Model output discussion - winter proper underway

[carinthian]

12 minutes ago, nick sussex said:

Morning all

A better start to the day for coldies than yesterday with the models playing with some different evolutions. Whilst nothing stands out within the T240hrs timeframe at least they want to displace the high to the sw further west and begin to angle the jet more se near the UK.

This comes in response to high pressure building into the Arctic from the Pacific side and some renewed amplification upstream.

At the moment Christmas Day is looking unsettled and close to average temp wise but the actual position of the jet this far out is subject to change. A southwards adjustment could develop some interest more especially for the north.

Given the re-newed upstream amplification hasn't started the downstream effects of that might take some time to feed into the outputs.

I wouldn't give up hope just yet regarding Christmas Day.

 

 

 

 

Yes, Nick I think changes for the better soon. NAVGEM gets mocked by some on here but it has shown consistency at 180t runs and offer a more amplified run prior to Christmas with the Atlantic mild air mass being squeezed as shown on the chart below. I think the US Navy model is fine out to its medium extent and is becoming a more valued with its outputs. It continues to be upgraded and is now a powerful model which is gaining respect in some minds. ECM offers hope this morning as you say with a different evolution .

C

 

[Summer Sun]

Low pressure gets slightly closer to Scotland on UKMO extended so it would be a bit breezier in the north with some spells of rain/showers in the west

[nick sussex]

3 minutes ago, carinthian said:

Yes, Nick I think changes for the better soon. NAVGEM gets mocked by some on here but it has shown consistency at 180t runs and offer a more amplified run prior to Christmas with the Atlantic mild air mass being squeezed as shown on the chart below. I think the US Navy model is fine out to its medium extent and is becoming a more valued with its outputs. It continues to be upgraded and is now a powerful model which is gaining respect in some minds. ECM offers hope this morning as you say with a different evolution .

C

 

Well the NAVGEM evolution is quite plausible given the others have something similar but a bit less amplified. Its not outlandish. As long as you get the upstream amplification that would tend to pull the limpet highs centre further west.

Fingers crossed we can see more amplification develop.

[bluearmy]

60% of the gefs at day 15 have high slp over scandi 

At day 15, eps have less 10%

the extended eps look pretty stormy with heights and slp dropping across w Europe in general as the jet sinks 

the gefs might be a bit progressive with scandi height rise or the eps might be a bit slow. A meeting point between the two ?  the op ecm seems to want to accelerate things somewhat but it does that from time to time, showing the broad way forward a little while before it comes to pass 

[northwestsnow]

7 minutes ago, bluearmy said:

60% of the gefs at day 15 have high slp over scandi 

At day 15, eps have less 10%

the extended eps look pretty stormy with heights and slp dropping across w Europe in general as the jet sinks 

the gefs might be a bit progressive with scandi height rise or the eps might be a bit slow. A meeting point between the two ?  the op ecm seems to want to accelerate things somewhat but it does that from time to time, showing the broad way forward a little while before it comes to pass 

Swing-o-meter slightly moved in favour for coldies this morning Blue- only a slight move but hopefully a bit of momentum can build.

Bit concerned glosea has lost its signal for a ssw- wonder if exeter were basing their outlook on that?

[bluearmy]

10 minutes ago, northwestsnow said:

Swing-o-meter slightly moved in favour for coldies this morning Blue- only a slight move but hopefully a bit of momentum can build.

Bit concerned glosea has lost its signal for a ssw- wonder if exeter were basing their outlook on that?

Better get that blocking in before the zonal winds descend then !!

[Guest]

SOME MISLEADING POSTS

I'll comment on some of the much improved 0z output later today with another cross-model analysis. In several recent posts I have tried to persuade a small number of other posters to be careful about commenting on the broader pattern while showing only the "Europe" view chart(s) and not the "Northern Hemisphere" view charts which are essential for viewing the upstream pattern. This minority continue to mislead us with this practise. Well, we have a perfect example of what I'm on about with today's ECM 0z T+240 charts:

          Europe view:                                                                                                   Northern Hemisphere view:  

Several comments referred to the first chart stating that the ECM looks dreadful towards the end. It might look like a train of LPs and a full on Atlantic but this would be an extremely inaccurate conclusion to come to. Look north!  There is a strengthening PNA  and a huge cut off HP over the Pole. HP is ridging down through Greenland and looking set to link up with the vast Azores HP as the Atlantic LP pushes eastwards. It's looking like this LP will be the last in the train with none appearing behind it. There is also a large belt of HP from northern Asia, through Siberia and ridging into the Arctic. In fact this whole ECM run is considerably more amplified than any of its last few runs. They "may" at last be sniffing out the broader pattern changes that GFS has been toying with (very inconsistently) from run to run over the last few days. This ECM 0z run pattern would first pull in a northerly behind the Atlantic LP (around D11/D12) but then all the indications are (from the positioning of the HPs) that this would veer to an easterly a few days after that (around D15/16). It's not surprising that the newbies to this subject and/or this model thread can get very confused. Those of us posting must try to provide proper context and accuracy to our comments and charts. Having said that, I must end with my usual warning:

CAUTION: One model, one run so do not get your hopes up too much just yet.

 

Edited December 16, 2017 by Guest
Correct typos and check charts

[swfc]

16 minutes ago, northwestsnow said:

Swing-o-meter slightly moved in favour for coldies this morning Blue- only a slight move but hopefully a bit of momentum can build.

Bit concerned glosea has lost its signal for a ssw- wonder if exeter were basing their outlook on that?

I didn't realise they had a signal for a ssw?

Anyway there forecast into the new year ie below av temps ete hasnt changed aa far as I know? ?

[Daniel*]

Much improved GEFS in the extended range.

I’d say the first week of January could be where we see our pattern change..

[northwestsnow]

1 minute ago, swfc said:

I didn't realise they had a signal for a ssw?

Anyway there forecast into the new year ie below av temps ete hasnt changed aa far as I know? ?

Glosea5 model had a decent signal for a SSW in January

Its lost the signal apparently..

There is however a whacking great high anomoly over the Pole on EC 00z- hopefully that will assist the jet tracking further south..

[northwestsnow]

After viewing the 00z EC i revert back to my original thoughts of height rises in the north Atlantic long term.

Ideally we will see the jet digging SE (perhaps a stormy spell first) - 

Fingers crossed

[TEITS]

1 hour ago, nick sussex said:

Morning all

A better start to the day for coldies than yesterday with the models playing with some different evolutions. Whilst nothing stands out within the T240hrs timeframe at least they want to displace the high to the sw further west and begin to angle the jet more se near the UK.

This comes in response to high pressure building into the Arctic from the Pacific side and some renewed amplification upstream.

At the moment Christmas Day is looking unsettled and close to average temp wise but the actual position of the jet this far out is subject to change. A southwards adjustment could develop some interest more especially for the north.

Given the re-newed upstream amplification hasn't started the downstream effects of that might take some time to feed into the outputs.

I wouldn't give up hope just yet regarding Christmas Day.

 

 

 

 

At last a sensible post as usual from Nick.The hysteria on here makes me laugh at times after reading some of the posts from yesterday.

As you know Nick I was confident of a return to milder weather next week many days ago. I was also confident that this could last until the New Year. However this isn't the case anymore in my opinion as I shall explain.

The GFS during the past 3 days has been laughable at times. The output has ranged from a bitter N,ly becomiing E,ly to very mild W,lys. We have seen runs range from blocking to our N to a strong Polar Vortex. These differences are perfectly highlighted in the scatter in the GEFS ensembles that WIB posted.

So what does this all mean to me? The answer is the models are likely to be volatile and your comment about Xmas day is spot on. I forsee many changes ahead in the output and these are beginning to show on todays ECM. A colder Xmas period than currently predicted is more than plausible as we could see a colder NW,ly opposed to the W,ly currently modelled.

Again though I see the predicted Scandi HP is a bust in my opinion. Any cold spell between Xmas and the New Year will come from the N/NW than the NE/E. Greater chance of me winning the Lotto than a Scandi HP.

[carinthian]

12 minutes ago, northwestsnow said:

After viewing the 00z EC i revert back to my original thoughts of height rises in the north Atlantic long term.

Ideally we will see the jet digging SE (perhaps a stormy spell first) - 

Fingers crossed

I like the look of the latest ECM chart at 240t . Strong Arctic high and a split in the Vortex. Must be promising going into the New Year.

C

[feb1991blizzard]

Disagree TEITS,

4 minutes ago, TEITS said:

At last a sensible post as usual from Nick.The hysteria on here makes me laugh at times after reading some of the posts from yesterday.

As you know Nick I was confident of a return to milder weather next week many days ago. I was also confident that this could last until the New Year. However this isn't the case anymore in my opinion as I shall explain.

The GFS during the past 3 days has been laughable at times. The output has ranged from a bitter N,ly becomiing E,ly to very mild W,lys. We have seen runs range from blocking to our N to a strong Polar Vortex. These differences are perfectly highlighted in the scatter in the GEFS ensembles that WIB posted.

So what does this all mean to me? The answer is the models are likely to be volatile and your comment about Xmas day is spot on. I forsee many changes ahead in the output and these are beginning to show on todays ECM. A colder Xmas period than currently predicted is more than plausible as we could see a colder NW,ly opposed to the W,ly currently modelled.

Again though I see the predicted Scandi HP is a bust in my opinion. Any cold spell between Xmas and the New Year will come from the N/NW than the NE/E. Greater chance of me winning the Lotto than a Scandi HP.

Disagree, any (meaningful) cold spell between xmas and new years is a bust, the only way any time afterwards will be via a scandi high.

[Frosty.]

1 hour ago, Summer Sun said:

Low pressure gets slightly closer to Scotland on UKMO extended so it would be a bit breezier in the north with some spells of rain/showers in the west

To be honest this much milder phase shouldn't come as any surprise, I was banging on about it showing this in the Gefs / Ecm ensembles during the cold spell but I was pretty much ignored during the cold frenzy..enjoy the milder spell, good news for daffs, squirrels and the elderly! 

[MR EXTREMES]

2 hours ago, West is Best said:

There will inevitably be some gloom around with the overnight runs, however I do urge that game is far from over for the month. The ensembles continue to show huge scatter with a significant number of cold or very cold members:

18z:

0z:

There is a hint at T240 of the ECM of something interesting:

Interesting indeed that really strong ridge in the northeast Pacific has in previous years been a pain in the butt.

But with an already punch drunk vortex it's not out of the question that a renewed attack and split interesting part being how close and cold there air will be to our east with cold plunges continued into northern and eastern Europe.

We are always so close to a real winter deluges of cold.

Anyway this year there's certainly a bigger portion of the polar vortex over the Eastern side of the pole into Scandinavia.

With ao reflection going deep negative in fi,

But the nao more reflective of slightly negative to neutral.

Although in time could plunge into a deeper negative territory.

Interesting to see if heights cutting through the pole could establish into Greenland.

Certainly no Scandinavia ridge just yet.

But interesting model watching.

Mean time we get little more settled and milder so pleasant up and through Christmas period.

Which is something we will have to endure until the mjo lag settles into a more phase 7 pattern.

But after seeing snow fall in November down here in the sunny Costa del south coast at least it's been different to recent years.

Fingers crossed this will build into something exciting into the heart of winter.

[swfc]

8 minutes ago, feb1991blizzard said:

Disagree TEITS,

Disagree, any (meaningful) cold spell between xmas and new years is a bust, the only way any time afterwards will be via a scandi high.

Hi feb

Imo a brave man would be calling any outlook bust 10 days plus away

On what basis do you arrive at this given the state of flux of the current output. Im not calling a cold pre new year but its not without merit

[Blessed Weather]

Looking at the 0z GEFS output for 25th December there's 6 members out of 20, plus the Op run, going for the -4C isotherm over London. So whilst a minority option, a more festive (colder) Christmas day can't be completely ruled out. Let's see if the 6z run improves on this. 

[feb1991blizzard]

2 minutes ago, swfc said:

Hi feb

Imo a brave man would be calling any outlook bust 10 days plus away

On what basis do you arrive at this given the state of flux of the current output. Im not calling a cold pre new year but its not without merit

The consistent thing is PV over GL, the only way out of it is WAA into the Arctic via a trough dropping South around the meridian.

[swfc]

2 minutes ago, feb1991blizzard said:

The consistent thing is PV over GL, the only way out of it is WAA into the Arctic via a trough dropping South around the meridian.

Arctic highs do have a forcing effect and do drop south causing disruption .many routes to cold imo without waa. Just a thought

[feb1991blizzard]

Could be a good run coming up here - Atlantic troughing has carved out a more defined ridge to the North of UK at 234, better cold pool will subsequently drop East and could even get the Easterly to advect it West by 384.

[Tracy Flick]

1 hour ago, northwestsnow said:

Glosea5 model had a decent signal for a SSW in January

Its lost the signal apparently..

There is however a whacking great high anomoly over the Pole on EC 00z- hopefully that will assist the jet tracking further south..

I wasn't aware of this either.  Maybe this is a negative side-effect of tweets/MetO-updates being religiously removed from this thread... I don't really have time to check every corner of this website so perhaps if one or two posts on these topics were allowed it would be helpful.

What is GLOSEA if it's not 'model output' anyway?

[Duane S.]

43 minutes ago, feb1991blizzard said:

Disagree TEITS,

Disagree, any (meaningful) cold spell between xmas and new years is a bust, the only way any time afterwards will be via a scandi high.

And I would disagree wholeheartedly disagree with that. That's 14 days time.

Even saying meaningful cold between now and Christmas is a bust would be on dodgy ground, albeit, yes, odds on to be correct, but not 'bust'.

I was about to write a post this morning regards the upstream amplification, associated-EPO and the MJO, all of which gives us, if nothing else, hope, of a cold spell incoming. Throw in the solar state and -QBO and we do at least have a ticket to the raffle. I didn't because Nick F put it all, far better than I could, on the previous page!

Assuming upstream amplification doesn't drastically recede, I do believe we are going to see a jet digging further and further south off the ES/ Mid Atlantic and are on the cusp of some very easy on the eye model evolutions over the coming week or so, bringing the end of month firmly into play. I wouldn't say it's going to happen at all, but no way can that period be written off at this stage with teleconnections as they are.

Edited December 16, 2017 by s4lancia

[swfc]

7 minutes ago, feb1991blizzard said:

Could be a good run coming up here - Atlantic troughing has carved out a more defined ridge to the North of UK at 234, better cold pool will subsequently drop East and could even get the Easterly to advect it West by 384.

Maybe close tbh!!!.just not there on this run

Edited December 16, 2017 by swfc

[blizzard81]

I have that funny feeling inside today. The feeling you get just before a major model flip at relatively short notice. A flip to cold. I can feel it in my waters