Model output discussion - 16th Nov onwards

[Daniel*]

These barrages of lows modelled are having a go eroding +ve heights in Western Europe something we need to look out for once pressure wanes interest grows as shown by end of latest GFS perhaps we may have to endure stormy, wet conditions in ushering something much more seasonal? Seems like a waiting game!

[Singularity]

It's looking more lively this morning as the storm tracks have shifted south enough to threaten some very strong winds at times across the north, less so across the south but still notable.

The above produces gusts to around 80 mph in the far northwest and has trended stronger from the 00z det.

 

Yet it pales in comparison to what the 00z came up with for next Thursday:

You rarely see a pressure gradient steeper than that around a baroclinic storm system. 

 

Unless, of course, you look beyond a week's range at GFS output:

 

 

It's the path of that extreme event - staying well west then northwest of the UK - that sets up that enormous Euro High for the following 7 days of output.

 

The 'seed' for that monstrous storm isn't even there on the GFS 06z det. which means the jet stream doesn't take up that SW-NE path from the Atlantic between +192 and +240 hours, keeping the Euro High much flatter and leaving us at the mercy of the Atlantic storms.

 

Eventually, as the tropospheric polar vortex becomes more ragged again following intrusions by high pressure on the Pacific side, the resulting increased meridionality of the jet stream places us in a trough that's digging south rather than a high that's building north as we saw with the GFS 00z det. So one way or another the patterns get a bit funky again - but the model will almost inevitably be overlooking some of the complications that usually stifle the effects all but the most powerful of blocking events.

 

Not only that but the ECM 00z det. is rather lacking in that Pacific-side Arctic High which allows the vortex to look rather more resilient by +240. So there's still little reason to adjust my expectations from major changes taking until mid-Jan at the earliest, despite yesterday's adventurous 12z and 18z GFS det. runs.

 

 

As a final thought for the morning, the models are exploring the potential for a 'trailing polar front' scenario for the middle of next week, and are keen to have a wave run along this which threatens to result in a prolonged spell of heavy rain somewhere across the UK, most likely affecting part of England and Wales. Arguably the further south the better, as the middle third of the UK has seen some large rainfall totals in places over the past few weeks, whereas the southern third has been near or even below average (for example, about 85% at my location which is a deficit of more than 40 mm).

[andymusic]

the danger is we waited throughout last winter for the same and it never turned up - hope that don't happen again - and I can't see it happening but you never know - weather is about balance - and we have had some stonking plus temps this year - and a very mild winter last time - so we have to assume that through all probabilities and percentages - I would put money right now on the winter getting very cold and snowy at some point shortly - especially with all the overall signs that we have right now - we have to be patient right now - possibly 2 - 3rd week of December could well have the turn around we seek - for now we watch - over all signs - el nino - extremely warm Pacific with Hawaii being surrounded by not one not two but three hurricanes at one point - Mexico was nearly wiped off the map too and the phillipines have had a hammering too - 5 years ago we had the coldest december

Edited November 25, 2015 by andymusic

[jgbgt]

the danger is we waited throughout last winter for the same and it never turned up - hope that don't happen again - and I can't see it happening but you never know - weather is about balance - and we have had some stonking plus temps this year - and a very mild winter last time - so we have to assume that through all probabilities and percentages - I would put money right now on the winter getting very cold and snowy at some point shortly - especially with all the overall signs that we have right now - we have to be patient right now - possibly 2 - 3rd week of December could well have the turn around we seek - for now we watch

 

I understand the point, but the balance only happens after a very long period, year to year is too short a time frame. Its like roulette, every time the wheel spins the odds reset, or for want of a clearer example, flipping a coin, intuition says if you flip ten times heads you are more likely to flip a tail next time,  but its not, this is the Gamblers fallacy (see Wikipedia) its 50:50 each time.

 

The short answer being we had mild last year, assume the new winter is a reset, then the likelihood of cold winter are not increased by a previous mild winter...

 

JG

[Polar Maritime]

The GFS continues to show Lows spinning in off the Atlantic on a cool N/W flow with inter-spread Westerly's at times giving average temps, Always more unsettled in the North with Snow at times on the Mountains. Pretty much what you would expect for the time of year as we head into the start of Winter.

Edited November 25, 2015 by Polar Maritime

[nick sussex]

A pretty underwhelming outlook in terms of some wintry weather, earlier signs of some more amplification upstream have somewhat diminished.

 

Having said this there is still a lot of uncertainty over the eastern USA with the development of low pressure there and the degree of phasing with the northern branch of the jet stream.

 

In terms of trying to find some interest I'm surprised theres not been mention of the ECM between T144 and T168hrs, the operational run shows a shallow feature running east across  the north of the UK, this does run into some colder 850's, this might give some snow on its northern flank.

[Frosty.]

Pretty much what you would expect for the time of year as we head into the start of Winter.

I agree PM, I have been reading lots of posts about how mild the outlook is but it looks like typical end of autumn / early winter UK weather to me.

[Mucka]

 

The  GEM this morning show some exceptionally mild weather at times as we enter week 2.

GEM

 

The GFS shows something a little more mobile in the longwave department.

It does however develop a robust Euro block in low resolution which eventually becomes a UK high at the end of the run.

 

Apart from an isolated GFS operational or ensemble member, the consensus again is on a mixed picture with the chance of anticyclonic conditions developing. A choice of one of the two depending on how far north the jet can move as we progress into December.

 

 

 

Alas the same can be true for searching and finding the coldest member of an ensemble suite and posting it claiming that it is a trend. In the end the key is to take all factors including model output, anomalies and background signals and then come to a rational conclusion. Unfortunately at the moment the conclusion is not one most on here will like.

 

 

Could you point me to such posts because I can't find any?

It is amazing how people constantly distort reality by rewriting other peoples posts or pointing to imaginary posts and all to prove what exactly?

 

There is room for all types of methodology here and just occasionally the pros ans cons of each method get discussed sensibly.

If people want to know what  the mean anomalies are showing then they can see that.

If they want to know how those anomalies are arrived at via individual members then they can see that.

If the operational output is deviating away from said anomalies they can see that.

 

I think most people have been here long enough to know what Knocker says is pertinent, there is a hunt for cold, but what is wrong with that so long as what is being discussed exists in the output?

It is rare to get deep cold over the UK and many weather enthusiasts here look forward to snow falling so it is natural for people to favour looking for that over a mundane Westerly regime.

 

Where people are looking outside the reliable forecast period for pattern changes to something Wintry they are playing against the odds before they begin - if people just wanted to play safe they would forecast charts 3 to 5 days ahead or post anomaly charts without any kind of verification or explanation between what they posted 10 days ago being different to what is represented in anomalies ten days later.

10-14 Anomaly charts are close to useless where there is wide scatter in pressure patterns among the ensembles and a pattern change is often preceded by wide scatter so really anomaly charts are much better used for forecasting continuity of long wave patterns than a pattern change unless that pattern change is very strongly signaled withing the ensembles but if that's the case what do we need anomaly charts for? 

 

I don't see why there has to be any sniping either way personally.

It is good that you have people looking at the likelihood of the overall longwave pattern via the ensemble mean and good that we have people who are looking at operational runs across models and ensemble output for possible signals or trends that may be developing.

Sometimes a signal such as the more amplified signal of yesterdays out put will not develop and the anomaly charts will prove a better guide but to be fair I think most people who mentioned yesterdays better charts also mentioned there was little support in the ensembles as yet. Should it not of been mentioned less god forbid it wasn't there today?

If you look back to our last brief cold snap the potential was picked up long before by people looking for signals that went against the anomaly chats at that time.

Of course the anomaly charts would eventually pick it up much later when the deal was done. Again that doesn't mean one method is better than another, they should compliment each other.

 

Let members take or leave what information they want, people have their own minds.

Edited November 25, 2015 by Mucka

[Methuselah]

Could you point me to such posts because I can't find any?

It is amazing how people constantly distort reality by rewriting other peoples posts or pointing to imaginary posts and all to prove what exactly?

 

There is room for all types of methodology here and just occasionally the pros ans cons of each method get discussed sensibly.

If people want to know what  the mean anomalies are showing then they can see that.

If they want to know how those anomalies are arrived at via individual members then they can see that.

If the operational output is deviating away from said anomalies they can see that.

 

I think most people have been here long enough to know what Knocker says is pertinent, there is a hunt for cold, but what is wrong with that so long as what is being discussed exists in the output?

It is rare to get deep cold over the UK and many weather enthusiasts here look forward to snow falling so it is natural for people to favour looking for that over a mundane Westerly regime.

 

Where people are looking outside the reliable forecast period for pattern changes to something Wintry they are playing against the odds before they begin - if people just wanted to play safe they would forecast charts 3 to 5 days ahead or post anomaly charts without any kind of verification or explanation between what they posted 10 days ago being different to what is represented in anomalies ten days later.

10-14 Anomaly charts are close to useless where there is wide scatter in pressure patterns among the ensembles and a pattern change is often preceded by wide scatter so really anomaly charts are much better used for forecasting continuity of long wave patterns than a pattern change unless that pattern change is very strongly signaled withing the ensembles but if that's the case what do we need anomaly charts for? 

 

I don't see why there has to be any sniping either way personally.

It is good that you have people looking at the likelihood of the overall longwave pattern via the ensemble mean and good that we have people who are looking at operational runs across models and ensemble output for possible signals or trends that may be developing.

Sometimes a signal such as the more amplified signal of yesterdays out put will not develop and the anomaly charts will prove a better guide but to be fair I think most people who mentioned yesterdays better charts also mentioned there was little support in the ensembles as yet. Should it not of been mentioned less god forbid it wasn't there today?

If you look back to our last brief cold snap the potential was picked up long before by people looking for signals that went against the anomaly chats at that time.

Of course the anomaly charts would eventually pick it up much later when the deal was done. Again that doesn't mean one method is better than another, they should compliment each other.

 

Let members take or leave what information they want, people have their own minds.

I'm sure we can. Doesn't alter the FACT that the models, almost as one, are indicating a predominantly mild outlook?

 

Anywho, it's time to do away with all this 'coldy' vs 'mildy' nonsense...

[Frosty.]

Doesn't alter the FACT that the models, almost as one, are indicating a predominantly mild outlook?

 

The experts say temperatures through the outlook period (6-15 day) will be around average for early winter but feeling colder in exposure due to the strength of the winds..no mention of mild.

[Chris K]

I understand the point, but the balance only happens after a very long period, year to year is too short a time frame. Its like roulette, every time the wheel spins the odds reset, or for want of a clearer example, flipping a coin, intuition says if you flip ten times heads you are more likely to flip a tail next time,  but its not, this is the Gamblers fallacy (see Wikipedia) its 50:50 each time.

 

The short answer being we had mild last year, assume the new winter is a reset, then the likelihood of cold winter are not increased by a previous mild winter...

 

JG

 

Agree. I don't really see how balance comes into forecasting the weather or looking at the models really. Studying analgogues and patterns from previous years I understand, but 'balance' in the way some use here, I am not so sure. Like you say, naturally I suppose it would over a longer period of time but isnt that similar to studying averages?

 

In my view, weather is a constant fluid system of cause and effect and chaos, not that we are 'due' any weather just because we have had a long spell of the opposite. Maybe I am wrong though? I have heard presenters mention the patterns often "balancing out" but I can only seem to relate that to something like the Jet Stream switching between unusual/normal states for the seasons.

Edited November 25, 2015 by Chris K

[Methuselah]

The experts say temperatures through the outlook period (6-15 day) will be around average for early winter but feeling colder in exposure due to the strength of the winds..no mention of mild.

But our winter climate is termed 'mild'...No matter how much you or I want it to snow (snow is what got me hooked on weather!), in the near future at least, it looks unlikely. And I'm no more of an 'oracle' than you are!

 

'Average' temps will not produce snow - apart from on northern hills and mountains?

[johnholmes]

 

 

Where people are looking outside the reliable forecast period for pattern changes to something Wintry they are playing against the odds before they begin - if people just wanted to play safe they would forecast charts 3 to 5 days ahead or post anomaly charts without any kind of verification or explanation between what they posted 10 days ago being different to what is represented in anomalies ten days later.

10-14 Anomaly charts are close to useless where there is wide scatter in pressure patterns among the ensembles and a pattern change is often preceded by wide scatter so really anomaly charts are much better used for forecasting continuity of long wave patterns than a pattern change unless that pattern change is very strongly signaled withing the ensembles but if that's the case what do we need anomaly charts for? 

 

I don't see why there has to be any sniping either way personally.

It is good that you have people looking at the likelihood of the overall longwave pattern via the ensemble mean and good that we have people who are looking at operational runs across models and ensemble output for possible signals or trends that may be developing.

Sometimes a signal such as the more amplified signal of yesterdays out put will not develop and the anomaly charts will prove a better guide but to be fair I think most people who mentioned yesterdays better charts also mentioned there was little support in the ensembles as yet. Should it not of been mentioned less god forbid it wasn't there today?

If you look back to our last brief cold snap the potential was picked up long before by people looking for signals that went against the anomaly chats at that time.

Of course the anomaly charts would eventually pick it up much later when the deal was done. Again that doesn't mean one method is better than another, they should compliment each other.

 

Let members take or leave what information they want, people have their own minds.

 

We obviously see things differently with regard to anomaly charts. That is if you are referring specifically to those you see me use. Over 7-8 years I have found them correct 70% of the time at 6-12 days, my interpretation of that period from the 6-10 and 8-15 day outputs, largely from NOAA but also using the ECMWF-GFS (they seem to have disappeared in the format I like just recently), and that includes a prediction of changing the wavelength of the main trough-ridge pattern to give quite different weather to what is occurring at day 0. Also it applies to those occasions when they show no change in the upper air pattern is the most likely outlook. I do almost always post after looking at other available data in that time scale, other anomaly 500mb charts, synoptic models, MJO etc. Folk can judge whether my predictions based on them is as I suggest above or not. Certainly they are not infallible and neither am I. Too many years experience of having egg on face for that during 30+ years in the trade. But I do disagree with some of your comments in your post about how useful they are.

Still it would be a dull old Net Wx if we all agreed. providing we discuss and at times disagree politely with one another then other ideas are how we individually and science as a whole moves forward.

Edited November 25, 2015 by johnholmes

[Frosty.]

But our winter climate is termed 'mild'...No matter how much you or I want it to snow (snow is what got me hooked on weather!), in the near future at least, it looks unlikely. And I'm no more of an 'oracle' than you are!

 

'Average' temps will not produce snow - apart from on northern hills and mountains?

Well Pete, I'm just pleased we are not looking at raging mild zonality with temps into the low teens celsius, to me it looks like generally normal late autumn / early winter weather, as I said before.

[Ravelin]

Back to the models...a bit more pronounced heights in NW Canada/Alaska and Siberia on the 12Z (top) compared to the 6Z (below)

 

 

 

 

Carries that theme on through the run too, especially around Alaska

 

Edited November 25, 2015 by Ravelin

[BLAST FROM THE PAST]

12z reducing this Euro HP idea further with LOT more seasonal weather than mild.  No N/S split here

 

 

 

 

This could be the start of the BFTP upgrade

 

BFTP

Edited November 25, 2015 by BLAST FROM THE PAST

[Cloud 10]

12z GFS with a PV split at day 10 which leads to some scandi high activity later on.

 

[That ECM]

The gfs fi shows why much could happen Keeps it interesting if nothing else. Choo choo😜😜

Edited November 25, 2015 by That ECM

[Ravelin]

12z reducing this Euro HP idea further with LOT more seasonal weather than mild.  This could be the start of the BFTP upgrade

 

BFTP

 

Out of curiosity I ran through each of the 12z frames looking at the 850 temp over the UK. Out of the 52 frames in total, Scotland is forecast to have 850s of <0C on 35 frames (67%), England/Wales on 25 frames (48%). It was rather subjective at times, I counted it if the 0C line covered at least 90% of the respective land masses.

 

The 850s stay in a range of around 4C to -4C throughout the whole run. No idea if this equates to 'mild' or not.

Edited November 25, 2015 by Ravelin

[phil nw.]

GFS not an overly mild run, in fact Scotland, and at times areas further south, see quite a number of 24-48hrs spells of polar maritme air through the run.

I would think upland areas in the north will see quite a few snowfalls.Plenty of wind and rain for the majority between the brief drier interludes.

A very mobile Atlantic and no sign of the Euro high becoming a fixture as the jet continues to push south behind the incoming lows.

[nick sussex]

Looks like there could be a lot of rain along the boundary between some colder air over the north UK and much milder conditions further south.

 

The GFS develops a shallow feature similar to this mornings ECM run which runs east along that boundary, the UKMO makes less of this but we still see a wave developing. I still wouldn't rule out some snow on the northern flank especially over higher ground.

 

Upstream at T144hrs the UKMO looks more amplified with the low moving out of the central USA, compared to the GFS and this could impact any ridging ahead.

 

It does look like we could see more phasing with a chunk of low heights off the PV and that low however many of the GEFS fail to make much of that central USA low and are less interested in phasing the two streams.

 

NCEP prefer the more developed low, the GFS and GEFS mean have been discarded after day 4 and not used because they're too weak with that low and have other issues.

Edited November 25, 2015 by nick sussex

[chris55]

Something interesting eventually pops up in far far away land lol,

 

 

Though overall I'm getting bored of the output at the moment, a cool high with some frost and fog would suffice.

[knocker]

GFS not an overly mild run, in fact Scotland, and at times areas further south, see quite a number of 24-48hrs spells of polar maritme air through the run.

I would think upland areas in the north will see quite a few snowfalls.Plenty of wind and rain for the majority between the brief drier interludes.

A very mobile Atlantic and no sign of the Euro high becoming a fixture as the jet continues to push south behind the incoming lows.

 

A good example Phil, Cold/mild,wet/windy, and there's snow in them there hills.

Charts weatherbell

Edited November 25, 2015 by knocker

[gottolovethisweather]

12z GFS with a PV split at day 10 which leads to some scandi high activity later on.

 

gfsnh-0-240.png

 

And over the last few runs from the GFS this appears to be a recurring trend, which I am certainly pleased to see. Should this NH setup continue over the coming days, December across a lot of NW Europe could well become much more favourable for colder than average Temperatures than currently forecast. A straw to clutch but I view the date of December 4th as a potential game-changer across a few runs of late. Most of this brought about a difference in behaviour of the NH Jetstream over the Pacific region which thereby affects the US and allows us to receive a quiet spell of weather. The Arctic High seemingly builds in strength around then and this then causes changes in the PV positioning. A few IFs, BUTS, and MAYBEs but it is a trend I have noticed which seemingly is gathering momentum. I thereby suspect a more settled pattern to things to develop across the UK by then and it will be a case of just where does the HP cell want to position itself over us, to our NE or to our West. 

 

Much agree as others have stated, there aren't that many milder days forecast over the coming 10-14 days so seasonally average it will be for most. In fact, the last double-digit Maximum at base camp was on the 19th November so hopefully we'll largely see a continuation of "how things feel" as to now for a while yet before something colder turns up later. 

Edited November 25, 2015 by gottolovethisweather

[gottolovethisweather]

Out of curiosity I ran through each of the 12z frames looking at the 850 temp over the UK. Out of the 52 frames in total, Scotland is forecast to have 850s of <0C on 35 frames (67%), England/Wales on 25 frames (48%). It was rather subjective at times, I counted it if the 0C line covered at least 90% of the respective land masses.

 

The 850s stay in a range of around 4C to -4C throughout the whole run. No idea if this equates to 'mild' or not.

 

I use the 850s as approximate guides to suggest what the surface Temperature might be in terms of average climatological Maximums during any given time. So for instance, -6 850s are pretty much needed for snow-forming synoptics IMBY come late November, which equates to 8/9 Celsius minus 6 Celcius dragging the AT down to nearer 2-3c at the surface which given other favourable parameters in tow, a snow-producing Temperature. Hope that makes sense? 

 

Basically the word average sums things up well based upon your figures above, in fact I imagine that is precisely the term the Met Office are probably using.

Edited November 25, 2015 by gottolovethisweather