Model Output Discussion 5/12/2012 18Z onwards - the one after THAT ECM

[johnholmes]

just one more post from me for a while-the models all seem to be showing much the same out to 120 perhaps 144, it will be cold, how cold remains to be seen, how much snow? How many times do some of you need to be told forget snow forecasting other than hopecasting beyond T+48 and more likely T+24. It rarely is ever correct in longer times frames, fact so stop worrying about it.

At T+48 you can look at GFS and its fine mesh brother NMM on Net Wx Extra, and compare it with UK Met and its brother NAE. At those times scales by all means watch each run as it comes out and compare. By T+12 they are USUALLY showing something fairly similar.

Please believe me.

Then there is the Net Wx Guide using all 7 or 8 parameters to see just what the model spot closest to you is showing, that is assuming it is showing precipitation

Edited December 6, 2012 by johnholmes

[weather eater]

There is a rather large difference though between 72hrs and 240hrs difference, which is about the time things really go wrong on this run.

As long as its cold and we keep some form of upper high near Greenland/Iceland, we will do ok.

I beg to differ Kold, I think at 144hrs you can see how the rest of the evolution is likely to go on the 12z at least in terms of how the easterly evolves in relation to the UK, rather than the Atlantic attack, Furthermore those charts were part of a run of 12 consecutive GFS runs all showing much the same evolution, so in fact they go back to about 162hrs, that’s a pretty good spot from any model. However that wasn’t my point, which is that the GFS is not as bad as it’s often made out to be. Sticking my neck out here I would suggest it may be better than the ECM at modelling easterly’s, not a popular point of view I know. But I think it’s a perfectly valid argument, although hard to prove either way.

[Essex Boy]

Ya know it's times like this when I wish the models didn't go as far out as they did.

[fergieweather]

Yeah, the raw UKMO-GM looks quite interesting really, as we head out into +6 days territory. Anyway - miles away; we'll see.

[Wadey]

To newer members and those who have already chucked their toys out of the pram i ask you to disregard operational output beyond T120hrs.

Clearly there are differences in the way the models incl.GEM show the shape of the vortex towards Canada beyond this point and this has a bearing later on.

They all look pretty close at T120hrs.with the main upper features-heights across our north with a very cold North Easterly flow setting in.Those wanting cold-look at the uppers

Nothing to grumble about there-or the ens means at T180hrs.

Good enough i reckon.Come on folks relax and enjoy whats coming-in this setup the snow will come in time.The cold is here now and will deepen after the weekend.

dosent look like any Atlantic attack there for a while ?

[Snowmad79]

Please for once can we have something spectacular models!! We never seem to achieve it and just get let dwn. Plz ecm ulmo gfs bring it to us. I Dnt believe in trends- we keep seeing them and they Dnt materialise!! Am sat on fence tonight....

Erm, Lots of people have already had decent snowfall and others, snow showers and sleet and you think the models never bring the output to reality ? As others have said already, Yesterdays output was magnificent for Winter, literally the creme de la creme so it shouldn't come as a surprise that we have slight downgrades today.

Don't forget we could also see upgrades again. It's not as if the runs so far today are a disaster.. far from it.

[bradymk]

Would you believe it another huge scatter in the ensembles past day 8 range. Lots of different outcomes in there, quite a few good runs aswell.

Until day 8, very good agreement now for an easterly with the mean at around -6c 850 but quite a few runs below this at around -7/-8c mark.

Longer term, well 12z shows a few runs below -10c 850pha and some above +5 so pretty good gefs ensemble agreement in the long term once more......i joke.

Exciting few weeks coming up, keep looking for signs of a GH and the relocation of PV in long term, this will cause more havoc again with the models.

Matthew

Edited December 6, 2012 by bradythemole

[IDO]

Full ensemble suite:

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=306&y=141&ville=Londres

No support for cold or zonal. Just no clue!

[DR(S)NO]

Ups and downs are the order of the day when it comes to model watching .Just looking back through the last week or so would show that nothing is ever certain.Pretty sure that things will continue to change over the next few runs too!

One things for sure though,would we not rather have what may be on offer than the general dross of this time last year.

It's the anticipation of what's to come that excites.Enjoy the ride in the knowledge that things will,no doubt,change again.

[Ian Brown]

A look through the GFS ensembles suggests the operational run has only small level of support, most runs still have either an attacking low that is getting sheared or the HP still in charge with an EASTERLY.

Slo in other words, throw the GFS op run onto the scrapheap...maybe not quite into the bin, but close enough!!

The way the OP set-up the Atlantic attack was all wrong, unless the block suddenly retreated, there is no way the LP would have been able to travel in the direction it ends up in.

[nick sussex]

Certainly you can't beat this thread for entertainment!

Instead of people worrying over some GFS lower resolution output why not celebrate the fact that we've got past the first hurdle with the shortwave.

Detail, strength of flow, snow chances will change from run to run at this timeframe. If people think any of the outputs so far this evening aren't up to much then I suggest looking back into the archives at many of the winters we saw where even an air frost was hard to come by.

Now that the GFS has done all the hard work in consistently showing the first hurdle its time for the ECM to pick up the mantle and hopefully give us an idea of where things might go.

[The Giant Daddy Jackpot]

The recent winters have shown a trend to colder and snowier ones due to low solar activity. The trend is towards lower winter temperatures in the northern hemisphere for the coming years and winter 2012/13 is shaping up to being another.

The Met Office were right to sit on the fence about this latest call as the models are chopping and changing and I would urge patience and optimism because, as we have seen so many times of past, the continental cold pool takes a lot of shifting. With uppers still on the right track to our NE, confidence is high that a NE - E flow will occur perhaps by the middle of next week at the earliest and if it does establish it could last well into the Xmas period. We are due a 1963 or even a 1947 and if it isn't this winter it will happen in this current run of colder winters I'm sure. Confidence in that is very high.

[Jupiters Winter]

I request Professional commentary on the ECM. Personally I am expecting it for also to pump up atlantic as that how it has been over the years with such blocking in place. For only the atlantic to give up nearer the timeframe.. READY FOR THE RIDE

[Alex95]

Full ensemble suite:

http://www.meteociel...1&ville=Londres

No support for cold or zonal. Just no clue!

But there's strong support for a cold easterly around the middle of next week, and that alone will deliver heaps of snow to the eastern fringes and loads of potential elsewhere.

[bobbydog]

if only the weather was as predictable as the mood in here after one 'dodgy' run.........

[chris55]

For those who are not to sure on ensemble interpretation,

If the main cluster of ensemble members follow the output of the Operational (the bright green line) then confidence in the outcome is high, if the ensemble members diverge from the operational run, then what is being shown on that operational run means confidence is Low.

Taking that in mind, from the 12z set of ens we can see that up to the 13th (with 850s at least) confidence in said outcome is relatively high, beyond this the operational has little support so confidence is Low/very low.

I would say this is typical of an easterly scenario where the Atlantic is trying to come back at the block. A very difficult thing to model correctly and with such large temp differences between the two airmasses small changes in synoptics will show as large shifts in weather type and temperature, hence the large scatter on the ens.

Edited December 6, 2012 by chris55

[Snowman.]

Eyes down for the newest ECM what's your predictions!

[Nick L]

Eyes down for the newest ECM what's your predictions!

A good run followed by more melodramatic nonsense from certain corners.

[Severe Siberian icy blast]

Certainly you can't beat this thread for entertainment!

Instead of people worrying over some GFS lower resolution output why not celebrate the fact that we've got past the first hurdle with the shortwave.

Detail, strength of flow, snow chances will change from run to run at this timeframe. If people think any of the outputs so far this evening aren't up to much then I suggest looking back into the archives at many of the winters we saw where even an air frost was hard to come by.

Now that the GFS has done all the hard work in consistently showing the first hurdle its time for the ECM to pick up the mantle and hopefully give us an idea of where things might go.

Thankyou for saying that its a joke on hear sometimes, too busy looking past 8days , what happened to that easterly for a whole wk?? Come on guys this is a fantastic period we are about to enter why not enjoy it?!

[Timmytour]

There seems to be a lot of embrace for predictions of snow-laden days aheads in here and disregard for mentions of it being cold but dry.

I hope for the former, but the latter cannot be discounted as a possibility. I remember a real flurry winter which must have been during the mid to late 70s.... it was cold for what seemed weeks but all we got were flurries. I loved the sight of those flurries when they first came but I ached for something more substantial which never came...so much so that i started really getting peed off with the flurries!

[Southender]

Eyes down for the newest ECM what's your predictions!

A downgrade from yesterday's 12z and mass hysteria posts claiming winter is over.

[Frosty.]

dosent look like any Atlantic attack there for a while ?

If the atlantic attacks. it will get a bloody nose and sent packing, the block to the northeast is all consuming and heading west.

[PubliusEnigma]

Yeah, the raw UKMO-GM looks quite interesting really, as we head out into +6 days territory. Anyway - miles away; we'll see.

Its the progged weak High over central Europe that is stopping the Shortwave to our SW traversing east and undercutting the Higher pressure

to the north. If it did, it would drag the low over southern Sweden SW into the North Sea down towards the South East of England.

[TAFKAP]

if only the weather was as predictable as the mood in here after one 'dodgy' run.........

And not even a 'dodgy' run might I add?

[TAFKAP]

A downgrade from yesterday's 12z and mass hysteria posts claiming winter is over.

I predict an excellent run in terms of the UK in December for those who have realistic expectations.