Model Output Discussion - 12th December Onward

[nick sussex]

ecm ens spread at day 10 does show a height rise mid atlantic (not nearly as amplified as the op though you'd expect that) plus a trend to dig the trough to the west of this height rise. whilst not enough support for the op to make it look like the mean, there must be a significant cluster that agree to a reasonable extent.

i also note the 850 spread showing a push sw of very cold uppers towards svaalbard - i assume in association with a chunk of siberian p/v being forced there by the arctic high. thats a solution also shown by the op and therefore, more support for its run.

Don't you find the mean can be very distorted in this type of set up especially if the operational decides to go its own way?

In terms of the pattern to the west what also stands out is events off the USA in terms of 850's spread, wouldn't that be in relation to the amplitude of any troughing? more amplified driving the southerly flow ahead of it as opposed to a flatter orientation?

[Mark Neal.]

Good Evening Everyone. Just thought i'd like to say a few words regarding the upcoming mild spell.

1. Things are going to get milder of late, but any wind will make it feel less mild.

2. I think many people will agree with me here, a mild spell now is better than in the middle of January.

Like Nick Sussex has explained there are signs at the end of the Ecm run that could spark something more interesting, best just to watch suttle changes. Before anyone says winters over, its only middle of December still got 2 whole months at least after this one.

[phil nw.]

The thums for EPS (ECM Ens.) are out.

T168 is as far as they go,a little soon to show evidence of amplication of the flow.

http://www.ecmwf.int...t!2009112700!!/

However some members show the core of the Azores High further west and possibly being in a position to be drawn NW-if any Troughing off the Eastern seaboard digs south.Unfortunately we cant see that far west on these maps.

[Frosty.]

At least when it's mild over christmas, the models might be looking a lot more promising for cold prospects if tonight's ecm has spotted a new trend..short term pain, the good thing about model watching is that even though they currently look rubbish for cold weather, it can change quickly.

[bluearmy]

Don't you find the mean can be very distorted in this type of set up especially if the operational decides to go its own way?

In terms of the pattern to the west what also stands out is events off the USA in terms of 850's spread, wouldn't that be in relation to the amplitude of any troughing? more amplified driving the southerly flow ahead of it as opposed to a flatter orientation?

it does look like a surge of cold air south across the states is possible - i am surprised that there is no appetite for cold runs on the extended ecm ens. whatever solution the op goes down, the ens members that support it cannot be as amplified as six days later, only a couple of cold runs in holland are evident..

[Kentish Kiwi]

Will certainly be interesting to see if the GFS 18z gives any support to the ECM 12z, or indeed its own 06z run, in raising heights in the mid-Atlantic towards Greenland around the +240h period.

If such a trend is to develop, as hinted at by OMM, it seems to have some support from stratospheric developments and forecasts.

Edit: Is it just me or at +129h are there already significant differences over and to the west of Greenland on this run compared to the 12z...

Edited December 18, 2011 by Kentish Kiwi

[bobbydog]

we might get snow this winter, we might not. we can tear the models apart looking for SSW's, Greeny highs etc, but we cant change the weather, no mattter how hard we analyse. if it happens, it happens. just enjoy life...

...and have yourself a merry little christmas time....

Edited December 18, 2011 by bobbydog

[Great Plum]

Well, excePt the far south west, temps stay pretty 'average' for the big day... http://www.wetterzentrale.de/pics/Rtavn16217.png

[Kentish Kiwi]

Actually, up to the +192h stage, things look notably different to the ECM's evolution, with the GFS drawing up very long fetch SW/Serlies as opposed to a flatter pattern from the ECM.

[Grimsby Snow Lover]

Well so close on this run for regression to Greenland of the Atlantic high. It doesn't quite happen on this run, but compared to the 12z a step in the right direction and not a million miles away from the ECM 240 chart. A reason to perhaps feel a little better regarding a possible pattern change as we approach new year.

http://www.wetterzen...s/Rtavn2281.png

Having said that FI is another huge dissapointment regarding a change from the status quo over Greenland

Edited December 18, 2011 by Grimsby Snow Lover

[Robbie Garrett]

Ooh is this what I think it is??? Only worrying thing with the heights trying to go to the north is that huge LP to the west of it, surely that will blast the **** out of the high?

[nick sussex]

it does look like a surge of cold air south across the states is possible - i am surprised that there is no appetite for cold runs on the extended ecm ens. whatever solution the op goes down, the ens members that support it cannot be as amplified as six days later, only a couple of cold runs in holland are evident..

Yes thats quite strange, looking at the ECM operational run you'd think some of those members would amplify that troughing a bit more, maybe this will be an operational run leading the way with ensembles to follow rather than the other way round.

Or it could just be a false dawn, we'll have to see what the models do over the next few days, more importantly will those stratosphere forecasts continue to improve, thats the key background signal we have to take into account when looking at these operationals.

Edited December 18, 2011 by nick sussex

[Robbie Garrett]

Yes thats quite strange, looking at the ECM operational run you'd think some of those members would amplify that troughing a bit more, maybe this will be an operational run leading the way with ensembles to follow rather than the other way round.

Or it could just be a false dawn, we'll have to see what the models do over the next few days, more importantly will those stratosphere forecasts continue to improve, thats the key background signal we have to take into account when looking at these operationals.

What would you say is an average timeline if things continue to improve over the next few weeks/days to see a potent cold blast?

[Kentish Kiwi]

Ooh is this what I think it is??? Only worrying thing with the heights trying to go to the north is that huge LP to the west of it, surely that will blast the **** out of the high?

You'd think that might be the case but...

http://www.wetterzentrale.de/archive/ra/1991/Rrea00119910202.gif

http://www.wetterzentrale.de/archive/ra/1991/Rrea00119910205.gif

Granted 1991 was a special occasion and I'm not suggesting anything similar is going to be repeated as things are currently significantly different synoptically, but just an example of how big low pressures off the west coast of Greenland can quite readily stall and are usually a positive sign as a pre-cursor to an easterly.

[feb1991blizzard]

we might get snow this winter, we might not. we can tear the models apart looking for SSW's, Greeny highs etc, but we cant change the weather, no mattter how hard we analyse. if it happens, it happens. just enjoy life...

...and have yourself a merry little christmas time....

Got nearly 2 inches of the stuff outside my window right now.

[BLAST FROM THE PAST]

..........models indicating Nothing on COLD side for at least 2 weeks... any talk of cold on this board is pure finger in the air stuff..

Sorry but that's a take GFS run as gospel post and sorry but is very tunnel visioned. GFS will continue to pump out is default

Now anyone looking at and noticing possible storminess for Boxing Day/27th? Still showing its hand and worth noting as it will squeeze any chance of Eurotrash establishing.

Interesting ECM tonight and shows what is in one's thoughts and how we may head that way. Anyway, things look Decemberish to me ahead.

Tell you what though there's no way its the MetO/BBC +1c here tonight.....clearly it must be central London temps.

BFTP

Edited December 18, 2011 by BLAST FROM THE PAST

[Robbie Garrett]

You'd think that might be the case but...

http://www.wetterzen...00119910202.gif

http://www.wetterzen...00119910205.gif

Granted 1991 was a special occasion and I'm not suggesting anything similar is going to be repeated as things are currently significantly different synoptically, but just an example of how big low pressures off the west coast of Greenland can quite readily stall and are usually a positive sign as a pre-cursor to an easterly.

Interesting that one mate, I know that LPs can't just shunt HP out the way - but blimey that's immense!! Saying that haven't our recent Low pressure stalled as they hit the Greenland highs?

[nick sussex]

What would you say is an average timeline if things continue to improve over the next few weeks/days to see a potent cold blast?

It's always risky talking about potent cold spells in here!

At this point theres absolutely no guarantees that we'll even see a potent cold spell this winter, we must really forget last December ever happened as that raises the bar so high that expectations can go through the roof.

I'm sure everyone has seen plenty of talk about the stratosphere in here over the last few weeks and that is very important, the much talked about possible sudden stratospheric warming is not certain to occur and even if it does it simply allows for the chance that we'll see some higher latitude blocking, at that point where the displacement of the PV goes will determine whether the blocking is in the right place for the UK to benefit.

Now if we're talking about cold snaps whereby we at least see snow more widely across the UK and less marginality than recently a SSW is not essential for this but we do need to see at least the current minor forecasted warming to continue, it doesn't look like we're going to get much help from the MJO which is currently weak and of course this is effected by other teleconnections.

So in terms of a potent cold spell it's impossible to say yes or no to that. I think it's best for us to see whats more realistically attainable without a SSW, if a SSW comes along then great but we shouldn't see this as the snow lovers utopia.

If we can get some more amplification upstream and at least see some temporary splitting of the PV then that would be a good start.

[Robbie Garrett]

It's always risky talking about potent cold spells in here!

At this point theres absolutely no guarantees that we'll even see a potent cold spell this winter, we must really forget last December ever happened as that raises the bar so high that expectations can go through the roof.

I'm sure everyone has seen plenty of talk about the stratosphere in here over the last few weeks and that is very important, the much talked about possible sudden stratospheric warming is not certain to occur and even if it does it simply allows for the chance that we'll see some higher latitude blocking, at that point where the displacement of the PV goes will determine whether the blocking is in the right place for the UK to benefit.

Now if we're talking about cold snaps whereby we at least see snow more widely across the UK and less marginality than recently a SSW is not essential for this but we do need to see at least the current minor forecasted warming to continue, it doesn't look like we're going to get much help from the MJO which is currently weak and of course this is effected by other teleconnections.

So in terms of a potent cold spell it's impossible to say yes or no to that. I think it's best for us to see whats more realistically attainable without a SSW, if a SSW comes along then great but we shouldn't see this as the snow lovers utopia.

If we can get some more amplification upstream and at least see some temporary splitting of the PV then that would be a good start.

Last year was just too immense to be forgotten, and I am well aware it was a very rare event in itself.

But surely it would be extremely weird to have all these signs/signals of a colder weather period in the winter cycles to have nothing completely this year, except the odd snow event, like we are getting now.

Talking of which, how did 09's snow form? What sort of conditions did we have before hand?

[ZONE 51]

GFS - 18z

This frame to me indicates what is quite possible at times, mostly i would say Scotland has chance of wintry weather at times over the next couple of weeks, with a quite strong area of high pressure knocking on the door of the south, trying to move up further at times, nothing is set certain, although the high pressure is likely now in the south, no sign of a prolonged cold spell, but flirts of cold and snow are possible(but hey thats good!)who knows whats on its way in the weeks ahead!

Edited December 19, 2011 by ElectricSnowStorm

[Timmytour]

What might take our minds off the lack of any imminent cold spell would be the eruption of the biggest volcano in Iceland in the short term......not just to see how the models portray the impact of the dust coming over the uk in such an event but also what impact if any such an event would have on the models . Personally I'm now resigned to the chances of such an event taking place before the New Year being greater then seeing any significant cold before then.

Edited December 19, 2011 by Timmytour

[reef]

New thread:

http://forum.netweather.tv/topic/71974-model-output-discussion-19th-25th-december/