Model Output Discussion

[Yeti]

ecm T240 has thickesses below 518dam over the north sea and a 515dam upstream. as nick says though, unlikely but pretty to look at.

[nick sussex]

True in terms of the Easterly, but personally I would rather see the low tracking right across us with mega hill snow; unfortunately none of these easterlies have associated deep cold pools and so they are unlikely to produce much convection. But then again, that's personal preference of someone who lives near and regularly climbs high hills

Its a difficult choice here, the ecm still looks to be able to tap into some cold upper air and so theres still a chance of some snow but of course if the low tracks further east you get the colder air in quicker but on the other side given the synoptics it looks never cold enough to deliver on lower ground. If you want the easterly you really need to forego a chance of earlier cold as the further west the low tracks the better but still with no guarantees that it can get from that point to the easterly. For me unless it was a proper sourced Arctic flow then I have to hope for the ecm to verify as that type of synoptics could still give me a chance here for some snow at my location, although conversely the gfs would provide some heavy snow for the mountains but not at my altltude! I think I'm going round in circles, basically for the chance to get the coldest conditions its the ecm as this would also provide a stepping stone to a possible Greenland high. This all could implode tomorrow so we might anyway just have to make the best of the gfs pattern.

[tundra]

If the ECM run came off as shown then it would produce the goods with powder snow even, but that is one hell of a big if and this could be one final winter wind up before spring starts.

On the other hand this could be the warming finally propagating down to the surface that we have been so patiently waiting for.

[PB22]

Oh dear, here we go again, this time its the ECM leading the way with obscure fantasy charts! I would be extremely surprised if things evolved like tonight's ECM. I'm not ruling out a potential easterly spell, but I'm not expecting anything like the 12z ECM. Still, it will keep the coldies happy and dreaming!

[nick sussex]

I've managed to dig up some support for the ecm from the JMA model, so at least thats something but still we need support from a major model.

http://www.wetterzentrale.de/pics/Rjma1921.html

[Guest North Sea Snow Convection]

=

Exactly - not just coldie dreaming!

Obviously no-one is suggesting that things will turn out exactly like the ECM 12z - but the output is perfectly plausible, if one is aware of some background factors

[J10]

http://www.netweather.tv/forum/index.php?s...p;#entry1495654

Latest skiing blog now out.

Going back to tonight's models, interesting to say the least, it's a pity they didn't happen a few weeks ago, but they will still be interesting if they occurred now.

[Frosty.]

Oh dear, here we go again, this time its the ECM leading the way with obscure fantasy charts! I would be extremely surprised if things evolved like tonight's ECM. I'm not ruling out a potential easterly spell, but I'm not expecting anything like the 12z ECM. Still, it will keep the coldies happy and dreaming!

I'm hoping for a blend of the gfs & ecm 12 with a Northerly followed by an Easterly, i'm not sure the ecm has much support but it has hardly changed from the 00z which is noteworthy. The gfs looks good up to and including next weekend before the wheels come flying off but the ecm would lock us into a prolonged unusually wintry spell for so late in the season.

[Snowaddict]

Oh dear, here we go again, this time its the ECM leading the way with obscure fantasy charts! I would be extremely surprised if things evolved like tonight's ECM. I'm not ruling out a potential easterly spell, but I'm not expecting anything like the 12z ECM. Still, it will keep the coldies happy and dreaming!

At least we now know that we won't be reaching anomolous warmth for at least a while again, which is fantasitc news!!!!

Infact cool to cold is the theme tonight with a nice change to unsettled and cold conditions.

Some bitterly cold medium term charts from ECMWF.

This output does tie in nicely with the multiple Oscillation forecasts, however huge caution needed at present.

Edited February 27, 2009 by Snowaddict

[Guest North Sea Snow Convection]

Hi Tamara,

That's a stunning ECMWF Output this evening, 850mb temps almost always at -5 from T+120, getting much colder still on the latter frames:

T+216

T+240

SA.

Thanks for those SA. Yes - most interesting model output in a long while. At least something to keep an eye on at last

We are never going to get the sort of bitter temps a month or so ago, but still, that sort of feed would give us some of the coldest we could get if it was sustained for a few days or so

[tundra]

I say all caution should be thrown to the wind. At this time of the year this could well be the last chance to see anything of any significance wintry wise for lowland UK by that i mean lying snow.

Therefore we should disregard anyone and any other model that does not support the ECM.

If this is in anyway deemed as some sort of bias towards ECM or disguised ramping then i am guilty as charged.

[NorthantsSnow]

Oh, ECM. You do tease us like this occasionally. Wondering if it could be onto something here or if it's just teasing. Hmm.

[Snowaddict]

Thanks for those SA. Yes - most interesting model output in a long while. At least something to keep an eye on at last

We are never going to get the sort of bitter temps a month or so ago, but still, that sort of feed would give us some of the coldest we could get if it was sustained for a few days or so

It sure is Tamara.

And although at daytime those charts would not be bitterly bitterly cold, there would still be the potential for convective snowfall and still very cold conditions. The T+240 chart is excellent from the point of view that it would lead to a very much sustained pattern, with reloads a distinct possibility.

Whether these charts materialise or not, it makes for excellent viewing and it's nice to see NWP outputs corresponding to some of the background siganals at this time.

SA.

Edited February 27, 2009 by Snowaddict

[nick sussex]

I say all caution should be thrown to the wind. At this time of the year this could well be the last chance to see anything of any significance wintry wise for lowland UK by that i mean lying snow.

Therefore we should disregard anyone and any other model that does not support the ECM.

If this is in anyway deemed as some sort of bias towards ECM or disguised ramping then i am guilty as charged.

Yes the rest of the models are rubbish, long live the ecm! You're right though this is probably the last chance to get a wintry spell that will give lying snow away from the overnight period and even though the gfs looks okay its very marginal and just won't bring the cold that the ecm could if of course it verified. The best outcome is the ecm upto the middle of March and then as we begin to see the continent warm too quickly then the Greenland high takeover till the turn of the month and then we can move on and enjoy spring, there thats all sorted!

[Snowaddict]

Yes the rest of the models are rubbish, long live the ecm! You're right though this is probably the last chance to get a wintry spell that will give lying snow away from the overnight period and even though the gfs looks okay its very marginal and just won't bring the cold that the ecm could if of course it verified. The best outcome is the ecm upto the middle of March and then as we begin to see the continent warm too quickly then the Greenland high takeover till the turn of the month and then we can move on and enjoy spring, there thats all sorted!

I like your thinking Nick.

Sounds fantasitc.

Very nice ECMWF this evening and it's good to see some support from JMA.

Thank you for posting the link to that chart.

SA.

[nick sussex]

I like your thinking Nick.

Sounds fantasitc.

Very nice ECMWF this evening and it's good to see some support from JMA.

Thank you for posting the link to that chart.

SA.

Well in an ideal world that would happen , easterlies in March normally only have so much longevity as we see the Continent really begin to warm up later in the month and then you really have to turn your attention to the north with Arctic flows which do produce those convective snow showers. Its a long road though to get to the ecm later output but at least the fall back is that at least it will turn colder regardless even with the other models, so if the ecm implodes although it will be a little disappointing at least it doesn't necessarily mean a mild outlook. The ecm has been a real tease in FI for much of the winter so lets hope it will finally get one pattern correct!

[mcweather]

I can't help but chuckle to my self a little. If the GFS were showing what the ecm is showing everyone would be saying I'll beleive it when the ecm shows it.

Now the ecm delivers some dream synoptics all be it a little way out and everyone is saying its not supported by the gfs which was roundly condemned by many last week as a completely useless model.

you couldn't make it up

[NorthantsSnow]

I can't help but chuckle to my self a little. If the GFS were showing what the ecm is showing everyone would be saying I'll beleive it when the ecm shows it.

Now the ecm delivers some dream synoptics all be it a little way out and everyone is saying its not supported by the gfs which was roundly condemned by many last week as a completely useless model.

you couldn't make it up

Even though this is showing on the ECM which is generally more reliable, these charts are still FI and ECM cannot be trusted either at this sort of timeframe.

If it shows this consistently for a few runs or more and preferably gains some support from another major model, then it'll be worth taking a bit more seriously.

GFS is toying with the idea of an easterly as well but not until much much later.

At least it won't be mild after tomorrow

[Cloud 10]

The ecm 12z operational is very much on the cold side of the ensembles towards the end of its run,although still showing a cool down.

Could be a new trend though.

[snowray]

I can't help but chuckle to my self a little. If the GFS were showing what the ecm is showing everyone would be saying I'll beleive it when the ecm shows it.

Now the ecm delivers some dream synoptics all be it a little way out and everyone is saying its not supported by the gfs which was roundly condemned by many last week as a completely useless model.

you couldn't make it up

I think that at the end of the day both GFS and ECM have not been terribly acurate in the T192-T240 period this Winter, but this is 7/10 days out so its never easy to forecast. The difference is that GFS has often had wild fluctuating output and very lttle consistancy at times even down to about T120.

Anything past T240 is complete fiction, GFS has consistantly, run after run sometimes, been turning up some mega cold plunges in deapest FI that have never materialised, like some sort of default.

UKMO just goes out to T144, certainly the most consistant in the short term, but can still struggle from around T96 onwards .

I wonder where the 18z will take us from here, friday night, bound to have been down the pub.

Edited February 27, 2009 by snowray

[LomondSnowstorm]

I think that at the end of the day both GFS and ECM have not been terribly acurate in the T192-T240 period this Winter, but this is 7/10 days out so its never easy to forecast. The difference is that GFS has often had wild fluctuating output and very lttle consistancy at times even down to about T120.

Anything past T240 is complete fiction, GFS has consistantly, run after run sometimes, been turning up some mega cold plunges in deapest FI that have never materialised, like some sort of default.

UKMO just goes out to T144, certainly the most consistant in the short term, but can still struggle from around T96 onwards .

I wonder where the 18z will take us from here, friday night, bound to have been down the pub.

the first time in a while that the short-medium term gfs looked more promising than the FI for snow

i think there's a good chance for some snowfall here and possibly some significant stuff if it comes at the right time

it certainly seems that with march snow events the further north you are the better (not always the case though, and sometimes fife misses easterly snow when everywhere else on the east coast gets hit)

[Paul]

Uncertainty is the keyword tonight, as all the models are doing their own thing with the low pressure system both in it's track toward and beyond the UK and in what happens beyond that (unsurprisingly).

Comparing all the models here:

http://www.netweather.tv/index.cgi?action=modelcomp;sess=

It really is a case of fairly subtle differences up to 120 hours, then the various outputs go on their merry way, each offering their own solution!

The ensembles give us a clue why, with several scenarios being shown from relatively early on, even at 102 hours there's a fairly wide spread of possibles, signifying that there are likely to be twists and turns to come right up to the day with regard to this atlantic depression:

At 120 hours the gaps between some of the members widen still

By 144, well the variation is even more evident, with some members having the low northwest of Scotland and others having it centred over southeast England!

Jumping out to 240 hours just for fun - the spread is massive, again indicating the difference in possibilities for this period.

So in summary - I expect the models will jump about for some time yet before they get to grips with where the low will track and how deep it is. Beyond that is certainly in the realms of being virtually impossible to model at this point in my opinion, so I imagine there could be pretty much every scenario under the sun painted from run to run and from model to model in the next few days or so..

Follow the ensembles here (free) - with both maps and graphs viewable:

http://www.netweather.tv/index.cgi?action=ensviewer;sess=

And the GFS, ECM, UKMO and Fax charts are viewable (again freely) from here:

http://www.netweather.tv/index.cgi?action=nwdc;sess=

[mountain shadow]

GFS continues to back down to the METO with the trough further north and west...

http://91.121.93.17/pics/Rtavn1201.png

The new GFS seems to be just as bad as the old one IMO.

Lets see if we can get some support for the ECM medium term outlook.

[johnholmes]

latest lrf ideas from me in the link below

http://www.netweather.tv/forum/index.php?s...p;#entry1495816

Edited February 27, 2009 by johnholmes

[J10]

GFS still looks cold enough for overnight snow with sub zero dewpoints overnight . (especially into Wednesday)