Model Output Discussion 18/11/2012 12Z onwards

[mcweather]

Very pleased with model developments tonight. The trend to some kind of blocked cold solution firms up with each day that passes. Some people have complained that it has been like pulling teeth watching the models for the last week trying to deal with the change from mobile Atlantic to high latitude blocking, but my Gran was a wise old bird and had a saying about the weather that has proved very useful over the years.

Long foretold Long to last

Soonest come soonest passed.

Remember how we watched the charts for about two and half weeks in Nov 2010 after the Meto's first hints in the 6-30day outlook early in the month. Just let it build and enjoy the results

[Tim Bland]

BOM looks tasty! http://www.meteociel.fr/modeles/bome_cartes.php?&ech=234&mode=1&carte=0

[Harve]

yes.

It always has- Everything shunted EAST from the 12z-

This bias generally applies when Scandi blocks are prevelent.

S

The GFS has always had a bias towards shifting things east too rapidly/too much? So it basically shows things to always be more zonal than what actually occurs? Right.

[Barry12]

I just dont get people who are moaning about the models not being cold enough for snow? the models are projecting below average temperatures, which is good enough for me, yes eventually I would like to see a change so we can get some snow, but at the moment getting below average temperatures is a massive relief. Before people complain, just be thankful that the models aren't projecting mild, mild, mild even into deep FI. Or a raging bartlett being predicted, yes it may not be the best, but what would you rather be discussing? - How mild it's going to be, or how cold is it going to be? I know what I'd rather have.

p.s this looks cold enough?

Edited November 19, 2012 by Barry95

[SMU]

The GFS has always had a bias towards shifting things east too rapidly/too much? So it basically shows things to always be more zonal than what actually occurs? Right.

GENERALLY

YES-

Eastward bias- which amplified across certain runs & certain situations will see the jet moving East instead of NE, moving NE instead of North-

In this situation if the jet is increased by a few M/S then that ridge wouldnt be alligned towards southern greenland- it would be flatter- also a flatter curve one side will be flatter on the returning side so less amplification.

S

[AWD]

The 500mb height anomaly charts from both the GFS & ECM are in broad agreement of heights to our N/NE/NW & a trough to the SSE of the UK;

http://www.meteo.psu.edu/~fxg1/ECMWF_12z/hgtcomp.html

If anything, the ECM slightly stronger with the signal, especially with the heights to the NW.

Edited November 19, 2012 by AWD

[Thundery wintry showers]

There is a fundamental issue with the latter stages of the ECMWF output though- continental Europe is still pretty mild at around T+120 to T+168, and as long as that remains the case, any easterly flow off the continent is unlikely to be cold enough for widespread snowfall. For this reason, any widespread snowfall before the end of November would have to come from the north rather than the east. However, with a strong likelihood of blocked patterns dominating as we head towards December, snowy easterlies may become a possibility further along the line, particularly if we get a surge of Arctic air into the near-continent- this will be likely if the mid-Atlantic block migrates to our north.

For what it's worth, I'd expect sunshine and wintry showers (snow to low ground in the north) from the initial northerly on the ECMWF run followed by a transition to mainly grey weather and some rain/sleet in the east from the subsequent easterly.

[The watcher]

I just dont get people who are moaning about the models not being cold enough for snow? the models are projecting below average temperatures, which is good enough for me, yes eventually I would like to see a change so we can get some snow, but at the moment getting below average temperatures is a massive relief. Before people complain, just be thankful that the models aren't projecting mild, mild, mild even into deep FI. Or a raging bartlett being predicted, yes it may not be the best, but what would you rather be discussing? - How mild it's going to be, or how cold is it going to be? I know what I'd rather have.

p.s this looks cold enough?

-6 to -8c uppers widely, yes, cold enough in regards to 850 temps. Still plenty of other factors to take into account though.

[Zenarcher]

Interesting weather on the way this week and some of it needs watching also interesting trends continue for the end of the month.

This weeks unsettled weather,

Tuesday - A low pressure system is situated to our West giving us wet and windy weather. The models struggled greatly with this low but now that we have agreement between them this seems like the most likely scenario.

Wind speeds across England could reach over 30mph.

Thursday - Another low pressure system sweeps by giving us much higher wind speeds of around 40mph and gusts over 70mph. Area's at the moment to be affected Western parts of England, Wales and Southern Scotland. All the models do show this even at 72 hours there is still time for upgrades and downgrades.

Friday/Saturday - As I mentioned in the Atlantic lows thread this could be another one to watch but at the moment there isn't much support for it. GFS and NOGAPS do show yet another low pressure system affecting the UK.

GFS shows a small low passing over Southern England,

NOGAPS makes it arrive later and deeper,

After a unsettled week signs of a settled end to the month - The models continue to show us a blocked pattern to end of the month at the moment they are changing all the time which is expected they show us a great cold run then suddenly a blocked run but the blocking isn't in the right place for any cold weather. I expect them to change around still for another few days. The important thing is they all still continue a blocking trend.

[summer blizzard]

Movements toward a solution this evening then with both ECWMF and GFS moving towards each other.

I'd agree that the day 10 ECWMF chart would not produce anything for low ground (above 200m and i think it would be enough) however at the very least it looks like a setup conducive to frost and sunshine. It's also notable that cold air is approaching from the east and the trough is being reinforced.

[Snowy Easterlies]

have the ECM ensembles come out yet ?

[Glacier Point]

Tonight's CPC 8-14 dayer, rock solid:

Mentions stable blocking structures N. Pacific and N. Atlantic.

It should be noted that 12z operational ECM was too progressive wr/r/t N. Pacific (loses the ridge too quickly).

We should now be looking for slow evolution in this pattern. The high latitude ridges will be persistent with the tendency of the Pacific ridge to shift its position northward and westward in time supporting a full blown -AO phase later on. Our ridge in the Atlantic may wobble around, first NW towards Greenland for 5 days and back again for another five, potentially becoming part of a very strong -NAO phase mid December when the polar vortex will be under full scale attack. This phase hasn't even got into the model's range yet.

Weatherwise, becoming increasingly cold.

[John Cox]

I’ve been through so many winters in the 90's and noughties and the synoptics we are seeing now are certainly encouraging. For so many winters we had low pressure’s continuously barreling in to Ireland and the UK from SW to NE relentlessly.

Add to this, the very cold summer and autumn of this year and the winter of 2010 (Early and Late), let’s just say, a little patience is called for and hopefully December will start to produce the winter that us cold lovers want.

PS, Just seen Glacier Points post. Follow him and Steve Murray and all the regular experienced posters (of course not excluding my real favorite John Holmes) and you shall be guided well.

Edited November 19, 2012 by John Cox

[SMU]

http://www.knmi.nl/exp/pluim/Data/PLUIM_06260_NWT.png

Stage 1 of the ensembles look great...

S

[UV-RAY]

Tonight's CPC 8-14 dayer, rock solid:

Mentions stable blocking structures N. Pacific and N. Atlantic.

It should be noted that 12z operational ECM was too progressive wr/r/t N. Pacific (loses the ridge too quickly).

We should now be looking for slow evolution in this pattern. The high latitude ridges will be persistent with the tendency of the Pacific ridge to shift its position northward and westward in time supporting a full blown -AO phase later on. Our ridge in the Atlantic may wobble around, first NW towards Greenland for 5 days and back again for another five, potentially becoming part of a very strong -NAO phase mid December when the polar vortex will be under full scale attack. This phase hasn't even got into the model's range yet.

Weatherwise, becoming increasingly cold.

That's all I need to know really as I was a little worried that those heights would be stuck too close to us for the foreseeable. So we could be looking at a lockdown sort of pattern, where high latitude blocking could be influencing our weather for the the rest of this year at least?

[Uncle_Barty]

Interesting times.

Obviously I'd much rather have a strong PV over Greenland and a large slug-like Bartlett showing its hand by now, but it's very clear from all the model output that it is light years away from that scenario, so.....

I think we were rather spoiled by the events of 2010. This isn't going to match it (things are set to change later than in 2010, for starters, and it is still November....) but the general progged pattern is oozing with potential, even if the synoptics arn't specifically showing us or mainland Europe in the freezer. So it's best not to get too hung up on the specifics like are the 850s going to be low enough etc etc. Look at the general picture.

The coldies amongst us will have to wait a little longer for the goodies to show up, but they will eventually if things carry along this track.

I remember Chio/GP (cant remember which) warning us quite early on in 2010/11 that the best of the winter would be early, and like in 1981/2, the 2nd half of winter would be disappointing for coldies in comparison. I'm trying to remember on what basis (stratospheric??) that was, and how it's looking this time.

Edited November 19, 2012 by Jim_AFCB

[Frosty.]

An excellent sequence of charts from the Ecm 12z op run from as early as T+168 hours onwards as we get an initial blast of polar maritime air to really drag the temperatures below average before we then import even colder air from the north and then eventually to the east, i'm sure we would get some wet snow from the later charts, so it's only 7 days until the change which is semi reliable timeframe, not dim and distant FI anymore. The Gfs 12z op run was a mild outlier so the ecm is probably going to be nearer the mark I think. As for the Gfs 12z ens mean, all looking good for a cold further outlook, the north and west of the uk would become settled with widespread frosts and light winds as high pressure topples in from the northwest, the south and east more unsettled and cold enough for a wintry mix of ppn with ENE'ly winds freshening, a cold further outlook and eventually all areas becoming unsettled again, there could easily be some extreme cold and snowy charts springing up in FI during the coming days, once we get into the much colder airmass, all bets are off.

[mcweather]

Tonight's CPC 8-14 dayer, rock solid:

Mentions stable blocking structures N. Pacific and N. Atlantic.

It should be noted that 12z operational ECM was too progressive wr/r/t N. Pacific (loses the ridge too quickly).

We should now be looking for slow evolution in this pattern. The high latitude ridges will be persistent with the tendency of the Pacific ridge to shift its position northward and westward in time supporting a full blown -AO phase later on. Our ridge in the Atlantic may wobble around, first NW towards Greenland for 5 days and back again for another five, potentially becoming part of a very strong -NAO phase mid December when the polar vortex will be under full scale attack. This phase hasn't even got into the model's range yet.

Weatherwise, becoming increasingly cold.

I imagine this might just be influencing you're winter forecast a little. GP

[Biggin]

I see quite a few posters worrying about the lack of cold air to draw on.

The cold air will come once blocking sets up in the right places That`s some time away and will take a few days after to establish-at this time of year particularly.

The first stage is to get the pattern change in that`s modelled for next week and this may only be surface cold under higher pressure to start with.

If and when that Greenland block builds we can then look for a drop in upper air temperatures.

Can I just ask a question?? posters say , "the cold air will come" but how come the models dont recognise this?? What I mean is why cant the models recognize that the cold will come?? Also how do i put certain wind up posters on ignore ??

[mcweather]

Interesting times.

Obviously I'd much rather have a strong PV over Greenland and a large slug-like Bartlett showing its hand by now, but it's very clear from all the model output that it is light years away from that scenario, so.....

I think we were rather spoiled by the events of 2010. This isn't going to match it (things are set to change later than in 2010, for starters, and it is still November....) but the general progged pattern is oozing with potential, even if the synoptics arn't specifically showing us or mainland Europe in the freezer. So it's best not to get too hung up on the specifics like are the 850s going to be low enough etc etc. Look at the general picture.

The coldies amongst us will have to wait a little longer for the goodies to show up, but they will eventually if things carry along this track.

I remember Chio/GP (cant remember which) warning us quite early on in 2010/11 that the best of the winter would be early, and like in 1981/2, the 2nd half of winter would be disappointing for coldies in comparison. I'm trying to remember on what basis (stratospheric??) that was, and how it's looking this time.

Hi Jim The thing is if the vortex comes under a really sustained attack in mid December it might not just be early winter that ends up being cold.

[Robbie Garrett]

Hello Nick,

I take it they have decided to proceed with caution? I remember in 2010 though, that initially an Easterly was forecast this then became a North Easterly then northerly.

Cheers.

They're unlikely to say much for the timebeing as theres still alot of uncertainty in terms of how the pattern could progress.

An easterly flow which could occur at the start is unlikely to be too troublesome for the general public as theres not the depth of cold available to the east to cause good convection over the North Sea, its whether the pattern retrogresses with a trough dropping into Scandi and high pressure to the nw, thats when theres more potential for snow.

[Geordiesnow]

Geordiesnow If we ended up with a raging Notherly, North Easterly then Easterly you still would not be happy.

Cheer up, it is only the weather. :-)

I'm not miserable, just pointing out the continent is too mild for any convective weather(snow showers) to form on this particular ECM run despite a decent looking chart synoptic wise.

I be happy if we get a Northerly if its at the 48-72 hour range, not at 200 odd hour range. The details will change but hopefully the trends won't, days previously I menturned that we seem to have the right ingredients but they just not coming together at this moment in time however today runs have suggested better angled blocking therefore better charts if albeit upper air temperature wise, its all average rather than anything especially cold.

Because of the timeframes involved, its still not certain its going to turn much colder, we may see a cooler spell but a colder one? I'm not quite certain about that basing on past experience sadly.

[Cloud 10]

PS, Just seen Glacier Points post. Follow him and Steve Murray

I've heard he is mint at forecasting..

Link to GFS/ECM ensembles.

Ensembles - GFS / ECMWF--

Long range ECM ensembles out at about 21.30

[kate1]

Can I just ask a question?? posters say , "the cold air will come" but how come the models dont recognise this?? What I mean is why cant the models recognize that the cold will come?? Also how do i put certain wind up posters on ignore ??

Go to your profile - where your name is, right at the top - and various options are given.

Not really a model-related post, so please forgive me, but it's quite exciting when respected posters start using words like 'excellent'... I have to say, the model thread has been fantastic so far this autumn/winter - I have learnt so much - massive thanks to all of you.

[Jayces]

Can I just ask a question?? posters say , "the cold air will come" but how come the models dont recognise this?? What I mean is why cant the models recognize that the cold will come?? Also how do i put certain wind up posters on ignore ??

I may be completely wrong but what I believe they mean is that as high pressure sets up over the NW in Greenland (and maybe expands E / NE?) the air flow will then come from the North pole down through Russia and then turn West and head to us slowly bringing temperatures down across Europe and sticking us in the freezer....or something like that

I think we want some sort of sausage high I believe.....