Model Output Discussion: 12Z (20/11/12) And On...

[Dave Kightley]

Is the -5 upper profile really that important for snow.. I swear we had had snow the other week under -1/-2 although it had to quite heavy. The cold-ish uppers do flirt with Scotland for a while

[phil nw.]

Yes although academic at this stage we can see on the ECM T240hrs the colder air is starting to come this way from the North East.

It`s been said so many times if the block establishes in the right area the cold will follow in time.

On that chart Chiono`,s hose is connected and the tap is ready to be turned on.

[Cheshire Freeze]

Yes it started so well and I had high hopes then it turned into mutton dressed as lamb! It looked good but a bit like one of those chocolates that look great until you bite into it and discover its one of those horrid liquer things people subject you to at Xmas!

The shape of that troughing is all wrong over continental Europe, we needed to see the elongated troughing further south and east to stop that milder air being pulled into the flow.

I think we're going to have to go the retrogression route to really deliver, hope I'm wrong but I just can't see any other way of advecting some deeper cold into the flow.

I think you're right Nick, looking like we'll be waiting 10 day+ for any attempt at sub -5 850s to infiltrate the UK. In this instance we have to hope that we continue to see the blocking hold firm past the initial attempt. I'm not confident on this by any stretch but should the second build of pressure around Greenland come off, we'll have more chance of seeing the uppers advected which will not rule out some of the white stuff falling!

[Nick F]

If we can get through to the 216hr chart the cold will slowly back west with time. You can clearly see a retrograde pattern in evidence when you run through the 216-240hr frames. Those sub -8 850s edge slowly westwards, encroaching Scandi etc.

Let's hope the blocking can hold to our north long enough to allow that cold air shown dropping into Russia to back west. Will need to keep an eye on upstream developments, but at least there are stronger signs from the models now of the upper flow energy from the west going south of the UK under the developing block rather than to the north, which may allow the block to hold into early Dec.

Not a quick and easy route to cold and snow, with hurdles to overcome to get there.

Edited November 20, 2012 by Nick F

[Mr Frost]

I can't actually believe that some people are whining about these glorious charts!

It looks a fantastic start to Winter, very seasonal!

Enjoy the ride, it could be so much worse!

[Cheshire Freeze]

Let's hope the blocking can hold to our north long enough to allow that cold air dropping into Russia to back west.

Yes, have just posted the same thing!

[Gibby]

Good evening. Here's my look at the 12zs of the big three tonight Tuesday November 20th 2012.

All models show a vigorous SW flow over the UK over the coming days. Tonight will see an active wave run NE over Southern Britain giving copious and persistent rainfall clearing slowly east tomorrow. Further North and West there will be less rain with some lengthy dry spells in places tomorrow and just an odd shower. On Thursday another vigorous depression winds up to the NW with an active and squally trough bringing gales and heavy rain slowly east once more exasipating the saturated ground problems over the UK. As this clears East on Friday a quieter spell of weather is shown for the rest of the day and Saturday as a weak ridge edges close to the SE. By Sunday the weather turns downhill again as the Low pressures to the Northwest slide down across Britain or the North Sea bringing further rain at times in temperatures that will gradually fall to near normal values or just below by the end of the weekend.

GFS then takes us through next week with a rather cold and unsettled first half of the week with further rain at times and perhaps some sleet or snow on higher ground. Winds will swing North or NE on Monday and remain from that quarter thereafter. The latter part of the week sees little change with cold and wet conditions likely in places, especially towards the SE with drier conditions reserved for more North-Western areas. The pressure gradient then becomes slack later in FI with a bias towards low pressure maintaining the risk of a few showers. With light winds the chance of frost and fog at night increase with slow clearances through the daytime, in fact many places could stay dull and cold with fog lasting all day should this phase verify. The end of the run keeps rather cold conditions going with showers at times in the South, still with some wintriness possible over the hills with the driest conditions likely in the far North.

The GFS Ensembles tonight show a very wet spell over the coming days in the South while uppers gradually fall to levels just below the long term mean over the following week. Late in the run there is a hint that uppers may recover to nearer to normal values. The operational was a colder member in the final third of the run for Southern locations. For Scottish locations the uppers pattern remains flat at normal values throughout with rain on occasion too over the whole run.

The Jet Stream shows little change from this morning with the SW to NE flow over the UK currently continuing for some while before a strong ridging through the Atlantic towards the middle and end of next week disrupts the flow to a large degree.

UKMO for midday on Monday shows Low pressure stretching from the Norwegian Sea to Denmark with an unstable NW flow over the UK with showers or rain at times. It would feel rather colder than of late.

ECM tonight shows a different scenario to UKMO with Low pressure down to the SW next Monday with a rather chilly and dull Easterly flow over the South with rain at times while Northern areas see somewhat drier conditions while staying rather cold. With High pressure well established to the North later in the run and a very disturbed area of Low pressure near the South there would be some concerning levels of rainfall for areas of Southern England and Wales should this run verify while Northern areas stay drier if rather cold in a strong Easterly flow. The run ends with low pressure receding and weakening to the South while most areas stay rather cold and cloudy with lighter winds than previous days.

There are some exciting synoptics being thrown out by the models at the moment which if very cold air was in place we would all be drooling with anticipation. As it is after the heavy rains and gales of this week there seems to be little respite on offer next week for the South at least as low pressure is favoured to get hung up close to Southern Britain. With High pressure to the North there is likely to be a steep pressure gradient over the UK with a cold and raw east or North-east wind blowing for many. However, apart from the highest ground of Southern Britain and more modest heights further North snow does not look a major problem at this time. Nevertheless, with the block in place to the North held in position by Low pressure to the South the longer the pattern remains the better the chances become of something much more wintry developing increases in the thereafter.

[cold snap]

Yes it started so well and I had high hopes then it turned into mutton dressed as lamb! It looked good but a bit like one of those chocolates that look great until you bite into it and discover its one of those horrid liquer things people subject you to at Xmas!

The shape of that troughing is all wrong over continental Europe, we needed to see the elongated troughing further south and east to stop that milder air being pulled into the flow.

I think we're going to have to go the retrogression route to really deliver, hope I'm wrong but I just can't see any other way of advecting some deeper cold into the flow.

how often have we said this i think il copy and paste this line

good potential at 240 on the ecm

[xioni]

Latest EC run is quite worrying actually, the blocking high near Iceland might look nice & impressive but most of the cold air is wasted/missed and the temps look around normal for England.

Its previous run and the latest gfs op run are much better for cold next week.

[Met4Cast]

Can we have a filter put on for the saying "850hPa temperatures are not cold enough" please?

Once the block is established, the cold WILL come. The cold is still out in FI at the moment, granted, but the building blocks are very much entering the reliable time frame and I think we're all agreed that some type of Northern Blocking is going to be setting up next week.

Initially it'll be surface cold, widespread frosts developing, a lot of mist and fog around, some cold, dry autumnal weather. But we've got the block in place by then, the cold will be working its way into the flow and towards the UK. Now, can we all stop mentioning it?

[January Snowstorm]

Awesome ECM tonight imo

The uppers are not being modelled correctly in FI

At 168 hrs, uppers are lower than they were forecast a couple of days ago

[DEYS(Kent)]

Nicholas Sussex! It is November the 20th!......Plenty of time for entrenched cold from way out east!

[phil nw.]

I don`t think we should expect too much in the way of cold upper air for much of next week as the pattern change starts to establish.

That trough will spend much of next week parked around the south as it gradually disrupts before easing away under building high pressure.

[seabreeze86]

Yes the 850s are not brilliant and as nick says the troughing over europe is not ideal. But lets take a step back for one second, these synoptics at this time of the year are not the norm thats for sure and if they continue the cold will come. I would just to the ECM for what it is extensive northen blocking and has massive potential down the line.

Of course things can change but the ECM is the form horse and the 32 dayer has been singing from the same hym sheet for a long time now.

[cold snap]

Yes it started so well and I had high hopes then it turned into mutton dressed as lamb! It looked good but a bit like one of those chocolates that look great until you bite into it and discover its one of those horrid liquer things people subject you to at Xmas!

The shape of that troughing is all wrong over continental Europe, we needed to see the elongated troughing further south and east to stop that milder air being pulled into the flow.

I think we're going to have to go the retrogression route to really deliver, hope I'm wrong but I just can't see any other way of advecting some deeper cold into the flow.

how often have we said this i think il copy and paste this line

good potential at 240 on the ecm

[Cheshire Freeze]

The mind boggles as to how cold some of these charts could have been if it had been Jan 20th rather than Nov 20th; with a deep continental cold pool already established. I'd wager hints at maximum disruption had it been the case!

Sadly January has often felt like a spring month in recent times!

Edited November 20, 2012 by CreweCold

[Zakos]

sorry its keeps coming up.but after every run it needs to said.

850s and the lack off

Very true, however, largely irrelevant at this stage.

The block has not even set up yet. We do not even know which direction the cold will be coming from, so the fact that there is currently fairly mild t850 values in FI means nothing. That kind of detail can change even within 144 hours away. let us get the block first and then we can worry about the cold potential.

I assume you are referring also to the latest ECM run, in which case I would have to disagree, as there is cold advancing from Siberia at the end of the run. if the ECM went out to 384 hours then I believe there would some extreme cold heading directly towards the UK.

The latest ECM is amazing. I have not a very experienced model watcher, but that is definitely within the top 5 best runs I have seen, amazing height anomalies at t240.

I understand people are frustrated at the lack of cold t850's on show, but patience is required in this setup.

Edited November 20, 2012 by Zakos

[Southern Storm]

sorry its keeps coming up.but after every run it needs to said.

850s and the lack off

Sorry to pick you up on your post but, can't we just be happy with the charts on offer? especially when we know

That the small details will change from run to run.

We see the same thing every winter and if I had my choice I'd rather have room for temperatures

To cool than have -10 uppers programed from T200 only to see them reduced as we get within a reliable timeframe.

Edited November 20, 2012 by thunderman24

[weather eater]

A good run from the ECM but as I said earlier those looking for snowmegeddon in the next two weeks are going to be disappointed, but let’s remember we are talking about very early December here and who knows how this will have developed in a week’s time as this is an evolving situation. As for a projected breakdown it will be surprising if we don’t get a return to more zonal conditions some time during December.

[Met4Cast]

I don't know why everyone wants to snow immediately anyway.

A week or so of surface cold is FAR better in my opinion if we're seeing widespread night time frosts, it freezes the ground so when the snow finally does arrive there's a much higher chance it'll settle. IF BLOCKING IS IN PLACE, THE COLD WILL COME < It really is as simple as that.

ECM is perfect, the extend of Northern Blocking is something we very rarely saw on the charts last year, I'm very happy with where we are at the moment and really cannot understand the negativity! We live in the UK, not the Arctic.

[nick sussex]

Nicholas Sussex! It is November the 20th!......Plenty of time for entrenched cold from way out east!

Lol! I'm not saying there isn't, but you can end up with something better whilst waiting for the pattern to retrogress with a few tweeks here and there.

Firstly the shortwave drops se into the Continent we get some elongation to the troughing further into Europe this stops any milder air being pulled into the flow.

Although we're lacking real deep cold the shallow cold surface layer delivers low temps with night time frosts, the ground cools in readiness waiting for the north/ne flow to deliver copious amounts of snow as the pattern retrogresses!

[xioni]

This EC run wouldn't give cold conditions in any month, the air mass at the surface is not cold at all and it's actually quite warm for most of the near continent.

Also the way this run ends doesn't guarantee that cold air would come eventually as we end up with a trough southwest of the UK

I wonder if all this is happening due to a much faster MJO progression, most models now predict convection over the Indian Ocean around the turn of the month, while until now we were supposed to get a nice, high amplitude phase 8 for early Dec.

More runs needed obviously but a very worrying EC12 run

[Backtrack]

This EC run wouldn't give cold conditions in any month, the air mass at the surface is not cold at all and it's actually quite warm for most of the near continent.

Also the way this run ends doesn't guarantee that cold air would come eventually as we end up with a trough southwest of the UK

I wonder if all this is happening due to a much faster MJO progression, most models now predict convection over the Indian Ocean around the turn of the month, while until now we were supposed to get a nice, high amplitude phase 8 for early Dec.

More runs needed obviously but a very worrying EC12 run

It's quite mild because we haven't seen any decent cold pooling over on the continent yet. When winter really does get going over there within the next few weeks you'll see a much colder air mass develop.

As someone has already mentioned, if this set up would of been happening in January rather than November, we would be in for a very disruptive cold spell to say the least.

I really don't see how the ECM is worrying at all? It's setting the building blocks for something far greater some time in the near future. If you want terrible charts, take a trip down memory lane to last winter.

[January Snowstorm]

Anyone know the dewpoints that the ECM forecasts ?

Or does it do dp's at all ?

I honestly think 850's of zero are fine under an Easterly, once dp's are low

[Dexter29]

what an epic ECM chart couldnt have drawn it better myself http://www.wetterzentrale.de/pics/Recm2161.gif!! Thats what i call northern blocking

From a guy who is learning here, yes that chart is great but could we be punished with having a great chart but not enough cold air to tap into? The uppers look crap.