Model Output Discussion 18th Nov.2013-12z onwards.

[tight isobar]

It does of course depend which 500mb anomaly charts one uses and how carefully one uses them. A correct prediction of 70% or more 10-15 days out over a 4 year period whatever the season makes we pretty confident using the 3 that I do use with their outputs. As always IF they show consistency over time and with themselves and are not at 180 degrees to other indicators. Never ever take one run, one model and use to predict what you think may happen. Use everything available and the first class inputs from other folk to help your assessment and analysis is something we can all do on Net Wx. I am constantly amazed at how many folk with no meteorological training have such depths of knowledge.

John, I think as a seasoned visitor to the threads he won't mind me saying that he has a very good grounding of the main essentials of weather computer model watching and consideration needs to be given as to the context in which he was discussing the use of these anomaly charts Whilst the majority of the anomaly charts will indeed prove very valuable to assessing and discussing the general macro scale pattern in the NH, it is also true that we must be cautious of what they mean for the UK on the micro scale in terms of assessing actual placings and orientation of pressure systems, and not to interpret them too much at face value.

 

We have seen in the last week or so that the 500mb charts have been broadly very accurate in the placings of the anomalies, but crucially they have not been able to tell us the degree of amplification we might have expected from the atlantic height anomalies depicted - that mean the difference between a proper polar incursion and what has turned out to be a relatively low key colder interlude of weather.

.

Agreed.some of us have the benefits of knowledge gained as way of science(etc) However It's quite clear there are seasoned to say the least" GENRAL model viewer's whom at times ridicule, the expectant of persons whom should indeed be represent of whole output resolve permiting a high shine better...

[Summer Sun]

Later next week had the potential for something colder from the north albeit temporary that has now vanished from GFS (3 run in a row now)

 

Other than a potential attack form the north on the 5th and 6th high pressure dominates the bulk of the GFS 12z run

 

Edited November 23, 2013 by Summer Sun

[Panayiotis]

The UKMO at 120hrs is much better than the GFS at the same time. The low leaving the US has a much better alignment to cause WAA towards to Greenland which may help give us the temporary ridge at 144hrs:

Edited November 23, 2013 by Panayiotis

[tight isobar]

hmmmmmmmmmmmmm. No wonder there aren't many comments on the GFS....a progressively Bartlettish borefest.

 

 

 

At least it's only the very start of winter - and i'd rather have thaot sort of yaw. ntfest early on allowing for my much expected but scientifically unsupported pattern change in time for the festive period....

W,jet It's a modeling not to any favours regaring cold output for UK atm.the HP dominant is firming...not to say this cant/won't change.However such synopsis as they progress become harder to De-establish!!!

[Mucka]

Today's GFS operational output should be used in medical trials as a possible replacement for nitrazepam. 

[Cheshire Freeze]

Regardless of what the NWP is showing at the present time RE synoptics in our locale, it's reassuring to see an unwillingness of the vortex to locate around Greenland. A Siberian side vortex is very much an important part of the foundations for a much colder spell of weather to take hold later on. The flat pattern (N Atlantic) we're seeing represented on some modelling in the medium range is very much a red herring and tells us little about likely synoptics as we head into winter proper.

Edited November 23, 2013 by CreweCold

[EML Network]

Well as has already been stated another zzzzzzz   run from the GFS, in fact today's run is about as dire as as boring as it is possible to get. 

 

This High pressure system centered jut out to our West ...

Takes almost an entire week to make the journey of a few 100 miles to end up here...

 

 

and if that's not enough then 10 days later and the end of this ''boring run of the century'' we end up in about the same place ..

 

 

How anyone can find this sort of set up even remotely interesting is beyond me 

[Frank Trough]

Regardless of what the NWP is showing at the present time RE synoptics in our locale, it's reassuring to see an unwillingness of the vortex to locate around Greenland. A Siberian side vortex is very much an important part of the foundations for a much colder spell of weather to take hold later on. The flat pattern (N Atlantic) we're seeing represented on some modelling in the medium range is very much a red herring and tells us little about likely synoptics as we head into winter proper.

 

.....and that's the scientific explanation for my "big Christmas give-away pattern change"!

[Summer Sun]

Anyone else got problems with UKMO? t144 appears to be stuck on the 00z update

[Tamara]

Regardless of what the NWP is showing at the present time RE synoptics in our locale, it's reassuring to see an unwillingness of the vortex to locate around Greenland. A Siberian side vortex is very much an important part of the foundations for a much colder spell of weather to take hold later on. The flat pattern (N Atlantic) we're seeing represented on some modelling in the medium range is very much a red herring and tells us little about likely synoptics as we head into winter proper.

The flat pattern unfortunately isn't a red herring into the medium range because it is a very real signal of the increasing strength of the westerly QBO winter time vortex and the +AO signature aligned with the -EPO ridge over the Pacific west coast. More mid latitude highs such as we currently see, and dependance on amplification of these is the only source to cold(er) conditions. Its true that the bulk of the vortex is based over Siberia and that will help further wave activity interaction into the Canadian arctic to try and assist amplification of the pattern - but the strength of the upper vortex has already shown its hand this last week in mitigating the amplification potential and with the vortex still to arrive at its traditional winter coldest then we cannot expect this situation to get any easier for some while to come.

 

Best we look at the pattern on these expectations - better things may come as we get further into winter

Edited November 23, 2013 by Tamara תָּמָר

[East_England_Stormchaser91]

Thank god we are seeing these outputs now, and not in the middle of Jan, then that would be a total waste of valuable time for some proper cold blasts. Things will change eventually, even if its after christmas.

[Frosty.]

Was that the most boring Gfs op run of all time?..I think so, high pressure, cloudy and dry = 

Edited November 23, 2013 by Frosty.

[Gaz1985]

Well as has already been stated another zzzzzzz   run from the GFS, in fact today's run is about as dire as as boring as it is possible to get. 

 

This High pressure system centered jut out to our West ...

Takes almost an entire week to make the journey of a few 100 miles to end up here...

 

 

and if that's not enough then 10 days later and the end of this ''boring run of the century'' we end up in about the same place ..

 

 

How anyone can find this sort of set up even remotely interesting is beyond me 

 

This is my dream come true, nice charts, if only we got these high pressure systems as persistent in the Summer but that never seems to happen!

[Stormyking]

Barlett High Anyone? 

 

Truly dire and Boring run, as stated by many of you, Ahh well its early days people!  

[MR EXTREMES]

hmmmmmmmmmmmmm. No wonder there aren't many comments on the GFS....a progressively Bartlettish borefest.

 

 

 

At least it's only the very start of winter - and i'd rather have that sort of yawnfest early on allowing for my much expected but scientifically unsupported pattern change in time for the festive period....

No Bartlett just wobble high pressure not going anywhere fast.

[Cheshire Freeze]

The flat pattern unfortunately isn't a red herring into the medium range because it is a very real signal of the increasing strength of the westerly QBO winter time vortex and the +AO signature aligned with the -EPO ridge over the Pacific west coast. More mid latitude highs such as we currently see, and dependance on amplification of these is the only source to cold(er) conditions. Its true that the bulk of the vortex is based over Siberia and that will help further wave activity interaction into the Canadian arctic to try and assist amplification of the pattern - but the strength of the upper vortex has already shown its hand this last week in mitigating the amplification potential and with the vortex still to arrive at its traditional winter coldest then we cannot expect this situation to get any easier for some while to come.

 

Best we look at the pattern on these expectations - better things may come as we get further into winter

 

Hi Tamara. I have to disagree with the prognosis of stable +AO conditions becoming 'bedded in'. What we're seeing modelled is anything but a traditional +AO or even +NAO. Given the pressure distribution which we're seeing being unravelled in the medium term by the NWP, I see it only as a matter of time before this 'holding pattern' breaks down. As far as holding patterns go, on the face of it it's not the most wintry scenario but should ultimately lead to something infinitely 'better' than what we're seeing at present. At the moment in time, I don't think a westerly episode will even see out the first week of December.

 

A +QBO isn't necessarily the death knell of winter.

 

Furthermore, as I understand it a -EPO is actually correlated to a -AO?

Edited November 23, 2013 by CreweCold

[shedhead]

hi Shed, i find your analysis a little odd. You seem to be dismissing what the ensembles are showing in their latter stages, without proper reasoning as to why. Of course, usual caveats apply to this output, but you were quick to point to breakdowns in the summer, when the ens pointed in that direction. Now, instead of "tempered" expectations, you completely dismiss. Odd.

Hi draztik...to be honest I wish I could find something +ive for the development of a cold pattern, whether that be within the ops, ensembles or even the teleconnctions.  However I can't, in fact all I can currently see is a slowing sinking HP dominated pattern, a slowly deepening PV and a resultant slow transition to milder, more unsettled conditions from the north.  You may see things differently, as may others, but no amount of wishful thinking, positive vibes or glass half full talk will change the overall picture...at least as I see it.

 

BTW, I seem to remember you singing from very much the same hymnsheet as me back in the summer, as several of your PM's back then atest.

Edited November 23, 2013 by shedhead

[Cheshire Freeze]

GFS 12z ensemble suite starting to possibly wake up to the idea now......

[cooling climate]

The Control run has gone off on one in the extended outlook.Major blocking up

north. Again the only way a pattern like this could develope is if we see very strong

wave breaking with enough amplitude to affect the lower to middle stratosphere.

[Mucka]

MetO has the pattern setting up much further West than GFS thankfully.

 

[johnholmes]

 

John, I think as a seasoned visitor to the threads he won't mind me saying that he has a very good grounding of the main essentials of weather computer model watching and consideration needs to be given as to the context in which he was discussing the use of these anomaly charts Whilst the majority of the anomaly charts will indeed prove very valuable to assessing and discussing the general macro scale pattern in the NH, it is also true that we must be cautious of what they mean for the UK on the micro scale in terms of assessing actual placings and orientation of pressure systems, and not to interpret them too much at face value.

 

We have seen in the last week or so that the 500mb charts have been broadly very accurate in the placings of the anomalies, but crucially they have not been able to tell us the degree of amplification we might have expected from the atlantic height anomalies depicted - that mean the difference between a proper polar incursion and what has turned out to be a relatively low key colder interlude of weather.

 

 

they have never to my mind been there to provide detail at low level, a guide yes, which is what I explain on here most times, and they do with practice and care enable one to see if the upper air is favourable for various types of surface weather to develop.

Even then they provide a much more reliable prediction than the synoptic outputs be they at 2 or 4x daily, but of course that is my view based in about 4 years experience and others, yourself included, are free to ignore what I say. I never really expected deep cold to be a main feature, or I hope that is the flavour I gave from my reading of the anomaly charts prior to the cold spell developing which they did predict pretty well and consistently.

[Cheshire Freeze]

The Control run has gone off on one in the extended outlook.Major blocking up

north. Again the only way a pattern like this could develope is if we see very strong

wave breaking with enough amplitude to affect the lower to middle stratosphere.

conrtol run.png

 

As I said, the ensembles may be waking up to this possibility. From my perspective, calling a zonal/westerly start to December is walking on shaky territory in terms of what may actually transpire. There's only so long you can have the major centre of the vortex held towards the Siberian sector before there's ramifications to the vortex as a whole.

[Mucka]

As I said, the ensembles may be waking up to this possibility. From my perspective, calling a zonal/westerly start to December is walking on shaky territory in terms of what may actually transpire. There's only so long you can have the major centre of the vortex held towards the Siberian sector before there's ramifications to the vortex as a whole.

 

yes the ensemble graph shows massive spread and on the positive side there are some cold runs including the control along with all the dross.

 

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=257&y=54

[Joe Levy]

A very large spread on the ens - this is for Central Southern England, just as a random location that I chose http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=271&y=122

 

EDIT ahh Mucka you got there first!

Edited November 23, 2013 by Joe Levy

[I remember Atlantic 252]

Barlett High Anyone? 

 

Truly dire and Boring run, as stated by many of you, Ahh well its early days people!  

 

No Bartlett that, infact in my location and many in the south, that could be potentially very cold, this model run 12Z GFS many may not like but I do, looks dry and possibly cold and foggy/frosty for 2 weeks and no rain!