Model Output Discussion - 30th November onwards

[Paul]

A new thread for discussing the model output - please keep it on topic and within the spirit of the community

 

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NMM-6 

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[lamppost watcher]

gfs t144 0z

This mornings gfs

[Stu_London]

ECM continuing with last year's theme of being the 'rampers' model of choice.

 

Even if it did outperform the GFS. I can outperform my wife at running, but doesn't mean I'm any good at it.

 

edit: actually that's not fsir - she would probably win

[Cecil Hogmanay Melchett]

Well out to Fri and the only places with snow potential are those in scotland and perhaps the hills of northern ireland and the cumbrian fells.

Pressure remaining stubbornly high to our south.

Nothing like ecm.

[Catacol]

Bluearmy - ref your post in the previous thread can you point me to the period where there was a disconnect? I have been following upper atmospheric patterns for a few years and have no memory of this. I'm asking a genuine interested question - not having a dig at you... I want to learn! Dashing out now for a bit.

[nick sussex]

Well out to Fri and the only places with snow potential are those in scotland and perhaps the hills of northern ireland and the cumbrian fells.

Pressure remaining stubbornly high to our south.

Nothing like ecm.

Yes its different but this is an upgrade synoptically on the 00hrs run, the shortwave disagreement is just part of the puzzle, its also now the phasing upstream.  At least we've stopped the negative trend from the 00hrs run but still have the UKMO which disagrees with both the ECM and GFS.

 

Lots of energy heading south into the mid Atlantic, I'm liking that trend!

Edited November 30, 2013 by nick sussex

[Cecil Hogmanay Melchett]

Not liking 06z,not cold enough for snow through friday for the vast majority and then a bone dry bitterly northerly lasting probably 24 to 36 hours.

A million miles from ecm unfortunately...

Better than its 0z run but....

[Ali1977]

Its not like the ECM as people say however isn't it more like the ECM than the 00Z, surely that's a better thing and step in the right direction for coldies?

[SMU]

The plucky 06z makes a step towards the ECM with the low neg tilted but as ever

More runs needed.

Im not posting any more long term thoughts until ukmo and ecm are in sync as they will need to be...

S

[bluearmy]

Bluearmy - ref your post in the previous thread can you point me to the period where there was a disconnect? I have been following upper atmospheric patterns for a few years and have no memory of this. I'm asking a genuine interested question - not having a dig at you... I want to learn! Dashing out now for a bit.

Catcol, I mentioned this in the strat thread a week or so back. Matt remembered it also. It wasn't last year so I can only assume was two winters ago, possibly three.We had a rampant upper strat vortex but the zonal winds didn't propagate down to the lower strat and we saw amplified trop patterns.

[lamppost watcher]

Next Friday

[That ECM]

Im not posting any more long term thoughts until ukmo and ecm are in sync as they will need to be...

S

[ribster]

Catcol, I mentioned this in the strat thread a week or so back. Matt remembered it also. It wasn't last year so I can only assume was two winters ago, possibly three.We had a rampant upper strat vortex but the zonal winds didn't propagate down to the lower strat and we saw amplified trop patterns.

Indeed, as I think has been said before, far too much emphasis put on the strat, it isn't the be all and end all, merely part of a very complex puzzle. To say we can't and won't get anything sustained is not in my view correct. Sure it helps, and we have seen plenty of evidence of that in the not too distant past. But I don't think it's as simple as 'strat says no'. Anyway, I'll get my coat...

[bluearmy]

Does anyone recall earlier in the year when ECM took the jet south ( the occasion when gfs didn't correct till T84!). Was ukmo in line at day 6 or did it take some time to agree with ECM?

I only ask because in my experience, if ECM op keeps on producing the same solution pre day 6/7then I can't recall it being wrong. The caveat on this evolution being that the margin for error is very small re the tilt on the flow off the eastern seaboard

[SMU]

Im not posting any more long term thoughts until ukmo and ecm are in sync as they will need to be...

S

The GFS is more believable than that!!

Basically you don't buy the ECM but want it to be correct. UKMO looks plausible but not as good?

[Captain Shortwave]

Low resolution GFS sees the return of Eurotrash 

Sorry couldn't resist that gag.

At least it's a better run in high resolution

Edited November 30, 2013 by Captain shortwave

[Ian Brown]

The GFS is more believable than that!!Basically you don't buy the ECM but want it to be correct. UKMO looks plausible but not as good?

Well now the 06 has run they all look believeable-The reason I worry is purely because of the UKMO. Im always consistent and that is until the UKMO is pn board its not happening...Also the other week when ECM saw polar ridging the UKMO didnt.... The UKMO was correctS

[carinthian]

Low resolution GFS sees the return of Eurotrash 

 

Feeling there will be no Euro trash, heights have been too low in Europe for a few weeks now,cant see a major change .

C

Sorry couldn't resist that gag.

At least it's a better run in high resolution

[IDO]

Another run, another possibility from GFS in FI. This time a settled cool HP dominated setup with an Euro High:

The ens on GFS have been showing no confidence in any pattern so its no surprise that the OP churns out what appears to be inconsistent runs; it is a reflection of the difficult background re specifics. The ECM is again resolute that a 2-3 day cold snap is on the way, I could not call that from the GEFS, and without the stamps from the ECMF I am not sure of their spread, so though previous posters suggest good support for a toppler, need more time for the GEFS to resolve the hi res.

Edited November 30, 2013 by i'm dreaming of...

[SnowObsessor90]

I wouldn't surprise  at all if all this model "uncertainty" actually turned out to be an Atlantic/Zonal signal trying to break through all along, as IB said the models are generally better at resolving something like that rather than picking out cold spells.

[Summer Sun]

Northern Scotland and parts of England have a decent chance of seeing some snow next Friday at this stage

 

 

South of the Midlands only sees sleet

 

Edited November 30, 2013 by Summer Sun

[MPG]

Think we can see where this is going. A colder weekend next week, wintry in the north at times. But soon the pattern sweeps through moving the cold east with the UK back is some kind of westerly flow. As people have said, the UK MET will be important but next weekend is miles away in terms of forecasting. So by Tuesday/Wednesday the true pattern will be shown...a cold few days with north seeing something wintry. The ensemble is consistent in showing a cold shot for a few days.

[Tamara]

Catcol, a couple of winters back the upper strat and trop were not in sync. Whether other factors not present at the moment were at play I don't know. To get a strong sustained neg AO without strat support would seem a reasonable assertion but to say we can't have a cold spell, especially with min solar input is, in my opinion, wide of the mark.

Copied from previous thread as it closed when I posted

 

I think it is true that the pattern, at least for the present time and first part of winter, does favour short cold snaps and in essence that is what CH is saying. As we know, there have been several instances of tropospheric and lower stratospheric interactivity through this year - and this has continued this autumn (albeit weakly). However it is all about equating how much forcing is required from this trop/lower strat activity to disrupt the net energy of the upper vortex and the signals are that it is going to take a lot more than we have seen in previous times to disrupt the vortex.

 

Without going into acronym land, there are reasons as detailed previously on here and ongoing in the technical threads why this winter looks less favourable for lower atmosphere activity to be successful on the upper vortex than we have seen in recent winters

 

The recent attempted downstream amplification the other week as triggered by wave activity from the continued presence of the Alaskan ridge was insufficient to disturb the vortex and amplify the atlantic ridge as much as suggested at one stage by the models - and the jury is still out as we know on the upcoming northerly as to how much amplification may be present and how the jet energy is handled upstream.

 

The jet stream is favourable in terms of a split flow being present to allow the possibility for the northerly - and we have the -EPO (Aleutian ridge) to thank for that - but the complicated upstream pattern is making the model calculations on degree of eastward moving energy and amplification of the atlantic ridge tricky and hence the erratic disagreements amongst the models - but, all that said, what we do know is that without background support for upper blocking, whether we get a more amplified and colder arctic incursion or not - the vortex is too strong, and wave activitity likely too insufficient, to make next weekends cold shot nothing more than a transitory affair.

 

There are continuing consistent signals in the modelling, post northerly, for the vortex to return towards Canada through Greenland and it is quite conceivable that the upcoming polar incursion presents the 'best' opportunity at wintriness before the pattern flattens out somewhat and the ridging de-amplifies and potential for northerlies reduces - at least for a while.

 

Both the GFS and ECM do agree on this even if they disagree on the northerly strength and duration itself.

[Duane S.]

Bluearmy - ref your post in the previous thread can you point me to the period where there was a disconnect? I have been following upper atmospheric patterns for a few years and have no memory of this. I'm asking a genuine interested question - not having a dig at you... I want to learn! Dashing out now for a bit.

 

 I think it was 3? years back. These 'disconnects' happen all the time, in particular the coupling between the strat and the trop is a wildly complicated affair that few have even got close to understanding.

 

It's not just higher up in the stratosphere where it occurs (or doesn't), I remember the MJO last winter, even when when at a well amplified state, it often seemed to have no influence on us at all, whether in a favourable phase or not so. Then there are times (not applicable now as it is neutral) when the Enso state seems to be controlling our weather and other times when the same state is present and is seemingly completely disconnected.  It's always been my belief that until we can resolve exactly why that is (and the reality is it may never happen), the accuracy of medium range forecasts won't improve in any great leaps.

 

Shame to see the runs today but far from unexpected, we are again looking at weak amplification leading to a cold 'snap', snow for the usual suspects up North. The options all involve too much energy in over the top, we can of course still get proper cold when that happens but generally speaking. not. There has never been a strong signal to build robust enough heights into Greenland for anything else. The fact we are even getting a small window of opportunity here is due to the Aleutian high. But the vortex is heading back west that is the only near certainty I can see.

 

I am a lot more confident of something of interest from the East as we head toward Xmas. Whether it will get as far as us is, as always, another story.

[Smiler1709]

The ECM will no doubt come into line with the gfs. It's looking increasingly likely that it will be a very brief affair and those living in England and Wales will just have a cold couple of days, no point looking at precipitation charts they are useless beyond 24 hours.