UKMO is far superior" to the ECM?, I must disagree.  That ECM was one to bank.
To be honest I think quite a few people saw the UKMO as a bit of a let down run in comparison; nevermind far superior! 

Edited February 21, 2018 by Rob Walker
minor corrections

[Connor Bailey Degnan]

Another stunning ecm mean. From 12z yesterday, each mean of the ecm has gradually become more and more favourable for us.

[Frosty.]

I'm banking the GEFS 12z mean for next week right now!!..nationwide freeze from the Beast from the East!

[karlos1983]

Very nice indeed 

-8 850’s formmost throughout!

 

[Spah1]

35 minutes ago, Man With Beard said:

OK here's the snow details on the ECM:

Monday - snow showers on the east coast from the off, pushing well inland, even to western areas

Tuesday - a trough from the NE crosses the UK affecting all except the SE and perhaps sheltered NW area - has cleared Wales and the SW by teatime. Snow showers carry on for the SE all the while

Wednesday: convective snow showers bubble up as the day goes on, particularly SE but could be anywhere

Thursday: Possibility of more organised troughs over central/northern areas, bringing snow

Friday: the trough becomes a very active front, much of central/western/northern areas would be absolutely buried in snow today. 

Saturday: The front heads east but fizzles out before reaching the east coast. Looks like more snow about the approach from the SW (perhaps rain in the extreme SW by this time)

Here’s the snow details from the UKMO model. 

Monday will be mainly dry with sunny spells, but snow showers will develop across some eastern and southern areas. 

Tuesday will be mainly dry with sunny spells, but snow showers will develop across some eastern and southern areas. 

[stodge]

1 minute ago, Rob Walker said:

Erm I'm not so sure about that stodge.  I mean I do get your point about prolonged cold; but "UKMO is far superior" to the ECM this evening?, I must disagree.  That ECM was one to bank.
To be honest I think quite a few people saw the UKMO as a bit of a let down run this eve; never-mind far superior! 

I'm being slightly provocative, Rob. ECM at T+264 isn't an easy chart to call and you have to hope heights will rise over Scandinavia otherwise it's probably game over as the Atlantic re-asserts.

GFS calls time on the cold spell as does JMA which does so incredibly quickly.

With UKMO there's no route back for milder air as far as I can see. Maybe GFS is being over-progressive as it often is but JMA takes the cold air so far north the milder air gets in to the south.

The thing is everyone today has complained about "southward correction" but ARPEGE is looking like a solid chart for cold if it can get the HP into Greenland.

My chart of the day so far is NAVGEM 12Z at T+180:

FIM 12Z at the same time close behind:

Note how the LP are kept far to the south.

[The Eagle]

NAVGEM is pretty good.

[Whether Idle]

19 minutes ago, stodge said:

The more I look at the UKMO the more I like it. The T+168 posted by Summer Sun above confirms there's absolutely no route in for milder air from the south or south west. The Atlantic LPs are over the Azores and Portugal. The airflow over the UK looks from the north and we can only speculate on any disturbances in the colder air over Scandinavia.

I know a lot of people want deep snow but I'd prefer extended cold so for me UKMO is far superior to GFS and ECM this evening.

Agreed Stodge, the UKMO run is a decent run, particularly for those in the SE.  Anyhow, being out in FI, the corresponding 144 chart will have altered a lot in 24 hours time.

[MattStoke]

I'm wondering what effect the second stratospheric warming may have on proceedings next week, if any. We had brilliant posts from the most experienced posters on here regarding the first warming but I don't think I've seen anything about the second warming?

[bluearmy]

9 minutes ago, Connor Bailey Degnan said:

Another stunning ecm mean. From 12z yesterday, each mean of the ecm has gradually become more and more favourable for us.

Yes - the eps mean continues to look sublime but as per this morning, it hides a cluster supporting the 00z op with the upper ridge close to the uk. The op and control jumping clusters continues to show the uncertainty. Not surprised to see the near term upgrade from the 00z run but day 6 onwards could yet  disappoint. Hopefully the poorer cluster drops off later in percentage terms and goes completely in the morning.

note the high height cluster against the mean below at day 7

  

[chris pawsey]

4 minutes ago, The Eagle said:

NAVGEM is pretty good.

Just love your animations The Eagle. Would be great to see all main models animated side by side for each run. Keep up the good work!! 

[Met4Cast]

So, before the 18z a quick one from me, let me just climb over this tower of Net Weather toys. 

Right. GFS is further South? The OP is, sure. But the ensemble mean is further North than the OP and the OP is on the milder side of the ensembles in the extended.

There is a general upward trend in the ensembles but the mean stays below -5 until the 5th and given the GFS tendency to be over progressive with breakdowns I don't think we really need to worry too much about that.

ECM OP and mean was absolutely solid and has been the best guidance in the mid-term for this cold spell, the GFS has not. 

UKMO further South similar to the GFS and whilst that is a worry, given the lack of support from the EPS I think we can be confident of a backtrack here, the UKMO hasn't really covered itself in glory recently, either. 

My point is, even though I generally hate ensembles they are the best guide in these circumstances. The secondary warming in the Stratosphere is probably causing some problems with the models again.

Eveything is fine. The cold air arrives Sunday night along with snow showers into the East/South-East. Now if we could stop throwing the toys out at the drop of a single OP run, this place might be bearable. 

[SMU]

Last one till 930

spectacular ECM mean 168-192 past the already passed & just as awsome 96-120-144 mean

pretty close to where historically you would expect a retrograde high to end up!

Edited February 21, 2018 by Steve Murr

[Rob Walker]

16 minutes ago, stodge said:

I'm being slightly provocative, Rob. ECM at T+264 isn't an easy chart to call and you have to hope heights will rise over Scandinavia otherwise it's probably game over as the Atlantic re-asserts.

GFS calls time on the cold spell as does JMA which does so incredibly quickly.

With UKMO there's no route back for milder air as far as I can see. Maybe GFS is being over-progressive as it often is but JMA takes the cold air so far north the milder air gets in to the south.

The thing is everyone today has complained about "southward correction" but ARPEGE is looking like a solid chart for cold if it can get the HP into Greenland.

My chart of the day so far is NAVGEM 12Z at T+180:

FIM 12Z at the same time close behind:

Note how the LP are kept far to the south.

Ahh the ole devils advocate approach I see. To hook, line and sinker me. 

You do raise some valid points I won't deny, and hadn't looked too closely at the NAVGEM, yes that +180 chart does look tasty!
 
The concern with the UKMO run is surely its southwards correction/and delays in the cold and extent of reaching our shores? It was still a decent run for the longer stint and those in the south/east intially.

And I still think you are undervaluing that ECM run; I mean when you're looking as far out as T+264 to pick fault a lot can change by then anyway  aha

Edited February 21, 2018 by Rob Walker

[The Enigma]

3 minutes ago, bluearmy said:

ng the 00z op with the upper ridge close to the uk. The op and control jumping clusters continues to show the uncertainty. Not surprised to see the near term upgrade from the 00z run but day 6 onwards could yet  disappoint. Hopefully the poorer cluster drops off later in percentage terms and goes completely in the morning.

note the high height cluster against the mean below at day 7

  

What % did this cluster make up on this mornings run?

[The Beast From The East]

1 hour ago, nick sussex said:

Can the UK squeeze out an extra 12 hrs of that easterly flow, just enough to get the purple blob west.

Very exciting ECM run regardless.

ECM looking amazing... can i just ask that if the high eventually moved to Greenland then would places inland and down south still get snow from that set up? Would it be different to our typical Northerlies where you tend to get the wishbone affect on the coasts?  Thanks anyone.. ?

[Southender]

Well that is a thing of beauty. What a mean out to day 10!

[Gerryhattrick]

The first stage of the SSW threw the models into turmoil for a while until the ECM latched onto the current cold run and the others slowly followed suit. This cold spell is now odds on for next week. Do you think the second SSW we have witnessed will also throw the models in the coming days?

Hope not as it will cause chaos in here, by the way last few pages in this thread have been bliss long may it continue. 

[BlackburnChris]

ECM showing Snow Showers Monday .

[Frosty.]

My feeling is the south of the uk definitely will see a bitterly cold Easterly next week with powdery snow blowing around, severe wind-chill and penetrating frosts..more uncertain further north across scotland due to the position of the high, especially the far n  / nw but with strong retrogression of heights to the NW the north would then join in with the snow showers and deeper cold..this is based on a blend of all the 12z output...if I was in the south / southeast i would be extremely confident about the upcoming potential..fingers crossed for a nationwide event!!

[Rayth]

I’m scared to trawl through all the catastrophe posts that came out after ‘that 12z GFS episode’earlier , but did anyone comment on Dr Ventrice’s tweet about the NAO going record breakingly negative ?

The record being  ( for the time of year) ... (-2.77sigma) models projecting (-3sigma) , guess my question is ... could this be playing havoc with output also ? 

Edited February 21, 2018 by Raythan

[Stuie]

1 minute ago, Raythan said:

I’m scared to trawl through all the catastrophe posts that came out after ‘that 12z GFS episode’

earlier , but did anyone comment on Dr Ventrice’s tweet about the NAO going record breakingly negative ?

The record being  ( for the time of year) ... (-2.77sigma) models projecting (-3sigma) , guess my question is ... could this be playing havoc with output also ? 

Please correct me if I am wrong but this might delay the transition of the HP to Greenland somewhat.

[East_England_Stormchaser91]

40 minutes ago, Stuie W said:

What the hell has the JMA picked up on? I suppose it is an evolution which is plausible, Greeny/Scandi HP block with no shortwaves dropping into Iberia.

GFS:

Not a million miles away

ECM:

Having none of it

GEM:

Can`t see the UKMO but akin to the last 2 charts IMO after looking at T144. 

GFS/JMA are deffo worth watching closely in the next 48hrs (as they all are but...)

The GFS and JMA believe it or not could give tremendous snowstorms before it ends up like the charts you have posted. The continent will be hard frozen don't forget, so SE winds even with marginal uppers could give a dumping. 1978 a text book example. 

[Chesil View]

Just now, Stuie W said:

Please correct me if I am wrong but this might delay the transition of the HP to Greenland somewhat.

No. A strongly negative NAO is highly indicative of a Greenland high.

[Stuie]

@East_England_Stormchaser91 Many thanks for your input mate.