Model Output Discussion 13/11/12 18Z onwards

[AWD]

From 168 right through till the end GFS is cool to cold with night-time frosts, cold below average days, and with fog developing widely (possibly freezing fog) And also to note is the high pressure is giving us more of a continental flow rather that one from the Atlantic hence the colder conditions at the surface.

Overall for me personally this is a nice end of Autumn pattern and beats mild Atlantic weather any day. Also with all this high pressure around and a meridional jet the chance for some cold snow bearing conditions to appear are higher.

That's where I think the split in opinion lies. For snow the GFS is poor, for cold, frosty conditions the GFS is good, which personally I would happily take.

The colder air is starting to enter the semi reliable now too, so increasing confidence IMO of a cooler anticyclonic spell in week 2.

After that, ain't gotta clue mucker!

[bradymk]

Good agreement from the ensembles for a build in heights in the Atlantic up towards Greenland.

[snow drift]

quite so but is it correct, or was the 06z more likely to be correct, how does anyone tell?

The one that shows cold, the rest are clearly wrong!!!!!!!!!!!!!

I am encouraged by the latest output as we are getting the models to show more of a settled and colder theme in the nearer time frame.

[MR EXTREMES]

a certain steve murr introduced a scandi heights into a post lastnight.

just goes to show how sometimes the models can be a nightmare to predict expecting nightmare model watching for atleast another few days.

[bluearmy]

a certain steve murr introduced a scandi heights into a post lastnight.

just goes to show how sometimes the models can be a nightmare to predict expecting nightmare model watching for atleast another few days.

And you think there is less chance of a scandi high in a weeks time than 24hiurs ago?

the route to an atlantic block remains uncertain. All roads appear to lead to this feature but which one will be right?

[Polar Maritime]

One thing that has been consistent across the models in FI for the last 2 weeks is high pressure to our North, producing an Easterly/Northerly. Obviously the models know that the current set-up we are in, will, at some point break into a such like cold pattern with blocking to our North. Very interesting model watching over the next few day's, when hopefully, things will begin to become more clearer as to where the blocking will end up.

[weather eater]

There really is only one thing to say about the 12z and that’s the blocked theme for the end of Nov beginning of Dec continues.

Steve is very fond of the phrase chocolate teapot, usually in relation to the GFS 06z and 18z runs, in truth the phase could be used on all the GFS output past 120hrs or so, frequently too progressive, has a tendency to shower short waves about like confetti, and is guaranteed to paint a totally different picture in FI every single run. Over the last few days we have seen bucket loads of solutions in regards how the block sets up and frankly, any or none of them could be correct, 240hrs really should be the limit of attention paid to the GFS because everything else is a case of pin the tail on the donkey, personally I advise that even 240hrs is really pushing the boat out

GFS viewing plan

Up to 96hrs, pay attention,

96hrs – 168hrs, put on patented sceptical viewing glasses

168hrs – 240hrs, peer with extreme caution through fingers

240hrs plus, hide behind sofa.

Edited November 17, 2012 by weather eater

[SMU]

Afternoon ALL- A fleeting visit tonight!

All going to plan today- awaiting ECM update- although look at the ECM ensembles!

It appears people on board with how poor the 06z is ( & Remember the 06Z ensembles are even lower resolution)!

GFS 06Z 144

ECM 144

UKMO 144

How far away is that !!

Its good people are beginning to see the GFS failings....

Anyway- I forecast a HUGE swing from the GFS starting on the 00z tonight..

S

[offerman]

Well i think its safe that we wont get any cold for the rest of november but better that way and hopefully december will bring some festive weather. Charts been showing atlantic weather through and through now. I still think winter might be a good one. Alreay had 1.5inches of snow here this year and 3miles away had 5inches so a good albeit breif start.

[SMU]

quite so but is it correct, or was the 06z more likely to be correct, how does anyone tell?

John why do you keep asking the same question...?Surely after explanations & links etc & showing run ups to cold spells the GFS 06z is a chocolate Hammer!

[summer blizzard]

GFS12z is closer to ECWMF0z than GFS6z in my opinion.

Another very cold FI at the surface.

We may not get the easterly but i do think that we be quite confident of a fair cool-down.

[SnowObsessor90]

So I take it not a lot of people think much of 'faux cold' then? I for one wouldn't mind it, the outlook could certainly be a lot worse imo

[Great Plum]

So I take it not a lot of people think much of 'faux cold' then? I for one wouldn't mind it, the outlook could certainly be a lot worse imo

The high pressure over the uk scenario is hardly favoured by the gfs 12z ensembles...

http://www.netweather.tv/index.cgi?action=charts;type=ens;sess=

[SMU]

http://www.meteociel.fr/modeles/ecmwf/runs/2012111712/ECH1-120.GIF?17-0

day 5 & the winds swing to the SE as the Scandi block starts to build-

S

[summer blizzard]

So I take it not a lot of people think much of 'faux cold' then? I for one wouldn't mind it, the outlook could certainly be a lot worse imo

I love it, sunshine, fog and frost.

The high pressure over the uk scenario is hardly favoured by the gfs 12z ensembles...

http://www.netweathe...;type=ens;sess=

Which setup is? I'd also add that upper temperatures are largely irrelevant when pressure is bang on top.

[SMU]

http://www.meteociel.fr/modeles/ecmwf/runs/2012111712/ECH1-144.GIF?17-0

Day 6 - even more of an undercut-

Scandi block - one of a Slightly low amplitude so not collecting huge amounts of cold air in from Russia- but this is the foundation of the PV getting a big kick...

S

[The Northern Ramper]

I enjoy reading your posts Steve, you come across very knowledgeable and recently i have enjoyed your more in depth posts.

However there is a nagging feeling i get sometimes that you are chasing the Scandi high Easterly like some kind of holy grail in an IMBY sort of way.

[SMU]

Its not the Easterly im Chasing its the pattern change & what doors the scandi block opens-

That initial high doesnt bring much in the way of cold- but its forcing of the pattern should change the behaviour of the jet to something more meaningful a few days later....

S

Edited November 17, 2012 by Steve Murr

[shotski]

Its not the Easterly im Chasing its the pattern change & what doors the scandi block opens-

That initial high doesnt bring much in the way of cold- but its forcing of the pattern should change the behaviour of the jet to something more meaningful a few days later....

S

Steve, Do you think we will end up with a mid-atlantic ridge come early december ? it seems to be the form horse.

[SMU]

Steve, Do you think we will end up with a mid-atlantic ridge come early december ? it seems to be the form horse.

I think the Scandi block sets up Slightly to far east & of low amplitude, so flat & Oval instead of that circular high that draws that deep cold in from the Arctic, the pattern will keep trying to retrograde west & link up with pressure building towards Greenland- - when hopefully they are drawn together & start to sharpen up.

So yes what underpins that link is the rigde moving up towards greenland in the first place- out of the atlantic- remember its not a true GH until you get it cut off- however we can reach that scenario through atlantic ridge meeting a retrograding scandi block that morphs into the right circular shape ( 18z last night)

The ECM 12z looks messy but contains the right ingredients to make its way to what the NAEFS has been projecting in the mean for a while- the difference was how we get there between the models...

240 chart scores 7/10 for attempt at that-

http://www.meteociel...H1-240.GIF?17-0

But we dont quite get the full link up- also its a difficult one to see whether thats enough vertical advection up greenland to sustain the build on this run.... but for day 10- not bad.

S

Edited November 17, 2012 by Steve Murr

[bluearmy]

i made a comment this morning that was edited as paul thought i was having a dig at you steve. i'll make it more clearly this time. do you have any confidence int he 00z and 12z gefs? you continually comment that the ens will fail to pick the pattern due to their lower resolution. however, naefs fi is rarely too far from the mark and this is a mean of all the ens data gefs and gem ? is it more a case that the individual runs will be quite useless overall but put together, there are enough of them such that the mean is meaningful ?

[Liam J]

But we dont quite get the full link up- also its a difficult one to see whether thats enough vertical advection up greenland to sustain the build on this run.... but for day 10- not bad.

S

Are you still confident with your prediction you made yesterday evening for the Scandi block setting up on day 8, which is now day 7?

The ECM takes the block a bit too far east allowing lower heights into Western Europe, close but not quite on this run.

[Barry12]

Well i think its safe that we wont get any cold for the rest of november

I wouldn't say it's 'safe' just yet...

Edited November 17, 2012 by Barry95

[bluearmy]

Are you still confident with your prediction you made yesterday evening for the Scandi block setting up on day 8, which is now day 7?

The ECM takes the block a bit too far east allowing lower heights into Western Europe, close but not quite on this run.

which is good as its part of the undercutting required to deliver cold.

I wouldn't say it's 'safe' just yet...

have you seen the london ecm ens? temps will be very much on the low side for the final week of november.

[Barry12]

have you seen the london ecm ens? temps will be verymuch on the low side for the final week of november.

Thats what I was saying, not too discount any cold for november.

Edited November 17, 2012 by chionomaniac
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