Model Output Discussion

[bluearmy]

ECM don't look that good either if you want cold ...

quickly maybe Nick - but could develop ok from there. we are making assumptions that the atlantic will definitely be strong. i think the urge from the northeast will also be strong. setting up fo a good old battle though exactly where the lines will be drawn - unknown. i wasnt expecting to see cold funneling this way by T240 on ecm. i wanted to see the arctic blocked and the vortex split and it remains so.

[cooling climate]

The ECM would have been a good run had it continued I think.

I think the ensembles will continue to trend colder tonight as well.

[Frosty.]

The ecm looks not bad at 240hrs and better than the gfs but the juries still out. The problem is that alot still needs to go right even to get to this point, the positive is that the ecm at least doesn't deflate the mood further in this thread!

Agreed nick, it could be a lot worse. I think we need GP to give us some good news, if there is any

[nick sussex]

quickly maybe Nick - but could develop ok from there. we are making assumptions that the atlantic will definitely be strong. i think the urge from the northeast will also be strong. setting up fo a good old battle though exactly where the lines will be drawn - unknown. i wasnt expecting to see cold funneling this way by T240 on ecm. i wanted to see the arctic blocked and the vortex split and it remains so.

Agreed at least its possible to plot a route to cold from the ecm 240hrs, the gfs 240hrs would have needed a very vivid imagination! Overall this evening however i think the odds on an easterly have lengthened, perhaps the models are being too quick or perhaps its just going to be one of those early season teases, you know you shouldn't but a bit like that bar of chocolate the urge just becomes too great!

[clark3r]

Here's the fella:

http://91.121.94.83/...-5-1-360.png?12

http://91.121.94.83/...-5-0-372.png?12

yep that was earlier 2day shame that model shows a complete different scenario now! but i expect it to keep chopping and changing in the next few days! hopefully will at least get a little shot from the north east before xmas!

[Nick F]

quickly maybe Nick - but could develop ok from there. we are making assumptions that the atlantic will definitely be strong. i think the urge from the northeast will also be strong. setting up fo a good old battle though exactly where the lines will be drawn - unknown. i wasnt expecting to see cold funneling this way by T240 on ecm. i wanted to see the arctic blocked and the vortex split and it remains so.

Could be rather long drawn-out process to get blocking to bring any worthwile cold our way ... each successive run seems to shunt ridging further east with Atlantic shortwaves getting past the Merdian now.

We have a strong jet barreling across the Atlantic plus, a pre-disposition for a trough just to our west thanks to downstream feedback of those cold SST anomalies east of New Foundland currently. However, if we can somehow get that jet energy to shift further south across Europe then this may allow cold air to advect towards us, but this still has yet to become a possibility in the model output.

A positive from the 12z ECM I suppose, is that the cold vortex sat our west eventually fills and 'warms out' which means that there is less energy eventually up against HP to our E and NE.

[ANYWEATHER]

Im not sure its worth talking about anything cold in the near future, apart from being up a Mountain in Scotland! What takes my fancy is the brutal onslaught of the Atlantic with these shortwaves making a prononced feature across the UK especially the West.I think very unsettled and at times stormy sums it up and the models are not looking an whole lot different from a month ago....ECM ...a storm to watch......?

[phil nw.]

The 12Z models have all pulled back from the cold evolution shown last night but the same approach applies when viewing these distant time periods whether cold or mild -keep perspective.

The pattern will probably flip around more than once in the next 2-3 days untill the we get closer to the now T192hrs area,which was +200hrs when things got exciting on earlier runs.

The spliting of the vortex and raising off heights over the pole was projected beyond the reliable and unless the models are picking up on new Telecon data we should hold judgement on developments not due for some days yet.

Subtle differences show at T144hrs.

http://www.wetterzen...s/Rtavn1441.png

http://www.wetterzen...cs/Rukm1441.gif

http://www.wetterzen...cs/Recm1441.gif

ECM hints at better heights to the NE whereas GFS goes on to develop the s/waves there.

The area over the pole is difficult to forecast in detail even at that range so nothing is certain at this stage.

The period up to Sunday/Monday has been consistently modelled for some runs now,cyclonic wet and temps. slightly higher so this should be no suprise.

The ens.for Warks.

http://charts.netwea...arwickshire.png

Split 50/50 mild or cold beyond day6 and quite a lot cold runs further on.The mean trending colder.

Edited December 2, 2009 by phil n.warks.

[Tom Quintavalle]

The rollercoaster has started then but I cant say I'm that disheartened by the 12z runs. Lets have a look at the GFS ensemble 850s from the last 3 runs. This is for Reading, cant find the London ensembles for 00z and 06z but Reading will do.

00z http://meteocentre.com/ens/gfs_ens_rdg_t850_00.gif

06z http://meteocentre.com/ens/gfs_ens_rdg_t850_06.gif

12z http://meteocentre.com/ens/gfs_ens_rdg_t850_12.gif

There appears to be a few more members dropping below -5 in the latter stages of the 12z run, than the previous 2 runs.

Obviously out in Fantasy Island territory but actually, as an ensemble, a better run than the 06z that caused all the excitement this morning.

I couldnt quite understand the comments re. the UKMO 12z at 144t, surely the excitement this morning was due to the GFS 06z, post 204t/216t. In fact theres not a lot of difference between the GFS 06z run at 144t, that eventually produced the stonking easterly and the 12z UKMO at 144t.

GFS 06z http://charts.netweather.tv/gfsimages/gfs.20091202/06/150/h500slp.png

UKMO 12z http://www.wetterzentrale.de/pics/Rukm1441.gif

I realise that it could well go pear-shaped but I dont agree that cold weather is less likely to occur because the 12z runs are that bad, going on the GFS ensembles, you could make a case for a cold spell being a little more likely after the 12zs' than was the situation after 06zs'.

I don't find the ECM 12z run too bad either.

As Nick S. said this morning, those of us that have been members for a few years now are a bit cynical re. those stonking GFS runs. Its best to keep a lid on expectations, virtually until you see a snowflake outside your window, otherwise Nicks' stocks of Prozac will be gone in no time.

What is obvious from the model runs this evening is there is to be no let-up in this unsettled regime of weather we're in at the moment. Flooding becoming a real concern for many places I would've thought. We had quite a downpour in S.E. London an hour or so ago and plenty more to come no doubt in the next week/10 days.

Regards,

Tom.

[nick sussex]

NOAA don't think much of the last 4 operational gfs runs and these have been discounted in their extended outlook, they go mostly with the ecm, gem and gefs ensemble means.

Edited December 2, 2009 by nick sussex

[Glacier Point]

NOAA don't think much of the last 4 operational gfs runs and these have been discounted in their extended outlook, they go mostly with the ecm, gem and gefs ensemble means.

Following up on those ensemble means...

http://www.cpc.ncep.noaa.gov/products/predictions/814day/814day.03.gif

Wedge of polar vortex centred central Russia + the above pattern. That would in all probability begin the advection of Arctic air west. How far it gets is the crux as we head into the second half of the month.

The longwave trough looks still to be a player in the Atlantic (it will all winter) however, the longer the AO and NAO stay negative, the further the cold air will be pulled west, eventually deflecting the jet southwards and locking the pattern IF it is sustained for long enough. It's going to be a long process though and probably not for another 10 days + before it starts to look realistic from an angular momentum perspective.

[cooling climate]

If a cold (very cold ) pattern does lock in I think we could be looking at quite a protracted

cold spell of weather, but as they say one step at a time.

[chionomaniac]

Following up on those ensemble means...

http://www.cpc.ncep.noaa.gov/products/predictions/814day/814day.03.gif

Wedge of polar vortex centred central Russia + the above pattern. That would in all probability begin the advection of Arctic air west. How far it gets is the crux as we head into the second half of the month.

The longwave trough looks still to be a player in the Atlantic (it will all winter) however, the longer the AO and NAO stay negative, the further the cold air will be pulled west, eventually deflecting the jet southwards and locking the pattern IF it is sustained for long enough. It's going to be a long process though and probably not for another 10 days + before it starts to look realistic from an angular momentum perspective.

It looks like any benefit that we may get from the polar vortex splitting won't be for around 10 days anyway, so hopefully this will fit in with the GLAAM.

[weather eater]

If a cold (very cold ) pattern does lock in I think we could be looking at quite a protracted

cold spell of weather, but as they say one step at a time.

And a long way to go, people shouldnt give up hope just because a few runs dont promise winter Armageddon any more than they should start thinking a pattern is locked in stone when they do. Evolution happens over a long period of time, sometimes it makes major jumps and at others its a slow process, and sometimes it jumps off at odd angles, sometimes when you least expect it.

Edited December 2, 2009 by weather eater

[Cecil Hogmanay Melchett]

Bugger my pc had crashed on the wz site.That said i managed to get to +96hrs and ive seen enough to realise cold and snow is off the menu for quite a while!

What on earth is causing this seemingly non stop energy into the Atlantic?

[I remember Atlantic 252]

Bugger my pc had crashed on the wz site.That said i managed to get to +96hrs and ive seen enough to realise cold and snow is off the menu for quite a while!

What on earth is causing this seemingly non stop energy into the Atlantic?

Still hope for a weakening of the Atlantic around 10th-11th, im really hoping for high pressure, trends been there in FI, I look at the pressure ensembles, hoping for the atlantic to run out of steam, not bothered about the easterly disappearing on 12Z, as long as the trend for a weaker atlantic remains for the 12th period

[Cecil Hogmanay Melchett]

18z = Rainfest.

At least it will be mild,euro high pumping up some very mild air for the time of

year,13 deg by tues.

Edited December 2, 2009 by happy days

[clark3r]

18z = Rainfest.

thats a suprise :-( lol

[Grimsby Snow Lover]

I am no way near an expert so please be kind. But what I've noticed upto the 144hr mark is that the low to the west seems to have hit a brick wall. Are highs over Scandi normally that strong in doing this or is that a particulary strong high?

Edited December 2, 2009 by Grimsby Snow Lover

[damianslaw]

The models will always flip and change beyond the reliable timeframe, so don't put any true faith in them. It is the general pattern people should look at for and to my eyes as we head towards the middle of December I foresee heights to the north east intensifying raising the chances substantially for a cold period as we the longwave trough displaced further east and a kicking of the jet on a more southerly course. For the next wee at least expect what is to be honest very standard fare for early Dec, i.e. predominantly very unsettled often windy and mild conditions, I never expect much from early-mid Dec. Be patient.

[Cecil Hogmanay Melchett]

I am no way near an expert so please be kind. But what I've noticed upto the 144hr mark is that the low to the west seems to have hit a brick wall. Are highs over Scandi normally that strong in doing this or is that a particulary strong high?

Hi,it would be very difficult for any scandy high to resist the bombs being progged by the models.

The problem we have is that the high will not get far enough west to influence our weather and we are basically

a sitting duck as far as these depressions are concerned.

The output is looking very ominous tonight,a quick mention for IB who has called it pretty damn well so far.

EDIT 18Z has a MINIMUM of 13 degrees on the south coast next wed,IF that were

to come off it would be most certainly classed as blowtorch.

Edited December 2, 2009 by happy days

[Shunter]

18z GFS T150 ......Atlantic Low heads North East and Arctic High South West on a collision course. Who will win this round ?

http://www.wzkarten.de/pics/Rtavn1501.png

[MrAdam]

Looks like we're in for yet another roller coaster winter based on the model outputs for the past few days. Oh british weather how I love you!!!

Here's to hoping they switch back to the very nice easterly we had on the cards although I wouldn't mind if it held out until a little closer to Christmas so I can finish some shopping ha!

[cooling climate]

T192 and the 06z has the potential to be a very good run.

Here's hoping.

Nope.

Edited December 2, 2009 by cooling climate

[azores92]

going by the experts analysis of the current situation, if the indicators are to be believed, things could be looking different in the next couple of weeks, with perhaps more evidence of heights developing over greenland and scandinavia?