General Model Output Discussion

[kold weather]

Marginal for the south coast but once your a little inland in the set-up the GFS is prediciting there is nothing at all marginal about it...

After Tuesday as TWs has said looks like we evolve into a slacker, drier but very cold set-up, the classic severe cold month type set-up that sees temps struggling upto freezing even with clear sunshine thanks to severe overnight mins.

[SP1986]

I honestly can't see it being dry with a chart set up like this and low pressure around.

Indeed, if that chart did come off there would be localised areas of very intense precipitation around, snow in this case which would locally lead to very signifiant accumulations! Unfortunately I fully expect that particularly chart to have changed considerably by the time the output date comes around.

[Methuselah]

I do think this chart will evolve and probably end up distincly different that shown there, as Ian said it's still evolving, lots of small, but minute details that will prove important in the coming days. The model output are subtly changing every day, this is the latest in a line.

Maybe yes, Ste - but maybe no...Should that slack LP pan-out, there'll be pockets of freezing-fog and some VERY low minima??? But I do agree - it's an evolving picture...

[Iceberg]

Meto is out and is pretty good still.

It builds a very quick 1030 Scandy high at 144Z, which is totally against GFS at that time range, so definately as others have said things far from settled.

[Barb]

Monday on it looks very messy - virtually anything could happen with these charts.

[Duncan McAlister]

Looks like a potential E'ly reload at the end of the run but completely irrelevant. Looks like fun and games for the weekend and early next week, it's Scotland's turn :lol:

[Upgrade]

Stephen, I fear you are about to be visited by the ghosts of Christmas past, present and future if you don't change your grumpy ways soon.

I should know.

The models have upgraded / lenthened the spell so i expect we could see some very cold and snowy weather before we're done. Its the timing that isnt nailed yet.

[sandstorm2]

Meto is out and is pretty good still.

It builds a very quick 1030 Scandy high at 144Z, which is totally against GFS at that time range, so definately as others have said things far from settled.

is that the latest 1200 charts? and if so could you give me a link, thanks

SS2

[Eugene]

What an incredible run even christmas day looks cold and we don't see double figures until dec 28th, just shows you how that deep cold will affect us even with comparatively mild uppers getting in the mix it does'nt really warm up much at all :lol:

Then we get a HP block forming just after the 28th

[Nick B]

Stephen, I fear you are about to be visited by the ghosts of Christmas past, present and future if you don't change your grumpy ways soon.

I should know.

I don't think he's actually being grumpy. The slacker the flow and the larger the central area of pressure, surely the more likely in this timeframe that the models will handle the data differently between now and the verification date and throw up something quite different looking. And I'm sure neither he nor I would necessarily mean less snowy or favourable for extended cold prospects. Just different.

[Iceberg]

is that the latest 1200 charts? and if so could you give me a link, thanks

SS2

http://www.meteociel.fr/modeles/ukmo2.php?carte=1594&ech=6

Cheers

[SP1986]

All this proves is if you dont shout snow from the rooftops, you're a criminal! - seriously there was no grumpiness there, grumpy would have been something like this: No chance of snow for the coming weekend or next week,, waste of time etc etc.

hmmm!

[Osbourne One-Nil]

All this proves is if you dont shout snow from the rooftops, you're a criminal! - seriously there was no grumpiness there, grumpy would have been something like this: No chance of snow for the coming weekend or next week,, waste of time etc etc.

hmmm!

Joke Stephen. I thought you knew me well enough by now.

[kold weather]

Not a great end to the 12z UKMO for the south but by that time we'd have been in a very sustained cold and hopefully snowy spell so it wouldn't be too depressing if it came off.

[cooling climate]

I am becoming more and more convinced that we will go into Christmas in a cold or very cold

set up.The models seem to be back tracking on bringing in any milder weather and I could

definitely see the UK back in a continental airflow by the time Christmas is here.

Back to the here and now and the charts in the reliable time frame are again excellent you can

really get complacent looking at these fantastic synoptics the last several days, forgetting how

many duff winters have gone by dreaming of charts like these that are evolving as we speak.

[SP1986]

I'm getting there, slowly! Besides I have a cold, so I suppose I am a bit grumpy today!

Just need a nice fall of snow to get rid of the grumpiness.

[karyo]

Obviously there is a lot of excitement for the next few days but I have to say I don't like the UKMO from 120 hours onwards! Many people discredited yesterday (it was the 144 hours chart then) but it has stuck with the same idea of the low coming from the southwest. Also look at the pressure rising over the Med and later central Europe promoting a southwesterly warm up there!

By 144hours it is evident that the Greenland high is moving westwards hence the risk of us getting locked into a southwesterly pattern, at least for a time!

http://www.meteociel.fr/modeles/ukmo2.php?nh=&ech=120&carte=1021

http://www.meteociel.fr/modeles/ukmo2.php?nh=&ech=144&carte=1021

Karyo

[Bottesford]

.... and back to the models or we will get our big deleting fingers out hehe...

[Thundery wintry showers]

The one possible evolution to a milder pattern around Christmas that we need to be wary of is the low slipping SW to our west and dragging warmer air up from the south, on the eastern flank of the southerly tracking jet, which is what UKMO hints at. GFS also shows this but way out at T+180. The UKMO output, to me, though, keeps us (just) in the cold air at T+144 except the extreme south.

[Upgrade]

The one possible evolution to a milder pattern around Christmas that we need to be wary of is the low slipping SW to our west and dragging warmer air up from the south, on the eastern flank of the southerly tracking jet, which is what UKMO hints at. GFS also shows this but way out at T+180. The UKMO output, to me, though, keeps us (just) in the cold air at T+144 except the extreme south.

on the balance of the models though , the majority are in favour of cold remaining and winning out, for longer.

[MR EXTREMES]

The one possible evolution to a milder pattern around Christmas that we need to be wary of is the low slipping SW to our west and dragging warmer air up from the south, on the eastern flank of the southerly tracking jet, which is what UKMO hints at. GFS also shows this but way out at T+180. The UKMO output, to me, though, keeps us (just) in the cold air at T+144 except the extreme south.

but is it not even colder to our south?

[andy_leics22]

12z run really downgrades the snow potential for the Midlands tomorrow and Friday. I hope it changes for the better again in the next 12-24 hours.

[kold weather]

Yeah TWS, FWIW quite a few GFS ensemble members suggest this is a possible evolution, would stil lbe cold for pretty much all of us, but very marginal in the south...

There is still clear disagreement from 120hrs onwards however and this could yet evolve any way imaginable, the south is most prone whilst for Scotland I'd have thought it'd take a mightly impressive push for you guys to warm up for xmas.

[Reading FC]

12z run really downgrades the snow potential for the Midlands tomorrow and Friday. I hope it changes for the better again in the next 12-24 hours.

Have to agree with that - I just can't see any significant PPN coming into the frame. Neither can I on the next few days just some light stuff now and again but nothing heavy. Happy for someone to prove otherwise but what I'm looking at just doesn't show it!

[Thundery wintry showers]

I agree that the general trend has been towards the cold air hanging on until after Christmas, especially in the north, and it may still continue to be that way. I am tending towards the view that a direct frontal attack from the SW this side of Christmas is becoming quite unlikely- but this slow evolution to a warmer southerly is appearing as a possibility (and no, it won't be very cold to the south by then- the southerly tracking jet will be bringing warm westerlies over southern Europe).

As the pattern is slowly evolving I just hope that this isn't the evolution that the models ultimately latch onto. There are of course many alternatives, most of which are cold and snowy.

Let's see what today's ECMWF brings, because this morning's run was cold and snowy out to T+216.