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Model output discussion - late November


Paul

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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.

And, as if to rub salt into the wound, the mighty GFS 12Z ends with what looks almost like textbook zonality...!:shok:

h500slp.png    h850t850eu.png

'Milder, windy, often wet conditions interspersed with briefs spells of colder showery weather, with snow in the North and on high ground' is what I recall...from a-thousand-and-one lunchtime forecasts... 

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Posted
  • Location: Camborne
  • Location: Camborne

The salient points of the ext GEFs this evening

Vortex over the Pole but bordering on a second lobe Siberia courtesy pf a strong Alaskan ridge which comprises part of a highly amplified North America with the vortex extension down the eastern half

A strong westerly upper flow exiting the eastern seaboard across the Atlantic but abating somewhat in the vicinity of the UK as it rounds the declining subtropical ridge and diverts to low Pressure in the Mediterranean area.

So probably changeable weather but not as intense as of late by a long way and with the high being influential tending to a N/S split. Temps a tad above average

gfs-ensemble-all-avg-nhemi-z500_anom_5day-5720000.thumb.png.c574b5402c459183584a0f1f08a9fad8.pnggfs-ensemble-all-avg-nhemi-t850_anom_5day-5720000.thumb.png.5f22b698f933a44b13d615e565413ac9.pnggfs-ensemble-all-avg-eur-t2m_c_anom_5day-5720000.thumb.png.db77fc110527934616ddeb816305c958.png

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Posted
  • Location: Örebro, Sweden
  • Location: Örebro, Sweden
35 minutes ago, Ed Stone said:

And, as if to rub salt into the wound, the mighty GFS 12Z ends with what looks almost like textbook zonality...!:shok:

h500slp.png    h850t850eu.png

'Milder, windy, often wet conditions interspersed with briefs spells of colder showery weather, with snow in the North and on high ground' is what I recall...from a-thousand-and-one lunchtime forecasts... 

That is cold zonality, look at those deathly cold -10 850hpa temperatures

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Posted
  • Location: Bexhill-on-Sea, East Sussex
  • Weather Preferences: Winter Snow, extreme weather, mainly sunny mild summers though.
  • Location: Bexhill-on-Sea, East Sussex

Well so far so good, ECM is running with the ICON, and yes the ICON is a pretty good model these days. HP builds out in the Atlantic, not over us.

ECE1-168.png

ECE0-168.png

Edited by snowray
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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.
30 minutes ago, Faronstream said:

That is cold zonality, look at those deathly cold -10 850hpa temperatures

Whose leg are you trying to pull, Mr F? t850Leicestershire.png There's nae one single ensemble-member (including the operational!) showing a -10C 850hPa temperature...:oldgrin:

Edited by Ed Stone
Clarification
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Posted
  • Location: Örebro, Sweden
  • Location: Örebro, Sweden
2 minutes ago, Ed Stone said:

Whose leg are you trying to pull, Mr F? t850Leicestershire.png There's nae one single ensemble-member showing a -10C 850hPa temperature...:oldgrin:

Looking at the operational is the only right thing to do, all those members are uneccesary

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Posted
  • Location: Buckinghamshire
  • Location: Buckinghamshire
13 minutes ago, Faronstream said:

Looking at the operational is the only right thing to do, all those members are uneccesary

In that case shall we just bin them then? The ensembles are generally better to look at its usually more useful when operational models are changing a lot.

Edited by jordan smith
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Posted
  • Location: Bedfordshire
  • Weather Preferences: Seasonal
  • Location: Bedfordshire

The end of the ECM provides a potentially horrible set-up beyond those frames. French High looking likely

WWW.WETTERZENTRALE.DE

Wetterkarten ECMWF Europe 12Z

However, there are still signs of pressure wanting to rise over Greenland at that time frame too. If that does happen (still the underdog option I reckon) then all those long range forecasts will have already bitten the dust. I'd say 75-25 in favour of mild winning out if ECM is right but I guess they're always the odds in any winter!

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Posted
  • Location: Bedfordshire
  • Weather Preferences: Seasonal
  • Location: Bedfordshire
4 minutes ago, Mike Poole said:

ECM T240, and you can see the next reload on the way, with further WAA into Greenland from the next low.

image.thumb.jpg.d935dfeb8d0c61ff70156823eb979457.jpg

 

Yes, definitely potential there but that low in Canada needs to take a direct northerly trajectory to drag that WAA into Greenland. If it heads east, it's game over and that High to our south and SW will just move into Europe - instead of being dragged kicking and screaming into the North Atlantic - and Glosea and other models might be proved correct for December

Immaterial, of course, as it probably won't look exactly like that but good to speculate

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Posted
  • Location: Buckinghamshire
  • Location: Buckinghamshire

Gfs and Gem on the track of tropical storm Sebastien. Arrow indicates the centre.

Gem.. Tomorrow midnight..

IMG_20191123_180749.thumb.jpg.68d7219f846a4cbac5e10849644e6eae.jpg

You can see the primary low just to the Northwest of Sebastien.. 

Monday midday..

IMG_20191123_180951.thumb.jpg.19e880fa237ff84b1b6aba093e4bc69c.jpg

IMG_20191123_181033.thumb.jpg.ba3e26c54f11247c22ea487edd947b32.jpg

You can see ex Sebastien now getting pulled into the primary low to the Northwest as we go through Monday into Tuesday you can see Sebastien and the other low pressure system dumbell around each other..

Monday night..

IMG_20191123_181422.thumb.jpg.b9e2b1f9143ab1285e296f5508433e8d.jpg

IMG_20191123_181532.thumb.jpg.ba35208c1e5f2261e1136c775d0d9218.jpg

Tuesday midday..

IMG_20191123_181842.thumb.jpg.6f634299cd5467b3be8a12de45cb31e3.jpg

before finally Sebastien is mostly absorbed into the primary lows circulation.. This then all moves into the uk during Tuesday afternoon and on into Wednesday.

Gfs take on things.. 

Tomorrow 6pm ex Sebastien

IMG_20191123_182047.thumb.jpg.c53377bfd6629396f847853d0f55f890.jpg

Monday 6pm.. Begins to interact with the primary low but is absorbed much quicker than the Gem.

IMG_20191123_182236.thumb.jpg.f244cb329f7d39acf4bef671b899b28d.jpg

Tuesday 6am..

You can see the lobe of heavy rain to the southwest of the UK containing the remnants of Sebastien which helps to intensify the rainband with the primary low at this point still out West.. 

IMG_20191123_182509.thumb.jpg.523a7f697503f19a07c52c75954898df.jpg

By Wednesday morning the frontal system has cleared the UK leaving behind heavy showers after bringing Very wet conditions indeed Tuesday night but as you can see the centre of low pressure that was out West is now across the southern half of England bring a spell of more persistent rainfall with showers elsewhere..

Wednesday 6am..

IMG_20191123_182635.thumb.jpg.acb39745474975cb2c3c284f38e6f65f.jpg

For the more extended range close to and around the day 10 mark putting the Ecmwf Gem and Gfs output together this is what's shown.. 

Saturday 30th..

Low pressure diving Southeast into mainland Europe with high pressure building over the top of the UK then sinking to the south with winds turning to a milder Westerley after perhaps a short north or northeasterly.

EUROPE_PRMSL_174.thumb.jpg.c23572e3551cc8b5307ebe3d06f654e7.jpg

Tuesday 3rd..

2013269002_EUROPE_PRMSL_240(2).thumb.jpg.01a044a81ed2dd25ba81b68980303026.jpg

Edited by jordan smith
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Posted
  • Location: Redhill, Surrey
  • Weather Preferences: Southerly tracking LPs, heavy snow. Also 25c and calm
  • Location: Redhill, Surrey
1 hour ago, Ed Stone said:

And, as if to rub salt into the wound, the mighty GFS 12Z ends with what looks almost like textbook zonality...!:shok:

h500slp.png    h850t850eu.png

'Milder, windy, often wet conditions interspersed with briefs spells of colder showery weather, with snow in the North and on high ground' is what I recall...from a-thousand-and-one lunchtime forecasts... 

Not with blues over us.....zoneality has yellows and oranges over us?

 

BFTP 

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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon
32 minutes ago, LRD said:

Yes, definitely potential there but that low in Canada needs to take a direct northerly trajectory to drag that WAA into Greenland. If it heads east, it's game over and that High to our south and SW will just move into Europe - instead of being dragged kicking and screaming into the North Atlantic - and Glosea and other models might be proved correct for December

Immaterial, of course, as it probably won't look exactly like that but good to speculate

Yes, agree and re the highlighted bit of your post, it is a T240 chart and is a guide to possibilities, features that may be in the mix at that time, but not necessarily in the position that they are currently modelled.  Interesting discussion in here this afternoon.

Edit, I feel the difficult bit that we need to get right first is the Greenland situation, and we know the models have difficulty, so that is my focus at the moment. 

Edited by Mike Poole
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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.
2 minutes ago, BLAST FROM THE PAST said:

Not with blues over us.....zoneality has yellows and oranges over us?

BFTP 

I've always assumed the word 'zonal' to imply a broadscale pattern (LP near Iceland, HP near The Azores, broad swathe of generally westerly winds in between) Fred...But, if an entrained blob of -6C T850s requires a name-change, it's fine by me...:oldgood:

All the text-books I've read were in black-and-white!:oldgrin:

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Posted
  • Location: Bedfordshire
  • Weather Preferences: Seasonal
  • Location: Bedfordshire
3 minutes ago, Ed Stone said:

I've always assumed the word 'zonal' to imply a broadscale pattern (LP near Iceland, HP near The Azores, broad swathe of generally westerly winds in between) Fred...But, if an entrained blob of -6C T850s requires a name-change, it's fine by me...:oldgood:

All the text-books I've read were in black-and-white!:oldgrin:

Agree - purples over Greenland, lows over Iceland, oranges over Spain - zonality. That would be a wild and chilly form of it though

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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon
1 minute ago, Ed Stone said:

I've always assumed the word 'zonal' to imply a broadscale pattern (LP near Iceland, HP near The Azores, broad swathe of generally westerly winds in between) Fred...But, if an entrained blob of -6C T850s requires a name-change, it's fine by me...:oldgood:

All the text-books I've read were in black-and-white!:oldgrin:

My take is it means flow zonal to a particular latitude, give or take.  As opposed to meridional flow  with a big up and down component.  My favourite recent period of zonal flow was March 2018, all the way from Russia (yes it can be easterly as well as westerly, it just doesn't happen very often).

And I am as convinced as ever that zonality is not a word - in fact even Netweather has just underlined it with a red squiggly as I type...

Anyway the models are hardly showing zonal flow in either direction on the 12z runs in the reliable,  

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Posted
  • Location: Bedfordshire
  • Weather Preferences: Seasonal
  • Location: Bedfordshire
12 minutes ago, Mike Poole said:

Yes, agree and re the highlighted bit of your post, it is a T240 chart and is a guide to possibilities, features that may be in the mix at that time, but not necessarily in the position that they are currently modelled.  Interesting discussion in here this afternoon.

Edit, I feel the difficult bit that we need to get right first is the Greenland situation, and we know the models have difficulty, so that is my focus at the moment. 

Yes, very true. As you say, Greenland is always the key in model watching, especially in winter. If pressure rises properly there, then everything else tends to fall into place. Although pressure was often high there this summer but, in my neck of the woods, it was still a decent summer aside from two weeks in the middle of June and a few days in the middle of August

The northern hemisphere view at 240 is encouraging for Greenland heights

WWW.WETTERZENTRALE.DE

Wetterkarten ECMWF Northern Hemisphere 12Z

 

 

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