Model Output Discussion 01/09/17

[Summer Sun]

ECM has London hitting the mid-teens at the end of next week maybe even a 16c in an isolated spot if conditions were right

 

Edited November 15, 2017 by Summer Sun

[blizzard81]

If ever we needed a stellar ecm op to settle the nerves it was tonight. Instead we await the eps with baited breath. 

[bluearmy]

Just now, blizzard81 said:

If ever we needed a stellar ecm op to settle the nerves it was tonight. Instead we await the eps with baited breath. 

Well the ecm 12z op fitted the largest cluster from the 00z run so not sure why anyone would be surprised by it ......

[knocker]

At least the ecm this evening is in the same ball park as this morning and certainly not without interest.

At T144 it has the strong ridge into southern Greenland with two upper troughs in the Atlantic, one west of the UK and the other just about to track east south of the ridge. But that is not all, there is another trough that has slipped around the north of Greenland which is about to phase with the trough to our west as it disrupts by T168.

Thus the surface front and rain that are affecting N. Ireland and Scotland at 12 Tuesday have tracked quickly north east and 24 hours later a large surface area of low pressure covers the UK and points east with a front and rain lying down the western side of the mainland which is under strong SW airstream This front also tracks quickly east but reinforcements are on the way and by T192 the Atlantic is dominated by low pressure. This would certainly be an unsettled outlook but needless to say not anywhere near a done deal

 

Edited November 15, 2017 by knocker

[The PIT]

Well Bobby the theme in ECM is zonal at the end. GFS the same but later. Thankfully in lala land. At the moment it's only if and will be for some considerable time.

[Stozzy]

Incredible differences between the ecm and gfs . Onto the 18z too see if I should get my coat on or my shorts and t shirt out 

[bluearmy]

Strangely the Atlantic teleconnections AO and NAO are broadly in agreement between gfs and ecm

the pacific ones are certainly not 

[LetItSnow!]

Bad ECM, bad dog!

[A.J]

Forget Bernie Madoff, the weather models are the mother of all ponzi schemes.....they draw you in offering huge returns in the near future, only then to drain you and suck you dry leaving you broken but no wiser as you keep on falling for it year after year.......lol

the outputs are are all over shop, but the overall NH profile looks promising for coldies, FI firmly at T120 IMHO

[comet]

I said a few days ago that the models could be making a meal out of the troublesome lows in the Atlantic that are hindering height rises north  this could still be the case. By Sunday we should definitely know one way or the other what sort of weather we can expect the weekend after next.

The EPs, Met etc will be no benefit either. I'm afraid they to have been just as fallible.

[blizzard81]

The only thing I know about the models at the moment is that they are all, without exception, totally out of their comfort zone. They find it very difficult to deal with the synoptics on offer. 

[frosty ground]

42 minutes ago, Summer Sun said:

ECM is not following GFS though after the ens run it isn't really a huge surprise

ECM & GFS at t192

 

I think the ECM would sit at the top of the GFS Ensembles 

[snowray]

18 minutes ago, bluearmy said:

Strangely the Atlantic teleconnections AO and NAO are broadly in agreement between gfs and ecm

the pacific ones are certainly not 

So in other words anything could happen past T96 then?

[blizzard81]

5 minutes ago, snowray said:

So in other words anything could happen past T96 then?

I would agree with that. 

[snowray]

Just now, blizzard81 said:

I would agree with that. 

I really do think that the models simple do not have a clue right now. Might have to go back to consulting the good old tea leaves or them geese entrails....or maybe the ever reliable 18z might be on the ball tonight. Its been pretty consistent of late, think its just come out of rehab or something.

[damianslaw]

Posting my last post from yesterday again here

 

'Expect more flip flopping from the models in the next few runs, wouldn't be at all surprised to see many showing high pressure settling in and over the UK once again, jetstream profile looks rather ragged and broken, suggesting ridge development and heights will ridge through the country, low heights becoming squeezed and diffuse'.

Alas the models are doing just this, GFS has reverted back to high pressure building over the country, so to did ECM midnight run, now its gone off on a SW fest. UKMO appears to be siding more with GFS.

Far too much uncertainty at the moment to put any faith in any model beyond a very short timeframe of just 72 hours.. 

[bluearmy]

AO watch 12z

ec: -4

eps: -4.1

gfs: -4

gefs: -3.9

gens: -4

[Singularity]

If the overall trend could continue a little further, ECM and UKMO would have no choice but to start reconsidering alternatives to the blowtorch-mega-thermal-gradient-storm chain as I expect the media would be keen to call it. 

 

I wonder just how much influence this tropical storm is having on the output. Perhaps quite a bit; GFS treats it very differently on the 12z;

 

Instead of staying independent of the jet stream, it becomes entangled, adding an extra loop south to that jet which holds up the pattern more than is seen in the case of ECM or UKMO.

I must say it's weird seeing a tropical system heading for the Canary Islands, although I expect cooler waters would probably force ex-tropical transition before arrival there. Probably.

 

Worth noting that UKMO looks in a better position to take the trough as a whole east of the UK by day 8 than ECM.

So somewhat ironically, it's the American model that's by far the closest to the UK Met's recent mid-range outlook updates. Really interesting how they describe a colder, drier north and milder (but not more than average), wetter (but not that wet) south. This is a matter for (and being well discussed in) another thread, of course.

[phil nw.]

Yes looking at the NH view of the vortex and it's clear to see why the +ve pressure anomalies continue to show up on the AO graph as deeply negative.

The problem for us is the way the lobes of the pv are situated and the amplification in the Atlantic being clean enough to drive the Arctic cold southwards.We currently continue to see a split jet pattern and lows cutting off the main pv in mid-Atlantic which makes modelling of the Atlantic/Azores high tricky.

A look at t144hrs on the 3 main models 

Note the little low in mid-Atlantic where the jet is split.

GFS on the left sends it further south and avoids thejoining of the 2 main vortex lobes over Canada and Scandinavia so this leaves the window open for another ridging attempt towards Greenland later.

T192hrs-GFS and then ECM

The ECM and and more than likely the later UKMO  are sending more energy across to the north shutting out the further ridging that the later GFS op goes on to show.Hence the cold v mild differences by T192hrs.

It's quite common in a split jet scenario that we see these type of differences and one occasion where a mean chart isn't much help.We just have to see how this is resolved in the next few runs.

 

 

[Frosty.]

I really don't think we should take the Ecm 12z as gospel, it's dampened the mood following the earlier 12z wintry runs but only this morning the Ecm 00z  was showing 520-522 dam arctic sourced air producing wintry showers of hail, sleet and snow with widespread frosty nights..as has been mentioned this evening, the models are all over the shop at the moment showing anything from arctic blasts to balmy sw'ly zephyrs. Being a coldie I hope we get a wintry spell before the end of this month and that possibility is still on the table this evening.

[karyo]

11 minutes ago, Singularity said:

If the overall trend could continue a little further, ECM and UKMO would have no choice but to start reconsidering alternatives to the blowtorch-mega-thermal-gradient-storm chain as I expect the media would be keen to call it. 

 

 

Worth noting that UKMO looks in a better position to take the trough as a whole east of the UK by day 8 than ECM.

So somewhat ironically, it's the American model that's by far the closest to the UK Met's recent mid-range outlook updates. Really interesting how they describe a colder, drier north and milder (but not more than average), wetter (but not that wet) south. This is a matter for (and being well discussed in) another thread, of course.

Indeed the UKMO chart is quite promising. It should throw an Atlantic ridge and a northerly of sorts.

[knocker]

Although the EPS and GEFs anomalies are in the same ball park there are differences in vital areas that will strongly influence the detail forthcoming from the det runs.

The main features in the Atlantic arena are fine with a high pressure over Greenland , a trough to the south over NE North America , a trough mid Atlantic and another Scandinavia. Thus there are two energy flows, the weaker arm around the Greenland high and the other west from the US seaboard south of the trough via the mid Atlantic trough to run more or less westerly over the UK

These two flows have a tenuous linkage in the eastern Atlantic as the northern arm swings south east, or south, in the Iceland area and this highlights one of the key differences, The orientation of the Greenland high cell. The EPS for example screams potential with it orientated in such a way that troughs could easily swing south and phase with Atlantic energy and drag some Arctic down into the mix, whereas the GEFS does not favour this. So no great help regarding the detail but it's still interesting.

[draztik]

27 minutes ago, Frosty. said:

I really don't think we should take the Ecm 12z as gospel, 

 

Indeed! If the model isnt showing what you want, discard! Tips for winter, folks. 

[damianslaw]

Not that it really helps clear the waters, but the jetstream profile forecasts, very much show a split jet flow, coming unstuck - disrupting with energy dissipating, they suggest heights building through the country this weekend will be quite robust to fight off any atlantic attack - it makes sense the atlantic has been in quiet slumber for some weeks now and its base state remains the same. Longer term, hard to decipher, but there looks a signal to develop heights to the NE with the UK sat on the colder side of the jet, once a deep trough anchors down through scandi.

 

[Frosty.]

32 minutes ago, draztik said:

Indeed! If the model isnt showing what you want, discard! Tips for winter, folks. 

That's got nothing to do with it, I was making the point that the Ecm 00z / 12z are completely different...however, I make no apology for seeking cold..most on here would agree!