Model Output Discussion 12z 30/11/2012

[SMU]

Evening All-

GFS 18z out to T84 is sharpening up the trough over iceland-

could this next slider event be a bit more snow orientated-

http://modeles.meteo...snh-0-90.png?18

S

Edited December 1, 2012 by Steve Murr

[bobbydog]

i feel a lot better about the models than I did last night after seeing that gefs 12z mean, glad the meto did not incorporate that into their update today or it would have read, on balance, a milder trend is anticipated with a lot of low cloud, hill fog and drizzle. Things are looking a lot more favourable for cold wintry weather, that is the trend tonight.

to be fair, things have never looked unfavourable for cold wintry weather. we've got it right now anyway! the models have, whilst not been consistent in the detail, shown cold all the way, with the odd, less cold, (not mild) blip on the way. with this pattern, its only a matter of time before we get what we're looking for. problem is, we've seen some good cold shots fail to happen but thats because they've been a finger of cold pointing at us, which would give us some great winter weather but at the range showing it, by the time we get there, its pointing somewhere else! what we need to see is the right synoptics to give us a wall of unstoppable winter heading towards us and hopefully we might just see that very soon!

[Panayiotis]

Much better northerly on the 18z at 87hrs..

Edited December 1, 2012 by panayiotis

[Geordiesnow]

Much better northerly on the 18z at 87hrs..

I would still prefer ECM/UKMO as its got a slightly better amplified ridge although it seems whatever happens, the Northerly will be short-lived but got the potential to produce some snowfall for sure.

Certainly the potential for another frontal event for Wednesday-Thursday morning across parts of Scotland in particular, long way still to go though to pin down the details on that one but an interesting short range period coming up potentially.

Edited December 1, 2012 by Geordiesnow

[SMU]

Look at the 21st of NOV 2010 type of advection over greenland at162-

http://modeles.meteociel.fr/modeles/reana/2010/archivesnh-2010-11-21-0-0.png then

now

http://modeles.meteociel.fr/modeles/gfs/runs/2012120118/gfsnh-0-162.png?18

not quite as good so the block will be positively tilted- still pretty good..

S

[JP1972]

Look at the 21st of NOV 2010 type of advection over greenland at162-

http://modeles.meteo...0-11-21-0-0.png then

now

http://modeles.meteo...nh-0-162.png?18

not quite as good so the block will be positively tilted- still pretty good..

S

Break this down into small pieces for babies please?!

[MR EXTREMES]

Look at the 21st of NOV 2010 type of advection over greenland at162-

http://modeles.meteociel.fr/modeles/reana/2010/archivesnh-2010-11-21-0-0.png then

now

http://modeles.meteociel.fr/modeles/gfs/runs/2012120118/gfsnh-0-162.png?18

not quite as good so the block will be positively tilted- still pretty good..

S

Case of almost but no cigar.

We were so close to a 09/10 type setup although still below average.

But still Jan and Feb to look forward to.

[SMU]

any time you get that mega split flow over Greenland- something big is coming

S

[Weathizard]

This looks a very messy run to me, not impressed but hey ho think i have too high of a standard, hopefully ensembles are alright, although, i'll put this into perspective comparing it to last year!

Edited December 1, 2012 by Weathizard

[nick sussex]

Latest UKMO fax charts:

96hrs

Occlusion heading south embedded in sub 528 dam , possible snow off this feature.

120hrs

Warm front approaching from the nw but still some cold air ahead of it, chance of some snow on the leading edge but better here if the track was more se with an occlusion.

[snowking]

More consistency from the GFS within the reliable, and even more especially out towards 192 with the placement of the ridge

SK

[Bristawl Si]

Case of almost but no cigar.

We were so close to a 09/10 type setup although still below average.

But still Jan and Feb to look forward to.

"We were so close!!??"........."But still Jan and Feb to look forward to!!??"

Have u banged your head or something and woken up to think it's December 31st or something?

[Great Plum]

This looks a very messy run to me, not impressed but hey ho, hopefully ensembles are alright

Interesting you say this because at least up to 180 hours (which is pretty deep FI), the country is largely under or close to -5 air and follows the same theme as the 12z...

http://www.wetterzentrale.de/pics/Rtavn962.png

http://www.wetterzentrale.de/pics/Rtavn1802.png

[SMU]

http://modeles.meteociel.fr/modeles/gfs/runs/2012120118/gfsnh-0-360.png?18

another brutal run from the GFS- sub zero maxima all the way from 264 & heavy snow edging west into the UK-

remember peeps this is your chart to CHASE

http://modeles.meteociel.fr/modeles/gfs/runs/2012120118/gfsnh-0-156.png?18 SPLIT FLOW OVER GREENLAND-

the rest will fall into place--

S

[Geordiesnow]

Latest UKMO fax charts:

96hrs

Occlusion heading south embedded in sub 528 dam , possible snow off this feature.

More interestingly, that nice little trough embedded in the flow that could give some decent accumulations in NE Scotland, and perhaps later in NE England. Although its nearly more or less set in stone, I'm a little surprised the Northerly is not a little bit more talked about in all honesty.

Height rises to our NE could become a feature as we go through December, shame the height rises develop after the very large PV in Russia heads back towards the pole otherwise we could of seen some really deep cold heading down on the eastern flank of any Scandi high. It is one to watch of course but it would not surprise me if the height trends disappear somewhat because of the timescale involved.

[If Wishes made Weather]

Well it appears that the 18z has largely followed the 12z - and quite closely in the more reliable time and somewhat out past the 144 mark. As Steve notes, the real wintery stuff starts once the ridge passes through around next Saturday/Sunday. Not that it will happen, but note the undercut developing in the western approaches on the last chart. Its a bit far north to bring snow throughout the whole of the southern counties, but the apparently meteorologically significant M4 would probably represent the boundary if it doesnt veer south.

[on the coast]

http://modeles.meteo...nh-0-360.png?18

another brutal run from the GFS- sub zero maxima all the way from 264 & heavy snow edging west into the UK-

remember peeps this is your chart to CHASE

http://modeles.meteo...nh-0-156.png?18 SPLIT FLOW OVER GREENLAND-

the rest will fall into place--

S

Something brewing cold wise coming up. GFS looking good so far in its runs from 168.

[bluearmy]

Another frigid soueaster to end a gfs run. The model is in danger of showing some continuity!

[misha]

It seems to me that the signals for cold weather with the models are very significant - although I think some members are seeing FI synoptics that really are not likely to come off! I've lurked and watched the posts from our more experienced members and none of them have suggested extreme cold (below average yes). Indeed, looks to me like an old fashioned winter with cold followed by mild then cold etc - nice snow events though! I think what we all have to keep in mind is that these very interesting synoptics are being produced in the first place.

[bobbydog]

http://modeles.meteo...nh-0-360.png?18

another brutal run from the GFS- sub zero maxima all the way from 264 & heavy snow edging west into the UK-

remember peeps this is your chart to CHASE

http://modeles.meteo...nh-0-156.png?18 SPLIT FLOW OVER GREENLAND-

the rest will fall into place--

S

lets hope you're right this time steve

[weather eater]

Simply put, pretty much as you were out to 120hrs, for the rest this is just one of many evolutions that we are going to see over the coming days, the trend though is the same.

[Jason T]

http://modeles.meteo...nh-0-360.png?18

another brutal run from the GFS- sub zero maxima all the way from 264 & heavy snow edging west into the UK-

remember peeps this is your chart to CHASE

http://modeles.meteo...nh-0-156.png?18 SPLIT FLOW OVER GREENLAND-

the rest will fall into place--

S

Question Please Steve...What is your Build theory and belief of the past and current output through-out. It seems the case of so close but no cigar, 10 days ago we started on this roller coaster and everything looked (Positive). Then the ECM came on board with a last second(Bloomer). In this thread it's stated that we post to what we see,Is seeing believing or drop like a hot bolt.?????. Gut instinct, 2012 Going to be a smasher.(2nd week)

[chris55]

GFS 18z

The elongated ridge at 192 stretching from Western France all the way up to Iceland is interesting, these sorts of high pressure ridges often are a precursor to something from the east evolving.

http://www.wetterzentrale.de/pics/Rtavn1921.png

Also remarkable consistency from the GFS in the last four runs, this is one area where I do rate GFS, it can be very good at picking up trends in FI if we see consistency from the Det. I wouldn't be surprised to see this theme continued over the next few days, it may well drop the idea from run to run but will be interesting to see if we get ens on board etc over the coming days.

[SMU]

Blind theory the atlantic tropical wave ( the second one ) helps kick the jet up the western part of greenland-

That loop goes round the pole & kicks the euro trough south- where we want it-

chances 60%- so not over committing.

remember the driving features are at 102-

http://modeles.meteociel.fr/modeles/gens/run/gensnh-0-1-108.png?18

Tropical wave developing SE atlantic will kick that energy thats over the NE states up the western part of greenland-

S

Edited December 1, 2012 by Steve Murr

[chris55]

How that Tropical wave interacts with the Atlantic high is crucial, if it stays West then the ridge is amplified like GFS

ECM has it slicing through the high cutting off the extended ridge

This completely changes the outcome with ECM allowing energy over the Greeny ridge whilst GFS links with heights to the north and east cutting of the Atlantic to the north.

http://www.wetterzentrale.de/pics/Rtavn2161.png

http://www.wetterzentrale.de/pics/Recm2161.gif

How this is finally dealt with in the shorter term is crucial.