Model Discussion Thread - January 13th

[Cecil Hogmanay Melchett]

There's a big yellow bar beneath the first post on every page, why not click the link in that to the fax and have a look?!

http://www.netweathe...;type=fax;sess=

Oh sorry i didn't know that.

[OldMetMan]

It seems the GFS is keeping to the same idea at 18Z. Also, the UKMet is killing off the current HP by T120 and is fairly close to the GFS.

Whether it is within the spirit of this thread or not I am not sure, but I sometimes think that, rather than simply comparing the different model outputs and what they show, perhaps each should be more subject to a "reality check",if you like, in terms of whether a particular model's predicted synoptic development looks realistic. By this I mean, are the stages shown from T0 to T120 (the only fairly reliable time frame I think) look as if they could happen as predicted, given the present starting point.

For example, we currently have something of a meridional flow, ridge over the uk, flanked by upper troughs either side, so does it seem reasonable for this to be bulldozed aside as shown by the GFS particularly? Are there other signs, other than model changes with successive runs, that suggest the predicted outcome of a model will actually happen? I am always pointing to satellite imagery, water vapour specifically but not exclusively, as it often shows the upper wave pattern very clearly and how it's changing (national hurricane centre uses this a lot to determine what going on aloft and where it is heading).

I also think it helpful to review recent developments to see how we got to the present situation and whether the models carry through the recent development in a way that looks possible.

Of course, this approach does assume some knowledge and experience how synoptic patterns can and have developed, with the proviso of course that no 2 situations are identical.

Forgive me mods if I am being in any way off topic with these ideas, or if this does indeed get discussed much more than I am suggesting (I don't always have time to read through the many interesting threads here) but I do like to read posts where reasons are given for why a particular model solution may or may not verify (for example, the state of the stratosphere). There is so much data available to review when attempting to see where the weather is heading so why not use all of it?

[in the vale]

short term London ensembles suggest op (and control) among the mildest runs 168-192hrs

http://www.meteociel...1&ville=Londres

Outliers, the pair of them, by quite a distance after 20/1. Interesting.

Edited January 13, 2012 by in the vale

[Cloud 10]

If we look at the mean height comparison's for the ECM and GFS,the differences are clear,with the ecm

having the trough over the uk,and the GFS not.

If we now compare with the latest CPC 500mb chart for roughly the same time period,which

seems closer,GFS or ECM?

Climate Prediction Center - 8-14 Day 500mb Outlook

I would quite happily "copy and paste"that chart for the rest of winter.

[phil nw.]

The differences being debated are really down to how cold the expected North Westerly flow will be as it arrives around next Friday.

The overall pattern is similar but the flow shown on the ECM is more buckled which brings the colder conditions.

The GFS recent runs persist with a more East to West flow and inhibits the extent of the cold to the north,at least at first.It keeps the Azores High closer to the south for longer although even this shows some tendency to ridge into the Atlantic a bit later.

At this range there`s still time for some changes to the jet flow so it`s best not to get hung up over too much detail beyond T120hrs i would say.

Edited January 13, 2012 by phil n.warks.

[swilliam]

If we look at the mean height comparison's for the ECM and GFS,the differences are clear,with the ecm

having the trough over the uk,and the GFS not.

If we now compare with the latest CPC 500mb chart for roughly the same time period,which

seems closer,GFS or ECM?

Climate Prediction Center - 8-14 Day 500mb Outlook

I would quite happily "copy and paste"that chart for the rest of winter.

Yes and that is because the upper low over the NE pacific is much deeper and greater in extent (especially s) on the ECM compared to the GFS

[Snowmadsam]

May I remind you all that if you feel you need to rest your brain then come on over to chat: http://forum.netweather.tv/chat/

Hope everything is ok here

ECM was good wonder what way the models will go in the morning

See you

Snowmadsam

[SMU]

18z GFS ensembles Starting to read the ECM script- reading between the lines the GFS ENS now look like a blend of the ECM...

Its becoming more amplified by the run- it just needs to be slower with the CONUS trough at 120 when it exits the US to allow the heights to build across the atlantic-

All in all GFS playing catch up-- starting to put energy UNDER the block & not over it-

S

[nick sussex]

I think whats most interesting about this current stand off is just how close in the disagreements start.

Generally one model backs down quite quickly but in this instance both the ECM and GFS operational runs are determined to stay the course.

I know I said this yesterday but surely we'll get a resolution to this in the morning!

[Jason M]

18z GFS ensembles Starting to read the ECM script- reading between the lines the GFS ENS now look like a blend of the ECM...

Its becoming more amplified by the run- it just needs to be slower with the CONUS trough at 120 when it exits the US to allow the heights to build across the atlantic-

All in all GFS playing catch up-- starting to put energy UNDER the block & not over it-

S

Yes, def some hints in amongst them. Once they go 'low res' though GFS blows up its usual super storms so its hard to get much of a steer beyond 200 hours.

[kold weather]

I think they are slowly moving towards each other. The ECM for the last 2 runs has slowly been weakening the upper ridge and reducing its strength, whilst the GFS has slowly been increasing the amplification around 168hrs.

I'm not sure either model is holding totally firm, consensus will probably be right in the middle of the two solutions, probably a strong intial shot then the GFS expects, but not sustaining as well as the ECM expects.

[phil nw.]

18z GFS ensembles Starting to read the ECM script- reading between the lines the GFS ENS now look like a blend of the ECM...

Its becoming more amplified by the run- it just needs to be slower with the CONUS trough at 120 when it exits the US to allow the heights to build across the atlantic-

All in all GFS playing catch up-- starting to put energy UNDER the block & not over it-

S

Actually Steve the GFS mean looks colder after T144-trough digs down much better by T180-a colder flow ala ECM op--Azores High shunted away.

Still time for changes at that range as we can see.

[Bobby]

The 18z GFS ensembles look pretty poor to me, fairly relentlessly zonal with a strong PV near us dominating the picture, with brief Northerly topplers about the best on offer. Not a single peturbation shows 850s below -7c for my spot, there's usually been quite a few proper cold runs recently. So a rather confusing picture, who knows what's going to happen.

Edited January 13, 2012 by Barb-

[kumquat]

I would hope that the last few days' model outputs have been scrutinised by the professionals in the field (would hope that this will be a major case study within their model improvement meetings). By taking the projected outcomes and comparing them with reality, tweaks could be made for both the big gun ECM and GFS and all of the lesser respected models. There must be an improvement process. In any business this has to happen. Mesoscale fine-tuning would be welcomed. Even to amateurs it's plain to see, in retrospect, that the models have their quirks when presented with certain synoptical scenarios and how they play them out. I'd love to get an inner view on the work that those guys must be doing.

Of course, far more data points could and should be thrown into the mix. It all comes down to money, of course. And sphere of influence from one model to the other in terms of their target geographies.

Fascinating model watching, though, without a doubt, and cold weather aside, a worthwhile hobby in its own right.

[bluearmy]

The 18z GFS ensembles look pretty poor to me, fairly relentlessly zonal with a PV dominating things with brief Northerly topplers about the best on offer. Not a single peturbation shows -7c 850s or below, there's usually been quite a few proper cold runs recently. So a rather confusing picture, who knows what's going to happen.

you need to look at the runs. i'd say at least 7 drop the trough over the east of the uk or better next weekend. low heights = not such low uppers required for the white stuff although fairly academic at this range.

[damianslaw]

I firmly believe the most likely synoptic next week will be for mid atlantic heights to build northwards towards Greenland but not into Greenland itself thus ushering in a NW blast by the end of the week after a temporary milder westerly flow mid week, and during the last week of Jan we will see a northerly incursion thanks to the trough digging SE across the country - the northerly quickly becoming a northeasterly thanks to more favourable robust heights developing over greenland/iceland.

Based on this projection, none of the models would verify as being suggested, what is required is a bit of a mix of GFS and ECM. GFS is being too bullish with its zonal attack - no surprise here, and ECM I think is being too progressive with the build of heights to our north and thus the easterly - mind its interesting to see GFS 18Z is going with an easterly right at the end of its output.

I'm expecting the ECM to back down from its easterly scenario over the weekend but continue to show a northeasterly set up at the 240 hr timeframe and stick with this theme - eventually it will verify but not probably until the latter stages of the month, whilst I am expecting the GFS to tone down its zonality assault over the weekend but only slightly so and it will be next week when the GFS finally starts to show the building of northern heights in its medium output.

UKMO as ever will probably yo-yo with both, with the Met office staying very conservative.

Later next week has strong potential to deliver quite low level snow to northern areas I imagine thanks to come cold uppers from the NW moving in.

Those worried the projected colder weather some have been forecasting is unlikely to occur, shouldn't fear,the upstream northern hemispheric signals are screaming a potentially very wintry February ahead with the promise of a bitter easterly airstream.

[Tom Montalbano]

Totally agree Steve re.18z GFS ensembles, which I've just flicked through, that low exiting Labrador at around t132, causing major headaches.

Lots of different solutions and a lot showing rather more amplification than the Op, which has the effect of lows diving SE closer to the UK than the Op and on into Europe. Even a couple of glancing northerlys and dare I say it, heights building NE of us on a few of the runs.

We also seem to be seeing that high pressure to our south, pulling away westwards, and out into the Atlantic, on the majority of members too.

Plenty more twist and turns to come no doubt before this is resolved.

Regards,

Tom

Edited January 14, 2012 by TomSE20

[Paul]

Last one from me this evening, but just to re-iterate the uncertainty in the ensembles tonight. At 102 hours we have 2 key areas of spread (the spread is shown as the colours and is the difference between the highest and lowest ensemble member - in this case it's sea level pressure), they're to the north of the UK and a major influencer later in the run is the one over Canada at that point.

Roll it forward to 168 hours, and much of the north atlantic, across the UK and into Scandi is at least +/- 10mb+. Not exactly conducive to nailing down a forecast..

[Daniel Miller]

I've not been able to check the models today so I was wondering if someone could tell me if the ECM has stayed as good as before?

Also, I came on earlier for 5 and I saw many comments about how people would be surprised in the ECM DIDN'T back down... I thought it would be a surprise if it DID, rather, seeing as it has been consistent :/

One other thing... Do the models show cold arriving from the N or the E, potentially? Thanks

Also.. Has anyone noticed the complete lack of worldwide snow stories this winter? Last winter and the one before that they were rolling in from Wisconsin, China, New York, Chicago, here.... Odd. Seems to be a worldwide lack of snow?

Edited January 14, 2012 by Daniel Miller

[kumquat]

I'm being a tad lazy and not getting your point, Paul. Which model's ensembles? What point are you making?

[davehsug]

Anyone remember if we have had a stand-off like this before? It's been 2 days+ now & in my years here I don't recall it. I keep expecting that one of the big 2 will suddenly collapse but so far it hasn't happened. I suppose the first major blink may have come in the GFS ensembles tonight, although ECM may have just fluttered a little in it's ensembles earlier. You'd normally say we'd have a clearer picture tomorrow, but who knows at the moment?

[kumquat]

Ah, I see these are anomaly charts.

Edited January 14, 2012 by kumquat

[Jackd]

When is the next ECMWF model run out? What time in the UK?

[Iceni]

I've not been able to check the models today so I was wondering if someone could tell me if the ECM has stayed as good as before?

Also, I came on earlier for 5 and I saw many comments about how people would be surprised in the ECM DIDN'T back down... I thought it would be a surprise if it DID, rather, seeing as it has been consistent :/

One other thing... Do the models show cold arriving from the N or the E, potentially? Thanks

Also.. Has anyone noticed the complete lack of worldwide snow stories this winter? Last winter and the one before that they were rolling in from Wisconsin, China, New York, Chicago, here.... Odd. Seems to be a worldwide lack of snow?

But they've had more snow in the Alps this week than they had the whole of last winter.

http://www.mirror.co.uk/news/top-stories/2012/01/11/freak-snowfall-traps-thousands-of-brits-in-austria-resorts-115875-23693758/

[TEITS]

Late night for me!

After reading the posts I don't understand how some can be so certain which model is correct. At this moment in time im not convinced either are right. My only negative comment about the models is in my opinion we are moving away from a very cold, prolonged spell towards a more shortlived cold spell. I hope when the 0Zs come out im proved wrong!