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Model output discussion - 7th January onwards


Paul
Message added by Paul

Please keep this thread solely to discussing the model output. The model banter thread is available for more loosely model related chat, ramps and moans.

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Posted
  • Location: Hampstead / Cambridge
  • Location: Hampstead / Cambridge
35 minutes ago, Steve Murr said:

JMA 228 - Vortex lobe touching the SE !!!

Deep deep cold -

30B62645-2F9E-4ADA-B764-EFED29523981.thumb.png.dc7647609711c3f936adb5f5a9095b84.png

My word that is some chart. Snowtastic 

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Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
14 minutes ago, Bruegelian said:

Hope it is OK to ask this - what is now the informed opinion about how well GFS is doing, what with the government shutdown?

Maybe it's performing perfectly alright I don't know.

This question about US gov shutdown affecting GFS has been doing the rounds for several days and the general consensus is the claims are unfounded and it’s business as usual from GFS, i.e. weaker skill and highly volatile behaviour compared to the likes of ECMWF, UKMO and even GEM or JMA.

The EPS mean has generally been the best guidance for last few weeks for the evolving pattern of Atlantic ridge amplification  and Euro trough, GFS operational finally catching up now. Looking at day 15 EPS z500 mean and it looks like the Euro trough has staying power!

BA8326D4-163F-4ACA-AD32-477568307BCF.thumb.jpeg.2a93a7ec0815f8be80d65d893d5e3e89.jpeg

Edited by Nick F
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Posted
  • Location: Lincolnshire - 15m asl
  • Weather Preferences: Frost and snow. A quiet autumn day is also good.
  • Location: Lincolnshire - 15m asl
11 minutes ago, snowray said:

Anyone seen a chart like this before verifying? In recent years anyway?:shok:

Curtesy of the JMA.

J252-21.gif

J252-7.gif

People use the word "buried" too often - but that truly would bury many parts. Wont verify though

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Posted
  • Location: Oyne Aberdeenshire 120m asl
  • Weather Preferences: SNAW
  • Location: Oyne Aberdeenshire 120m asl
2 minutes ago, Steve Murr said:

I would love it to verify just to see the max/minima !

So - newbies out there.

T126 mean 18z- which will be 120 on the 00z is all but reliable timeframe.

126 Mean is more amplified & there is no escaping a snow event for Many 132-144..

212043AE-F578-4DEF-A6D3-0D33C7A3B2DC.thumb.png.861893f4351d38e6c2334a283ccbc707.png

Just a quick one steve if i may, if we can see this from the models why is it that the bbc website doesnt show anything like it? i mean if we can see it how come they dont etc.

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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
1 minute ago, bigsnow said:

Just a quick one steve if i may, if we can see this from the models why is it that the bbc website doesnt show anything like it? i mean if we can see it how come they dont etc.

They must have used the 0z ECM

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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
Just now, Catacol said:

People use the word "buried" too often - but that truly would bury many parts. Wont verify though

Famous last words Catacol?

Now who does that remind we of out of the weather presenters from the 1980's, I remember now, it was a windy Autumn in 1987, hint, hint.......

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Posted
  • Location: Oyne Aberdeenshire 120m asl
  • Weather Preferences: SNAW
  • Location: Oyne Aberdeenshire 120m asl
2 minutes ago, feb1991blizzard said:

They must have used the 0z ECM

so basically not to be trusted then?

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Posted
  • Location: Remote North Yorkshire 474ft ASL
  • Weather Preferences: All seasons veteran of the 1981 winter
  • Location: Remote North Yorkshire 474ft ASL

First the T162 chart nice easterly. 

Below is a picture of the last easterly on the second day of the easterly. 

Taken off my dash cam.

This projection of the easterly at T162 is quite potent .

And pictures below could become a scene across much of the country 

19012312_1618.gif

20180301_114534.jpg

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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
2 minutes ago, bigsnow said:

so basically not to be trusted then?

I cant say for sure but it will either be the ECM / GFS - i suppose they could use the UKMO - but the 12z was a stonker so it wouldnt be that, theres no other better model they could use because they are not in partnership with the Met Office now so mogreps not an option - so basically it can only be the models we see - and all the 12z runs are great, if it is any other model then its going to be a lesser one than the ones ive just described as they are the top 3

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Posted
  • Location: Truro
  • Weather Preferences: Cold
  • Location: Truro
8 minutes ago, feb1991blizzard said:

They must have used the 0z ECM

I have always assumed the professionals have access to much better models than we do on this forum no matter who they work for

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Posted
  • Location: Weymouth, Dorset
  • Location: Weymouth, Dorset

Wouldn’t it be boring if the chart output was all super accurate?!

Next few days... Nerves of steel required. Emotions firmly in check. Its gonna be hairy...

Nice direction the chart output has taken today, following on from the average 00Zs. Of course, we should expect a more conservative output from the 00Zs again tomorrow, this has been the recurring theme. It would be pleasing, for once, to wake up to an absolutely cracking set. So to speak.

Nice green colours starting to emerge in all the right places, this surely only as a result of the reverse uwinds now downwelling into the troposphere. 

My take is that we are firming up on trough disruption and energy dropping NW-SE over us come early next week. Much water to pass under the bridge before an Easterly to follow gets firmed up though.

Certainly very plausible but it is currently coming about, from what I can see, by the meandering Arctic High influence and combining with moderate Atlantic ridging  (possibly as a result of MJO lag). Now the signal for some Atlantic ridging may be fairly solid but the behaviour (if not the actual presence) of pole heights is not likely to have been correctly modelled. It needs to be a player, so we don’t want to see it slipping back over the other side of the pole. If it doesn’t get involved, unlikely we will see an Easterly next week. No reason to think this will happen and who knows, maybe the even better charts are still to come!

And yes. JMA. WOW...

 

 

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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
3 minutes ago, Philbill said:

I have always assumed the professionals have access to much better models than we do on this forum no matter who they work for

The ones at the Met Office do, the ones at the BBC don't anymore.

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Posted
  • Location: West Ipswich, Suffolk
  • Location: West Ipswich, Suffolk
31 minutes ago, snowray said:

Anyone seen a chart like this before verifying? In recent years anyway?:shok:

Curtesy of the JMA.

J252-21.gif

J252-7.gif

Was the big snowfall of last year not made up of 3/4 small circulations sliding through the UK as the trough disrupted.

I distinctly remember seeing the moisture feed pumping across from Germany for hours and running round the circulations as they came through.

Probably on a smaller scale than the JMA is showing but lots of snow.

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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

GFS ensembles for North Midlands, for a change. Operational was a mild outlier quite clearly there. Mean looking very cold indeed around -5/-6c from D4 onwards, lots of snow symbols too.:oldsmile:

graphe_ens3.gif

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Posted
  • Location: Dorset
  • Weather Preferences: warehamwx.co.uk
  • Location: Dorset

A lot of useless posts appearing again.. Yes, there are some exciting times coming up, but please, think about what you're posting.

If it's not model discussion,  then it goes HERE

Thanks folks. 

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Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
38 minutes ago, Ravelin said:

IMG_20190116_223414.thumb.jpg.0b5520c88bdae849d73ae4da27858f63.jpg

Just to illustrate with regards to 'uppers'. That's my back garden tonight, turned from sleety mess to snow 5pm or so and started accumulating around 8pm (ground was very wet), with uppers that should be around -5C according to 12z GFS. Now I know I'm in what might be considered a 'favourable location ' compared to most, but it still shows the uppers don't need to be ridiculous for snow to fall. 

Indeed, I don’t think the T850s are always a good guide for snow to fall , the temp at that level may seem high, but so long as it’s at least a few degrees below 0 and there is the depth of cold below ( below 128dm on 1000-850 hPa partial thickness charts good for that) and surface dew point of 0C or below to stop the snow melting as it falls, the freezing level is crucial too. Helps being as north as you are too and closer to the source with less surface moderation of the arctic flow than say southern England and the fact it’s dark helps too.

but we’ve seen many a time T850s around -5C (or maybe a degree or so higher) is adequate for frontal snow so long as surface is cold enough and dew point at or below 0C. it’s when it comes to a dry continental easterly flow with no fronts we need those lower T850s to create steep enough lapse rates over the warmer North Sea to develop convection and pick up moisture from the sea to create snowfall.

Edited by Nick F
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Posted
  • Location: Longton, Stoke-on-Trent.
  • Location: Longton, Stoke-on-Trent.
5 minutes ago, edinburgh_1992 said:

GFS P.... Ouch.

gfs-1-174.png

gfs-0-174.png

Yep. Horrible run. Should be a warning to people to retain some caution.

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Posted
  • Location: Raynes Park, London SW20
  • Location: Raynes Park, London SW20
4 minutes ago, Nick F said:

Indeed, I don’t think the T850s are always a good guide for snow to fall , the temp at that level may seem high, but so long as it’s at least a few degrees below 0 and there is the depth of cold below and the surface dew point 0 or below to stop the snow melting as it falls, the freezing level is crucial too. Helps being as north as you are too and closer to the source with less surface moderation of the arctic flow from source than say southern England and the fact it’s dark helps too.

but we’ve seen many a time T850s around -5C (or maybe a degree or so higher) is adequate for frontal snow so long as surface is cold enough and dew point at or below 0C. it’s when it comes to a dry continental easterly flow with no fronts we need those lower T850s to create steep enough lapse rates over the warmer North Sea to develop convection and pick up moisture from the sea to create snowfall.

It can snow with T850s of just below zero. Experienced it once in the U.K. when I was in Ipswich as the zero line didn’t get over to the extreme east. 

Edited by mulzy
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Posted
  • Location: Hernia Bay
  • Weather Preferences: Heavy Snow
  • Location: Hernia Bay
11 minutes ago, snowray said:

GFS ensembles for North Midlands, for a change. Operational was a mild outlier quite clearly there. Mean looking very cold indeed around -5/-6c from D4 onwards, lots of snow symbols too.:oldsmile:

graphe_ens3.gif

Where can I find this on the site please 

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