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Model Output Discussion; into 2015


martthefart

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Posted
  • Location: st albans
  • Location: st albans

No news about this from the experts over in the strat thread, so this comment is a bit confusing

take my word for it john - there is no technical SSW currently predicted. The reason for the lack of posts on that thread is

1) andrej is visiting his girlfriend

2) the ECM charts have backed off the evolution that would have led to a SSW

there may be something within two weeks but as far as the situation only two days ago where some wee musing as to whether a SSW as was imminent - it isn't now.

That doesn't preclude the upcoming warmings doing some damage to the trop zonal flow so don't give up hope.

IDO, I don't see any extended ens evidence yet that the vortex will be on the move from Canada in week 2.

this is where my thoughts re possible scandi height rises comes from. A move back east from Canada to Siberia of the vortex would indeed not allow that.

And finally, I'm no strat expert. very few are which is why we got suckered into the ECM solution from a couple of days ago. We don't have enough data info.(especially when andrej isn't around)

Edited by bluearmy
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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

No news about this from the experts over in the strat thread, so this comment is a bit confusing

It doesn't help that the key charts from Berlin Uni have gone missing which just adds to the mystery especially with some Twitter quotes saying a SSW is underway.

 

The confusion I think rests with the terminology being used there which doesn't separate major from minor warming.

Edited by nick sussex
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Posted
  • Location: Horsham, West sussex, 52m asl
  • Location: Horsham, West sussex, 52m asl

This is the strat warming for the GFS:

 

So the GFS 00hrs run to T168hrs:

 

attachicon.gifgfsnh-2014123100-10-168.png

 

And the GFS 06hrs run to T162hrs:

 

attachicon.gifgfsnh-10-162.png

 

You can clearly see the stronger warming, because of the suggested coupling between strat and trop at the moment then IMO its this change that has caused the improved GFS run from 00hrs to 06hrs.

 

You don't always get this hand in hand type type situation with the strat but for those who have been reading the strat thread we are currently in this type of scenario.

nick, you use the term "suggested coupling". this is what has me wondering. if it is difficult to predict the effects of strat warming on the trop, would it not be fair to say that the models would also struggle at longer ranges? if so, until they can 'see' a direct link between the strat and the trop (which may be at fairly short range) could they not potentially be very wrong at longer ranges when a strat warming is occurring?

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Posted
  • Location: Bude
  • Weather Preferences: Extreme weather...heavy snow and heat waves
  • Location: Bude

With due respect, Bluearmy is one of those experts. It was nice for him to update us on a busy day.

 

CFS week 3-4 anomalies: attachicon.gifwk3.wk4_20141230.z500.gif

Sorry I should have worded that differently- there has been no discussion with other experts over in the strat thread regarding no SSW.

This may well be they are busy on new years eve

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Posted
  • Location: st albans
  • Location: st albans

It doesn't help that the key charts from Berlin Uni have gone missing which just adds to the mystery especially with some Twitter quotes saying a SSW is underway.

The confusion I think rests with the terminology being used there which doesn't separate major from minor warming.

The warming is major nick, it's just that it doesn't do damage to the strat vortex heights where we need it to and doesn't sustain over the pole to force another split. And it's not a technical SSW or MMW because it doesn't force a reversal of zonal flow at 60N 10hpa. tbh, when we had the Berlin charts to look at, it wasn't far away by day 7 so it's possibly a bit pedantic to say that one hasn't occurred. However, a reversal that generates a neg AO in the trop looks unlikely to be achieved in the short term but there were signs on Berlin a couple of days ago and also on the extended gfs that further wave breaking is occuring and that may well 'do' for this vortex. Incidentally, the ridge being thrown up by the recent modelling n of scandi may look like it gets nowhere and is flattened but it could be the straw that breaks the camels back re wave breaking and it's consequences high up. Edited by bluearmy
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Posted
  • Location: Reigate Hill
  • Weather Preferences: Anything
  • Location: Reigate Hill

IDO, I don't see any extended ens evidence yet that the vortex will be on the move from Canada in week 2.

this is where my thoughts re possible scandi height rises comes from. A move back east from Canada to Siberia of the vortex would indeed not allow that.

And finally, I'm no strat expert. very few are which is why we got suckered into the ECM solution from a couple of days ago. We don't have enough data info.(especially when andrej isn't around)

 

I was referring to the trop vortex at 500hPa. 

 

D9: post-14819-0-97773000-1420029392_thumb.p D16: post-14819-0-51440100-1420029392_thumb.p

 

It is the journey rather than the arrival, after D9 that concerns me re heights to the NE.

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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

nick, you use the term "suggested coupling". this is what has me wondering. if it is difficult to predict the effects of strat warming on the trop, would it not be fair to say that the models would also struggle at longer ranges? if so, until they can 'see' a direct link between the strat and the trop (which may be at fairly short range) could they not potentially be very wrong at longer ranges when a strat warming is occurring?

It really depends on what type of warming is occurring, if you have a major SSW then you can get a quick trop response before the actual downwelling, that occurred I think in February 2009. There is research that suggests that if your base condition ie state of AO at the time is positive the response longer term will be greater, the signal becomes more muted if the AO is already negative, indeed one could argue that the pieces could be re-arranged in a more unfavourable manner in terms of where any blocking might occur if you're already in a cold European set up.

 

In terms of the strat/trop link that can be sometimes difficult because other variables might mute out the signal. At the moment we seem to be in this more strat/trop connection.

 

The complexities of the strat and trop interplay are still being researched, it's all very complicated, I'll be honest the strat isn't really my forte, I do my best but generally leave that area to the strat thread and the much more learned members in there!

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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

The warming is major nick, it's just that it doesn't do damage to the strat vortex heights where we need it to and doesn't sustain over the pole to force another split. And it's not a technical SSW or MMW because it doesn't force a reversal of zonal flow at 60N 10hpa. tbh, when we had the Berlin charts to look at, it wasn't far away by day 7 so it's possibly a bit pedantic to say that one hasn't occurred. However, a reversal that generates a neg AO in the trop looks unlikely to be achieved in the short term but there were signs on Berlin a couple of days ago and also on the extended gfs that further wave breaking is occuring and that may well 'do' for this vortex. Incidentally, the ridge being thrown up by the recent modelling n of scandi may look like it gets nowhere and is flattened but it could be the straw that breaks the camels back re wave breaking and it's consequences high up.

I think the problem BA is the terminology that seems to add to the confusion. I only use major if it fulfils all the criteria, minor if it doesn't.

 

Then with it then being called technical or not I think you can see why it causes problems.

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Posted
  • Location: st albans
  • Location: st albans

I was referring to the trop vortex at 500hPa. 

 

D9: attachicon.gifgfsnh-0-192 (4).png D16: attachicon.gifgfsnh-0-384 (3).png

 

It is the journey rather than the arrival, after D9 that concerns me re heights to the NE.

That's an op chart at 16 days on a low res model IDO. I can't debate on that basis - sorry. beyond day 6/7, I can only work with ens, their anomolys, clusters and spreads. My three year old may as well be generating the ops in week 2!

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Posted
  • Location: Reigate Hill
  • Weather Preferences: Anything
  • Location: Reigate Hill

That's an op chart at 16 days on a low res model IDO. I can't debate on that basis - sorry. beyond day 6/7, I can only work with ens, their anomolys, clusters and spreads. My three year old may as well be generating the ops in week 2!

 

Fair enough.

 

NAVGEM continues with last night's warming at 10 hpa: post-14819-0-75814500-1420030359_thumb.p

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

There are quite a few cold and stormy 6z perturbations and the mean at T+240 shows rather cold and very unsettled weather, especially for Scotland, cold enough for snow at times..so I think there is scope for wintry weather at times during the first half of January..it's not all mild by any means according to the mean. :-)

post-4783-0-46166400-1420030557_thumb.pn

post-4783-0-78396900-1420030577_thumb.pn

post-4783-0-11087000-1420030594_thumb.pn

post-4783-0-79600200-1420030612_thumb.pn

post-4783-0-68449700-1420030630_thumb.pn

post-4783-0-81465600-1420030654_thumb.pn

post-4783-0-53187400-1420030673_thumb.pn

post-4783-0-61940600-1420030697_thumb.pn

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Posted
  • Location: Nuneaton,Warks. 128m asl
  • Weather Preferences: Snow then clear and frosty.
  • Location: Nuneaton,Warks. 128m asl

Certainly some interest around T144hrs wrt Scandinavian ridging.

It's been showing on the 3 main overnight runs and more so on the 06z GFS so a continuing picture.

If we look at the NH pattern at around day 6/7 we can see how close we get to a proper split in the vortex before later frames show it reforming.

Looking at that angry dark blue/purple blob of the Canadian pv it does look too powerful to think any ridging heights ahead of it would hold,as IDO suggests in his earlier post.

Never say never though just compare our 06z GFS T144 chart with the evolution from a similar pattern in 1991.

 

Today 144

post-2026-0-06495200-1420030215_thumb.pn 

 

1991

post-2026-0-89921600-1420030233_thumb.pnpost-2026-0-33968700-1420030243_thumb.pnpost-2026-0-97496100-1420030251_thumb.pn

 

of course the background signals could have been different but this is to show how an apparently strong vortex can be overcome by warmer air being drawn into it's core.

A sign of that happening can be seen on the images where the vortex  starts to tighten up and wind in on itself like a coiled spring.

Just a little something to while away the time until the 12z runs come out.

 

It may be a false dawn but let's see if  the afternoon outputs can squeeze anything more out of that ridging.

 

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Posted
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.

Yes Phil, That's the one reason i'm not looking past the 8th Jan as i posted this morning, re-PV split. The GFSP has been toying with this idea for a good few runs now. And also some 'hints' of it from Meto employees..

Edited by Polar Maritime
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Posted
  • Location: Horsham, West sussex, 52m asl
  • Location: Horsham, West sussex, 52m asl

It really depends on what type of warming is occurring, if you have a major SSW then you can get a quick trop response before the actual downwelling, that occurred I think in February 2009. There is research that suggests that if your base condition ie state of AO at the time is positive the response longer term will be greater, the signal becomes more muted if the AO is already negative, indeed one could argue that the pieces could be re-arranged in a more unfavourable manner in terms of where any blocking might occur if you're already in a cold European set up.

 

In terms of the strat/trop link that can be sometimes difficult because other variables might mute out the signal. At the moment we seem to be in this more strat/trop connection.

 

The complexities of the strat and trop interplay are still being researched, it's all very complicated, I'll be honest the strat isn't really my forte, I do my best but generally leave that area to the strat thread and the much more learned members in there!

thanks nick. it will be interesting to see if the models lead us in a different direction over the next few days as they pick up on stronger signals from the strat.
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There are quite a few cold and stormy 6z perturbations and the mean at T+240 shows rather cold and very unsettled weather, especially for Scotland, cold enough for snow at times..so I think there is scope for wintry weather at times during the first half of January..it's not all mild by any means according to the mean. :-)

 

 

The recent post xmas day cold spell didn't interest alot on here so you may as well call it mild for your legion of fans. :w00t:

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

The recent post xmas day cold spell didn't interest alot on here so you may as well call it mild for your legion of fans. :w00t:

I didn't think I had any fans apart from me, myself and I. Anyway, the outlook won't all be mild, there will be colder days and nights too.

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Posted
  • Location: Essex, Southend-On-Sea
  • Weather Preferences: Warm, bright summers and Cold, snowy winters
  • Location: Essex, Southend-On-Sea

Anomalies of the GEFS bia-corrected 6z

 

T192 gensbcnh-21-5-192.png?6

T240 gensbcnh-21-5-240.png?6

T384gensbcnh-21-5-384.png?6

 

To me they at least show the Candian vorticity weakening but do show a very stormy and unsettled period for us in the UK and on the cooler side as the depressions dig further south.

 

It may just be a case of the pattern re-amplifying off the East coast before we see anything. 

Edited by SN0WM4N
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Posted
  • Location: Nuneaton,Warks. 128m asl
  • Weather Preferences: Snow then clear and frosty.
  • Location: Nuneaton,Warks. 128m asl

Yes Phil, That's the one reason i'm not looking past the 8th Jan as i posted this morning, re-PV split. The GFSP has been toying with this idea for a good few runs now. And also some 'hints' of it from Meto employees..

Yes it always raises uncertainty when we see a near split like this PM.

A case of how much more warm air does it take to tip the balance and break the jet flow.Current modelling has it driving north of Svalbard before it flattens out from upstream.

It may amount to nothing more than a transient feature on this occasion but with the overall outlook looking very average at least it gives us something interesting to focus on.

btw i went straight to the 1991 archives as i recalled it,there may be others showing a similar fightback against the vortex,if anyone fancies looking and maybe posting out of interest. 

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Posted
  • Location: Brentwood, Essex
  • Weather Preferences: Hot summer, cold winters.
  • Location: Brentwood, Essex

I didn't think I had any fans apart from me, myself and I. Anyway, the outlook won't all be mild, there will be colder days and nights too.

I am a fan of yours frosty.l love your winter posts, a man after my own heart.fear not my friend the polar express will arrive.it is just a little delayed........mushy is lying on the track!!!!!! Happy new year to all on netweather.EW
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Posted
  • Location: North Wales 208m asl
  • Weather Preferences: crisp frosty days in Winter
  • Location: North Wales 208m asl

Well, it could get complicated if you think like that. If it's 00:00 then it's the next day, keeps it simple, like the zulu time on the left.

Temps will drop behind it, yes. It does stay on the milder side for southern counties, still a far cry from recent temperatures for most of us.

Thanks yes the 00:00 and 00:01 thing was not really the point the original post was supposedly indicating a mild day. All I was trying to show rather clumsily as it turned out was that was a midnight image for New Years day and the values would fall as the night progressed, I was not trying to say the following day would be cold mild or whatever. The 00:00 or 00:01 was supposed to be amusing not a serious question. It could be a sketch for the newly formed double act Frosty & Mushy! 

I shall retire into obscurity now......

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Posted
  • Location: Bude
  • Weather Preferences: Extreme weather...heavy snow and heat waves
  • Location: Bude

The recent post xmas day cold spell didn't interest alot on here so you may as well call it mild for your legion of fans. :w00t:

The weather definitely interested me post xmas...gave us a real taste of winter down here in cornwall...three crisp fridget ice days, the likes we haven't seen since March 2013... Gave a real yearning for more

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Posted
  • Location: Horsham, West sussex, 52m asl
  • Location: Horsham, West sussex, 52m asl

Totally agree. All tricky in terms of accurate communication and uncertainty of outcome. Exeter note increased prospect of MJO Phase 6 later this month, with this (plus ongoing GloSea strat diagnostics) underpinning currently low probability phrasing of settled/drier phase possible later Jan (perhaps even emerging at end of current trend period... Some mistrust of the bullish current zonal signal out at far end timescale in NWP ).

hi ian, could you explain what is causing this mistrust? stratospheric conditions perhaps?

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

hi ian, could you explain what is causing this mistrust? stratospheric conditions perhaps?

 

I would imagine their own models at that range are not agreeing with some others, Ian may help out here?

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