Model output discussion - here comes the beast!

[swfc]

Phew!!! Kids school holidays eh.So the ukmo is granted slightly further south and gfs goes way north on the 12z . people have commented on great runs from a week ago ete and how things have changed?? Tbh im know expert but isn't that generally what happens nearer the actual event. I think the second ssw has skewed things hence the discrepancy and void between the gfs 6Z and 12z. Icould be way off the mark and talking b------- but just a thought.as we say in Sheffield "be reight"!!!

[Southender]

10 minutes ago, Mucka said:

Anyone want to bet a virtual pint that GFS Op isn't even supported by its own control run out 144 to 192? 

I will bet it will be hard to find more than 2 members that support it in the ENS. Especially past 192. It's lost it big time. In my opinion of course.

[nick sussex]

What you want is a correction north of the UKMO as it’s overall pattern is very good.

The GFS with that shortwave could end in tears as it phases with low heights to the sw.

I don’t care much for bitter cold and dry weather so these southwards corrections are irritating , I’m looking to be as close to the milder boundary here to get a front close and snow on the northern flank.

So you’re all welcome to the direct hit of very cold uppers. 

[WalsallWeather123]

This is the ideal chart from CMA- Chinese model. Perfectly positioned HP equalling cold uppers and low pressure systems bringing an epic snow event.

[mulzy]

GEFS having very little to do with a southward correction.  Like the GFS Det it's pushing things slightly north.

 

[mountain shadow]

16 minutes ago, mulzy said:

With the exception of the GFS, all other models have shifted south - some slightly, some more so.  ARPERGE (shown below) probably the most southward.  I believe its the shortwave to the north of Iceland that is putting the southward pressure on the block - but I could be wrong?.

We await the ECM with baited breath as this was was the first model to call out the southward shift.

I think what has happened is that the models have moved away from the UK ridge merging with the Svalbard High to form an upper high over Scandi.

Instead we have the UK high moving NW to Greenland.

Whether that's the second Strat warming or something else I don't know.

[Team Jo]

What the bloody hell happened!? Secondary warming = slightly wonky output. I know a week ago seems like a lifetime away but I do recall major warming = very wonky flip flop output. 

Lots of people taking stuff on face value again.  This is not a done deal and I am disappointed that we have people making quite frankly ludicrous comments among charts that I and most other people would have sawed their arm off for last year, and the year before and the year before and.. you get my point. Don’t feed the trolls. Just report the posts.

<lies down in dark room>

[Banbury]

Control at 144 ......as S Powell has just said even if the Siberian air goes South its still very cold, windchill and snow possible

 

[Day 10]

For me I'm extremely happy with how day 3 looks never mind day 5, 6, 7, 8, 9, 10. We have been pining for charts like these for a long time and now they are at t72 yes t72!

Why do people always look past the reliable timeframe for things to go wrong? Yes there has been a slight shift South, but hasn't there been a slight shift North before that and then a shift South before that etc etc, who knows it may shift North again tonight or in the morning. The cold is coming and I'm pretty sure we will all see snowfall over the next few weeks.

 

[WalsallWeather123]

Very little difference in GEFS 12z mean vs 6z at T162. OP clearly too far north

[shaky]

6 minutes ago, mulzy said:

GEFS having very little to do with a southward correction.  Like the GFS Det it's pushing things slightly north.

 

Control supports the op by a mile!!think ecm might go middle ground here!!ukmo is still okay!!

[Mucka]

There goes my virtual pint!

Though in actuality it is a fair bit more realistic in that it pushes the trough through instead of blowing it up, stalling it and then filling it in over Scotland

Op/control

Edited February 21, 2018 by Mucka

[ukpaul]

The GFS appears to be leading the dance here, wherever it goes then other models toy with it 12/24 hours later. Yesteday’s high issues, for example, now showing more widely whilst GFS embeds cold then pushes through all sorts of opportunities.

Where does the dance end up? I think most models will look GFS like by tomorrow and just hope that the GFS op doesn’t waltz off in yet another direction! 

Edited February 21, 2018 by ukpaul

[Frosty.]

1 hour ago, Frosty. said:

there is still uncertainty whether the uk will be hit full on or whether the strongest thrust of severe cold will be diverted further south into france.

This is the point i made earlier and is what the ukmo 12z shows although southern uk would still be in the firing line whereas further north would be dry and bright with light winds and not as cold...of course I want to see the high further north with a nationwide freeze but me wishing that won't make any difference, whatever will be will be!

[Banbury]

168 mean

[Nimbus Nix]

To properly understand the current model discrepancies around the UK in terms of northward/southward shifts etc, many would be better off concentrating on the behaviour of the block around Svalbard and Northern Russia. Here is this morning's ECM at 96H, and corresponding 12z GFS at 84H showing the starting position with a circa. 1050mb High around Svalbard (Focus on heights (colours) only!):

     

From here, the UKMO starts to split the ridge 12 hours later, slowing down the progression of cold air:

The 0z ECM is similar to the UKMO 12 hours later, weakening the ridge over Svalbard and inflating the Icelandic ridge:

Whereas the 12z GFS keeps a nice elongated ridge connected fully across Svalbard, pushing the colder air further west:

This is what you need to look out for on tonight's ECM, forget the Europe view, switch to NH. Can we keep heights high at Svalbard, or does the ridge get broken down as the ECM did so this morning:

[pages]

the 12z ensembles not much use showing a direction they all widely different by t-144 but there are some crackers this is my favourite

[ukpaul]

GEFS is excellent at 192, only a few being tempted by a supposed southwards movement. Ship steadying?

 

[Banbury]

216 Control

216 OP ermmmmm

[Nick123]

I'm so confused. Are things looking good??

[warrenb]

I got a feeling the latest warming has really confused the models.

[ukpaul]

1 minute ago, Nick123 said:

I'm so confused. Are things looking good??

Depends where you look and where you live. GEM, GFS control and GEFs good for all, GFS op better for the midlands northwards, UKMO not very convincing for anyone, ICON potentially poor for all.

[Banbury]

5 minutes ago, Nick123 said:

I'm so confused. Are things looking good??

For us turning cold yes , we might and it is just might miss the exceptionally cold air but nevertheless the cold is coming

[Southender]

GEFS T+192 850's mean. What's not to like?

 

Edited February 21, 2018 by Southender

[karyo]

1 minute ago, ukpaul said:

Depends where you look and where you live. GEM, GFS control and GEFs good for all, GFS op better for the midlands northwards, UKMO not very convincing for anyone, ICON potentially poor for all.

Yes, that's a fair summary. 24 hours ago they pretty much all looked good. Still plenty of time for things to change.