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

[TAFKAP]

Perhaps you'd prefer this kind of setup?

http://www.wetterzen...00120111128.gif

The projected synoptics are rare, especially at this time of year, my advise would be to enjoy them while you can and hope they verify in one form or another if they do the forecasts will be full of wintry conditions

LOL! There really are some pessimistic, miserable buggers out there. It could be -20 outside with 2 feet of snow on the ground and they'd be moaning and whining about poor synoptics and talking about a breakdown progged at 1000hrs.

[summer blizzard]

Extremely impressive run synoptically from the ECWMF with the cold uppers breaking through at day 9 (a day behind GFS and JMA).

My personal expectation past day 10 from the ECWMF would be for the Atlantic High to amplify west of the UK and conglomerate with the Arctic High between Svalbard and Greenland so certainly no danger in my opinion of the pattern sinking.

[Snowmad79]

I never said anything was nailed.

My point is we rarely see such good charts, yes it may not be Siberian air. But it's cold enough to produce snow during the later part of next week.

As always we will always have members picking out a negative outcome before its even begun

Fair point. However, just because someone points out the possible risks of where a breakdown could occur doesn't mean they are being negative. Much in the same way a cold evolution can be plucked from a seemingly mild outlook (straw clutching so to speak). I'm sure most would agree.

[Snowy Easterlies]

http://modeles.meteo...nh-0-234.png?12

no chance of a sinker from this right ?

shame its only the BOM how much credit does it have ?

Edited November 21, 2012 by Snowy Easterlies

[Gibby]

Good evening. Here is the latest report of the 12z output from GFS, UKMO and ECM for today Wednesday November 21st 2012

All models continue to show very disturbed conditions over the UK for the coming 5 or 6 days. Low pressure areas innitially to the NW with further centres moving up from the SW over the weekend will maintain flood alerts over the UK as well as strong winds at times. By Monday the Low pressures will move down towards the South of the UK with continuing rainfall coupled by lower temperatures by then.

GFS then shows Low pressure anchoring to the SE of the UK with an increasingly cold and bleak NE wind driving down over the UK with rain, sleet and snow in many places through the middle days of the week. Things improve only slowly through the end of the week and weekend as Low pressure to the East weakens and the Northerly flow weakens in response to a weak ridge moving down from the North. After several days of a further mix of wintry precipitation drier conditions develop from the North though still cold with a frost risk developing by night. Towards the end of FI things moderate dramatically after a spell of less cold but strong NW then West winds things turn much milder as very mild air seeps North over the UK with rain for the North and West in a light Southerly flow at the end of the run.

The GFS Ensembles show a cold spell on the way with uppers falling below the long term mean by several degrees throughout the run after the weekend. the weather looks like staying unsettled with rain or possibly sleet or snow in places at times. The operational was as expected a wild mild outlier at the end of the run.

The Jet Stream shows the flow currently running NE over the UK ridging high over the North Atlantic before turning South over Ireland before turning East over Southern Europe in a week's time.

UKMO for midday on Tuesday shows Low pressure over Southern France with a cold and windy NE flow over the UK. Southern areas in particular will still be at risk of rain or possibly sleet on the hills while the best of any drier weather will occur over the far North close to a High pressure belt centred in a belt from Iceland to Northern Scandinavia.

ECM shows a similar synoptic pattern with Low pressure just to the South of Britain and an increasingly cold, strong, raw and dull airflow over the UK with rain or sleet persistent at times through the middle and end of the week. The run ends with a distinctly wintry prospect as bitter uppers approach from the NE with snow, sleet and strong winds turning things potentially very nasty late next week should it verify.

In Summary the weather will be turning colder after the next 3-4 very wet and potentially newsworthy days have passed. In essence the weather looks very disturbed next week too though with Low pressure to the South and High pressure to the North the implications on temperatures and the feel of things at the surface couldn't be more different. A strong NE flow looks likely with rain and sleet for many with the chance of snow increasing with time as uppers continue to fall slowly. ECM hints at a major wintry blast to end next week and just goes to show what can quickly develop when the pressure patterns set theirselves up in the correct place.

[Ice BIast]

http://modeles.meteo...nh-0-234.png?12

no chance of a sinker from this right ?

shame its only the BOM how much credit does it have ?

Not much, but a nice chart all the same.

[Met4Cast]

NCEP Chart Update.

Hows this for cross polar ridging

[SnowObsessor90]

I have to see I agree with those who are being more cautious, the saying 'slow and steady wins the race' immediately springs to mind here.

[Paceyboy]

To echo the voices of Crewe Cold et al about caution.

Level headedness is crucial but as always the output will change , I suspect upgrades on arrival and depth of cold and also longevity as we get nearer.

Please dont jump on more experienced members' backs who are urging caution, after all they are the ones that keep the synergy of knowledge and realism ticking in this thread whilst also supporting some excitement!

[mcweather]

NCEP Chart Update.

Hows this for cross polar ridging

not much sign of a breakdown there

[Snowman.]

Don't want to derail anything here should I warn people about next week yet or not I like to give people a heads up view.

(not for snow just saying it could get cold with POSSIBLE snow)

[chionomaniac]

I think that it is possible to both enjoy the synoptic output and still be cautious.

That's what I am doing!

[Frosty.]

WOW can't believe the upgrade in the last 24 hours, the ecm charts tonight look so similar to some we had in december 2010, imagine another 100 year event just 2 years after the last one, it would be totally EPIC, it's impossible not to ramp things up with charts like this, I would like us to tap into those purples over norway

[TAFKAP]

http://modeles.meteo...nh-0-234.png?12

no chance of a sinker from this right ?

shame its only the BOM how much credit does it have ?

Yum! The BOM is being a real tart with these sexy charts. I'll need to take a cold shower if it goes on like that.

[dr snow]

First post in this thread so please be gentle! The NCEP chart posted above by Daniel doesn't appear to show a sinker and this goes into early December. Think as has previously been suggested by John et al these are probably better tools to use at this range?

[nick sussex]

NCEP Chart Update.

Hows this for cross polar ridging

This is a better tool than looking at the operational outputs in FI.

For those who have been following GP's posts thats more inline with the expected pattern than tonights ECM operational output.

Theres still a good chance of some colder uppers into the UK with some snow before retrogression so if things fall right you get the best of both worlds.

For longevity you do need to see that type of pattern, historically all the best cold spells have a fluidity to the blocking with Greenland high, some flattening of the ridge with an easterly on the southern flank then back to Greenland.

Edited November 21, 2012 by nick sussex

[Frosty.]

I think that it is possible to both enjoy the synoptic output and still be cautious.

That's what I am doing!

I think your garden hose will freeze up if the ecm 12z verifies chio

[legritter]

Yet again another good day modell watching ,id say brilliant , but signs of the Prozack bottle syndrome creeping in . the weather going by todays charts and data will be making headlines for quite a while . lets all get in a time machine and go back to some epick winters .nothing realy changes except today we are more advanced with computer modells etc .lets arrive say JAN 24TH 1963 ,BITTER, But looking at todays modell output back in 1963 the modells are saying that an area of high pressure to our north will collapse south in about 4 days ,allowing the Atlantic back in , well it did but then a new high took charge . the rest is history .enjoy todays modells im looking foreward to tonights MET Fax ,and of course tonights GFS spot the difference ,cheers

[Polar Maritime]

WOW can't believe the upgrade in the last 24 hours, the ecm charts tonight look so similar to some we had in december 2010, imagine another 100 year event just 2 years after the last one, it would be totally EPIC, it's impossible not to ramp things up with charts like this, I would like us to tap into those purples over norway

Yes Frosty, who would of thought.. amazing chart's tonight. Let's see what the GFS has to offer

EDIT -

Edited November 21, 2012 by Polar Maritime

[tinybill]

http://www.meteociel...?mode=2&ech=204

slowly get a little hopeful for the end of nov to the first week of dec for some cold weather and possible white stuff at the moment

Edited November 21, 2012 by tinybill

[Chris D]

First post in this thread so please be gentle! The NCEP chart posted above by Daniel doesn't appear to show a sinker and this goes into early December. Think as has previously been suggested by John et al these are probably better tools to use at this range?

Definitely agree, these 500mb anomaly charts I really like and are a much better indicator imo of a pattern change than anything else at mid-range. (Although in this case it is now inevitable that a pattern change will occur)

It is now a matter of detail, which we really can only start to grasp like 5 days ahead, or in these sorts of set ups, more like 1-3 days (esp in terms of cold and snow detail)

But yes I am thrilled by the ECM output tonight like everyone else on this thread haha!

[Biggin]

481 users on this thread?? is something afoot ??

[Dexter29]

Fair point. However, just because someone points out the possible risks of where a breakdown could occur doesn't mean they are being negative. Much in the same way a cold evolution can be plucked from a seemingly mild outlook (straw clutching so to speak). I'm sure most would agree.

Agreed, but even still with amazing charts like this, that we wait and wait and wait and wait to appear, we still have talk of breakdowns in la la land

It's not needed.. Yes it will breakdown we all realise that, but I personally don't concentrate on anything 7 days out because it will 100% change.

All I know is that next week is turning colder and with charts like that I for one think its absurd that anyone would moan about them or find breakdowns way out in FI...

Just look at at 2010 - every run delayed the breakdown - and delayed and delayed.

Once a block like what is being shown has formed it is very hard for the zonal train to return, so my point about talking break downs is just a little premature, considering the cold spell hasn't even started/ we have no clue about the intensity or duration.

I mean you may not even have to worry about a breakdown because there will be nothing there to breakdown ;-)

Edited November 21, 2012 by Dexter29

[Ice BIast]

Decent ECM ensemble charts, with heights reaching greenland, unlike the operational:

[Matty M]

ECM means are very good although some may be disappointed with the mean 850hPa temps

Mean at 240hrs

Yes please!