Winter Model Discussion - The Hunt For Cold -18z 17/12/12

[johnholmes]

The ECMWF-GFS 500mb anomaly output this morning might be a happy sight for some cold lovers. Well the ECMWF version.

These two have shown quite marked changes over the past 4-5 days, sometimes westerly sometimes north of west 500mb flows into the UK but the ECMWF this morning is the most extreme.

NOAA has not altered all that much over the same time period

http://www.meteo.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

as you can see below it shows a more westerly type and has done throughout the last few days.

http://www.cpc.ncep.noaa.gov/products/predictions/610day/500mb.php

None of them suggest any mild air other than briefly on the forward side of lows tracking across the Atlantic and none of them for several days have had much sign of the Russian block or at least not the western area block. The uuper air pattern on all of them is fairly conducive to surface lows developing and travelling quite qickly west to east, not easy to place them as to how far north they will be but the overall shifting of -ve heights in the UK area suggests not the far north of Scotland, somewhere further south?

I have to say I am not convinced of this with some form of ridging likely to be slow to be eroded NE/ENE of the UK tending to hold the main centres of low pressure well west for several days yet. Bad news for the flood threatened areas.

[nick sussex]

So the end of another mini cold tease which brings to an end a fruitless few weeks of model watching.

Which now leaves us hoping that we don't end up with a western based negative NAO. Unfortunately the ECM operational runs have been consistently showing that elongated ne/sw troughing into the Atlantic, with this forcing the Azores high ne again.

Some of the ensemble members do look much better and I certainly hope we see one of those picked up because a western based negative NAO would surely really be the final insult !

Overall then the limpet slug high will depart leaving in its wake broken promises, emotional carnage and sledges left untouched!

The sooner it goes the better to allow a chance of something a bit more interesting to develop.

[phil nw.]

All the 00z runs now show a similar picture after the GFS broke ranks yesterday.

As expected the Atlantic conditions look set to dominate now and through Christmas with a +NAO setup.

Rainfall amounts now an issue over the next few days as successive frontal troughs move NE across the UK over the next week.

Edited December 19, 2012 by phil n.warks.

[WhiteFox]

Thing is it's all well and good seeing suggestions of the block being pushed east in FI (in the ensembles) but then we read about 20,000 posts all describing how the high is "much further west than originally modelled" as we get nearer the reliable.

Absolutely, hence the operational runs favouring the solution showing the high remaining further west. Looking at an ensemble split seven days hence is straw-clutching at its most tenuous, but it's all we've got right now! For now, I'll go for the straw-clutching as the last thing I want to see is a big blocking high over Europe which is bad for two reasons:

1. The chances of cold arriving are lowered and

2. It increases the likelihood of fronts stalling over the UK and giving further unneeded prolonged rain.

[essexblue]

I'm the eternal optimist so I still expect big changes on all the models between 60 and 72 starting with the GFS in about 10 minutes.

[Cloud 10]

ECM ensemble mean at 240 hrs has a lot of cold stacked on our side of the hemisphere,so

any northerly outbreak towards the end of the month would be a potent one.

http://www.meteociel...1-240.GIF?19-12

Maybe something like this from the gefs.

http://modeles.meteo...h-5-1-240.png?0

[TEITS]

Still quiet alot of scatter early on for De Bilt and the Op was warmer than the mean.

http://www.knmi.nl/e...E_06260_NWT.png

So whilst I feel the chance of an E,ly is very remote those ensembles do show a high degree of uncertainty.

Im spotting some notable differences even at +48 looking at the NAE compared to the other models. Seems to develop and take the other SW further SE than the other models that had this tracking ENE.

http://expert-images.weatheronline.co.uk/daten/proficharts/en/nae/2012/12/19/basis06/eses/pslv/12122106_1906.gif

Edited December 19, 2012 by THE EYE IN THE SKY

[IDO]

Still quiet alot of scatter early on for De Bilt and the Op was warmer than the mean.

http://www.knmi.nl/e...E_06260_NWT.png

So whilst I feel the chance of an E,ly is very remote those ensembles do show a high degree of uncertainty.

Bearing in mind we are just likely (north) to miss out on the easterly it is no surprise that de Bilt will possibly get the westerly edge of that easterly (cold members). The spread is more to do with the possibility that De Bilt will also be too far west to get the effect of the easterly (milder members). The UK looks certain to miss it, though there may be a chance it will clip the far NE (based on the colder members).

[Glacier Point]

All the 00z runs now show a similar picture after the GFS broke ranks yesterday.

As expected the Atlantic conditions look set to dominate now and through Christmas with a +NAO setup.

http://www.meteociel...20-21.GIF?19-06

Rainfall amounts now an issue over the next few days as successive frontal troughs move NE across the UK over the next week.

Actually Phil, that's a pretty strong -NAO.

GEFS days 6-10 has a very well defined blocking structure over NE Canada and Greenland.

Looking very likely now that December will come in as a -NAO / -AO month.

[TEITS]

Bearing in mind we are just likely (north) to miss out on the easterly it is no surprise that de Bilt will possibly get the westerly edge of that easterly (cold members). The spread is more to do with the possibility that De Bilt will also be too far west to get the effect of the easterly (milder members). The UK looks certain to miss it, though there may be a chance it will clip the far NE (based on the colder members).

Personally I feel its these changes with these shortwaves that is causing the big differences in these ensembles. Im not even seeing much consistency from the NAE at +48.

The key timeframe for me is at +96. Does the HP slowly move E allowing a mild SW,ly or do we see the undercut??

Looking very likely now that December will come in as a -NAO / -AO month.

As you predicted mate. Keep up the good work Stewart.

Edited December 19, 2012 by THE EYE IN THE SKY

[No Balls Like Snow Balls]

I find the De Bilt ensembles pretty useless to be honest when De Bilt is at least 200 miles East of the most Easterly point in the UK.

As we all know we are quite often the last stopping point for cold air and even more so we are in the middle of the battle of the mild atlantic air and cold European air, and it's quite apparent that De Bilt is more often than not likely to be in the cold european air, while us in the UK miss out.

[bradymk]

Actually Phil, that's a pretty strong -NAO.

GEFS days 6-10 has a very well defined blocking structure over NE Canada and Greenland.

Looking very likely now that December will come in as a -NAO / -AO month.

Yes good work Stewart. What are your thoughts on a colder spell between christmas and new year. ECM, GEM and GEFS all showing heights building to the NW around day 10 so just wondering what your take is on this? Could it be too west based? Thanks.

[Methuselah]

I'm still not buying into the notion that 'it's the shortwaves what done it' school-of-thought...Surely the 'shortwaves' are a result of the overall pattern; they cannot be drivers, in their own right?

[TEITS]

I find the De Bilt ensembles pretty useless to be honest when De Bilt is at least 200 miles East of the most Easterly point in the UK.

As we all know we are quite often the last stopping point for cold air and even more so we are in the middle of the battle of the mild atlantic air and cold European air, and it's quite apparent that De Bilt is more often than not likely to be in the cold european air, while us in the UK miss out.

Im not saying those De Bilt ensembles mean we are going to see an E,ly. Im just highlighting the uncertainty.

My focus is now more towards after xmas. Looking at the charts GP posted and ideally I would like to see the blocking slightly further E. Rather than the core of blocking being between Greenland/Canada I would like to see the reds towards E side of Greenland.

[TEITS]

I'm still not buying into the notion that 'it's the shortwaves what done it' school-of-thought...Surely the 'shortwaves' are a result of the overall pattern; they cannot be drivers, in their own right?

The depth and track of these can have an impact on the synoptics at +144 and beyond. Pretty much common sense really that the reason why the differences in model output increases with time is because of the slight differences early on (chaos theory). Im very much a believer of the chaos theory in the model output which is why I personally feel any models that go beyond 10 days are a waste of time. The CFS for example is laughable.

[chionomaniac]

Still quiet alot of scatter early on for De Bilt and the Op was warmer than the mean.

http://www.knmi.nl/e...E_06260_NWT.png

So whilst I feel the chance of an E,ly is very remote those ensembles do show a high degree of uncertainty.

Im spotting some notable differences even at +48 looking at the NAE compared to the other models. Seems to develop and take the other SW further SE than the other models that had this tracking ENE.

http://expert-images...122106_1906.gif

I can't quite believe the split in the ensembles for de Bilt at such a close range. Occasionally, you may get 1 or 2 go off at a tangent but not such a significant cluster. I still don't think that the bulk of the UK is in the firing line for the split cluster - but interesting none the less.

[Methuselah]

The depth and track of these can have an impact on the synoptics at +144 and beyond. Pretty much common sense really that the reason why the differences in model output increases with time is because of the slight differences early on (chaos theory). Im very much a believer of the chaos theory in the model output which is why I personally feel any models that go beyond 10 days are a waste of time. The CFS for example is laughable.

Of course, I accept that algorithmically-generated 'shortwave' will cause mayhem, in a numerical computer-model; but my doubts relate to the atmosphere and not to the necessarily digital computer outputs...

Anyhoo, back to models...

[TEITS]

. I still don't think that the bulk of the UK is in the firing line for the split cluster - but interesting none the less.

No I don't unfortunately.

Looking at +48 and its rather complicated really because the track of the SW isn't resolved at +48 and at the same time we have a phasing of the two LPs in the Atlantic. We then have the HP to our E and as I highlighted last night with previous ECM output these models struggle in these situations.

Personally I just want to get rid of this HP and for the rest of the winter I want to see a GH rather than a Siberian/Scandi HP.

[EML Network]

YUUUK :-(

The models just keep going from bad, to worse, to even worse, to complete disaster..I think were going to have to wait until well into January to find a way out and a route back to cold if charts like these were to verify :-(

[phil nw.]

Actually Phil, that's a pretty strong -NAO.

GEFS days 6-10 has a very well defined blocking structure over NE Canada and Greenland.

Looking very likely now that December will come in as a -NAO / -AO month.

Yes i am aware of the mean height anomalies forecasted to our NW beyond Christmas Stewart.In fact i posted on those the other day in the other thread.

However the next week with those Iberian Heights and low pressure just south of Iceland fit a more +NAO pattern-for now.

We need to see those anomalies translated in to actual upper heights further north to stop those south westerlies.

Edited December 19, 2012 by phil n.warks.

[MR EXTREMES]

Just a quick one from me.

The glimmer of hope yesterdays 12Z GFS gave us has not been followed up on this mornings runs. So now the possible E,ly is looking unlikely, we ideally need to see this HP sink SE and allow the LP to travel E and this is especially the case considering the increasing heights over Greenland.

Have to say I've never known a month like this when following the models over many years. Seems the output has always teased us into thinking a cold spell is just around the corner with all the key ingredients and yet I still haven't seen a snowflake this winter!

We will I'm confident nw is were to look next.

But like u said let move the alantic in let's get a pattern reset and start again.

I'm now on 50mg of Prozac and drinking heavily lol.

[Ian Brown]

Actually Phil, that's a pretty strong -NAO.

GEFS days 6-10 has a very well defined blocking structure over NE Canada and Greenland.

Looking very likely now that December will come in as a -NAO / -AO month.

Yes, just a desperate shame how it is actually played out for a little island like the UK.

We really don't want to see something like the 06z verify, the collapsing of the heights into Europe and that long draw jet SW to NE.

[Severe Siberian icy blast]

To be honest all the gfs keeps throwing out seems to be one hurdle after another, now we have the Azores high and low pressure working together to pump continuous warm air toward us, the facts are we could have a strongly negative NAO for the entire winter but still have endless low pressure and southwesterly winds , so all this talk of strat conditions mean nothing unless we get high and low pressure in the right places.

[bradymk]

YUUUK :-(

The models just keep going from bad, to worse, to even worse, to complete disaster..I think were going to have to wait until well into January to find a way out and a route back to cold if charts like these were to verify :-(

Sorry but I don't agree, i thought the charts this morning were good for cold for day 8+ period. GEM, ECM, GEFS are all showing height rises to the NW and trough into scandi this morning. The GFS op is not so good though but this isn't really a problem at the moment for me. I would be more worried if the ECM was showing similar pattern.

Edited December 19, 2012 by bradythemole

[Duane S.]

I find the De Bilt ensembles pretty useless to be honest when De Bilt is at least 200 miles East of the most Easterly point in the UK.

As we all know we are quite often the last stopping point for cold air and even more so we are in the middle of the battle of the mild atlantic air and cold European air, and it's quite apparent that De Bilt is more often than not likely to be in the cold european air, while us in the UK miss out.

Agreed. I think whilst (medium term) the general concensus is not to be looking East, what the De Bilt ens show will not be any where as relevant as when we are looking for a BFTE type pattern as in the other week.