General Model Output Discussion:

[snowking]

Let me get this straight you believe the gfs 06hrs run over the ecm and the general model guidance!and anyway this would bring major snow and is totally different to this low currently as its running into cold air embedded at the surface, anyway i don't know why i'm even talking about this gfs run as it pulls the block too far west and so is rubbish and won't verify.

The other thing that makes me laugh Nick is that this poster clearly hasnt got the concept of embedded cold, or, for example, even taken the time to look at something such as dew points as the LP moves in:

http://www.wetterzentrale.de/pics/Rmgfs1328.gif

This is obviously indicative of the fact that away from the very far SW the cold spell is by no means over

Don't get me wrong, its fantastic to see so many people trying to contribute to the model discussion, but people can't go making claims about the models which they cant substantiate due to lack of knowledge - its not just helpful for everyone else trying to learn

SK

[Cecil Hogmanay Melchett]

it comes good in the end with a huge icelandic low lol.

We get cold whatever happens it seems.

:lol:

[BLAST FROM THE PAST]

I was really just looking for possible snowfalls and temperatures expected from these charts. I've come to realise the outlook can change and who knows but I'm now hearing reference to very cold charts etc etc. BFTP's post looked knowledgable and I thought he could elaborate for me on the output of these charts.

Impossible to say who'll get most snow and when. look at Steve MURR's posts. The very very cold air gets entrenched over the UK, we get Shortwave coming down from Norway, undercutting LP from the SW and further shortwave from NE. Its cold and very snowy for different parts of the UK at different times. 3-5 Jan, 7-10 Jan and 15-20 Jan and 29-31 Jan are dates to watch for. I haven't changed or added these dates [LRF covers this But I am more specific on timings now] as the cold was likely to quickly dig in just after New Year [albeit up north has remained cold] For me this pattern is driven from external forcing and prolonged cold are the signals.

BFTP

Edited December 30, 2009 by BLAST FROM THE PAST

[bluearmy]

here's a thought.

i know you all hate the 'xmas data' stuff but there might be something in it.

brian on TWO (maybe paul can verify this) commented that the xmas day runs were short on flight data. (yes, i know someone posted that there are plenty of xas day flights but this info was from the initialistation dump of the runs). now once we got past xmas, hey presto, the greeny block bacame stronger on the output across all the models and the runs improved for extended cold. the point i am getting to is that brian also mentioned that the 06z run has less flight data info fed into it on a daily basis. am i wrong but did the 06z runs suffer on the previous cold spell with a desire to drop the block faster?

just a thought?

[snowking]

Not sure where your getting marginal from as this is a band of heavy snow across Wales, Midlands, E Anglia.

http://www.wetterzentrale.de/pics/Rtavn1624.png

However I would prefer the 0Z. At +144 the 06Z is very much at odds with the ECM/UKMO.

Its a band of heavy snow right across the south dave, apart from the very far SWern tip where the 850's get above 0c

Dew points else where would be sub 0c widely given the continental feed associated with the LP with embedded cold already established across france

SK

[kold weather]

The 06z synoptics between 192-240hrs is utterly amazing for our location, the PV itself drops a lobe over the UK and we have true Arctic air over the Uk, have a look at the maxes...

http://www.wetterzentrale.de/pics/Rtavn25217.png

Longer range of course the GFS does its usual blowing up the Atlantic low stuff of course as it desperatly tries to bring in milder stuff!

The whole run is a TOTALLY different run from 192hrs from every other model I've seen thus far.

[Guest North Sea Snow Convection]

here's a thought.

i know you all hate the 'xmas data' stuff but there might be something in it.

brian on TWO (maybe paul can verify this) commented that the xmas day runs were short on flight data. (yes, i know someone posted that there are plenty of xas day flights but this info was from the initialistation dump of the runs). now once we got past xmas, hey presto, the greeny block bacame stronger on the output across all the models and the runs improved for extended cold. the point i am getting to is that brian also mentioned that the 06z run has less flight data info fed into it on a daily basis. am i wrong but did the 06z runs suffer on the previous cold spell with a desire to drop the block faster?

just a thought?

I find the GFS 06z output to the be the least reliable one - and that is irrespective of what it is showing. Why this is I wouldn't want to say - or go down a date conspiracy route! Where does Brian get his information from ?

[TEITS]

here's a thought.

i know you all hate the 'xmas data' stuff but there might be something in it.

brian on TWO (maybe paul can verify this) commented that the xmas day runs were short on flight data. (yes, i know someone posted that there are plenty of xas day flights but this info was from the initialistation dump of the runs). now once we got past xmas, hey presto, the greeny block bacame stronger on the output across all the models and the runs improved for extended cold. the point i am getting to is that brian also mentioned that the 06z run has less flight data info fed into it on a daily basis. am i wrong but did the 06z runs suffer on the previous cold spell with a desire to drop the block faster?

just a thought?

Im convinced there is some data lacking in the xmas output. I witnessed this last xmas and this xmas.

Back to the 06Z and this is why I don't like the GFS. At +240 the 06Z replaces HP with a LP system! You wouldn't find such erractic modelling from the likes of the ECM.

Still having said this the 06Z does bring plenty of snow but I prefer the safer more reliable route of the ECM. Also I don't find the 06Z to be one the most reliable runs.

[Lewis]

The 06z synoptics between 192-240hrs is utterly amazing for our location, the PV itself drops a lobe over the UK and we have true Arctic air over the Uk, have a look at the maxes...

http://www.wetterzentrale.de/pics/Rtavn25217.png

Longer range of course the GFS does its usual blowing up the Atlantic low stuff of course as it desperatly tries to bring in milder stuff!

The whole run is a TOTALLY different run from 192hrs from every other model I've seen thus far.

Hi,

Any chance of making your posts more about the whole of the U.K when talking models, and not just the South? You, Steve, are the worst for it lol.

This post will probably get deleted, but all you guys are talking about is the South...

Lewis

[nick sussex]

Can we just get one thing straight here the low progged later in the output is a totally different scenario from the one at present, the current one did not run into embedded cold, as the low moves in it will pull a flow from the east to se from the Continent which will be below freezing with negative dew points but regardless as i said it WILL NOT VERIFY!

[Yeti]

here's a thought.

i know you all hate the 'xmas data' stuff but there might be something in it.

brian on TWO (maybe paul can verify this) commented that the xmas day runs were short on flight data. (yes, i know someone posted that there are plenty of xas day flights but this info was from the initialistation dump of the runs). now once we got past xmas, hey presto, the greeny block bacame stronger on the output across all the models and the runs improved for extended cold. the point i am getting to is that brian also mentioned that the 06z run has less flight data info fed into it on a daily basis. am i wrong but did the 06z runs suffer on the previous cold spell with a desire to drop the block faster?

just a thought?

To be fair, "Brian on TWO" claims that there is missing data every Christmas (or at least every Christmas when the models are disappointing). It's an old favourite here on NW. I've always been suspect of this idea and have never seen any evidence of it myself.

A more likely cause is the established fact that the 6z is the least reliable of all the GFS runs, and that's saying something. Each run has different data fed into it (the 6z will have more of other types of data I should imagine - can't remember the details right now but they are in the guides somewhere).

The NOAA discussion later today should give us an idea of which model is most favoured - yesterday they favoured the GEM/ECM and slated the GFS; hopefully this will continue.

Edited December 30, 2009 by Yeti

[BLAST FROM THE PAST]

Sorry but that is wrong.

If this was 40yrs ago then exactly the same would of happened. The reason yesterday didn't bring widespread, heavy snow is because the front wasn't meeting a very cold pool of air.

I mean this in the nicest possible way but if anyone cannot see how fantastic the model output currently is then im afraid your misreading the models.

So true. I remember Jan 85 in Swansea we were forecast very heavy snow in a strong easterly from a LP approaching from the SW. We woke up to heavy rain. The cold hadn't embedded it self but 5 days later when we had a second strike it was very heavy snow. COLD has to be in place first in a situation like we have just had.

BFTP

[The PIT]

Looking at CFS this indicates a breakdown and a normal service returning around the 11th of Jan. CFS isn't two bad I've being using it for sometime too look a month ahead and I would say around 60% of the time it's pretty close. I've noticed GFS has also picked this up. Anyway a long way in FI so perhaps this will be it's 40% wrong.

As for erratic programming in deep FI yes the ECM does do about changes as much as GFS it's just that people forget about it.

[NorthNorfolkWeather]

Am I alone in being amazed at the average temps shown in the Ensembles. Norfolk has an average close to, or below 0C for 3 to 4 days, and throughout the run never gets any mild air (+8 or above) apart from one member of the ensembles out at T+384.

Only one word for this -- COLD.

[John Snow]

I don't get all the GFS bashing

They called yesterday's event spot on they said that the front would get as far as the north and it did they also said the snow would be marginal and it was so their data can't be that screwed ATM, GFS was the only model that called yesterday right

I think that the "flight data" is just a caveat used by people when a run doesn't suit their agenda

[BarnetBlizzard]

Hi,

Any chance of making your posts more about the whole of the U.K when talking models, and not just the South? You, Steve, are the worst for it lol.

This post will probably get deleted, but all you guys are talking about is the South...

Lewis

I can't see where he mentions the south once. Stop being paranoid.

Anyway, 6z still pretty good. Has a low which on the surface looks pretty similar to the current low. But the cold air will be embedded and the dewpoints and upper air temps will be lower. I find this low will take a more southerly track as the gfs especially the 6z normally makes the low too progressive. Over all, though, the gfs would still be rather tasty!

[Lewis]

I don't get all the GFS bashing

They called yesterday's event spot on they said that the front would get as far as the north and it did they also said the snow would be marginal and it was so their data can't be that screwed ATM, GFS was the only model that called yesterday right

I think that the "flight data" is just a caveat used by people when a run doesn't suit their agenda

Totally agree, the GFS did have yesterday spot on, it was the only model to stick to its guns.

Regarding flight data etc, it's a load of rubbish, people don't like what they see so they make themselves believe its something causing it so they feel better in themselves.

Lewis

[stewfox]

The other thing that makes me laugh Nick is that this poster clearly hasnt got the concept of embedded cold, or, for example, even taken the time to look at something such as dew points as the LP moves in:

http://www.wetterzen...s/Rmgfs1328.gif

This is obviously indicative of the fact that away from the very far SW the cold spell is by no means over

Don't get me wrong, its fantastic to see so many people trying to contribute to the model discussion, but people can't go making claims about the models which they cant substantiate due to lack of knowledge - its not just helpful for everyone else trying to learn

SK

I thought this was a model discussion thread ?. Not a cold ramping thread ?

A mild outlier was spotted and commented on , no need to be nasty about such comments just because you dont want to see/ hear about mild outliers. How many times do we see post of GFS charts of blizzards at T240 or T384.

Post a mild chart at T240 and you would be jump upon as it being 'unreal'

Edited December 30, 2009 by stewfox

[TEITS]

I don't get all the GFS bashing

They called yesterday's event spot on they said that the front would get as far as the north and it did they also said the snow would be marginal and it was so their data can't be that screwed ATM, GFS was the only model that called yesterday right

I think that the "flight data" is just a caveat used by people when a run doesn't suit their agenda

No the GFS didn't call it right until the final hr. The GFS had the LP so far N that my max temps today would of been 7C. However my max temps will be around 3/4.

As for the data issue may I ask did you follow every run of the GFS last xmas and this xmas. If not then to be honest you can't comment. I did and the modelling was very odd indeed but its funny how on the 27th normality resumed.

Sorry but some of the comments on this thread this morning have been very bizzare indeed. The quest of looking for 20ft drifts is causing members to miss the bigger picture. I shall explain why when i've returned from my shower.

[Richie V]

Can we just get one thing straight here the low progged later in the output is a totally different scenario from the one at present, the current one did not run into embedded cold, as the low moves in it will pull a flow from the east to se from the Continent which will be below freezing with negative dew points but regardless as i said it WILL NOT VERIFY!

Do you want to borrow my hammer and chisel :lol:

The 06Z is quite frankly a joke, this would never varify. that low over the southern uk does'nt move dispite the ne flow, how silly. :lol:

[Geordiesnow]

GFS was right in terms of PPN whilst the UKMO for example, had it further South and i would imagine the ECM did aswell, however the GFS placed the low too far north and east but in all honesty, it was not that far off. However ecm/ukmo probably were closer in terms of the lows final position.

This morning's runs are not too bad, the trend as far i can see it is still a cold one in my eyes but i can't see a severe cold spell occuring at the moment.

[Shunter]

The other thing that makes me laugh Nick is that this poster clearly hasnt got the concept of embedded cold, or, for example, even taken the time to look at something such as dew points as the LP moves in:

Don't get me wrong, its fantastic to see so many people trying to contribute to the model discussion, but people can't go making claims about the models which they cant substantiate due to lack of knowledge - its not just helpful for everyone else trying to learn

SK

I fully understand embedded cold scenarios thank you. What I was stating though is that the 06z operational run at T120 brings about a return of what we currently have in the South. The run shows the Trough moving N/ NE bringing in turn warmer dew points and a snow to rain event as it progresses. Yes it is only one run from one model but that is what it shows.

[Iceberg]

Yep that's what the model shows and if it brought day temps of -8 and 1 ft of snow, everybody would be quoting it, as it doesn't it must be wrong :lol:

There has been a trend for the models to bring in more LP more, however the 06Z is certainly over doing it, which brings the happy medium of snow for the south begining of next week and the cold to follow after !.

Yes.....

Edited December 30, 2009 by Iceberg

[kold weather]

Do you want to borrow my hammer and chisel

The 06Z is quite frankly a joke, this would never varify. that low over the southern uk does'nt move dispite the ne flow, how silly.

its not that it can't happen because its what will happen IF the upper high builds a little too far west and the northern part of the complex low is too strong...however even then it would get shunted eastwards in the end as the PV comes down.

Anyway going to have a look at the ensembles, I've not a sneaky feeling the 06z GFS will be at the very least one of the mildest runs for southern areas, further north it'll probably within the mean of the others.

[Guest North Sea Snow Convection]

I fully understand embedded cold scenarios thank you. What I was stating though is that the 06z operational run at T120 brings about a return of what we currently have in the South. The run shows the Trough moving N/ NE bringing in turn warmer dew points and a snow to rain event as it progresses. Yes it is only one run from one model but that is what it shows.

The GFS is I feel wrong on this output, a repeat of this week is very unlikely. Good reasons for this have already been given