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Model output discussion - winter proper underway


Paul
Message added by Paul

Please only post model discussion in this thread. 

For more general chat and banter, or moans and ramps loosely around the models, please head to the banter thread:
https://www.netweather.tv/forum/topic/86721-model-moans-ramps-and-banter/

For general weather chat including about the snow/cold chances around the country, please go to the regional threads:
https://www.netweather.tv/forum/forum/142-regional-discussions/

Thank you!

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Overnight runs heading the right way for cold fans. The GFS operational is on the mild side in FI.

ECM is also a massive improvement.

The PV shift to our north-west is now showing up regularly.

This is a very interesting transition period. Plenty of room for optimism.

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Posted
  • Location: st albans
  • Location: st albans
20 minutes ago, Interitus said:

You are adding a near surface temperature criteria but it doesn't negate the fact that using a traditional understanding there is a lobe of the tropospheric polar vortex over and to the north of the UK -

tpv1.thumb.png.942d99e0ab7396b74779cf5349edb921.png

tpv2.thumb.png.ca29805209ece4707fc727f13363e2e5.png

What is a polar vortex? - http://sites.krieger.jhu.edu/waugh/research/polarvortex/

Traditions? 

technicals?

like I said, it was once a proper part of the vortex and perhaps it's technically speaking still part of the vortex but if we are to start referencing the vortex being over the uk with uppers barely below zero and thicknesses around 540 dam then it's going to make it difficult to manage expectations on here in the future! 

Thansk anyway ?

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1 minute ago, bluearmy said:

Traditions? 

technicals?

like I said, it was once a proper part of the vortex and perhaps it's technically speaking still part of the vortex but if we are to start referencing the vortex being over the uk with uppers barely below zero and thicknesses around 540 dam then it's going to make it difficult to manage expectations on here in the future! 

Thansk anyway ?

Well to manage expectations, the UK will NEVER see a vortex lobe accompanied by sub -28°C 850hPa temperatures like the US in Jan 2014 :)

vortex2014.thumb.png.dfa603ee8c70cc7952aedc970e730420.png

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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

npsh500.png npsh500.png npsh500.png

LP no longer running over the Pacific ridge on day 6... brings the 00z GFS close to getting a wedge of higher heights in between the Canadian and Scandinavian vortex lobes on day 7. By day 9 the situation is akin to yesterday's 00z ECM run but then the poleward ridging on the Pacific side is bulldozed and the run loses interest.

npsh500.144.png npsh500.192.png npsh500.240.png

ECM 00z has made similar progress on the Pacific side but has also dropped momentum on the Atlantic side so much that we lose out on the consolidated trough over Scandinavia which then means a longer wait for the major trough to get east of us. Oh the irony! Wacky finishing pattern though and with the vortex being subjected to a lot of peripheral wave action.

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Posted
  • Location: Coniston, Cumbria 90m ASL
  • Weather Preferences: wintry
  • Location: Coniston, Cumbria 90m ASL

Question, excuse my naivety...How good are the models at dealing with solar output as a variable?

What I mean is that the nwp models will all be programmed with algorithms based on laws of science and previous developments. When Solar activity changes the results from that are (I understand) somewhat more randomised, which I guess may make the models struggle regarding accurate prognoses.

We've seen this late autumn and winter some fascinating shorter-than-usual-term changes when the models have suggested the Atlantic tonal low fest is upon us, only to get a more meridonal pattern in reality.

So if the models aren't able to cope (yet) with solar output fluctuations or low levels, then maybe there is less to worry about regarding cooler weather this winter.

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Posted
  • Location: Ski Amade / Pongau Region. Somtimes Skipton UK
  • Weather Preferences: Northeasterly Blizzard and sub zero temperatures.
  • Location: Ski Amade / Pongau Region. Somtimes Skipton UK

Well there we have it from ECM at day10. A sub tropical maritime flow into much of Europe. Not want we want to see in the Alps for the holiday period. Think the snow making machines will be redundant under a big drip feed. However, I think this is the extreme outcome of this morning models at this stage but overall not looking good for festive cold cheer even in Stockholm where I will be for my festive break . Still time hopefully for adjustments to a colder outcome in the models as this week progresses.

C

ECMOPEU00_240_2.png

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Posted
  • Location: st albans
  • Location: st albans
13 minutes ago, Interitus said:

Well to manage expectations, the UK will NEVER see a vortex lobe accompanied by sub -28°C 850hPa temperatures like the US in Jan 2014 :)

vortex2014.thumb.png.dfa603ee8c70cc7952aedc970e730420.png

With the Oceans around us, of course - however, the small chunk that visited us in Dec 2010 was not modified enough and everyone was content to use the wording. 

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Posted
  • Location: Camborne
  • Location: Camborne

The ecm continues the theme of last evening, supported to some extent by the mean EPS anomaly, of reorientating the Alaskan ridge and in the process displacing the Canadion vortex. Resulting in the orientation of the NA trough also being adjusted, a major trough in the Atlantic and the very strong jet forced south east around the latter and thus also disrupting the west to east momentum to some extent. Still portending windy around the Xmas period with outbreaks of rain albeit temps , maybe above average.

ecm_z500a_5d_nh_11.thumb.png.9659a01d17e8424735975490d10b8c31.pngecm_t850a_5d_nh_11.thumb.png.10fdedc494097bc9c91a975f8301a8c0.png

Just to add the EPS is not adverse to this scenario this morning

Edited by knocker
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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
10 hours ago, Frosty. said:

From a cold perspective, the 12z model output looks as good as the England cricket team in australia..shockingly bad..putting it mildly.:santa-emoji::D

Essentially, in a nutshell, from a cold perspective, the 00z models don't look any better than yesterday's 12z..and the same goes for the shambolic joke of an England cricket team getting a damn good shellacking down under!:santa-emoji::D

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Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

UKMO extended showing an unsettled start for Santa on Christmas day with rain and wind moving in - what we can't see is just how low the temps get and whether any snow would fall especially so in the north

ukm2.2017122500_168_lant.troplant_prp_fcst.gentracker.thumb.png.36846af798ccea936737b30f677c573b.png

:ball-santa-emoji:

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Posted
  • Location: Heckmondwike, West Yorkshire
  • Location: Heckmondwike, West Yorkshire
1 hour ago, JeffC said:

Question, excuse my naivety...How good are the models at dealing with solar output as a variable?

What I mean is that the nwp models will all be programmed with algorithms based on laws of science and previous developments. When Solar activity changes the results from that are (I understand) somewhat more randomised, which I guess may make the models struggle regarding accurate prognoses.

We've seen this late autumn and winter some fascinating shorter-than-usual-term changes when the models have suggested the Atlantic tonal low fest is upon us, only to get a more meridonal pattern in reality.

So if the models aren't able to cope (yet) with solar output fluctuations or low levels, then maybe there is less to worry about regarding cooler weather this winter.

Very good post and although I don't have any answers, I do believe solar output has a large bearing on north west European winters. 

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Posted
  • Location: Heckmondwike, West Yorkshire
  • Location: Heckmondwike, West Yorkshire

Quite a bug scatter even at 4 days out on ecm debilt ens. Unfortunately both the op and control go with the mild bunch at that time. Something to keep an eye on though. 

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Posted
  • Location: st albans
  • Location: st albans
16 minutes ago, blizzard81 said:

Quite a bug scatter even at 4 days out on ecm debilt ens. Unfortunately both the op and control go with the mild bunch at that time. Something to keep an eye on though. 

De bilt just on the edge of the western spread of the northerly flow further east at day 4/5

 

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Posted
  • Location: Heckmondwike, West Yorkshire
  • Location: Heckmondwike, West Yorkshire
5 minutes ago, bluearmy said:

De bilt just on the edge of the western spread of the northerly flow further east at day 4/5

 

Yes, thought that was the case. Do you have any positive news from the eps?

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Posted
  • Location: Peterborough N.Cambridgeshire
  • Location: Peterborough N.Cambridgeshire

GEFS ensembles sum up the period into the New year.

;prmslAberdeenshire.pngt850Aberdeenshire.png

Unsettled but cool at times especially after Xmas day. Hints of pressure beginning to rise into the New year.

No evidence of an E,ly into the New Year though as the Berlin 850hpa are no colder than -5C.

t850Berlin.png

Edited by TEITS
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Posted
  • Location: Raynes Park, London SW20
  • Location: Raynes Park, London SW20

No point sugar coating it, the NWP is pretty poor from a coldie's perspective.  We are fast reaching the point where we are reliant on some warming in the stratosphere as Crew Cold mentioned last night.

We have seen so many times over the years, once the PV takes hold around the Greenland locale, it's tough to shift.  I am also very wary of any modelling that shifts the polar front jet to the south.  We often see modelling that shows the jet digging to the south of us at mid range but invariable this gets shifted north (I believe this is a known model bias).

The positives remain the MO long range forecast and it's something I will be watching over the next few days to see if there is a subtle change of wording.

 

 

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Posted
  • Location: Heckmondwike, West Yorkshire
  • Location: Heckmondwike, West Yorkshire
12 minutes ago, mulzy said:

No point sugar coating it, the NWP is pretty poor from a coldie's perspective.  We are fast reaching the point where we are reliant on some warming in the stratosphere as Crew Cold mentioned last night.

We have seen so many times over the years, once the PV takes hold around the Greenland locale, it's tough to shift.  I am also very wary of any modelling that shifts the polar front jet to the south.  We often see modelling that shows the jet digging to the south of us at mid range but invariable this gets shifted north (I believe this is a known model bias).

The positives remain the MO long range forecast and it's something I will be watching over the next few days to see if there is a subtle change of wording.

 

 

Great points. Especially about the jet digging south. Pressure remains much higher over Europe than originally modelled in almost all cases. This is probably why NAVGEM is wrong this morning. 

Edited by blizzard81
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Posted
  • Location: Ski Amade / Pongau Region. Somtimes Skipton UK
  • Weather Preferences: Northeasterly Blizzard and sub zero temperatures.
  • Location: Ski Amade / Pongau Region. Somtimes Skipton UK

Make what you want from the latest NAVGEM run. Christmas Savoury or Just a dream ? Anyway this chart gives some hope with signs of the zonal jet pushing further SE  on each run. Wonder if UKMO thoughts are moving this way for Christmas Day ?

 C

NVGOPNH00_180_1.png

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Posted
  • Location: Heckmondwike, West Yorkshire
  • Location: Heckmondwike, West Yorkshire
6 minutes ago, carinthian said:

Make what you want from the latest NAVGEM run. Christmas Savoury or Just a dream ? Anyway this chart gives some hope with signs of the zonal jet pushing further SE  on each run. Wonder if UKMO thoughts are moving this way for Christmas Day ?

 C

NVGOPNH00_180_1.png

Let's hope NAVGEM can break the habit of a lifetime and be the odd run out for all the right reasons this time. 

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Posted
  • Location: Ski Amade / Pongau Region. Somtimes Skipton UK
  • Weather Preferences: Northeasterly Blizzard and sub zero temperatures.
  • Location: Ski Amade / Pongau Region. Somtimes Skipton UK
8 minutes ago, carinthian said:

Make what you want from the latest NAVGEM run. Christmas Savoury or Just a dream ? Anyway this chart gives some hope with signs of the zonal jet pushing further SE  on each run. Wonder if UKMO thoughts are moving this way for Christmas Day ?

 C

NVGOPNH00_180_1.png

Not sure I have ever seen such a huge high from what looks like covering the whole of North America !

C

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Posted
  • Location: Raynes Park, London SW20
  • Location: Raynes Park, London SW20
8 minutes ago, carinthian said:

Make what you want from the latest NAVGEM run. Christmas Savoury or Just a dream ? Anyway this chart gives some hope with signs of the zonal jet pushing further SE  on each run. Wonder if UKMO thoughts are moving this way for Christmas Day ?

 C

NVGOPNH00_180_1.png

It's something I have been guilty of over the years too but anyone quoting the NAVGEM, BOM, CMA , NCMRWF or CPTEC should face the ban hammer!;)

 

 

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Posted
  • Location: Ski Amade / Pongau Region. Somtimes Skipton UK
  • Weather Preferences: Northeasterly Blizzard and sub zero temperatures.
  • Location: Ski Amade / Pongau Region. Somtimes Skipton UK
2 minutes ago, mulzy said:

It's something I have been guilty of over the years too but anyone quoting the NAVGEM, BOM, CMA , NCMRWF or CPTEC should face the ban hammer!;)

 

 

Its really quite respected over here anyway. It has recently been upgraded so is showing improved results in the medium term forecasts. Whatever, I see post 180t from the other big models is hardly bullet proof accuracy .

C

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Posted
  • Location: st albans
  • Location: st albans
26 minutes ago, blizzard81 said:

Yes, thought that was the case. Do you have any positive news from the eps?

Not really although I think the extended Atlantic trough from Canada to the uk is unsustainable for more than a week

my attention currently on whether the Alaskan ridge can get far enough towards Greenland to keep the chunk coming around from e Asia away from getting to Canada around day 10

the spreads say no but the ridge is more marked on the op 

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