Model output discussions pm 31/12/15

[nick sussex]

1 minute ago, SLEETY said:

well will the meto mention any sigms of this in next update i hope ,of colder weather 2nd half of jan

I'd be shocked if they didn't. I think the uncertainty at the moment is more how cold rather than if it will turn colder.

[Singularity]

There is this strange tendency for the 06z and 18z GFS det. runs to be more amplified than the 00z and 12z runs.

With such strong signals for a negative AO and amplification from the U.S. to the Atlantic, this could be taken to mean that the 06z and 18z runs are a better guide, while the ECM runs are the best guide of all due to their own amplification bias.

That may just be wishful thinking of course!

 

Generally though, given the poleward wave flux now underway, I'm inclined to be suspicious of any model run that attempts to displace high pressure away from the pole and absorb it into the mid-latitude ridges.

With that high over the pole, the eastward progression of mid-latitude troughs is impaired and a mid-Atlantic or UK ridge stands a far better chance of reaching the high-latitudes and, ideally, linking with that Arctic High.

The 06z kicks things off with a UK ridge, which while not the quickest route to snow, does effectively entice the Arctic High to extend down into the Atlantic. We then get the amplification upstream occurring further west, building a mid-Atlantic ridge for the linkup with the Arc.H there, and boom - we're in the money. 

 

The ECM 00z det. run doesn't have such an effective shape to the Arc.H at +240 but the Canadian trough is looking less than healthy with signs of disruption and WAA almost where it needs to be- just upset by that weak shortwave feature.

The sheer strength of the Arc.H allows for some belief that even if that first attempt didn't quite make it, the next one would.

 

So yes, as many have said already, it's still very positive this morning. The ECM ensemble means have impressed with that mid-Atlantic ridge.

We saw a similar period of great model promise last year, that's true, but the signals back then were less inspiring, as we had forcing taking place in not the best of locations, meaning a massive SSW was needed to be able to deliver the goods. This time, we have trop. led forcing doing a lot of work before a SSW has even come into the picture, thanks to the feedbacks with the SAI and Eurasian blocking playing out nicely after that faliure last year, which itself is likely down to there being an El Nino atmospheric state this time around (it was more the La Nina type last winter). Come to think of it, I wonder how well the October Pattern Index is faring - if it's even been applied this autumn/winter?

[Newberryone]

1 hour ago, knocker said:

The ext ecm is showing some signs of trying to join the party with a little more amplification in the eastern Atlantic with Azores HP ridging over the UK and the trough just east of Scandinavia down into eastern Europe. The consensus from the woodshed is that the trough is a little far east and that at this stage, with the ridging not extensive, that the surface analysis would favour more a settled anticyclonic influence over the UK  This would leave temps around average or maybe even a little above.

Could this be the aforementioned Uncle B we all detest so much during the ever frenzied season trying to join the party for all the wrong reasons from the southwest I wonder. At least, the main models have now seemed to back off or greatly modified these dartboard lows which some members on here  had envisaged bringing  disruptive weather between the dates of the 10th and 15th

Edited January 4, 2016 by Polar Maritime
To resize to proportion.

[bluearmy]

I wouldn't take much notice of how the extended eps mean/anomolys deal with the scenario at the moment 

going to need clusters to make a decent assessment and only Ian on here has access to those 

[feb1991blizzard]

The 6z GEFS are an absolute snorter when compared to previous runs.

[bobbydog]

12 minutes ago, Newberryone said:

Could this be the aforementioned Uncle B we all detest so much during the ever frenzied season trying to join the party for all the wrong reasons from the southwest I wonder.

lol no. thats the atlantic ridge we need to link up with the arctic high. what knocker is saying is, if everything is a little further east, we would be under more settled conditions... for a short while... the 06 GFS shows it at around +234 before it links with the arctic high so the ECM and GFS not a million miles apart. the ECM would probably go on to show something similar to the GFS in the later stages.

Edited January 4, 2016 by bobbydog

[feb1991blizzard]

All aboard the Stewart train.

 

Last run

Edited January 4, 2016 by feb1991blizzard
include more evidence

[Harsh Climate]

Fantastic GFS 6z this morning but we must have this backed up on the 12z GFS/ECM/UKMO runs (or at least 2 of them) and for momentum to build over the coming days.

Yep the upstream signals are good, expected negative AO/NAO etc but far too early to get excited.

[Troubleatmill]

06z ensembles are the best we have seen so far this winter from the GEFS. Although there is still large scatter so nothing either way is a given yet, but good to see a fair few go for more than a toppler

 

Edited January 4, 2016 by Nicholas B

[karlos1983]

Scrolling through the 06z GEFS Purbs in fl it really is a question of take your pick, only a few don't favour deep cold of some sort and the ones that do not, have a high bang smack on top of us. 9 in particular is a beauty! linked below

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=216&code=9&mode=0&carte=1

850s

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=216&code=9&mode=1&carte=1

[mulzy]

20 hours ago, Greenland1080 said:

2 hours ago, nick sussex said:

I'd be shocked if they didn't. I think the uncertainty at the moment is more how cold rather than if it will turn colder.

The T252 shows us mid Jan potential

Knockers woodshed would be raided 10 times over of possible incoming....

 

The MO say "No" in their latest update.

Meanwhile the NAEFS day 10 anomaly seems to suggest troughing over the UK - stubborn heights in the Med persist.

 

 

Edited January 4, 2016 by mulzy

[Polar Maritime]

17 minutes ago, mulzy said:

The MO say "No" in their latest update.

Meanwhile the NAEFS 10 day anomaly seems to suggest toughing over the UK - stubborn heights in the Med persist.

 

 

Without taking it any further off topic they do state a cold spell within this period model'd shown here; https://forum.netweather.tv/topic/64157-meto-uk-further-outlook/?page=78

Thereafter detail is prone to change as is always stressed, You can see these changes reading there updates on a daily basis, But especially more so now as per models.. With big changes in the N/Hemisphere.

 

Edited January 4, 2016 by Polar Maritime

[Man With Beard]

Did anyone post the UKMO FAX chart for Friday? 528 dam line through central England. #snowpotential

[nick sussex]

I think the problem with the outlook is the lack of agreement now developing upstream with the pattern in the eastern USA:

From the NCEP forecast for New York:

THEN, A SECOND STORM IS SUPPOSED TO DEVELOP IN THE GLFMEX AND MOVE
NEWD. THE MDLS DIFFER ON THIS SYS AS WELL. YDY, BOTH THE GFS AND
ECMWF WERE HINTING AT SOME SORT OF COASTAL, TODAY, THE GFS BRINGS
A WK CSTL GENLY S OF THE REGION, WITH A GLANCING BLOW LATER SUN.
THE ECMWF, HAS A MUCH STRONGER STORM THAT IT BRINGS UP THE OH VLY
AND WOULD BRING A BETTER CHC OF RAIN LATER SUN.

The down stream effect you can see when you look at the ridge building ahead of this or in the GFS case the lack of this.

ECM 00hrs run T168hrs

 

GFS 06hrs run T162hrs

 You can see the GFS is less amplified.

Although todays ECM 00hrs run was less festive I think it would be better to have the ECM upstream pattern verify at T168 rather than the GFS. The ECM spreads still show solutions that back a stronger ridge to the nw so this may well re-appear tonight but with the GFS you'd have no chance of building that ridge and you then have to rely on a lot more things going favourably well into FI.
 

Edited January 4, 2016 by nick sussex

[gottolovethisweather]

11 minutes ago, nick sussex said:

I think the problem with the outlook is the lack of agreement now developing upstream with the pattern in the eastern USA:

From the NCEP forecast for New York:

THEN, A SECOND STORM IS SUPPOSED TO DEVELOP IN THE GLFMEX AND MOVE
NEWD. THE MDLS DIFFER ON THIS SYS AS WELL. YDY, BOTH THE GFS AND
ECMWF WERE HINTING AT SOME SORT OF COASTAL, TODAY, THE GFS BRINGS
A WK CSTL GENLY S OF THE REGION, WITH A GLANCING BLOW LATER SUN.
THE ECMWF, HAS A MUCH STRONGER STORM THAT IT BRINGS UP THE OH VLY
AND WOULD BRING A BETTER CHC OF RAIN LATER SUN.

The down stream effect you can see when you look at the ridge building ahead of this or in the GFS case the lack of this.

ECM 00hrs run T168hrs

 

GFS 06hrs run T162hrs

 You can see the GFS is less amplified.

Although todays ECM 00hrs run was less festive I think it would be better to have the ECM upstream pattern verify at T168 rather than the GFS. The ECM spreads still show solutions that back a stronger ridge to the nw so this may well re-appear tonight but with the GFS you'd have no chance of building that ridge and you then have to rely on a lot more things going favourably well into FI.
 

And another issue I saw on the ECM 0z is the tendency for heights to rebuild over mainland Europe from the 9th January, which sadly if this becomes the new trendsetter we will likely continue as we were in the UK. Nonetheless Temperatures are never truly mild for the foreseeable over the UK more seasonal than anything else, on Wednesday (the driest day this coming week) Temperatures will be relatively chilly with 850s of -3 to -5. These upper Air Temperatures suggest surface Temperatures approximately the same amount below average for once, if only for one day. Friday into Saturday still looks interesting for some more widespread wintriness as I have stated before. Hopefully the overnight European setup  as predicted by the ECM is incorrect and will revert back to something better for coldies, if not I'll be giving things another week to ten days before getting excited again.

 

[nick sussex]

3 minutes ago, gottolovethisweather said:

And another issue I saw on the ECM 0z is the tendency for heights to rebuild over mainland Europe from the 9th January, which sadly if this becomes the new trendsetter we will likely continue as we were in the UK. Nonetheless Temperatures are never truly mild for the foreseeable over the UK more seasonal than anything else, on Wednesday (the driest day this coming week) Temperatures will be relatively chilly with 850s of -3 to -5. These upper Air Temperatures suggest surface Temperatures approximately the same amount below average for once, if only for one day. Friday into Saturday still looks interesting for some more widespread wintriness as I have stated before. Hopefully the overnight European setup  as predicted by the ECM is incorrect and will revert back to something better for coldies, if not I'll be giving things another week to ten days before getting excited again.

 

The build of heights is temporary and weak and not another Euro high slug, its just a response to the trough orientation over the UK. The NH pattern is completely different to that seen during December. I think panic sets in now even if a build of pressure is shown there in one frame! lol

In terms of this mornings ECM 00hrs whilst it was not that exciting, the tweeks needed are quite minor, just a bit more amplification and the low seen at T168hrs running more ne to develop better WAA towards Greenland.

[gottolovethisweather]

24 minutes ago, nick sussex said:

The build of heights is temporary and weak and not another Euro high slug, its just a response to the trough orientation over the UK. The NH pattern is completely different to that seen during December. I think panic sets in now even if a build of pressure is shown there in one frame! lol

In terms of this mornings ECM 00hrs whilst it was not that exciting, the tweeks needed are quite minor, just a bit more amplification and the low seen at T168hrs running more ne to develop better WAA towards Greenland.

Nick, to my mind, heights largely remain throughout from t+120hrs through to the last frames of the ECM 0z, at least that's how I viewed the operational run. Having said that, this will hopefully be a rogue run and not a trend-setter as I stated previously. It is but only one aspect in a much bigger and complex global picture (can't pick the right words I need) and other parts of this system to contemplate are suggesting for better signs for coldies. Second half of January is most definitely up for grabs of course.

Edited January 4, 2016 by gottolovethisweather

[phil nw.]

It looks like the rest of this week sees us with further rain or showers from the slow moving Atlantic trough stuck across the Uk before something of a change next week as upstream ridging extends out of the Arctic.

The ens. from both ECM and GFS show this develpment building nicely by  around day 10 with heights then situated to our north west and the trough drifting east.

so something more wintery from the north or northwest looks quite likely for the UK but there is stillsome uncertainty on the degree of ridging and on how long it may last at this stage.

A look at the latest combined temp graph for London

shows the cooling trend with a good clustering of colder members in week 2.

How cold it will be remains to be decided as detail from this wrt the amount of amplification in the Atlantic and the exact direction of the flow.Still it's good to this pattern change and gives us hope that with time the continuing weakening of the vortex will tip the balance in favour of a proper cold spell.

 

Edited January 4, 2016 by phil nw.

[Mucka]

Much improved GFS 06z suite for cold prospects but nobody has yet mentioned that the Op really takes two bites at the cherry to build an Atlantic block as does the Parallel run which of course carries some delay of the cold and more risk than building the ridge first attempt. It would also likely require a clean link up with the arctic high to provide any prolonged cold so although it is improved output it is far from as suggestive of a cold spell than last nights ECM output.

ECM 00z is far more progressive than last nights Op but the trough is fairly deep into Europe which is a big plus and it looks as though it would go on to build a ridge NE through to Scandi and with the Arctic high in the vicinity that may actually produce an Easterly going forward although ECM is not building heights through Scandi a la GFS out to day 10.

ECM London ensembles show temperatures falling away from the 12th and a chilly few days  thereafter with a small but significant cluster going for prolonged cold but also a bit of a split developing among the scatter.

I'm a long way from convinced we are going to get a strong Atlantic ridge and useful Greenland high as yet but I would love to see it as I was talking up the models dropping the Scandi high but building an Atlantic ridge down the line before Xmas and improved amplification through January way before that but above personal gratification and trumpet blowing I just want some snow, please. 

Also worth noting that a signal for a pressure rise from the SW either across the UK or in the Atlantic toward mid month has been around for a very good while within GFS ensembles (last mentioned Dec 30th but also previously) and while it did not strengthen, it never got dropped either - still mixed signals now but it is at least gaining strength.

So mixed signals from the models and mixed signals from me, some positives, some negatives, ultimately though I feel this has a much better chance of leading to cold for the UK than the last effort (though perhaps not as we currently envisage? )

 

Edited January 4, 2016 by Mucka

[gottolovethisweather]

22 minutes ago, phil nw. said:

It looks like the rest of this week sees us with further rain or showers from the slow moving Atlantic trough stuck across the Uk before something of a change next week as upstream ridging extends out of the Arctic.

The ens. from both ECM and GFS show this develpment building nicely by  around day 10 with heights then situated to our north west and the trough drifting east.

so something more wintery from the north or northwest looks quite likely for the UK but there is stillsome uncertainty on the degree of ridging and on how long it may last at this stage.

A look at the latest combined temp graph for London

shows the cooling trend with a good clustering of colder members in week 2.

How cold it will be remains to be decided as detail from this wrt the amount of amplification in the Atlantic and the exact direction of the flow.Still it's good to this pattern change and gives us hope that with time the continuing weakening of the vortex will tip the balance in favour of a proper cold spell.

 

Thanks for this Phil, makes me think I might have been overly up thread, perhaps I should stick with my thoughts from yesterday, which largely replicate your own views. The thing is, I just couldn't elevate myself to the same level of excitement expressed by a few forum members yesterday evening, especially given that the best (wintry type) charts were seemingly out in la la land anyhow.  Nonetheless, let's give things another week or so and should these Arctic heights, displaced Vortex and the proposed stratosphere changes come ever closer into the reliable, I'll be jumping around like the proverbial madman at the Winter wonderland prospects. 

 

 

Edited January 4, 2016 by gottolovethisweather

[Alexis]

1 hour ago, Man With Beard said:

Did anyone post the UKMO FAX chart for Friday? 528 dam line through central England. #snowpotential

850s are only about -1 to -3 though. I find the 528 line no use at all personally, 850 temperatures of -8 are a better indicator for snow (assuming it's not a continental feed).

[phil nw.]

2 minutes ago, gottolovethisweather said:

Thanks for this Phil, makes me think I might have been overly pessimistic earlier, perhaps I should stick with my thoughts from yesterday, which largely replicate your own. The thing is, I just couldn't elevate myself to the same level of excitement expressed by a few forum members yesterday evening, especially given that the best (wintry type) charts were out in la la land. Nonetheless, let's give things another week or so and should these Arctic heights, displaced Vortex and the proposed stratosphere changes come ever closer into the reliable, I'll be jumping around like the proverbial madman at the Winter wonderland prospects. 

 

 

I think we will see some form of north/north westerly as the height anomaly charts are consistent on that mid-month pattern.It looks like the Operative runs are still working out detail from this range although odds on a proper GH are long at the moment i reckon.

http://modeles.meteociel.fr/modeles/gens/naefs/run/naefsnh-0-0-348.png?0

Latest narfs shifing those heights south east across the UK later.

[Mucka]

Nice block building in the Atlantic first attempt on the 12z.

 

[That ECM]

Gfs T168 looks like a stronger ridge in the Atlantic helped by the cold digging deeper in us. Northly coming. Is it brief or longer lasting?

[ALL ABOARD]

Gfs goes the same way as 00zs ECMWF with better amplification at 162 hours than previous run... ?