Model Output Discussion - 21st - 28th November

[Jason T]

This Euro high is brilliant and long may it last until end of year. GFS tries to change pattern downstream but keeps backing off whereas ECM keeps it going.

Perfect for building my double extension, no frost, no rain except for 2 heavy shower days in last 7 weeks. Brickwork up and roof going on.

Plus the gas bills gonna be really low :-)

Nick your prayer's been answered and so have the rest of us coldies,Good on ya jimbo 36 lets see what the output brings now.

[Grimsby Snow Lover]

This Euro high is brilliant and long may it last until end of year. GFS tries to change pattern downstream but keeps backing off whereas ECM keeps it going.

Perfect for building my double extension, no frost, no rain except for 2 heavy shower days in last 7 weeks. Brickwork up and roof going on.

Plus the gas bills gonna be really low :-)

if the Euro high was to continue until end of the year then you might be looking at severe drought conditions in your part of the country. As much as I like the cold we all in the east and south need the rain. However from a builders point of view I do understand how the current conditions could favour your work.

[mcweather]

If the ECM verifies its certainly the final nail in the coffin for the European ski resorts in terms of early December skiing, absolutely dreadful output.

Someone please nuke this Euro high!

The ECM is of course not supported by any other longer range output and hasn't been very representative of its ensembles however its not the best global model by chance.

If we put aside everything after 168hrs and stick to a comparison of the general output there is close agreement on the overall pattern, it does look like the Newfoundland high pressure will likely verify.

How much this impacts down stream in Europe is still open to debate.

From what John Holmes was saying recently Nick The GFS is out performing the ECM interms of verification at the moment.

[Grimsby Snow Lover]

The ensemble mean chart for 240hr on the ECM looks a little more promising, looks cooler with winds from a more NW quadrant.

[Geordiesnow]

One thing for sure is that the outputs do agree that we could be heading into a more blustery and windy spell which will add a bit more "excitment" to the weather make things Autuminal in terms of wind, the temperatures is hard to judge because it will depend if there is any kinks in the jet whether we get a mild SW'ly or a polar NW'ly and the runs are inconclusive at this stage.

Both the GFS and ECM suggest the newfoundland high will form so if they keep this idea, it be interesting how this will effect the output.

I think some are just taking the output too literally in my eyes but I will admit, those who are looking for snow at this stage may have to wait a bit longer for it too arrive.

[bluearmy]

reading noaa cpc, there is plenty of disagreement re the east coast american trough. they have low confidence in their output in the 6/10 day range and even though the models are in better agreement in the 10/14 day range, the fact that they start the period with poor alignment means that this period is also low in confidence. fwiw, they refer to the strong north atlantic high anomoly shown in all the models and their charts show a mean nw flow over the uk with the jet over northern france. could be a lot worse but i guess we need to wait for the models to firm up on the east coast trough before we can get a good handle on whether we get a sw/ne, w/e or nw/se jet.

http://www.cpc.ncep.noaa.gov/products/predictions/814day/814day.03.gif

the 12z ecm ens mean has retrogressed the lw trough somewhat and seems to be half way to the naefs compared to its last two runs. note the spreads show a very deep shortwave days 8 thru 10, mid atlantic sinking slowly se towards nw iberia whilst filling in conjunction with another shallower depression centre drifting slowly from the uk down into the low countries. i guess this shows that if we are to have a strong flow, there are likely to be some weird and wonderful developments within it. looks a bit of a nightmare trying to pin anything down at the moment.

[snowlover2009]

Once again the ecm has no support whatsoever from the ecm mean. In fact, the 240 chart couldn't be any different to the mean 240 chart. The control goes to the freezer, one of the coldest runs. From that point of view, the euro high at least moving away from us, for the time being and I am confident enough to believe will be seeing plenty of PM incursions, so some snow possible for high ground in the north. None of the ensembles or other models support any euro high on the scale of October and this month, from what I can see.

If that big block of high to the west of Greenland and north east Canada on Ecm verifies, then I wonder if that could help us shift to something much colder through next month.

Edited November 21, 2011 by snowlover2009

[Grimsby Snow Lover]

Once again the ecm has no support whatsoever from the ecm mean. In fact, the 240 chart couldn't be any different to the mean 240 chart. The control goes to the freezer, one of the coldest runs. From that point of view, the euro high at least moving away from us, for the time being and I am confident enough to believe will be seeing plenty of PM incursions, so some snow possible for high ground in the north. None of the ensembles or other models support any euro high on the scale of October and this month, from what I can see.

If that big block of high to the west of Greenland and north east Canada on Ecm verifies, then I wonder if that could help us shift to something much colder through next month.

Well that would be a start, I don't think the majority on here could cope with another month of Euro high orientated weather. Looking forward to seeing what the pub run has on offer in around an hour and a halfs time.

[Robbie Garrett]

One thing for sure is that the outputs do agree that we could be heading into a more blustery and windy spell which will add a bit more "excitment" to the weather make things Autuminal in terms of wind, the temperatures is hard to judge because it will depend if there is any kinks in the jet whether we get a mild SW'ly or a polar NW'ly and the runs are inconclusive at this stage.

Both the GFS and ECM suggest the newfoundland high will form so if they keep this idea, it be interesting how this will effect the output.

I think some are just taking the output too literally in my eyes but I will admit, those who are looking for snow at this stage may have to wait a bit longer for it too arrive.

Can't wait for some gusting conditions to go flying again, went flying in Gusting 25knots and 40-60mph upper winds at 2000ft, was very bumpy but could have done with a co-pilot or a GPS as navigating using DR was extremely difficult, but I agree if it's not snow some windy and extremely wet weather would be great to end 2011.

[Backtrack]

The ECM seems to be performing strangely inaccurate as of late... is there anything that could be possibly affecting its performance?

It was this time last year when the ECM was making a show of the GFS, picking up on features way before hand if I remember correctly...

[johnholmes]

From what John Holmes was saying recently Nick The GFS is out performing the ECM interms of verification at the moment.

Did I say that, I thought they are about neck and neck on a day to day basis, ECMWF is rarely below GFS if you look at T+120 or 144 but I'd best go and look at what the last few days are showing.

Remember also that the verification tables I use only go out to T+144. Beyond that and there is a mixed body of opinion as to which T+240 verifies most often.

It really is best to check all of the models at that range with the 500mb anomaly charts.

[snowlover2009]

The ECM seems to be performing strangely inaccurate as of late... is there anything that could be possibly affecting its performance?

It was this time last year when the ECM was making a show of the GFS, picking up on features way before hand if I remember correctly...

All runs seem to wobble at times. GFS has also been on the milder side of things recently, but only further out in runs, but as we know it has been on the colder side too, whereas ecm seems to be going on the mild side quite early with little support. I love the ecm mean anyway.

BTW I disagree, I remember the ecm the odd time, disagreeing with gfs cold synoptics, but there were times where it was vice versa. Gfs had the holy grail of charts last year and the best I have ever seen from all models put together.

Did I say that, I thought they are about neck and neck on a day to day basis, ECMWF is rarely below GFS if you look at T+120 or 144 but I'd best go and look at what the last few days are showing.

Remember also that the verification tables I use only go out to T+144. Beyond that and there is a mixed body of opinion as to which T+240 verifies most often.

It really is best to check all of the models at that range with the 500mb anomaly charts.

Are the verifications stats for the ensembles or the ops? If it is for the whole lot, then take into account the ecm has no support from the other pack of ensembles. Edited November 21, 2011 by snowlover2009

[damianslaw]

Once again the ecm has no support whatsoever from the ecm mean. In fact, the 240 chart couldn't be any different to the mean 240 chart. The control goes to the freezer, one of the coldest runs. From that point of view, the euro high at least moving away from us, for the time being and I am confident enough to believe will be seeing plenty of PM incursions, so some snow possible for high ground in the north. None of the ensembles or other models support any euro high on the scale of October and this month, from what I can see.

If that big block of high to the west of Greenland and north east Canada on Ecm verifies, then I wonder if that could help us shift to something much colder through next month.

Yes all eyes should be on developments over NE USA and SE Canada up to west greenland in the coming days - if we do see a strong build of pressure in these regions it may ridge southeastwards and this could have a mjor impact on the upstream pattern, one which would be much more conducive for a colder period of weather here as we would see strong building of heights over mid atlantic with a NW-SE titled jet and lots of polar maritime air.. our change will come when the change comes over NE USA and SE Canada. At this stage far from certain whether such a synoptic will verify but it is a very plausible one. I will be keeping a close eye on developments far to our NW in the coming days.

[johnholmes]

Are the verifications stats for the ensembles or the ops? If it is for the whole lot, then take into account the ecm has no support from the other pack of ensembles.

this is the link

http://www.emc.ncep.noaa.gov/gmb/STATS/STATS.html

[phil nw.]

Well the outlook hasn`t changed from yesterday with a fairly straightforward Zonal pattern modelled up to T240hrs. by the 12z output.

ECM Op. has High pressure closer to the South than it`s mean later on which would give warmer uppers for a spell but the general flat looking Atlantic flow remains.

Both ECM and GFS mean runs show a very similar sypnotic setup by T240hrs.

Looking at Ens.the Op runs on both models are fairly close to the mid-range showing a small cooling trend from day 5.

http://www.knmi.nl/e...M_06260_NWT.png

http://hw.nwstatic.c...arwickshire.png

It should feel somewhat cooler than of late further North at times where brief incursions of Pm air occur.

It may well continue mainly dry in the South and East for much of the time with that High closer by over Europe and still with some mild days.

Edited November 21, 2011 by phil n.warks.

[johnholmes]

The NOAA 500mb anomaly chart this evening, as indeed over the past 3 issues, shows a largish +ve anomaly off Newfoundland, as do the ECMWF and GFS versions. (see the post from blue army with the link given earlier this evening). They all 3 also show a -ve area at 500mb, initially centred over the UK but trending more to the NE of the UK, NOAA especially. 500mb heights have also been predicted to fall by 6-10DM over this area over the past 3 outputs. The overall 500mb flow is about westerly but there are signs, not large at the moment, of the flow buckling over the states and some veering beginning to show in the 500mb flow over the Atlantic.

GFS and maybe to a lesser extent ECMWF will not quite flip from run to run but expect a degree of non continuity shall I say as they gradually take on board the less volatile outputs from the 500mb anomaly charts.

There is very little in the longer term teleconnections to support a major wavelength change but that is not totally vital for a spell of such. yes it does help if they are all agreed but one thing does tend to lead to another even if it seems that their sequence is not necessarily in the order we may think of them.

I have already posted about one instance where ALL parameters promised one thing and nothing happened so do not be surprised at the obvious beginning of a change of type to carry on down that line.

Certainly instead of the anticyclonic period we have had it looks much more unsetted and less mild shall we say.

Edited November 21, 2011 by johnholmes

[Grimsby Snow Lover]

The NOAA 500mb anomaly chart this evening, as indeed over the past 3 issues, shows a largish +ve anomaly off Newfoundland, as do the ECMWF and GFS versions. (see the post from blue army with the link given earlier this evening). They all 3 also show a -ve area at 500mb, initially centred over the UK but trending more to the NE of the UK, NOAA especially. 500mb heights have also been predicted to fall by 6-10DM over this area over the past 3 outputs. The overall 500mb flow is about westerly but there are signs, not large at the moment, of the flow buckling over the states and some veering beginning to show in the 500mb flow over the Atlantic.

GFS and maybe to a lesser extent ECMWF will not quite flip from run to run but expect a degree of non continuity shall I say as they gradually take on board the less volatile outputs from the 500mb anomaly charts.

There is very little in the longer term teleconnections to support a major wavelength change but that is not totally vital for a spell of such. yes it does help if they are all agreed but one thing does tend to lead to another even if it seems that their sequence is not necessarily in the order we may think of them.

I have already posted about one instance where ALL parameters promised one thing and nothing happened so do not be surprised at the obvious beginning of a change of type to carry on down that line.

Certainly instead of the anticyclonic period we have had it looks much more unsetted and less mild shall we say.

Thanks for this information John, I don't understand all of it but the probability of more unsettled and cooler conditions will at leat help things feel more seasonal. The met office update earlier also goes along the lines of more unsettled and cooler conditions affecting us as the month draws to a close. All in all a change from the past 3 months could finally be on the cards.

Edited November 21, 2011 by Grimsby Snow Lover

[nick sussex]

Going back to the verification stats, I'm sure people must wonder why the ECM is classed as the best global model when in recent days its had all manner of synoptics in its FI output, indeed last winter it pulled out some very inconsistent post 168hrs output.

The key to the ECM reputation is its much less likely to go awol within 144hrs, I've known the GFS to be totally out of line at 96hrs on many occasions.

For the timebeing we can view the operational solution of tonights ECM as low probability, however if it continues that to the 144hrs timeframe then thats the time to start getting very worried!

Theres often alot of talk about outliers, all new patterns often start as just that, the main reason being the higher resolution of the operational output, its rare you'll find a sudden jump of the majority of the ensembles at the same time as the operational run.

In terms of the chopping and changing of the ECM control run, this has swung from very cold to mild regularly over the last few days which lowers further confidence in the operational run.

[SP1986]

To me it looks like very average November fare, average temperatures, average weather. Should we be surprised though, as apart from a few month the year has mostly trended average (or a little bit the side of)

As for the ECM, surely we shouldn't just assume because it's pulled away from it's ensemble pack it's wrong? How can we truly say that the ECM operationals are wrong?

The GFS has often had to pull to it's ensemble pack but the ECM has better verification stats, and I'm sure it wouldn't be the first time an operational has shown the way. Although whether the ECM will verify is another question but still, you simply can't write it off just because it stands, relatively, alone.

[phil nw.]

The NAEFS NHemisphere Pressure Anomalities for T240hrs.

http://www.meteociel...40&mode=0&map=1

seems to kick the pattern a little further East with the Atlantic trough over the UK locked between Hts over E.Europe and off the Canadian coast.

This would likely give rather unsettled and cooler conditions,much in line with the latest Met.Office outlook.

Edited November 21, 2011 by phil n.warks.

[johnholmes]

I know I bang on about it but I do urge folk to make use of the daily output of the 3 500mb anomaly charts.

They are far more reliable and subject to far less chopping and changing than the routine 2x ECMWF and 4x GFS outputs at time scales beyond the T+144 range.

IF and only IF they consistently predict a similar upper air pattern for several days its about 80% if not 90% likely that is how the upper air pattern will turn out.

remember its the UPPER air NOT surface. That is another difficulty, no offence intended, for amateurs to try and 'marry' upper air pattern down to what the surface overall pattern may be. Do not expect the detail hardly ever to be correct at the surface 10 days out-just get a feel for how the pressure pattern will most likely look like. It should for instance tell you pretty clearly the difference between a settled anticyclonic spell and a less settled one as well as a good idea which direction the isobars are going to come from.

Expect more? then expect to be constantly disappointed!

Edited November 21, 2011 by johnholmes

[wolvesfan]

I know I bang on about it but I do urge folk to make use of the daily output of the 3 500mb anomaly charts.

They are far more reliable and subject to far less chopping and changing than the routine 2x ECMWF and 4x GFS outputs at time scales beyond the T+144 range.

IF and only IF they consistently predict a similar upper air pattern for several days its about 80% if not 90% likely that is how the upper air pattern will turn out.

remember its the UPPER air NOT surface. That is another difficulty, no offence intended, for amateurs to try and 'marry' upper air pattern down to what the surface overall pattern may be. Do not expect the detail hardly ever to be correct at the surface 10 days out-just get a feel for how the pressure pattern will most likely look like. It should for instance tell you pretty clearly the difference between a settled anticyclonic spell and a less settled one as well as a good idea which direction the isobars are going to come from.

Expect more? then expect to be constantly disappointed!

please keep banging on john,its posts like yours that are giving amateurs like me a greater understanding of what we are viewing.cheers.

[Iceaxecrampon]

18z rolling out.

528 down to Cumbria - this is almost getting reliable.

Decidedly chilly tonight here when the wind rises wouldn't call it mild at all.

[Geordiesnow]

GFS18Z is a good run for some proper Autumnial weather with a mixture of polar and tropical airmasses and it shows that it could be quite a windy period, perhaps those with only snow tinted specs are missing that in terms of this GFS run, its not that bad in terms of seasonal weather.

I'll certainly bag the first 144 hours of this run for sure but until we get agreement that the Azores high won't be more of a factor than the Atlantic low pressure systems then I won't get carried away but its certainly an interesting run on my POV.

[feb1991blizzard]

I seem to remember the ECM not coming on board for the arctic outbreak in mid december untill it was well inside the reliable causing a lot of stress on here, i wasnt panicking to be honest because just about every other global NWF model had nailed it and the mets monthly outlook had been outstanding and not flinched for over a month but i can see why some were worried - because it was the ECM not the GFS going off on its own.