Model Output Discussion 13/11/13 >

[Matty M]

Very good ECMWF run.

 

Lots of potential going forward there.

 

With regard to the stratospheric temperature, if i am correct the 2010 freeze up was not Strat related.

 

So yes SSWs can lend to increased cold outbreaks to mid-latitudes but they are not the be all and end all to cold outbreaks.

 

Long term forecasting is a massive jig-saw of which we only have a handful of pieces and haven't even began to try and piece

a picture together yet.

[EML Network]

If the ECM was good then the JMA is nothing short of spectacular..

NATION WIDE snow fest anyone ?? well it would be marginal for some but a white out for many....IF ONLY eh ??






The ECM tonight isn't showing quite the same snow fest, BUT...Look at this for the same time frame as the JMA ...

 

 

 

[PolarWarsaw]

The signs were there for this weeks cold spell, the stratospheric charts showed low pressure into Europe and a ridge getting as far as Iceland but not penetrating into the polart vortex, which inevitably leads to mid-lattitude blocking rather than high-latitude blocking. This time the vortex is splitting with each lobe moving away from the North Pole. This should enable Northern blocking for a time

 

Edit: Example of this:

 

 

 

I wholeheartedly agree, I'm just urging on the edge of caution. I'd say there's a good 10 times per winter where cold and snowy synoptics initiate at around t200+ and then appear quite consistent, but just as we start to firm up and bring them into a slightly more reliable timeframe - they get scuppered and we come out on the other side having been 'carrot dangled'. The background signals are more consisntently positive towards colder weather/high pressure at the moment - but 1 ECM run at 200+ hours odd really shouldn't be read into as much as it is IMO. 

 

(That's coming from someone who wants anything cold to come to fruition as well).

[Snowy L]

Very good ECMWF run.

 

Lots of potential going forward there.

 

With regard to the stratospheric temperature, if i am correct the 2010 freeze up was not Strat related.

 

So yes SSWs can lend to increased cold outbreaks to mid-latitudes but they are not the be all and end all to cold outbreaks.

 

Long term forecasting is a massive jig-saw of which we only have a handful of pieces and haven't even began to try and piece

a picture together yet.

 

It was strat related and very similar to this year. If I remember correctly what Chiono said it was a wave breaking event over Greenland that caused the disruption to the lower and mid stratospheric vortices even though they continued to cool down, exactly the same thing is going on now.

[Cheshire Freeze]

I think the stakes have just been upped this evening. The GFS is a MILLION miles away from the ECM and JMA runs, which both show the route to a potential extended cold spell of weather.

 

At day 7 we either have this

 

 

or this

 

 

on the table.

 

On balance, how many times over the past few years have we been here with the GFS?

[Frosty.]

The Ecm 12z op run is screaming with potential tonight from the top of it's lungs for a severe spell of wintry weather beyond next week, retrogression is initiated on this run and the charts through FI have a remarkably Nov / Dec 2010 look about them, it's not the first time we have seen 2010 esq charts and i'm sure it won't be the last either, anyway, here are some eye candy charts to feast on, the thickness charts during the coming days are impressive enough for late autumn with the 522 dam line digging down to the south coast but just imagine if tonight's ecm run followed through with that late FI...it would be gob smackingly awesome..I want a lot of cobra runs, might not have long to wait

 

It's a complex set up this week, some areas will get surprise snowfalls, it's the opening wintry salvo of the season....  

[MPG]

And other posters only post about the cold potential in every chart yet we don't see you questioning them.

Sorry but you totally miss the point. That setup Gav posted would lead to cold or potentially very cold outcome. How can anyone comment on a chart and not say what it actually shows? It seems Gav totally ignored what was staring him in the face. If the charts showed mild and zonal that's exactly what he would of said. Sorry Gav didn't want to mention you that much but you were the example!

Edited November 17, 2013 by MPG

[Cloud 10]

I haven't had time to check, is there anything similar to the 12Z ECM in the 12Z GEFS suite?

 

Don't know about the individual ensemble members,but certainly not

much to be gleaned from the 10 day ensemble mean chart!

 

http://modeles.meteociel.fr/modeles/gens/run/gens-21-1-240.png?12

[syed2878]

@steve murr. A qs. Can we trust the ecmf output after the farss of this week? Look at the charts earllyer on this week. So then can we trust the outputs passt 120h? How can u be sure that the gfs is heading for another fale?

[Frosty.]

I think we can trust the Ecm, the ens mean has been solid.

[SMU]

@steve murr. A qs. Can we trust the ecmf output after the farss of this week? Look at the charts earllyer on this week. So then can we trust the outputs passt 120h? How can u be sure that the gfs is heading for another fale?

 

If you get the vertical alignment over western Greenland then PROPER cold for the UK is 99% guaranteed-

 

We cannot 100% put all our eggs in the ECM basket - especially without full UKMO support-

 

So really it will be the 144 timeframe to look at in future runs-

 

Another 2 days to be sure..... ( 12z tues)

 

S

[Ian Brown]

It's a different NH profile from the ECM, but even if you take days 9 & 10 at face value there is no guarantee that you would get the orientation needed to advect the cold uppers towards the UK. The ECM has often been guilty of falsely building heights towards Greenland in the past in the outer reaches of the output.

[Chess01]

Yet again we find our selves in a dilemma of which model to trust it happens every winter and it's only November now anyway Im hoping we can get all the jigsaw pieces toghether than rush into the cold because I think if we get the cold now then later down the line when we have months that can gives us more potential things then we would be all wishing for it to happen then instead of now. We seem to be in a good position But we are missing the final parts to the jigsaw. We need to get the strat warmed up and some HLB to get the right ingredients for a good winter

Edited November 17, 2013 by Chess01

[MPG]

Maybe it's because Gav cannot read the chart? Or should I say he can describe that frame but not what comes next?

Its not the place to mention individuals. But the charts had cold all over them!

[Snowy L]

It's a different NH profile from the ECM, but even if you take days 9 & 10 at face value there is no guarantee that you would get the orientation needed to advect the cold uppers towards the UK. The ECM has often been guilty of falsely building heights towards Greenland in the past in the outer reaches of the output.

And the GFS has been guilty of reverting to zonal in 99% of the outer reaches of its output yet we still hear everyday about how zonal will take over any day now...

[The Northern Ramper]

At 120 you would back the ECM against any model, however you would not back any model at 240.

[Frosty.]

We have a few GEFS 12z perturbations toying with the Ecm 12z idea with big cold plunge just to the east which may push our way, hopefully this idea will gain momentum in the days ahead and mean that the anticyclonic spell later in the week will be brief before the next bigger wintry reload.

Edited November 17, 2013 by Frosty.

[Man With Beard]

My take this evening:

 

The initial 48hr-72hr period looking innocuous for snow though not a complete dead duck yet.

 

Beyond that, fine details a little all over the place but all except GFS want some sort of pressure rise extending north of us, so the UK looks set to be influenced by weather from the east/north-east for a while, meaning it will be cold (daytime maxes maybe 2C to 7C).

 

Chances of snow seem slim at least until T168+ but wouldn't take big changes on some charts to increase the chances.  

[lorenzo]

It's a different NH profile from the ECM, but even if you take days 9 & 10 at face value there is no guarantee that you would get the orientation needed to advect the cold uppers towards the UK. The ECM has often been guilty of falsely building heights towards Greenland in the past in the outer reaches of the output.

 

I like the ECM when it is being guilty. In fact it can keep committing these terrible crimes against Greenland Highs as much as it wants..

 

Much easier on the eye than a 200 km/h bulldozer Jet streak..

[Summer Sun]

Latest from Gibby

 

All models show a change to colder conditions soon. The change comes in two tiers, the first being a rather unsettled tier with a band of rain crossing SE tonight and tomorrow and introducing a rather cold and showery NW flow for 24 hours or so with wintry showers over the hills and most frequent in the North and West. Then a depression crossing SE down the North Sea on Wednesday brings a spell of wind and rain for all with sleet or snow on the highest ground before a change to colder and more showery weather returns on Thursday, leading us into the second tier. This phase then shows strong rises in pressure with an Anticyclone shown to be firmly over the UK next weekend with attendant still, cold and frosty conditions with the potential for dense and freezing fog patches reluctant to clear by day.

 

GFS then shows it's entire remainder of the run with the UK bathed in High pressure either over or nearby to the NW. As a result little change from this cold and settled theme with frost and fog coming and going day to day seems likely with very little rainfall for anyone.

 

UKMO closes it's run with High pressure firmly across the UK with fine and settled conditions with the twin winter perils of frost and fog in abundance for most of the UK.

 

GEM tonight shows a more temporary phase of High pressure next weekend before it drifts away to the NE before collapsing altogether late in it's run at the expense of deep Atlantic Low pressure with wind and rain moving slowly in from the SW and West. Temperatures would be held somewhat below average until the milder air associated with the wind and rain arrives later.

 

NAVGEM keeps High pressure close to the NW with a cold NNE drift across the UK for most of the time. This would be insufficiently strong to prevent frost and fog problems developing night and morning in an otherwise dry and sunny spell of weather.

 

ECM shows High pressure over the weekend and being reinforced from the NW later with cold conditions sustained across all areas with copious amounts of frost and freezing fog too if the light NE feed stays slack enough. By Day 10 High pressure lies close to NW Britain with a chilly and dry theme for most with a cold wind from the NNE with some sunshine by day but still with the risk of frost and freezing fog overnight. 

 

The GFS Ensembles are unavailable tonight.

 

The Jet Stream flow is unavailable tonight. 

 

In Summary the weather looks like becoming and staying rather cold for a week or so at least. There are strong signs from GFS and possibly GEM later that an Atlantic breakdown will end the colder theme while ECM is more dogmatic with a new surge of cold sinking over Europe and then SW over Britain following several days of cold and frosty conditions. Which is right will need more runs to solve but there is plenty of scope shown from reliable model sources that cold weather will never be far away over the coming few weeks.

 

http://www.norton-radstockweather.co.uk/Model-Analysis%282859336%29.htm

Edited November 17, 2013 by Summer Sun

[syed2878]

@steve murr. Thanks for your reply. I'm stil doutful regarding tonights ecmf outputs.

[Man With Beard]

T216 from ECM Mean - baack to preferring a Scandi-based High?

Edited November 17, 2013 by rjbw

[bluearmy]

you wouldnt say the ecm mean is supportive of the op but then it isnt unsupportive. still amplified though further east than the op. what is apparent on the 12z run 850 spreads is the potential flood of colder uppers into europe to our east. that indicates that the ridge could be further west than the mean shows. vortex still split late on but perhaps not as well as the 00z by day 10. 

[radiohead]

ECM ENS leaning more towards a Scandi or Icelandic high rather than a Greenland one. But at least the trend is still there for high pressure to our north/northwest. Can't really complain!

 

[Gavin Hannah]

ECM ENS leaning more towards a Scandi or Icelandic high rather than a Greenland one. But at least the trend is still there for high pressure to our north/northwest. Can't really complain!

 

 

 

It's really the kind of pattern we want for winter. HP wobbling between Scandi and Greenland.  Lots of potential for arctic incursions and easterlies.  With LP konocking up against the HP, it would bring plenty of snow the deeper we get into winter.  In between would see lots of dry settled spells.