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Posted
  • Location: nr Guildford, surrey
  • Location: nr Guildford, surrey

Looks like the death Knell for the cold weather if the 12z GFS is to be believed , can't believe the difference between the 06z and the 12z...why would 2 runs be so different

Because it probably doesnt know what is going to happen

it could be right but sense it will be slower than that

I reckon the Atlantic may make a push but is not this year guaranteed to win. Expect a period of swinging output for a while

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Posted
  • Location: Cwmparc, South Wales.
  • Location: Cwmparc, South Wales.

Not true Derry

What the Fax charts show is the upper air starting to warm out, hence the 'upper' warm font shown on 1 or 2 of them, then the main frontal zone is show on the T+120 as pretty well along the south coast.Nick F makes similar comment in his blog and is correct.

This has been, already, the longest and coldest spell over much of the country for perhaps 20+ years.

Once really cold air gets settled, believe me, its unlikely that the first Atlantic push will bring milder, let alone, 'blow torch' air rushing over the UK.

It may well make it into some SW'ern coastal areas, might, but as to the end of the cold spell by Wednesday-no chance.

What happens beyond it is very much up in the air in my view.

The forecast for the start into the middle of next week is a forecasters, just about, worst nightmare.

Very cold surface air, only slowly being modified with moist warm air over the top. How far, will any genuinely mild air get at the surface, will it snow, will it be freezing rain, how much, for how long, and will the cold push the mild back again.

Like I say a forecasters nightmare after the relatively easy bit of the past 4-5 days!

Many thanks for that John....

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Posted
  • Location: Dorset
  • Location: Dorset

And the number of 00Z ECM ensembles that agreed with GFS ops run at 144 is.......0 out of 50. enough said IMO

And the number of 06Z GFS ensembles that agree with the GFS ops run at 144(taking Dorset as the example) is.....0. Enough said again !

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Posted
  • Location: st albans
  • Location: st albans

the ens mean T180 from GEFS shows a scandi block tilted nw/se and an atlantic trough similarly nw/se into italy with a draw of se winds ahead of the trough. into the low res and the block sinks se with the draw becoming slack s and then sw. dont really care too much for low res GEFS apart from when its together with the GEM ens in the NAEFS whereby the 50 runs on offer help add a bit of validity.

anyway, looking at the GEFS, the cold wouldnt 'relax' its grip next week and the chance of a big snow event increases along with the chance of any breakdown.

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Posted
  • Location: Haverfordwest Pembs
  • Location: Haverfordwest Pembs

I'm very much in the amateur section here, still, I'd be pretty surprised if we got anything but snow from the Sunday event given that is happens,and considering the fax and where the air is coming from, you could expect snow from that in a normal winter never mind an entirely sub zero European landmass that we have now. If I had to make a bet I would be putting the stake on the white stuff.

(Of course, when cooking I put the white stuff on the steak!) :pardon:

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Posted
  • Location: Wigan 259 ft ASL where it always rains
  • Weather Preferences: Hot Sun ,Snow and Cold
  • Location: Wigan 259 ft ASL where it always rains

oh and for those 'looks like the end of the cold spell' comments based on comparing 06-12z or any other 2 consecutive runs - I no longer make comment about those of you that do that.

tears and toys out of prams so many many times over the past years as well!

I was merely making a comment that if you believe the 12z then it's all over , but made a comment that the 2 runs were like chalk and cheese ...if thats not what is wanted on here then i'm sorry..but i thought that this thread was about comment on models

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Posted
  • Location: G.Manchester
  • Location: G.Manchester

I was merely making a comment that if you believe the 12z then it's all over , but made a comment that the 2 runs were like chalk and cheese ...if thats not what is wanted on here then i'm sorry..but i thought that this thread was about comment on models

There is the indepth model discussion for hope casting a break in the cold. Every single post (from the usual gang) is about "it's going to break down xxxx" while the rest of us are trying to look at things more logically. There are more compressing issues to worry about over the weekend and the start of next week. I suggest if you are serious about the end of next week and beyond, the indepth discussion is where you should be posting your prognosis for that far ahead.

For the record the AO doesn't support mild'er conditions until the 16th.

In the immediate future it's very cold, record breaking temperatures. More snowfall and although minima may be less cold in the south over the weekend the wind will make the frtost very penetrating.

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Posted
  • Location: Worcestershire
  • Weather Preferences: Forecaster Centaurea Weather
  • Location: Worcestershire

I would recommend a quick look at 850 hPa temperatures for UKMO, GEM, GME and NOGAPS. They hold the cold pool in place and set up a potentially very snowy period with lows generally passing to the south of the UK, in line with broad hemispheric ensemble mean guidance.

Most models programme sub -5 850 values throughout, indeed there is a reintroduction of -12C air from the near continent t96-t120 coinciding with the attempted attack from the SW.

Edited by Glacier Point
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Posted
  • Location: Ware, Herts
  • Location: Ware, Herts

The GFS control run is very similar to the ECM and 06z GFS op - high building again over Greenland, high pressure over Iceland and northern UK and over Scandinivia, with low pressure forced south of and over the south of Britain.

This keeps up the E/SE flow up until +180.

Also - anyone else having problems with meteociel? The site is very slow and sometimes isn't working at all. Is there anywhere else I can get my charts?

Edited by Tommyd1258
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Posted
  • Location: Scarborough, North Yorkshire
  • Location: Scarborough, North Yorkshire

I would recommend a quick look at 850 hPa temperatures for UKMO, GEM, GME and NOGAPS. They hold the cold pool in place and set up a potentially very snowy period with lows generally passing to the south of the UK, in line with broad hemispheric ensemble mean guidance.

Most models programme sub -5 850 values throughout, indeed there is a reintroduction of -12C air from the near continent t96-t120 coinciding with the attempted attack from the SW.

Yes looks cold for the RELIABLE time frame. Lots of posts about a breakdown which is FI. Long way to go yet.

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Posted
  • Location: Wigan 259 ft ASL where it always rains
  • Weather Preferences: Hot Sun ,Snow and Cold
  • Location: Wigan 259 ft ASL where it always rains

There is the indepth model discussion for hope casting a break in the cold. Every single post (from the usual gang) is about "it's going to break down xxxx" while the rest of us are trying to look at things more logically. There are more compressing issues to worry about over the weekend and the start of next week. I suggest if you are serious about the end of next week and beyond, the indepth discussion is where you should be posting your prognosis for that far ahead.

For the record the AO doesn't support mild'er conditions until the 16th.

In the immediate future it's very cold, record breaking temperatures. More snowfall and although minima may be less cold in the south over the weekend the wind will make the frtost very penetrating.

And i for one will be happy if it doesn't end yet....I can't believe that discussion is so difficult and that people have to resort to 'dissing' less technically au fait members :unsure:

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Posted
  • Location: East Anglia
  • Location: East Anglia

I was merely making a comment that if you believe the 12z then it's all over , but made a comment that the 2 runs were like chalk and cheese ...if thats not what is wanted on here then i'm sorry..but i thought that this thread was about comment on models

It is, but we need to beware of talking about each run as if it supersedes all previous output, not a comment aimed at you I hasten to add. We see the comment, “if this run verifies” far to often in the model threads, I try to look at all recent model runs in an attempt to build up a picture of future events, I never look at any run believing that it will come off. So taking the 12z run as it stands at the moment then it looks out of kilter with the other models and the GFS models own recent out, this may change but I don’t think it can yet be called a trend or even be seen as the start of one.

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Posted
  • Location: Wigan 259 ft ASL where it always rains
  • Weather Preferences: Hot Sun ,Snow and Cold
  • Location: Wigan 259 ft ASL where it always rains

It is, but we need to beware of talking about each run as if it supersedes all previous output, not a comment aimed at you I hasten to add. We see the comment, "if this run verifies" far to often in the model threads, I try to look at all recent model runs in an attempt to build up a picture of future events, I never look at any run believing that it will come off. So taking the 12z run as it stands at the moment then it looks out of kilter with the other models and the GFS models own recent out, this may change but I don't think it can yet be called a trend or even be seen as the start of one.

... i was only trying to encourage discussion and find answers as to why 2 runs can be so different

Thanks

Ian :unsure:

Edited by Spurry
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Posted
  • Location: Devizes Wiltshire
  • Location: Devizes Wiltshire

waiting for ian to come on and hopefully shed more light on to sundays event. but i belive sunday holds a lot of potential.

Edited by lfcdude
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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)

Come on guys this is model discussion ... photos and media weather forecasts aren't really needed in here!

Be intersting to see the path ECM takes, I feel that it will go for the trough disruption route with Atlantic low pressure sliding east to the south of the UK, with the block maintaining over the north of the uk ...

As for Sunday, looks like a fair bit of snow progged over southern England by UKMO.

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Posted
  • Location: Weardale 300m asl
  • Weather Preferences: Snow
  • Location: Weardale 300m asl

I was merely making a comment that if you believe the 12z then it's all over , but made a comment that the 2 runs were like chalk and cheese ...if thats not what is wanted on here then i'm sorry..but i thought that this thread was about comment on models

Models are mathematical algorithms which spew out variations on the data fed into them… John Holmes is an experienced and practical forecaster, with 30+ years as a pro weather forecaster. Comment on the models sure, but don't take them as gospel — there's a lot of interpretation involved and we are very lucky to have JH around.

The facts are that cold air is denser and 'thicker'. Once embedded (the whole of the country's white with snow and will have been for well over a week by Wednesday) it takes quite a lot of wellie to shift it and if the 12z shows that happening overnight, it's plain wrong.

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Posted
  • Location: East Anglia
  • Location: East Anglia

... i was only trying to encourage discussion and find answers as to why 2 runs can be so different

Thanks

Ian :cray:

No problem with that on my part. As to why two runs can be so different, I would say because the models are not as good as some think they are. That's not say they are not very good, given the complexities involved I'd say they do a pretty good job. The main problem seems to come about because some insisted on taking each new run as much more likely than the last.

Edited by weather eater
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Posted
  • Location: Home :Peterborough Work : St Ives
  • Location: Home :Peterborough Work : St Ives

Francis Wilson stated quite categorically that the cold weather will end on either the 19th or 20th of this month. Why at this stage would he make a statement like that if he didnt have access to far superior charts than on here? Sky news 2 hours ago.

The met office have a finer resolution model but that does not go out to anywhere near 12 days. No model can be that specific. GFS does go out that far but to take it as gospel borders IMO as lunacy

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Posted
  • Location: Weston Super Mare , North Somerset
  • Location: Weston Super Mare , North Somerset

So, the broad theme from tonight's UKMO and GFS for mid-week next week is an attack from the Atlantic with milder air trying to nudge in from the SW but cold air in place over UK will put up a battle. UKMO looks more likely IMO than GFS in that the trough/low arriving to the SW stalls with the low held back - the trough would eventually disrupt with low pressure sliding E over the continent with the block to the northeast maintaining the status quo with the cold easterly or southeasterly feed continuing.

The difference being though Nick , the UKMO looks a little strange , where you would expect the model to send this South , it actually pushes this low back West and let's the Scandi High take control, Not a bad run from the UKMO in my opinion , it keeps options open anyway .

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Posted
  • Location: Milltimber, Aberdeen ~ 80m asl
  • Location: Milltimber, Aberdeen ~ 80m asl

Francis Wilson stated quite categorically that the cold weather will end on either the 19th or 20th of this month. Why at this stage would he make a statement like that if he didnt have access to far superior charts than on here? Sky news 2 hours ago.

Seems a foolish thing to say IMHO. Given how many days away that is, no one can be certain what will happen. If this cold spell is to go into the second half of the month I do however think we need to see pressure re-building over GL. I can see the Scandi block slowly eroding away otherwise, introducing mild S’ly or SW’ly winds.

The ECM is starting to come out now – will be interesting to see what it shows for the 120-144hrs time zone.

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Posted
  • Location: Kesgrave, just East of Ipswich
  • Weather Preferences: April!
  • Location: Kesgrave, just East of Ipswich

I don't claim to be an expert when it comes to the models but all I will say is that earlier this week, the GFS was having none of this weekend's Easterly and kept placing the High bang on top of us (with the exception of the far SE). Therefore, I'm not buying this quick breakdown next week unless it is supported by the ECM in particular.

I'm with Nick S on the GFS recent record; it always seems to be playing catch up to the Euro models.

Edited by Chalk Serpent
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Posted
  • Location: Kesgrave, just East of Ipswich
  • Weather Preferences: April!
  • Location: Kesgrave, just East of Ipswich

Just a quick question to all the experts out there; the 12Z GFS snow risk charts show a lessening of the risk for all of the south as the ppn feature comes in on Sunday. All the 90%+ figures are replaced with 60-70% ones. All those nice purples are replaced by oranges!

Is this is a sign of possible marginality due to slightly higher upper temps or is the GFS just having a wobble? :rolleyes:

Thanks!

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Off topic I know, but I'm really missing the input from our more 'valued' members, one or two are dropping in now and then which is appreciated, but certainly not with the frequency I have become accustomed to over the years. It's a real shame, but I can perhaps understand why they are not frequenting this thread at the moment.

ecm looking good!! very good out to 144

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Posted
  • Location: nr Guildford, surrey
  • Location: nr Guildford, surrey

ECM not going with the GFS from what I can gather from the charts [which I dont know how to post], looks as though the lows are further west and may end up forced under the block

so I wouldnt be writing off this spell just yet whistling.gif

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