Model Output Discussion - The Start Of Winter

[nick sussex]

Yes Nick, we just need Ian to pop in now and say last night's cluster signal has vanished! Trying to muster something positive from that ECM run but it's difficult. Maybe the high to our south gets sucked west by the high exiting the States post 10 days? That might keep some cold options alive as we go forward but it's all desperate conjecture I'm afraid.

This was the ECM 00hrs ensemble mean:

 

 

And the spreads, you'll see some take lower heights into southern Europe:

 

 

We can compare those later to tonights, I'm not convinced the pattern will be as flat upstream as suggested by that operational run.

[bluearmy]

I thought Ian already gave us that news this morning ??

[blizzard81]

I thought Ian already gave us that news this morning ??

Yes, that's correct BA. I was referring to the 12z output to see if that nasty trend continues.

[blizzard81]

This was the ECM 00hrs ensemble mean:

 

EDH1-240.gif

 

And the spreads, you'll see some take lower heights into southern Europe:

 

EEH1-240.gif

 

We can compare those later to tonights, I'm not convinced the pattern will be as flat upstream as suggested by that operational run.

Yes, will be interesting to compare. The pv over Greenland on that mean chart looks ferocious still. The bane of our lives!

[legritter]

I still think all is to play for out past 7 days ,and certainly seeing the possibility of high pressure being modelled closer to our shores ,Does not put the fear of [big mushy ]up me .this high pressure could eventually be modelled further north .I do accept tonights ECM is not showing any christmas cheer in its later stages but let the winter Mature ,we sometimes or quite frequently get a knock in the gool ...but remember tomorrow is another new day in our hunt for cold .we still have some incoming wintry weather ,and for most more than last year already ,  

[Froze were the Days]

I know what you are saying but it would be preferable to have those charts in summer.

 

And the charts we had this summer we want this winter, consistent high pressure near Scandinavia or just to the north, sods law!!

[Eugene]

Think we will welcome it, at least it looks dry, most of us in the south will be fed up of the rain by then, FI anyway

 

 

Been cold and very dry here this december, i welcome some decent rainfall, those charts look unpleasantly humid to me something we've had almost all year so definately don't need more, i think the jet will flatten any strong heights to our south anyway like on JMA 12Z, i like that run.

[john mac]

Seems to be a lot of negativity on here tonight. Let's just remember, the ECM has been pretty poor lately so we shouldn't get hung up on it too much. I think we've relied on it to be our saviour over recent winters so may be we need to look at the bigger picture as a whole. Nick don't start reaching for the Prozac just yet haha!!

[bluearmy]

mean ecm looks like it promises little next week but there is a spread supporting the more amplified solution with colder uppers days 7 thru 9. may not show too well on de bilt though as its possibly too far east and an onshore flow is normally moderated in n holland anyway,

 

so we have a possibility of another cold 'toppler' type scenario early next week before the azores pushes east. this eastward push of the AH into europe to our south has been well advertised by the extended ecm mean. it seems inevitable but may well be transient.

[BLAST FROM THE PAST]

PTB 12 touting the week 3 change.....

 

http://www.meteociel.fr/modeles/gefs_cartes.php?code=12&ech=6&carte=1&mode=0

S

At last a run that looks like its on the money....lets see what next couple of days bring...I'm not convinced by this eastward push....not yet anyway 

 

 

BFTP

[OldMetMan]

Out of all the latest model runs this evening, I think the only one that seems to have any sort of a handle on future developments past 3 days is the GEM. The GFS has seemed to bring the colder air slowly southwards over successive runs, but both it, and the ECM seem quite clueless as to longer term trends.

I would say that as a general rule, once a W-NW cyclonic flow has become established, as it will have within 24 hours, any subsequent frontal development that may occur to the NW, in the Iceland/ S Greenland area, would tend to head SE and reinforce the upper trough that is now developing to our N. As a result, progressively colder air tends to get dragged further S.

I'd go along with the initial wave development over the next couple of days which looks reasonable, possibly having quite a tight gradient on its western side, but beyond that things seem to come a bit unstuck.

The latest GFS analysis:

The upper low is digging SE. Bear in mind we still have a weakish vortex in the Med area which this is feeding into. Good HP upstream developing S of Greenland, whilst the upper trough over the E Us/Canada seems to be going nowhere. Further upstream from that, quite a pronounced upper vortex heading into the SW USA from the Pacific, which I would think likely encourage heights to rise over the central US. All in all, quite a stable pattern I would say, looking likely to persist for a few days.

Now, as I see it, this is how the GEM is taking it forward and its chart at T180 is a logical and quite plausible progression from where we are now.

So, we are left at that stage with a cold, unstable airmass, always with the possibility of small convective disturbances (polar lows/troughs) forming within it, which can mean snow almost anywhere.

Beyond that, well, as I mentioned earlier, the possibility of a pressure rise over us and importantly, as the low fills, a chance for a pressure rise over Scandinavia and an opportunity for some significant continental coldness to head our way.

All the above I base on what I have seen happen before in similar circumstances. Hardly conclusive I know but I do feel the models are struggling a bit with future developments, We'll have a better idea within a day or 2 I think.

[damianslaw]

All models painting a very unsettled picture for the foreseeable future and on the colder side of average in the main - this is backed up by Met Office Update which is noteworthy for one of the few times this year it states temps on the colder side of average rather than above albeit slightly so - it suggests a continuation of current conditions through next week, this to me would mean the azores high will stay in current situ rather than ridge east into Europe. It also suggests the jet will continue on a more NW-SE path and we will see further incursions of low pressure from the NW, look how quickly another low is set to pounce on us come Sunday, the models were suggesting a drier quieter window Sat into Sunday but this now looks shut barely lasting 24 hours.

 

In such a volatile topsy turvy fluid set up, there is marked room for error post reliable timeframe, and I would therefore not get too hung up on output at 240 hours, the models will struggle with Thursday's secondary low system until it hits us..

 

Keep an open mind in these set ups for features to spring out of nowhere and keep an eye on the stratosphere thread for possible signs of longer term developments.

[carinthian]

A very uninspiring ECM run, flat as a pancake upstream and the Azores high moving into southern Europe. It's 00hrs ensemble mean didn't support this Azores high love-in so hopefully this operational run is not some new trend.

 

Ghastly is being kind to it!

The latest ECM blows away the persistent lower heights over Southern Europe in a blink of the eye. This run can be discarded.

C

[bluearmy]

i have found the straw on the ecm 12z run and tbh, its rather more than a straw

 

lets look at the day 10 spread

 

 

off the eastern seaboard, we can see the cluster of runs which build a ridge. ive marked it to help.  what could it lead to? well the control has it (a little delayed than the mean spread) and it amplifies to deliver a huge european cold trough with southerly tracking lows into it. the blocking left around iceland/greenland nothing too big but very effective.  i guess this is what ian was referriing to yesterday.

 

 

[winterof79]

Interest in the near term for the Northern Half of mainland uk on Thursday am.

http://expert-images.weatheronline.co.uk/daten/proficharts/en/euro4/2014/12/09/basis12/ukuk/prty/14121106_0912.gif

http://expert-images.weatheronline.co.uk/daten/proficharts/en/euro4/2014/12/09/basis12/ukuk/th85/14121106_0912.gif

[Nick F]

Something that slightly raised my eyebrow looking at the 12z ECMWF ENS H500/anomaly plot for t+240 is the strong southern stream across the US emerging out across the western Atlantic off the eastern seaboard as a -ve anomaly - a product of the emerging El Nino:

 

 

In combination with a buckling of the northern stream over the NW Atlantic and a mid-Atlantic ridge building north, that could lead to a west based -NAO initially then perhaps towards more of an east based -NAO if we head in the direction of GEFS P12 that Steve flagged earlier:

 

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=192&code=12&mode=0&carte=1

 

Bit of a wild card .. I admit!

Edited December 9, 2014 by Nick F

[Cloud 10]

Quite a difference between the NAEFS and the ECM ensemble mean at day 10,with the ECM wanting to flatten the pattern,whereas the NAEFS looks to continue the pattern we have now and also has a much more influential Russian high.

 

naefs..  ecm..

[shaky]

That shortwave keeps moving south at 60 hours! ! Yesterday acorss northern England and now today across the midlands!! Think some people will have a bit of snowfall maybe from Midlands north from that little low!!

[blizzard81]

Out of all the latest model runs this evening, I think the only one that seems to have any sort of a handle on future developments past 3 days is the GEM. The GFS has seemed to bring the colder air slowly southwards over successive runs, but both it, and the ECM seem quite clueless as to longer term trends.

I would say that as a general rule, once a W-NW cyclonic flow has become established, as it will have within 24 hours, any subsequent frontal development that may occur to the NW, in the Iceland/ S Greenland area, would tend to head SE and reinforce the upper trough that is now developing to our N. As a result, progressively colder air tends to get dragged further S.

I'd go along with the initial wave development over the next couple of days which looks reasonable, possibly having quite a tight gradient on its western side, but beyond that things seem to come a bit unstuck.

The latest GFS analysis:

h500slp_12091214.png

The upper low is digging SE. Bear in mind we still have a weakish vortex in the Med area which this is feeding into. Good HP upstream developing S of Greenland, whilst the upper trough over the E Us/Canada seems to be going nowhere. Further upstream from that, quite a pronounced upper vortex heading into the SW USA from the Pacific, which I would think likely encourage heights to rise over the central US. All in all, quite a stable pattern I would say, looking likely to persist for a few days.

Now, as I see it, this is how the GEM is taking it forward and its chart at T180 is a logical and quite plausible progression from where we are now.

Rgem180_12091214.gif

So, we are left at that stage with a cold, unstable airmass, always with the possibility of small convective disturbances (polar lows/troughs) forming within it, which can mean snow almost anywhere.

Beyond that, well, as I mentioned earlier, the possibility of a pressure rise over us and importantly, as the low fills, a chance for a pressure rise over Scandinavia and an opportunity for some significant continental coldness to head our way.

All the above I base on what I have seen happen before in similar circumstances. Hardly conclusive I know but I do feel the models are struggling a bit with future developments, We'll have a better idea within a day or 2 I think.

I do hope your instincts are correct on this but the GEM is the king of the amplifiers and has seemingly performed quite

badly recently. What better time though to thoroughly redeem itself   

Edited December 9, 2014 by blizzard81

[Biggin]

i have found the straw on the ecm 12z run and tbh, its rather more than a straw

 

lets look at the day 10 spread

 

EEH1-240.gif

 

off the eastern seaboard, we can see the cluster of runs which build a ridge. ive marked it to help.  what could it lead to? well the control has it (a little delayed than the mean spread) and it amplifies to deliver a huge european cold trough with southerly tracking lows into it. the blocking left around iceland/greenland nothing too big but very effective.  i guess this is what ian was referriing to yesterday.

Loving your detective work ba. Keep your eye on it as it progresses plse and keep us informed To a novice a circle and a few arrows and and explanation of what to look out for, what should happen next is gold to us novices. Sorry if off topic mods but to the novice observer some posts go a bit over my head technical wise, so a tiny simplification and  helpful indications (where you can) really make this thread enjoyable / encouraging for me and I am sure others of a similar ilk..

Edited December 9, 2014 by Biggin

[492]

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=6&code=0&mode=2

06Z GFS T+78 and T+84 shows a period of snow across the extreme south as a shallow low travels along the English channel.

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=6&code=0&mode=2

18Z GFS T+84 also shows a hint of snow along part of the S coast of UK and this time within a patch of -6 C 850 temps .The channel low is slightly further south but does seem to keep popping up in the GFS output.  

[blizzard81]

I am afraid that the trend for today on the op runs has been to build pressure to our south towards day 10,

never a good sign imo. Once high pressure takes hold over south western Europe in Winter, it can take a hell

of a lot of shifting. GFS 18z and GFS P 18z carry on this tend. Lets hope it's a blip and tomorrow shows more promise.

Edited December 9, 2014 by blizzard81

[Midlands Ice Age]

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=6&code=0&mode=2

18Z GFS T+84 also shows a hint of snow along part of the S coast of UK and this time within a patch of -6 C 850 temps .The channel low is slightly further south but does seem to keep popping up in the GFS output.  

 

Big differences tonight in the models for just 48  -60 hrs.

Latest GFS (above) shows the secondary coming straight across the Midlands with a period of back-edge snow.

BBC (UKMO) has temps of 9C for the Midlands at  the same time with Severe gales and the secondary crossing central Scotland.

 

Who will be correct?

 

MIA

 

.

Edited December 9, 2014 by Midlands Ice Age

[blizzard81]

I am afraid that the trend for today on the op runs has been to build pressure to our south towards day 10,

never a good sign imo. Once high pressure takes hold over south western Europe in Winter, it can take a hell

of a lot of shifting. GFS 18z and GFS P 18z carry on this tend. Lets hope it's a blip and tomorrow shows more promise.

Hold that thought! GFS P maybe going the same way as the ECM control run which was kindly described to us earlier

by Bluearmy.

 

Edit again - Maybe not!

Edited December 9, 2014 by blizzard81

[Nick F]

Have done a synoptic analysis for the coming 10 days or so - including the weather 'bomb' tomorrow and the wintry spell following for northern areas, then the pattern next week/beyond:

 

http://www.netweather.tv/index.cgi?action=news;storyid=6340;sess=

 

Not a strong heavy snow signal from 18z GFS early Friday as that wave and associated fronts move through, with precip likely to turn to snow quite light and heavier precip further south in the milder air. But could change - so one to keep a close eye on.

 

18z seems to have flattened out the flow mid-week next week too to more in line with ECM, 12z op was more amplified.

Edited December 9, 2014 by Nick F