General Model Output Discussion

[BLAST FROM THE PAST]

No worries it's probably a nerve shredding time for many members with the chance of the best wintry spell for over 30 years so close.

The actual high is really a red herring here, what delivers the Scandi high is the ridge backing west coupled with the southern european low, the Greenland high actually will sink and become absorbed in all the output, it looks on first sight on some of the output that this high edges ne, it does indeed just act as a buffer to the west, with the jet pattern northern arm right the way north running west to east, the southern arm with good energy in it as can be seen by that southern european low and the Atlantic trough disrupting, its a split flow pattern.

http://www.meteo.psu.edu/~gadomski/ECMWF_0z/hgtcomp.html

If you look here notice how the jet splits to the west of the UK with the energy distributed between the northern and southern arms of the jet.

Indeed Nick HP to the NE forms and backs west. The pattern shows retrograde down the line prolonging the cold. I believe another GHP would develop again after the easterly thrust....but so much to get through until then. Those currently with a nice snowcover will keep that for a couple of weeks yet. Agree to re the UKMO model, not a sinker and would develop to produce the easterly. Very cold pattern locked in now. I'll stretch to say the cold pattern will last 2/3rds Jan with last 7-10 days bringing less cold air in.....but certainly an awful lot of people will be wishing for milder air to come the time this cold setup starts to breakdown. Anticipate that there could be quite a few 'local' snow upgrades over the coming days.

Just to throw in interesting re GPs tentative thoughts re Feb...that is in line with RJS and my thoughts in our winter LRF....but having said that that month at time of posting had the most mixed signals and was the most uncertain of the months...it still is...and its so far away...who cares.

Been to get milk, cold.

BFTP

Edited January 2, 2010 by BLAST FROM THE PAST

[Guest North Sea Snow Convection]

No worries it's probably a nerve shredding time for many members with the chance of the best wintry spell for over 30 years so close.

The actual high is really a red herring here, what delivers the Scandi high is the ridge backing west coupled with the southern european low, the Greenland high actually will sink and become absorbed in all the output, it looks on first sight on some of the output that this high edges ne, it does indeed just act as a buffer to the west, with the jet pattern northern arm right the way north running west to east, the southern arm with good energy in it as can be seen by that southern european low and the Atlantic trough disrupting, its a split flow pattern.

http://www.meteo.psu...0z/hgtcomp.html

If you look here notice how the jet splits to the west of the UK with the energy distributed between the northern and southern arms of the jet.

Morning nick

need I say more!?....

As many have said, something for everyone in the model output this morning.

On thing to bear in mind is that with the much less marginal conditions we are going to see for a change, it means that the roads etc will be better due to the dry nature of the snow. One reason why countries like Canada and the northern european continent copes better than we do

[SteveB]

Morning nick

need I say more!?....

As many have said, something for everyone in the model output this morning.

On thing to bear in mind is that with the much less marginal conditions we are going to see for a change, it means that the roads etc will be better due to the dry nature of the snow. One reason why countries like Canada and the northern european continent copes better than we do

Yep ice shouldn't be a problem from now on in either.

[kold weather]

I agree blast IF we can get the upper high far enough west then in the end I'd expect an attempt to link up back to Greenland, probably between the 15-20th...

Anyway the set-up between 120-144 and the easterly has suddenly become much more dodgy...the whole lot now sets-up a good bit further east on the models and we need it to come somewhat back westwards to really drag the cold easterly air in.

As per yesterday, its going to be bitterly cold regardless of the evolution but I'm never happy depending on that sort of set-up to get to the evolution we want.

Make no mistake however, these runs are yet again quite insane!

[BLAST FROM THE PAST]

I agree blast IF we can get the upper high far enough west then in the end I'd expect an attempt to link up back to Greenland, probably between the 15-20th...

Anyway the set-up between 120-144 and the easterly has suddenly become much more dodgy...the whole lot now sets-up a good bit further east on the models and we need it to come somewhat back westwards to really drag the cold easterly air in.

As per yesterday, its going to be bitterly cold regardless of the evolution but I'm never happy depending on that sort of set-up to get to the evolution we want.

Make no mistake however, these runs are yet again quite insane!

Its the details that will change indeed BUT not unreasonable to anticipate the stronger easterly flow option [not in this type of cold pattern], but it seems the overall evolution is panned out before us. I agree with your timings re 15-20, I have earmarked that as a very snowy/disturbed time for the south...basically HP to north with southerly tracking LPs [breakdown attempt].

BFTP

[TEITS]

Amazing consistency from the GFS with regards to blocking in F.I. This is very unusual for the GFS because it does have a tendancy of underestimating blocking. Based on the GFS runs and the ECM ensembles there is very little sign of a breakdown of our cold spell.

[East Herts Snow]

Amazing consistency from the GFS with regards to blocking in F.I. This is very unusual for the GFS because it does have a tendancy of underestimating blocking. Based on the GFS runs and the ECM ensembles there is very little sign of a breakdown of our cold spell.

Must admit I'm surprised there is no ramping for +192 hours onwards. The Denmark low slips SW and produces a heavy snowfall set-up for most areas.

This is really starting to remind me of the 7/8th February 1991 setup, where a low tracked Westwards along the English Channel and produced heavy snowfall for many areas.

However this is in the lower resolution run and purely FI, but could this be a more likely outcome?

Edited January 2, 2010 by North Londoner

[TEITS]

Must admit I'm surprised there is no ramping for +192 hours onwards. Continous heavy snowfall set-up for most areas.

However this is in the lower resolution run and purely FI, but could this be a more likely outcome?

For me personally there is far too much weather between now and +120 to get through before looking in F.I.

Overall though the short, medium, long term is looking fantastic. Im just happy enough with the +72 hr NE,lys at the moment.

[Duane S.]

Must admit I'm surprised there is no ramping for +192 hours onwards. The Denmark low slips SW and produces a heavy snowfall set-up for most areas.

This is really starting to remind of the 7th February 1991 setup, where a low tracked Westwards along the English Channel and produced heavy snowfall for many areas.

However this is in the lower resolution run and purely FI, but could this be a more likely outcome?

Yes, the ECMWF +192 chart is just awesome. The 00z ECM charts are just about as good as it can get for me.

Question to everyone... I think I know the answer to this but where can I view ECM runs other than the operational?

[East Herts Snow]

Must admit I'm surprised there is no ramping for +192 hours onwards. The Denmark low slips SW and produces a heavy snowfall set-up for most areas.

This is really starting to remind me of the 7/8th February 1991 setup, where a low tracked Westwards along the English Channel and produced heavy snowfall for many areas.

However this is in the lower resolution run and purely FI, but could this be a more likely outcome?

For me personally there is far too much weather between now and +120 to get through before looking in F.I.

Overall though the short, medium, long term is looking fantastic. Im just happy enough with the +72 hr NE,lys at the moment.

This is the chart sert-up I was referring to from 7/8th February 1991 that produced the best snowfall I've ever seen and also the best weather forecast I've ever seen....!

Anyway a long way into FI I know, but this is a possible outcome that the charts are showing at present.

Edited January 2, 2010 by North Londoner

[PB22]

Here's the ECM 00Z ensembles for London:

http://www.meteogrou...e_forecast.html

Looks like becoming windy too as the cold sets in - that would help blow snow well inland.

Edited January 2, 2010 by Paul B

[weather eater]

For me personally there is far too much weather between now and +120 to get through before looking in F.I.

Overall though the short, medium, long term is looking fantastic. Im just happy enough with the +72 hr NE,lys at the moment.

Absolutely, an inch of snow this morning here not forecast. The Easterly looking much more likely now, very pleasantly surprised to see the ECM this morning had upgraded this, however lots to get through before then and lots of detail changes to come with how that easterly sets up.

[BarnetBlizzard]

This is the chart sert-up I was referring to from 7/8th February 1991 that produced the best snowfall I've ever seen and also the best weather forecast I've ever seen....!

Anyway a long way into FI I know, but this is a possible outcome that the charts are showing at present.

The forcast is legendary . But that easterly looked perfect. Tight isobars, perfect wind direction and im pretty sure those upper temps were very low. Also those temperatures were ridiculous, not often you see dover the coldest place in the uk with a max of -5. I believe easterlies can bring the coldest and snowiest weather over the UK.

[Duane S.]

Here's the ECM 00Z ensembles for London:

http://www.meteogrou...e_forecast.html

Looks like becoming windy too as the cold sets in - that would help blow snow well inland.

look at the incredible model divergence between GFS and ECM for Stockholm! Can't be right can it?

[kold weather]

Well the ECM would be a stunning set-up, no doubt there would be a big snowfall event in the south, the GFS shows a broadly similar evolution...

However the simple facts are regardless of the exacts of the set-up we will have a very cold airmass above the UK and thus the very good agreement on the cold setup from the models and esp the ECM ensembles.

Ps, I'd love to see what the control run does to get that cold, must be a 1987 re-duex I'd imagine...

[PB22]

look at the incredible model divergence between GFS and ECM for Stockholm! Can't be right can it?

It is a strange one! Not sure what that is all about, but wouldn't have thought its right. Here's the Stockholm 2m temperature ensemble from Wetter:

http://www.wzkarten.de/pics/MT2_Stockholm_ens.png

[If Wishes made Weather]

Morning nick

need I say more!?....

As many have said, something for everyone in the model output this morning.

On thing to bear in mind is that with the much less marginal conditions we are going to see for a change, it means that the roads etc will be better due to the dry nature of the snow. One reason why countries like Canada and the northern european continent copes better than we do

.. and the other reasons being that snow tyres are compulsory (we have two sets of wheels and tyres for the car) and - completely inexplicable in lowland UK world - deicing is only done on major routes, on other routes loose snow is ploughed off, and 3mm grit is spread onto the remaining packed snow and you are expected to be able to drive on it.

[PB22]

Another stunning set of ensembles from the 06Z GFS:

http://91.121.94.83/modeles/gens/graphe_ens3.php?x=356&ext=1&y=92&run=6&runpara=0 (for East Anglia)

Worth noting that two days ago the mean rose back above -5C on the 11th, this morning that has been put back to the 15th.

[karyo]

The models are looking fantastic for a prolonged cold spell!

Regarding the precipitation forecasts, I am amazed by how bad the ECM can be at even a short range. It didn't pick up the signal for todays streamer over northwest England. The gfs picked it up only yesterday but underestimated the intensity of it!

Now I am sitting pretty on 2cms of fresh snow!

Karyo

[Cloud 10]

The models are looking fantastic for a prolonged cold spell!

Regarding the precipitation forecasts, I am amazed by how bad the ECM can be at even a short range. It didn't pick up the signal for todays streamer over northwest England. The gfs picked it up only yesterday but underestimated the intensity of it!

Now I am sitting pretty on 2cms of fresh snow!

Karyo

Do you have a link for the ecm short range precip?

[Frosty.]

Another stunning set of ensembles from the 06Z GFS:

http://91.121.94.83/modeles/gens/graphe_ens3.php?x=356&ext=1&y=92&run=6&runpara=0 (for East Anglia)

Worth noting that two days ago the mean rose back above -5C on the 11th, this morning that has been put back to the 15th.

Hi Paul,

This is incredible, we are on the cusp of a severe wintry outbreak through next week and even this weekend is cold & wintry already. Next week looks like producing a lot of disruptive snowfalls in most of the uk and with strong winds at times there will be drifting, the model agreement is stunning for a continuation of the very cold weather into the following week as well with a scandi high, people talk a lot about Jan 1987 but this wintry outbreak currently looks as though it will last much longer than that spell.

[meerkat63]

Regarding the precipitation forecasts, I am amazed by how bad the ECM can be at even a short range. It didn't pick up the signal for todays streamer over northwest England. The gfs picked it up only yesterday but underestimated the intensity of it!

Karyo

To be fair the ECM is not a short-range forecasting tool. It was not designed for that purpose.

The ECM is a medium-range forecasting model best utilized for the 72 - 168hrs range if I am not mistaken.

Edited January 2, 2010 by winterman

[karyo]

Do you have a link for the ecm short range precip?

Here it is: http://en.vedur.is/weather/forecasts/atlantic/#type=prec

Karyo

[Duane S.]

Hi Paul,

This is incredible, we are on the cusp of a severe wintry outbreak through next week and even this weekend is cold & wintry already. Next week looks like producing a lot of disruptive snowfalls in most of the uk and with strong winds at times there will be drifting, the model agreement is stunning for a continuation of the very cold weather into the following week as well with a scandi high, people talk a lot about Jan 1987 but this wintry outbreak currently looks as though it will last much longer than that spell.

That is the beauty with this setup. Unlike Jan 1987 which was outrageous in terms of its severity but was over fairly quickly, this pattern should keep us 'locked in' for at least 10 days I would say. Exciting times lie ahead.

[cheeky_monkey]

oh the irony of it all...there is me looking to go back to Canada in the next 2 weeks and the model outputs could mean i get stuck in the UK due to cold and snow ..im tempted to hang on in the Uk until the end of January just to see if it all pans out?

Edited January 2, 2010 by cheeky_monkey