Model output discussion - another cold spell on the horizon?

[bluearmy]

Looking at the eps mean, I would think a wedge or cut off weak upper ridge in the greeny area is favoured as week two progresses with the jet fairly flat below. Hopefully that runs into the base of the sceuro trough ....the fi gfs runs recently with the Atlantic running the lw trough into nw Europe may it be too far away .......

[SMU]

Just now, Man Without Beard said:

Fair enough wrt the mean, but about 1/3 had a N Atlantic high ridging into Greenland, and another 1/3 had a full blown Greenland High. I suspect some deep troughs over Greenland on the other members flattened the mean

Look at the mean here.

( & others )

The 552 Contour is what we use to distinguish the wave height & whether thats a GH or an atlantic ridge.

The ECM 00z 240 mean has that contour adjacent to Ireland.

That means the GH cluster could be scrapped essentially.

 

When there is going to be a cut off GH that contour will be way up there over Greenland even at day 9/10.

[Daniel]

Ecm clusters a lot of them

[Vikos]

Hey folks, my package from Wish! just arrived

[Scott Ingham]

5 minutes ago, Steve Murr said:

You keep saying theres a GH on the means. There isnt.

Theres no GH on the GEFS means either.

So what your posting is totally wrong.

GEFS 12z Mean 192.

No GH.

EPS 00z Mean

No GH

12Z  GEM Means

 

The only model is the GFS operational.

Which means its 99% going to be wrong.

In all fairness a mean isnt going to show a full greenland high at that range Steve.

Anyway you have your opinion and me mine and naturally a ssw has led us to this debate such is the state of flux

[Scott Ingham]

3 minutes ago, bluearmy said:

Looking at the eps mean, I would think a wedge or cut off weak upper ridge in the greeny area is favoured as week two progresses with the jet fairly flat below. Hopefully that runs into the base of the sceuro trough ....the fi gfs runs recently with the Atlantic running the lw trough into nw Europe may it be too far away .......

Thats where my head is too. Purely on them jet patterns

[bluearmy]

5 minutes ago, Steve Murr said:

You keep saying theres a GH on the means. There isnt.

Theres no GH on the GEFS means either.

So what your posting is totally wrong.

GEFS 12z Mean 192.

No GH.

EPS 00z Mean

No GH

12Z  GEM Means

 

The only model is the GFS operational.

Which means its 99% going to be wrong.

Almost half the eps in the extended are in a distinct greeny ridge cluster ?. Those clusters days 9/10 looked very amplified around in greeny aswell 

I’m not sold on anything more than a decent wedge at the moment .....may well be enough given a strong sceuro trough 

[Battleground Snow]

How it looks on meteociel ECM OP v mean at 216, where the low goes at 144 won't be pinned down for a while yet, and will cause a big divergence in FI expect further swings both good and bad

 

[bluearmy]

3 minutes ago, Daniel said:

Ecm clusters a lot of them

Not good to see the op cluster growing as a percentage of largest option ......

[SLEETY]

Lets hope we get another stonking gfs or gfs p run,later,feels a bit downbeat in here at the moment,remember none of what being modelled actually exist yet,including the crud ECM run!,but trends are important,so lets have another historic pub run!

 

[Man With Beard]

Here's a link to the ECM ensembles of a small town at the base of Greenland - a useful guide as to whether there might be a Greenland High in the majority of the ensembles.

ECMWF 14-day ensemble weather forecast for Narsaq

WEATHER.US

---

Narsaq, Greenland - The ideal weather forecast for the next 14 days. See the results of all 50 ensemble members of the ECMWF model in direct comparison for several parameters.

In

[Mike Poole]

Not posted today, having a day off in the main.  ECM mean T240, that’s not great to be honest.  

But the uncertainty is earlier.  

[SMU]

7 minutes ago, bluearmy said:

Almost half the eps in the extended are in a distinct greeny ridge cluster ?. Those clusters days 9/10 looked very amplified around in greeny aswell 

I’m not sold on anything more than a decent wedge at the moment .....may well be enough given a strong sceuro trough 

Just looked at the 12z EPS.

Chances of a GH. 0% with 99% confidence.

552 Contour at 12z 216 EPS -

168 Jet to much positive tilt. GH will come from a northward vertical ridge not a ridge out of Canada.

A proper Greenland high

A lot of confusing wording on here being posted that should be made clearer for some of the newbies....

The *Best* case scenario is as @Kasim Awanmentioned a block in the atlantic that holds in situ long enough to deflect the atlantic track further south whilst the trough to the forces cold air south..

Edited January 10, 2021 by Steve Murr

[Frostbite1980]

4 minutes ago, Mike Poole said:

Not posted today, having a day off in the main.  ECM mean T240, that’s not great to be honest.  

But the uncertainty is earlier.  

Looking good for the states again surprise surprise

[phil nw.]

UKMO latest fax at t72 compared to t84 from the earlier run shows a little change with the fronts coming in held further west.

Looking east we can see that block of deep cold gathering.

We have seen this before when a weak Atlantic comes up against a cold block it has trouble making inroads and as time ticks down modeling gets adjusted to reflect this.

[Jordan S]

You can see how the frontal system with the milder air on Wednesday moves in.. looks like a slow process it sinks southeast through the country and fades away as the cold air accompanied by high pressure to the east and west effectively squeeze it from both sides the main energy going into france with the rest of the front slowly fizzling out ..the cold air in the east of the uk looks like it may not leave at all and may come back westward again by Thursday and Friday which as a couple of others have posted may bring a little snow ..

Saturdays synoptic much different on the latest ecm so expect more changes with this one..

For interest only ..the Gem looking promising if you want something more significant for cold and snow not likely to evolve exactly like this though but there is some support..

The low pressure and rain on the gem or what the ecm showed as some snow as well for Saturday is followed by quickly to cold but moderated air from the north on this model, potential troughs with organised showers longer spells of rain sleet and snow moving south or southeast across the country

Saturday

Sunday

Monday 18th

Wednesday 20th

Have a good evening everyone 

Edited January 10, 2021 by jordan smith

[Zak M]

ECM op was an outlier at day 9 and 10...don't panic!

Edited January 10, 2021 by Zak M

[I remember Atlantic 252]

not as good as 10 years ago to the exact day/date much colder air, but similar setup, this delivered a snow day here, Atlantic did break through on Fri 15th 2 days later with rain

[Frostbite1980]

If we look at 'trends' the the ECM mean has been solid with mid Atlantic height rises towards Greenland until tonight which although has reduced this slightly is still there so my advise is let's see if the trend to moving heights towards Greenland being watered down by tomorrow evening then we should take notice but until then we have 2 GFS runs to look forward to which might perk us up a bit

Edited January 10, 2021 by Frostbite1980

[NeilN]

Well, it seems the handsome Chris Fawkes has said it will possibly turn colder from Thursday onwards on the Countryfile Forecast!

There is hope, and a mild spell isn't the end of the world. 

[stodge]

Evening all

The end approaching of two weeks of below normal temperatures and while it may have yielded no more than some frosts and a bit of fog for lowland East London, if you've had snow, good luck to you.

The model output this time yesterday suggested any reversion to milder conditions "could" be short lived with three of GEM, GFS OP, GFS Parallel and ECM all going for cold solutions at T+240 albeit of differing kinds and by differing routes. There was also more than a hint of more "normal" conditions later in the month with a resurgent vortex and an active Atlantic.

Plenty of uncertainty even as early as T+120 - will we see resolution or will we be in the need for salvation after this evening's musings?

12Z GEM: T+120 takes us to Friday by which time an anticyclone covers the British Isles with centres over south west Norway and a larger centre to the south and west of the British Isles. Calm conditions prevail for most with a slack SW'ly flow for northern and western areas. An Atlantic LP is close to Iceland at this time. Uppers of zero to -4 a this time over the British isles, coldest in the east and south. From there. the Atlantic LP meanders east and north east and forms a complex but vigorous LP over northern Scandinavia while heights rise upstream in the Atlantic with a ridge from the Azores to Greenland. This leaves a flow of NNW'ly PM-sourced air over the British Isles by T+180. Colder air is moving down from the north and north west removing the last of the positive uppers from south east England by this time.  The trough over northern Scandinavia sinks slowly south and by T+140 covers the British isles and much of north-west Europe as a complex feature. 850s of -8 cover much of the British isles by this time.

 

12Z GFS OP - a cold evolution from GEM. On then to the American OP and by T+120 it's quite similar to GEM with a long ridge of HP from just west of Iberia through the British isles to southern and western Scandinavia. Colder air has returned with uppers of -4 to -8 with the coldest air on the southern and eastern sides of the ridge. The HP weakens away to the south from there as the LP to the south-west of Iceland at T+120 moves slowly east then south east to be over north-west Britain by T+180 having phased with a residual trough far to the east. Heights have developed over Greenland and extend south and east as a narrow ridge into mid-Atlantic. Uppers of zero to -4 over the British Isles by this time with the warm sector in the LP crossing at that time.  As heights develop further over Greenland, the LP over the British isles sinks south but merges with a new LP approaching from the south west. The battleground is the British Isles with -8 850s and a chill NE'ly wind in the north and milder air trying to come in from the south and south west.

12Z Parallel - OP screams a battleground evolution and there would inevitably be snow for someone somewhere were that to verify. Parallel will be intriguing as always - at T+120 the immediate difference is in the upstream profile with a shallower LP further south than on GEM or GFS OP. By T+120 milder air over Ireland and uppers to zero to -4 elsewhere. From there, the divergence really begins. There is no attempt to build pressure through to Greenland. The LP over the Atlantic at T+120 passes to the north of Scotland by T+180 with a new LP approaching from the west. The cold air is kept well to the north with the HP over or to the west of Iberia keeping a WSW'ly flow across the British Isles. Uppers of zero to -4 across the British Isles at this time. From there, the evolution goes in a diametrically opposed direction to the OP. The LP moves across the British isles and pulls down a cold N'ly but by T+240 there's a clear Atlantic-driven profile with heights lowering over Greenland and a familiar SW'ly flow across the British Isles. By this time, the brief cold plunge is already on its way out as positive uppers approach from the west.

12Z ECM - Parallel very different from the OP. Let's see where ECM is at the same time. It was out on its own with its evolution yesterday but at T+120 it's broadly aligned with the other models though I note the Atlantic profile is different again with a more complex trough. Milder air perhaps trying to come in from the west but some residual cold air over eastern parts of the British Isles at this time. The Atlantic LP moves east to Scandinavia and with heights developing in the mid-Atlantic to Iceland a NNW'ly air flow covers the British Isles. Uppers of -4 to -8 by T+192 keeping it cold. However, there's no amplification and instead shallow areas of LP are crossing from south of Iceland to Scandinavia in a WNW'ly flow by T+240. Milder air is back across the British Isles by this time.

After last evening's 3-1 win for cold, it ends 2-2 tonight with GEM and GFS OP in the cold camp and Parallel and ECM ending milder. Moving further ahead, a look at far FI from both GFS OP and Parallel and given their huge divergence at T+240 I suspect they will be similar as two dissimilar things in a pod 

OP is cold and very decent for snow fans - Parallel rather less so. Both want to restore the PV to its usual place and strength by the end of FI. For the second night running, Control stays cold throughout.

Looking elsewhere, as for the 10 HPA charts, little change from Control with another strong warming after mid month exerting further pressure on the PV. OP is very similar as is Parallel. None of them force a second split but all keep the PV under pressure.

Conclusion: we seem tonight to have a milder path and a colder path and a lot depends on the evolution from T+120 to T+180. If we can get a new push of amplification into Greenland by T+180 and split the Atlantic trough, we're more or less set for a colder evolution. If not, the Atlantic prevails and we stay on the milder aide of the trough and if it's the latter it could be a long journey back to cold. If we can get that amplification, we could have several days on the colder side of the trough with all the possibilities flowing from that but it's finely balanced tonight.

[chris55]

17 minutes ago, Steve Murr said:

Look at the mean here.

( & others )

The 552 Contour is what we use to distinguish the wave height & whether thats a GH or an atlantic ridge.

The ECM 00z 240 mean has that contour adjacent to Ireland.

That means the GH cluster could be scrapped essentially.

 

When there is going to be a cut off GH that contour will be way up there over Greenland even at day 9/10.

What if 17 went for a solid Greenland high, 17 went for an Atlantic ridge, and 17 went for an Azores/Euro ridge. How would that show in the mean?

 

 

 

Edited January 10, 2021 by chris55

[Frostbite1980]

7 minutes ago, Zak M said:

ECM op was an outlier at day 9 and 10...don't panic!

Is that 3 outliers on the trot?

[fromey]

1 minute ago, NeilN said:

Well, it seems the handsome Chris Fawkes has said it will possibly turn colder from Thursday onwards on the Countryfile Forecast!

There is hope, and a mild spell isn't the end of the world. 

I’ve noticed a few pro’s now edging towards cold by the end of the week, some saying the ECM will be an outlier.

we wait and see! 

[MJB]

33 minutes ago, Djdazzle said:

If the EPS are worse as is the Exeter update, surely this is significant when backed up with the ECM op?

Not the one I have read or are you talking about the next update