Model Output Discussion 26/11/2012 18Z onwards

[chionomaniac]

Right all,

Here we go again .

The next instalment of the gripping drama that is model watch.

On this evening show we have ECM ensembles, the GFS18Z run, FAX charts, NOAA updates and much, much more.

Stay tuned and post responsibly.

Thanks.

[JCP]

@Isolated Frost -- I don't understand your point about the 72hr fax and the Norwegian short wave?

It is also on the 72hr UKMO run tonight, and pretty much gets 'smoothed out' by 96hrs.

[Bobby]

Even if the UKMO is right, there'd a brief moderate cold snap, then if it went out beyond +144 it would very likely show the Atlantic moving in eventually and that's about the best case scenario. There isn't a single model or barely even an ensemble run that's not showing a breakdown at around day 7 or so.

NOGAPS looks like UKMO at 144, but 24 hours later the Atlantic moving in

NOGAPS:

UKMO:

Then NOGPAS +36 hours later

Hardly mild but no big freeze we're after. There's still potential for another cold snap later in the month, pehaps better, and winter hasn't even started so plenty of reasons to be positive.

Not popular maybe but that's how I'm calling it.

[khodds]

Sorry - can't resist this - Post Responsibly... Is this because we are all on prozac?! I'm too scared to look in here sometimes. Its the longest roller coaster I've ever been on. I feel sick!

[karlos1983]

what time does it all kick off this evening?

[HammerJack]

what time does it all kick off this evening?

There you go....

[Grimsby Snow Lover]

what time does it all kick off this evening?

GFS 18z rolls out at 9.30 with the all important faxes around an hour later I believe.

[summer blizzard]

The front next sunday is actually rather interesting, it would not take much to produce a snow event.

[cheshire snow]

what time does it all kick off this evening?

GFS 18z about 21.30

C.S

[chionomaniac]

Even if the UKMO is right, there'd a brief moderate cold snap, then if it went out beyond +144 it would very likely show the Atlantic moving in eventually and that's about the best case scenario. There isn't a single model or barely even an ensemble run that's not showing a breakdown at around day 7 or so.

NOGAPS looks like UKMO at 144, but 24 hours later the Atlantic moving in

NOGAPS:

UKMO:

Then NOGPAS +36 hours later

Hardly mild but no big freeze we're after. There's still potential for another cold snap later in the month, pehaps better, and winter hasn't even started so plenty of reasons to be positive.

Not popular maybe but that's how I'm calling it.

I also think that it is likely that pulses of energy will cross the Atlantic. It is not defininitive that this will occur, but I think that anyone expecting any mild interlude will be disappointed as after any pulse the door will be slammed shut again by Atlantic heights rebuilding.

The question is how long and wide is the door going to be opened in the first place? For not too long and not too wide I suspect.

[Dave Kightley]

Even if the UKMO is right, there'd a brief moderate cold snap, then if it went out beyond +144 it would very likely show the Atlantic moving in eventually and that's about the best case scenario. There isn't a single model or barely even an ensemble run that's not showing a breakdown at around day 7 or so.

NOGAPS looks like UKMO at 144, but 24 hours later the Atlantic moving in

NOGAPS:

UKMO:

Then NOGPAS +36 hours later

Hardly mild but no big freeze we're after. There's still potential for another cold snap later in the month, pehaps better, and winter hasn't even started so plenty of reasons to be positive.

Not popular maybe but that's how I'm calling it.

Even if the UKMO is right, there'd a brief moderate cold snap, then if it went out beyond +144 it would very likely show the Atlantic moving in eventually and that's about the best case scenario. There isn't a single model or barely even an ensemble run that's not showing a breakdown at around day 7 or so.

NOGAPS looks like UKMO at 144, but 24 hours later the Atlantic moving in

NOGAPS:

UKMO:

Then NOGPAS +36 hours later

Hardly mild but no big freeze we're after. There's still potential for another cold snap later in the month, pehaps better, and winter hasn't even started so plenty of reasons to be positive.

Not popular maybe but that's how I'm calling it.

Nice Greenland high! That's a nice chart. Heights remain high over our N.W. N.Easterlys would soon be digging back

[Isolated Frost]

@Isolated Frost -- I don't understand your point about the 72hr fax and the Norwegian short wave?

It is also on the 72hr UKMO run tonight, and pretty much gets 'smoothed out' by 96hrs.

It's not on the 72hr UKMO- it's a shortwave kink in the longwave pattern- but is no norwegian short wave- though what is important is that the 72 came before the more positive ECM ENS, not afterwards--

Another major difference between the ECM-ENS and the UKMO is the ridging that the Svalbard high brings down into scandi- the ECM ENS rejects the arctic high moving s'wards at 72, whilst the UKMO promotes it and the flow gets squeezed- I don't see that in the ECM ENS, which I see the FAX morphing into-

the facts are that the t72 fax update shows shortwave activity outside w norway, more pronounced than on the ECM ENS and the UKMO- we will find out tonight, but the view is surely veering towards a movement towards the less conductive ECM ENS from Exeter tonight...

[LomondSnowstorm]

I'm not convinced I see the difference IF is talking about. I mean I see the difference between yesterday's fax and today's but looking at the UKMO output it looks very much like the 72 hour FAX chart:

Compare this to the ECM ensemble mean:

Both are close to identical at this stage, but UKMO does has pressure significantly higher across Scandinavia than the ECM ensemble, and the FAX chart certainly appears to be closer to it. I think there will be a degree of modification but I tend to agree with Nick and Steve's analysis: the operationals are simply better at modelling this kind of small detail than the ensembles at short range, and when the operational is an outlier from its ensembles within about +96 hours, as long as it is consistently so, it tends to be right, and I think that, bar a few tweaks, it will look much like the UKMO does. The UKMO looks to have just as much support among the ECM ensembles as it did last night, probably moreso, and they are a colder set of ensembles than yesterday's also.

[German Sheperd]

All good fun. I love it on here in winter.

I can't help but feel, looking at the models, that the block will prove more stubbern than is being progged, along with the yet to be determined shortwave and low pressure lottery results.

We have got a lot to look forward to, if your interested in the weather.

Finally, if I may, I would like to copy this post in from TWO where Rustyroo quite succinctly explains our current predicament :-

"So to sum up;

We are certain of the uncertainty in GFS but uncertain of the certainty of the UKMO while we are uncertain of any certainty a certain model is about to show?

Glad that has been clarified then."

Quality!!

[mackerel sky]

Surely when everything was lost the GFS 12z offers the opportunity of at least frontal snow, if albeit temporary? Only a slight westwood shift is required for a nice little early battleground, because FI is now rather good again. ECM wants to bring on a raging (cool) westerly now doesn't it? After apparently being the model of choice, just because it was the last to downgrade in the short term for straw clutching. I'm surprised with you lot, and some should know better having observed this happen 60/40 of of the time since the very start of the netweather forum. But people do get carried away I suppose and then look for a big stick to either beat themselves or others with.

[bluearmy]

Re the cpc charts - they are 6 day mean output which means that they cant show you where the individual features are likely to be at any one time. they say we are looking at a mean ridge to our north and a mean trough to our east. You can fill in the gaps yourself.

Nice upper ridge greenland up into the arctic to our ne on ecm day 10 mean.

All in all, a chilly to cold outlook and as i said earlier, anything between gfs and jma can verify without the cpc output being incorrect.

[Isolated Frost]

I'm not convinced I see the difference IF is talking about. I mean I see the difference between yesterday's fax and today's but looking at the UKMO output it looks very much like the 72 hour FAX chart:

Compare this to the ECM ensemble mean:

Both are close to identical at this stage, but UKMO does has pressure significantly higher across Scandinavia than the ECM ensemble, and the FAX chart certainly appears to be closer to it. I think there will be a degree of modification but I tend to agree with Nick and Steve's analysis: the operationals are simply better at modelling this kind of small detail than the ensembles at short range, and when the operational is an outlier from its ensembles within about +96 hours, as long as it is consistently so, it tends to be right, and I think that, bar a few tweaks, it will look much like the UKMO does. The UKMO looks to have just as much support among the ECM ensembles as it did last night, probably moreso, and they are a colder set of ensembles than yesterday's also.

Today's FAX for Thursday 12pm on the top- Yesterday's FAX for Thursday 12pm on the bottom-

I've edited it to show the shortwave that appears on today's FAX that was not noted on yesterday's- this is a crucial part of the puzzle as it'll likely move s'wards and disrupt the east flow in scandi- as they ride over the shortwave and we in turn get a northerly-

As shown on the bottom edit- a plain and simple flow with no shortwave movement in between- allowing the colder uppers to reach quickly-

Of course if the shortwave is pulled back into the pattern at t96 on the FAX- it's very much game on re: north-easterly for this upcoming wknd- but I expect the shortwave to behave a la GFS- mainly because it's a pattern that the GFS has had engrained in it recently- and only really the UKMO has stuck against it

[Weathizard]

Could someone be so kind to do a brief summary of which models stand where, NOT with regards to the Snow potential but the handling of the low pressure around Greenland?

Obviously we know the UKMO, JMA, NOGAPS are on the same team, would the more experienced say that the ECM ensemble mean makes it on the same team? Or is that more of a middleground scenario?

[Jaffusmaximus]

Could someone be so kind to do a brief summary of which models stand where, NOT with regards to the Snow potential but the handling of the low pressure around Greenland?

Obviously we know the UKMO, JMA, NOGAPS are on the same team, would the more experienced say that the ECM ensemble mean makes it on the same team? Or is that more of a middleground scenario?

“ [T]here are known knowns; there are things we know that we know.

There are known unknowns; that is to say there are things that, we now know we don't know.

But there are also unknown unknowns – there are things we do not know we don't know. â€

—

United States Secretary of Defense, Donald Rumsfeld

[SMU]

Here an interesting one that nobodys picked up on-

to monitor snow chances from the atlantic in a slider type situation we look at the 850s to see where the 0c isotherm peak is sliding-

whats very interesting is the ECM has peaks-

http://www.meteociel.fr/modeles/ecmwf/runs/2012112612/ECH0-144.GIF?26-0 ICELAND

http://www.meteociel.fr/modeles/ecmwf/runs/2012112612/ECH0-168.GIF?26-0 NORTH SEA

http://www.meteociel.fr/modeles/ecmwf/runs/2012112612/ECH0-192.GIF?26-0 CENTRAL FRANCE

ECM ENSEMBLES- less eastward energy like the JMA

http://www.meteociel.fr/modeles/ecmwf/runs/2012112612/EDH0-144.GIF?26-0 CENTRAL ATLANTIC

http://www.meteociel.fr/modeles/ecmwf/runs/2012112612/EDH0-168.GIF?26-0 SOUTH OF IRELAND

192 has flattened into Spain.

other than UKMO thats the best bit of news all night-

Awaiting the extended ECM ENS- expecting a double dip- maybe with a minimal kink upwards compared with the op & Control-

S

[chionomaniac]

Just browsing through some ensembles.

Here are the Icelandic slp's from the GFS 12Z today.

Worth noting that at the crucial period (3rd Dec) the operational is towards the deeper end of the ensembles and that there are only 2 others and the control that lower pressure quicker. If anything we should expect the 18Z to follow the ensembles then the short wave crossing the Atlantic may be more delayed and less deep - which should also give it a more southerly track.

After that the ensembles are as mad as a box of frogs!

[bluearmy]

Here an interesting one that nobodys picked up on-

to monitor snow chances from the atlantic in a slider type situation we look at the 850s to see where the 0c isotherm peak is sliding-

whats very interesting is the ECM has peaks-

http://www.meteociel.fr/modeles/ecmwf/runs/2012112612/ECH0-144.GIF?26-0 ICELAND

http://www.meteociel.fr/modeles/ecmwf/runs/2012112612/ECH0-168.GIF?26-0 NORTH SEA

http://www.meteociel.fr/modeles/ecmwf/runs/2012112612/ECH0-192.GIF?26-0 CENTRAL FRANCE

ECM ENSEMBLES- less eastward energy like the JMA

http://www.meteociel.fr/modeles/ecmwf/runs/2012112612/EDH0-144.GIF?26-0 CENTRAL ATLANTIC

http://www.meteociel.fr/modeles/ecmwf/runs/2012112612/EDH0-168.GIF?26-0 SOUTH OF IRELAND

192 has flattened into Spain.

other than UKMO thats the best bit of news all night-

Awaiting the extended ECM ENS- expecting a double dip- maybe with a minimal kink upwards compared with the op & Control-

S

Run through the spreads on meteociel and watch the spread energy running down to our west rather than our east. That pretty well represents what the jma op run showed on its 12z run.

[Ice BIast]

Looking at the high res NAM model, it shows the low travelling up to greenland in a good position, quite far west and its also quite deep like on the UKMO. Small differences though, and a shame it doesn't model areas further east.

[SMU]

Run through the spreads on meteociel and watch the spread energy running down to our west rather than our east. That pretty well represents what the jma op run showed on its 12z run.

http://www.meteociel.fr/modeles/ecmwf/runs/2012112612/EEH1-240.GIF?26-0

good agreement on an east based NAO at the end as well

S

[mcweather]

Here an interesting one that nobodys picked up on-

to monitor snow chances from the atlantic in a slider type situation we look at the 850s to see where the 0c isotherm peak is sliding-

whats very interesting is the ECM has peaks-

http://www.meteociel...H0-144.GIF?26-0 ICELAND

http://www.meteociel...H0-168.GIF?26-0 NORTH SEA

http://www.meteociel...H0-192.GIF?26-0 CENTRAL FRANCE

ECM ENSEMBLES- less eastward energy like the JMA

http://www.meteociel...H0-144.GIF?26-0 CENTRAL ATLANTIC

http://www.meteociel...H0-168.GIF?26-0 SOUTH OF IRELAND

192 has flattened into Spain.

other than UKMO thats the best bit of news all night-

Awaiting the extended ECM ENS- expecting a double dip- maybe with a minimal kink upwards compared with the op & Control-

S

Hi Steve , This is something that I've been wondering in that if these lows that some models suggest could sneak through next week lose a bit of energy then could they not become a series of sliders