General Model Output Discussion

[bluearmy]

how many of us are out later when the T120 FAX comes out??? a much awaited chart methinks. again the general trend is well referred to by steve.

[Turnedoutniceagain]

This may be slightly off topic, but looking at the radar ATM, the showers coming in off the North Sea are clearly organised in lines or bands. Movement of the showers is along the band, as well as the bands moving slowly SE in themselves. What causes this, clearly its not topographic over water?

What sort of Dewpoints are we looking at ??

[weather eater]

Yes the UKMO is very nice, just wish I had more faith in its output past 72hrs. Support from the ECM this evening would certainly give it more weight.

[kold weather]

Yep no denying thats a stunner of a 12z, very cold first 10 days and the next 3-4 days after that don't exactly look much milder, a slower broad evolution as the 06z GFS but with a better middle part to the run thats for sure!

[pyrotech]

Another FANTASTIC set of runs from the models today with a trend continuation of cold with snow chances throughout the period from the North right down to the south east. 528 dam right south of the whole UK in the reliable timeframe. Gfs gets a little progressive maybe in the latter part of the run but its all in Fi and 10 days + of cold before it.

For those like my self down in the southwest there may be some disapointment about the channel low. Yes your short term snow event has slipped and i know myself how we are patiently waiting our first proper snow of the season, BUT that low sinking increases the chancs of a more persistant cold spell and with that chances will occur for snow for all.There was no point in a possible short lived snowfall that then led to less cold. It is a long while since we have seen such a cold spell over us in the UK with it relaunching throughout the recent weeks. Slight changes over the next week will appear and surprise snowfall will occur. The only percipitation charts that really get my notice on events like this are the NAE. Its a great set up for the whole UK and in the short term for Snow the areas above mentioned.

May i wish everyone a happy new year and that 2010 carries on as 2009 ended - Cold with opportunities for snow

Edited December 31, 2009 by pyrotech

[bluearmy]

interestingly, having built a substanbtial polar p/v by T192, the run stuffs a block into the pole from the pacific northwest which blows the p/v apart again. worth watching over the next few runs as its a pattern we've seen several times already this winter.

[kold weather]

Very nice 12z UKMO thats for sure though I'm not sure it would evolve quite as nicely as the GFS does after that point but alas who knows...and really cares to be honest if that comes off!

[weather eater]

Good run from the GFS we open with a GH and we close with one, can't ask for much more than that.

[SMU]

Very nice 12z UKMO thats for sure though I'm not sure it would evolve quite as nicely as the GFS does after that point but alas who knows...and really cares to be honest if that comes off!

Darren Look again at the UKMO 144- the trough over scandi is sinking SW- it will end up pretty much like the 12Z GFS- at 168

People thinking that the timeframe of 144 is FI are very much mistaken tonight- the SLOW cut off jet over Southern Greenland would take some SIGNIFICANT change in proggs to move that anywhere other than favourable for the UK-

168 is the FI tonight-

watch the ensemble agreement out to day 7 especially for the SE ( london ensemble will be very consistent)

Steve

Edited December 31, 2009 by Steve Murr

[kold weather]

Yep bluearmy it somewhat rebuilds the -ve AO yet again and by the end of the run we are back with a upper high back over Greenland...

This is almost exactly the pattern I'm expecting to evolve an its one that has been increasingly hinted at, moving away from the Euro high solution of a few days ago...

Anyway a 10 day cold spell looks nailed on now, possibly extending longer as well, very exciting times it has to be said!

[Iceberg]

The problem though is that the 144Z is quite different to this mornings 144Z, I would like a see a bit of joined up writing between the models, times and ensembles more before I believe, but I hope your right Steve as that would be a good 144 even for Dorset.

[kev238]

Great output-- it is going to be chilly!!!!

I think there will be some unexpected surprises next week once we pull in the North East flow-- and the good things is with temperatures likely to be frigid for at least 10 days anything that falls from the sky is not going to go very far once on the ground.It doesn't take inches of snow to transform a landscape and make it look beautiful!

[Bristawl Si]

An obvious statement from me that the models progging the coldest spell of weather for many a year, but in my view, predominately dry for the first few days. I can only go on past experience of life and that is - there is a 50% chance of pressure falling gradually over the continent to produce snow in the south, increasing amounts of heavy snow showerrs for the east facing coasts, filtering inland if the winds increase or, worst case scenario, stays cold and dry for next 10 days.

I know some of the more learned contributors are saying "Be patient, these cold situs can develop with snow eventually coming", but i remember many a spell like this in my early days where it stayed just cold and dry.

I'm sure the models will give us a better idea of snow developments over the next couple of days' runs, but don't bank on it.

[Optimus Prime]

GFS 12z looks like something from the 1963 winter. Complete reload towards the end.

[kold weather]

Darren Look again at the UKMO 144- the trough over scandi is sinking SW- it will end up pretty much like the 12Z GFS- at 168

People thinking that the timeframe of 144 is FI are very much mistaken tonight- the SLOW cut off jet over Southern Greenland would take some SIGNIFICANT change in proggs to move that anywhere other than favourable for the UK-

168 is the FI tonight-

watch the ensemble agreement out to day 7 especially for the SE ( london ensemble will be very consistent)

Steve

The broad pattern would be similar I agree but its delayed and importantly I think that gives the upper high more scope to sink further southwards, however really the broad pattern would indeed be similar, but IMO not quite as good as the 12z...BUT the 12z GFS for the whole N.Hemisphere is a peach, the 12z UKMO isn't that far from it either really.

Also totally agree about what you say with regards with the evolution, I think its pretty solid myself at the moment, I still also think we will see a eastern -ve NAO develop, but thats some way away yet to be honest!

[cooling climate]

interestingly, having built a substanbtial polar p/v by T192, the run stuffs a block into the pole from the pacific northwest which blows the p/v apart again. worth watching over the next few runs as its a pattern we've seen several times already this winter.

Incredible run from the 12z GFS and yes if as NOAA says a very substanstial +PNA develops over western America

then this is likely to send another strong ridge or block into the Arctic which could well aid in building heights over

Greenland again.

This could very well keep Europe and the UK locked in a very cold pattern.

At the moment though that is way way in the furture and with the models looking to upgrade the upcoming very

cold spell in terms of both cold and snow theres plenty to keep us interested for several days to come at least.

[Mikel Nimbus]

GFS 06z was far too quick in flipping the AO towards positive and was rightly written off on here. 12z has slowed the rate of this progression by about 2 days. I still feel that the GFS has a bit more backtracking to do regarding the high sinking over us next week. This may leave us with the high situated a bit further north, leaving the UK under a slacker flow, but still none the less very cold.

Since I started chart viewing in the BBC snow watch days, I've never seen such incredible cold potential as we have for next week. Some very interesting times ahead.

[winter watcher]

Darren Look again at the UKMO 144- the trough over scandi is sinking SW- it will end up pretty much like the 12Z GFS- at 168

People thinking that the timeframe of 144 is FI are very much mistaken tonight- the SLOW cut off jet over Southern Greenland would take some SIGNIFICANT change in proggs to move that anywhere other than favourable for the UK-

168 is the FI tonight-

watch the ensemble agreement out to day 7 especially for the SE ( london ensemble will be very consistent)

Steve

Steve what chances would you rate the gfs and the ukmo being on the money? Because up to now i thought both models was being over progressive and inconstant a few members kept saying stick with the ECM AND GEM

[SMU]

And there we have it guys- probably the first time in the internet history-

http://91.121.94.83/modeles/gens/run/gens-21-0-180.png?12

ENSEMBLE MEAN at 180 thats day 8 has -12C touching London-

END

S

[Rob]

And there we have it guys- probably the first time in the internet history-

http://91.121.94.83/...21-0-180.png?12

ENSEMBLE MEAN at 180 thats day 8 has -12C touching London-

END

S

That is, i have to say a dream chart!

[❄️❄️❄️❄️❄️❄️❄️❄️❄️]

And there we have it guys- probably the first time in the internet history-

http://91.121.94.83/modeles/gens/run/gens-21-0-180.png?12

ENSEMBLE MEAN at 180 thats day 8 has -12C touching London-

END

S

Sorry to put a downer on it, but that chart shows the -12 isotherm not even touching the south east.

Not too shabby though!

[J10]

An obvious precipitation upgrade on the 12Z. I also believe that precipitation is modelled to be convective rather than frontal, but with the low being progged further west with each run, it creates a more prominent westerly flow for western areas early on the 2nd, and then a more prominent cold easterly flow for eastern areas late on the 2nd and through to the 4th. The result- an easterly loaded with convection instead of a mainly dry one.

The snow upgrades mainly concern eastern areas because in the west, the westerlies draw in slightly more modified air making conditions more marginal out towards western coasts especially for Wales and south-west England.

Certainly willing to take the risk, certainty the chance of (light) overnight snow from that. Seems a very similar setup to the one that give around an inch of snow a few days before Christmas.

Overall I think it's a belter of a run, very encouraging to see the GFS trending towards the ECM, and even with the milder looking upper temps towards the end of the run, it would stay cold right throughout to T+384. As for the Greenland High, it is trying to retain its influence as well.

[SMU]

Steve what chances would you rate the gfs and the ukmo being on the money? Because up to now i thought both models was being over progressive and inconstant a few members kept saying stick with the ECM AND GEM

90%- very high

UKMO looks a little progressive & deep with the shortwave at 144, this has unanamous model agreement- wait to you see the London ensembles- they will be tightly clustered-

S

[❄️❄️❄️❄️❄️❄️❄️❄️❄️]

90%- very high

UKMO looks a little progressive & deep with the shortwave at 144, this has unanamous model agreement- wait to you see the London ensembles- they will be tightly clustered-

S

Indeed, a small spread

Edited December 31, 2009 by RAIN RAIN RAIN

[phil nw.]

The projected NHemisphere pattern for the next few days is just about perfect for the coldest air to reach us along with severe frosts and bands of snow for many.

Short waves and minor disturbances forming in the bitter Polar continental air being ejected by the Scandi trough,here at different points,-NE and E.Scotland first in line.

http://www.wetterzentrale.de/pics/Rtavn481.png

http://www.wetterzentrale.de/pics/Rtavn721.png

http://www.wetterzentrale.de/pics/Rtavn1201.png

That`s the sort of setup needed to get cold and unstable air.

In this situation snow showers or even longer spells of snow can appear at relatively short notice so these will not always show up on the models.

The UKMO is none too shabby either.

http://www.wetterzentrale.de/pics/Rukm1201.gif

Remarkable sypnotics.

Edited December 31, 2009 by phil n.warks.