Model Output Discussion - 8th December Onwards

[chris55]

De blit 12z, make of them what you will. 25% stay cold beyond day 6, the rest let in the Atlantic.

Edited December 8, 2012 by chris55

[nick sussex]

This one already has:

Pretty much the same split as this morning but pretty ominous still.

Right towards the end of the period the trend is slightly downwards - thats about the best I could say for these tonight

SK

Yes pretty grim reading, a few solutions that still offer hope. Do you remember that Grand National winner coming in at 150/1, well the odds are better than that I'd say about 10/1! shame cold synoptics didn't have that success rate we'd all be happy!

It must seem to some that we have to do about 80 fences and then a loose horse called Shortwave Nightmare runs into our leading horse after the last hurdle unseating the rider!

I think we'll have to see whether the limpet low is likely to just sit there being fed energy from upstream or whether we can find some way of deflating it quicker!

[Summer Sun]

De blit 12z, make of them what you will. 25% stay cold beyond day 6, the rest let in the Atlantic.

The main thing is some of them are still staying cold its better than having no cold options at all I guess

[Man With Beard]

i just had a look back at the ecm runs from the middle of last week to see where they went wrong as i just dont buy the scandi shortwave for causing the complete failure. and surprise surprise, it didnt. its a combo of the scandi shortwave preventing the russian ridge from supporting our fledgling block plus there should have been a ridge coming off the eastern seaboard tomorrow/monday which would deflect the second shortwave on a more ne interior track and enable this east coast ridge to add support to our block from the west. the lack of this east coast ridge is a double whammy. firstly, it means there is absolutely no support for our ridge due to the shortwave drama to our northeast and secondly, (more importantly) the second shortwave now flows straight into the west atlantic depression and gives it the energy to rush straight across the atlantic. our ridge stands no chance and to make matters worse, the shortwave to our northeast is sufficiently far enough north as it tumbles the energy southwest to draw the low heights of atlantic attack at that lattitude towards it. take the scandi shortwave away and we would probably have the cold air far enough west to repel the initial atlantic attack to our south giving a dramatic battleground scenario. keep the east coast ridge and the atlantic isnt strong enough to smash through our ridge and the cold would tumble in from the northeast. i dont think the combination of these two things happening at less than day 6 could reasonably have been factored into any forecast. thats why the cold period upcoming will be so shortlived.

Fantastic post - I could add that the development of a mini-high over France/The Alps also keeps the northern blocking further north - what an amazing start to the winter season with two heavyweights battling out, northern blocking knocking the Atlantic to the floor, it looks like a knockout only for the Atlantic to get back up and lay out the block, reminds me of Eubank vs Watson 20 years ago!...

Seriously though, the fact that there is both unexpected strength in the Atlantic and a continued signal for northern blocking tell me this battle is not going to be conclusively won this week. Writing off Christmas to the Atlantic is far too premature; the Atlantic may stronger this week but any drop in intensity will let blocking push back, as indeed many FI charts already suggest could happen. Indeed, some tiny changes even in the next 48 hours could lead to big changes at T96 - when you have weather hitting each other from two opposing angles any margin for error will be multiplied - so personally I will be watching closely all the way until Thursday this week as I expect surprises even at T24.

[Frosty.]

De blit 12z, make of them what you will. 25% stay cold beyond day 6, the rest let in the Atlantic.

Hope springs then, like i said before, hints of undercut with SEly winds ahead of the advancing low could suck colder air into the mix from the near continent and make things more interesting from midweek, maybe the 00z will show the snow risk for more of the uk apart from scotland. It would probably just be delaying the inevitable but I would rather the cold air left kicking and screaming than with a faint whimper.

[mulzy]

De blit 12z, make of them what you will. 25% stay cold beyond day 6, the rest let in the Atlantic.

More like 10% rather than 25%.

[JP1972]

Yes pretty grim reading, a few solutions that still offer hope. Do you remember that Grand National winner coming in at 150/1, well the odds are better than that I'd say about 10/1! shame cold synoptics didn't have that success rate we'd all be happy!

It must seem to some that we have to do about 80 fences and then a loose horse called Shortwave Nightmare runs into our leading horse after the last hurdle unseating the rider!

I think we'll have to see whether the limpet low is likely to just sit there being fed energy from upstream or whether we can find some way of deflating it quicker!

Off topic and no doubt this will be deleted, but I think an "Alternative Model Output Discussion" thread with you as chair would make fascinating reading!

You're a star mate!

[bobbydog]

hmm.... looking at the latest runs again, mainly GFS and ECM, lots of mention of the atlantic breaking through and sweeping the block away. "return to zonal" etc. however, (and i'm fairly sure our more expert members have noticed but if its been mentioned i've missed it) the atlantic DOES NOT break through. it seems to throw low after low at us, which we do feel the effects of, but they are absorbed and dissipated. like breaking waves on a beach. at no point do i see low pressure break through the high pressure over scandi. at some point, something has to give and if it's not the block then it has to be the jet. in FI, the GFS has an azores high linking to the block giving us another teasing easterly. the ECM hints at the large LP system (which due to the fewer frames appears to be just one big one bouncing about in the north atlantic) trying to find a way out and heading south east. either way would bring cold weather back our way. how long it takes is anyones guess but i dont think this is over by a long shot.

comments please......

Edited December 8, 2012 by bobbydog

[Stoxs]

yes and 3 days ago 90% were showing no atlantic force at all!

-8 all the way to T384,

Really no point in looking any further ahead than wednesday/ thursady at the moment.

Very interesting models at the moment , I found the charts comparing 62/63 to the current ones most intersting and something i am going to watch for now.

The weather will be what it will be, no one/ model will change that!

[chris55]

More like 10% rather than 25%.

Well 12 runs for next sat are below 0c, there are 51 runs so 12 makes roughly 25%, no?

[nick sussex]

Off topic and no doubt this will be deleted, but I think an "Alternative Model Output Discussion" thread with you as chair would make fascinating reading!

You're a star mate!

Thats really nice of you but if you gave me that much license it could be carnage!

I do tend to get overly dramatic at times and rather prone to be rather too Hollywood!

[I remember Atlantic 252]

Off topic and no doubt this will be deleted, but I think an "Alternative Model Output Discussion" thread with you as chair would make fascinating reading!

You're a star mate!

agree with that, nick legendary but his location, nick would need a massive shift southwards to see snow!

[Methuselah]

Come on peeps - back to the models...

[nick sussex]

agree with that, nick legendary but his location, nick would need a massive shift southwards to see snow!

I really don't mind you guys hogging all the snow in the UK , I'm lucky here with the Pyrenees, 30 minutes from the nearest ski resort, lovely views and we do always get to see some snow down in the valley here a few times during the winter.

Anyway I'd better get back on topic.....Just looking at the longer range ECM ensembles they seem to be flatlining around a narrow range.

But as we've seen recently they can flip just as quickly as the operational outputs.

[damianslaw]

There is great room for error in the models at present - as we have seen in the past 48 hours, short-term developments have resulted in major changes in there medium period outputs and don't be surprised to see further changes in coming runs...

All models show a very significant build of heights over west russia - up to 1055mb during the course of the week, which is very strong indeed and these won't shift quickly, alas once again we are seeing charts showing the longwave trough becoming unstuck directly over the country towards next weekend, it is a pattern we have been very much locked in since April and on so many occasions the trough has been forced to drop SE as heights build out to the NW and the jet stays on a southerly course- which in winter is a cold wintry pattern, and I very much expect this to be the eventual outcome as we approach christmas i.e. the trough will simply become squeezed in time as greater forces i.e. movement of polar vortex to siberia and resultant rise in heights over Greenland becomes the dominant factor.. aided by the southerly tracking jet.

[bluearmy]

http://www.weerplaza.nl/15daagseverwachting/?type=eps_pluim&element=&r=zuidwest

I never noticed that the bottom chart 'windrichting' shows wind direction for the ecm ens.

also, remember those gfs deepest fi runs from a week ago which consistently kept introducing a stiff soueaster as the trough came in from the west and met the block from the northeast. Given that they were at two weeks range, they weren't a bad effort. Take a look at one of them

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=384&mode=0&heure=12&jour=1&mois=12&annee=2012&archive=1

Edited December 8, 2012 by bluearmy

[nick sussex]

Going back to a post made by BA, yes I think it was a combo of two factors, I've been looking at the archives and because we didn't get that shortwave track ne we didn't get the troughing to the west sharpened and splitting, instead as BA our forensic investigator rightly said this piles too much energy east.

In terms of the GFS 18hrs run so far not much change so far but look upstream to the low out of the eastern USA at 54hrs, this originally was expected to track inland with an amplified ridge ahead this sharpens the trough ahead stretching this diffusing some of the energy.

Anyway thats in the past...... Lets see what the later output brings, how far east the Atlantic gets.

[Gavin Hannah]

At t.63 on the 18Z and that Low to our west is slightly further north and west. Cmon 18Z, lets have the good stuff tonight.

t.72 and the Azores has linked up with the Euro/scandi.

Edited December 8, 2012 by IBringTheHammer

[Col Berkshire]

Could this be the turning point?

[karyo]

Not much change so far, compared to the 12z gfs. By Wednesday the cold uppers are starting to retreat.

Karyo

[Gavin Hannah]

Could this be the turning point?

It depends on what happens at around t.96. That's round about when the Low really winds up on the past few runs. It's starting to deepen earlier and further out west than on the 12Z.

Edited December 8, 2012 by IBringTheHammer

[karyo]

The front is coming in such an angle that it brings a southwesterly flow so not much chance for breakdown snow apart from hills.

[Gavin Hannah]

It looks like we could be set for a big storm if this Low gets any deeper...... and if it moves south and east, it could bring in a trailing front of snow. All in all, i would say its game over for the Beasterly this time round. (Egg on the face of the Daily Express again lol) But this storm could bring in some really wintry conditions as passes by.

Edited December 8, 2012 by IBringTheHammer

[I remember Atlantic 252]

The front is coming in such an angle that it brings a southwesterly flow so not much chance for breakdown snow apart from hills.

Feb 4th wasnt ideal angle, infact archive chart looks mild, but at least on 18Z front weaker thurs looks coldish and dry, after light overnight rain on wednesday

[snowking]

The front is coming in such an angle that it brings a southwesterly flow so not much chance for breakdown snow apart from hills.

Yep couldn't really be at a worse angle at present

It's this that I'm really focusing on at present, just hoping we can get it to push a little further south and become slightly more stretched NW-SE in shape, similar to the UKMO 0z. It's pretty futile at the moment I must say, but there's every chance of change IMO right up to +48 in the current scheme of things.

It's a big ask though

SK