Model Output Discussion - 28th November - 4th December

[johnholmes]

A borefest is slang for very mundane

ta muchly

[legritter]

A BOR FEST is a festival in the arctic circle,about a week before a mayor change of pressure they bring out the bors and roast them . its a celebration that only happens about every 10/15 yrs . they then sit around watching N/W europe freeze on their tellys . i will post a seriouse post later , cheers gang .

[weathe20]

A borefest is slang for very mundane

Ok chaps, yes mundane with fog and frost from the 12z. Just wondering from my newbie stance where this pattern could lead.

(bor fest - might catch on here!)

[cyclonic happiness]

Just had a mooch through all of the 'lesser' models and cannot seem to find that amplified shortwave that drags up all the mild 850's on wednesday/thursday.

So now I'm a little more confident of us staying in a resonably cold upper airflow.

I don't know why I got upset about a 24 hour period of warm uppers, but I did, but now I'm not??

[nick sussex]

Not long now till the ECM comes out, it would very ironic now if it decided to follow the GFS!

The GFS is lower risk in terms of perhaps being able to hold on to some surface cold, for down here it would be quite cold given a likely east to ne flow. Of course that could eventually develop much more interest but equally the whole thing could drag on with the high never making it far enough north.

The UKMO could go badly wrong in terms of being able to hold on to some colder conditions if you don't get sufficient amplification upstream .

If you read the NOAA morning update they do expect the east Pacific ridge to rebuild after a temporary back seat and they did highlight the downstream uncertainties.

The ECM 96hrs looks similar to the UKMO!

Upto 120hrs its still similar but a slightly less favourable upstream pattern, if the shortwave cuts se at 144hrs its game on, if it pushes east then game over!

Edited December 4, 2011 by nick sussex

[Uncle_Barty]

Well, still no sign of southwesterlies and mild weather despite the stratosphere being very cold for quite some time now. I think another signal is override the cold stratosphere.

Karyo

Cold strat most likely to lead to strong polar vortex. makes high lat blocking (often a key ingredient to sustained cold weather) much less likely, and zonal conditions much more likely. Doesnt necessarily mean blowtorch southwesterlies though.

[SMU]

Ian there will be no mid lattitude high out of the azores if it does it will come from Greenland & drift east

The GFS looks out on its own tonight after a stella UKMO & a good ECM out to 120-

Whoever called zonal ^^^^ Ian - et al is on shakey ground tonight- you dont get trough disruption within a zonal jet- only on a diffluent block

S

Edited December 4, 2011 by Steve Murr

[nick sussex]

If theere is to be a mid-latutude high, it can't transfer into a favourable place for UK cold whilst the PV remains in place to the NW and the general NH profile remains as it is. It would just be a time filler until the jet sinks it.

Yes thats why I don't like the GFS, I'd rather the high risk Euros.

I think we've all had enough of Euro highs, it would be cold down here but could just turn into one long yawn!

The ECM is semi-game on! a bit messy but certainly far better than the GFS watching paint dry operational run.

Edited December 4, 2011 by nick sussex

[SMU]

http://www.meteociel.fr/modeles/ecmwf/run/ECH1-144.GIF?04-0

awsome chart balanced on a knife edge that is now ECM + UKMO V GFS

S

[Snowstorm1]

Yes thats why I don't like the GFS, I'd rather the high risk Euros.

I think we've all had enough of Euro highs, it would be cold down here but could just turn into one long yawn!

The ECM is semi-game on! a bit messy but certainly far better than the GFS watching paint dry operational run.

Yes Nick weve had the safe route before with Euro High rubbish we just need to gamble now and save our sanity one way or the other imo SO UKMO + ECM V GFS - whos ya money on mine first one please...

[shedhead]

ECM will deliver height rises over UK, a la GFS, it just take a few days longer to do it.

Edited December 4, 2011 by shedhead

[SMU]

http://www.meteociel.fr/modeles/ecmwf/run/ECH1-168.GIF?04-0

not quite as good as hoped-- so thats 3 different models with 3 different outsomes at 168

S

[Frosty.]

If the Gfs 12z outlook is the new trend (very anticyclonic) then the meto outlook is on very shaky ground as it suggests the northern half of the uk remains generally unsettled with snow on hills and windy at times, the gfs in FI is the polar opposite of unsettled.

[nick sussex]

Yes Nick weve had the safe route before with Euro High rubbish we just need to gamble now and save our sanity one way or the other imo SO UKMO + ECM V GFS - whos ya money on mine first one please...

The ECM at 168hrs isn't so good but I've seen enough to think it could go either way, especially as the PV has decided to head west.

We have to think what the charts showed a few days back, alots already changed since then, could be more changes.

It may all end in tears and tantrums but I'm with you here I've been there and done that and got the Euro high t-shirt! so I don't really need to see that for a while, it may end up that we get lumped with it but you never know...

[shedhead]

If the Gfs 12z outlook is the new trend (very anticyclonic) then the meto outlook is on very shaky ground as it suggests the northern half of the uk remains generally unsettled with snow on hills and windy at times, the gfs in FI is the polar opposite of unsettled.

Agreed PL - something more akin to the latest GEM run looks more realistic imo, a kind of half way house senario... http://www.meteociel.fr/modeles/geme_cartes.php?&ech=144&mode=0&carte=0

Edited December 4, 2011 by shedhead

[Thundery wintry showers]

It really depends on what you're after- a mid-latitude high is the most reliable bet for cold, but also the most reliable for absence of snow, since for snowfall you need precipitation. The GFS 12Z anticyclone would most likely bring bright frosty conditions for the majority judging by the origin of the airmass, but it's very common for mid-latitude winter highs to start off with a couple of sunny days and then turn relentlessly overcast as moisture spreads in from either the Atlantic or the North Sea.

If it's a Scandinavian High you're after, then you might as well bank on something like the ECMWF 00Z which had the jet deflected south, and eventual pressure rises over Scandinavia- I agree with Ian Brown that a mid-latitude block over the UK would most likely fill some time with quiet weather before sinking south again, as happened in the Decembers of 2006 and 2007, as in that scenario the jet is implied north and the strong PV would hinder any advance on 24-36 hour northerlies.

Overall the GFS is sticking with the mid-latitude high but ECMWF/UKMO keep on with a slight NW-SE tilt to the jet and continued average to cold zonality in the north, milder at times in the south.

[SMU]

PM box is full Steve

ive cleared it- PM me if not email me-

192 ECM everything going south again... I dont think the 168 chart is right- especially with those X2 lows so close together over scandi

We shall See

S

[kold weather]

http://www.meteociel...H1-168.GIF?04-0

not quite as good as hoped-- so thats 3 different models with 3 different outsomes at 168

S

I'm near 100% certain the UKMO would be similar to that at 168hrs Steve judging by the way the LP shoots NE between 120-144hrs on the UKMO and deepens by 10mbs at the same time.

GFS is actually the safest and probably coldest evolution into a cold spell...ECM could evolve into a cold spell but we are depending on multiple sliders...a tough ask!!

[jethro]

Question from a complete thicko......After reading through here and the Strat thread I thought the PV was supposed to be very intense and unlikely to split in the foreseeable. In the charts linked above from SM the PV seems to be already split into several segments and scattered all over the place - someone please explain to idiot here.

[nick sussex]

Isnt that good nes ?? confused??

Yes you need to see the PV heading west away from the heart of Greenland, we can get away with it in western Greenland but stuck where it is you will not see cold spells, more just snaps, theres no chance of a Greenland high but you can still get an easterly or ne even with a cold stratosphere.

[Thundery wintry showers]

I agree that GFS is the safest evolution into a cold spell, but I'm just mindful of the fact that a lot of people were disappointed during January 2011 because of the lack of snow in southern areas in spite of the month as a whole being near average to fairly cold. I'm also mindful of the fact that the winter of 1991/92 was arguably the most snowless of the twentieth century, despite not being particularly warm away from Scotland, primarily because of these mid-latitude highs.

Re. Jethro's questions, an interesting point- the UKMO/ECM are indeed suggesting some disruption to the polar vortex. On the UKMO the PV is becoming fragmented by T+144 while on the ECMWF it is heading west, which would again give potential for pressure rises over Scandinavia, even if they don't end up featuring on the operational run. Interestingly even the GFS with its mid-latitude high also has the PV fragmenting and the majority of it heading west. Thus, the strong polar vortex is showing consistent signs of fragmenting on the latest set of runs.

[Frosty.]

Agreed PL - something more akin to the latest GEM run looks more realistic imo, a kind of half way house senario... http://www.meteociel.fr/modeles/geme_cartes.php?&ech=144&mode=0&carte=0

I'm hoping the ecm/ukmo are closer to the eventual reality because the gfs outlook is just boring with no risk of snow with the really cold weather many hundreds of miles to the east.. and more importantly, no help for the drought in southeastern uk.

[kold weather]

Another burst of cold zonality likely by 240hrs on the ECM, not as good for sustained cold as the GFS but probably higher chance of snow for Scotland.

AO actually not too positive by 216hrs either...at least compared to recent days!!

[nick sussex]

Question from a complete thicko......After reading through here and the Strat thread I thought the PV was supposed to be very intense and unlikely to split in the foreseeable. In the charts linked above from SM the PV seems to be already split into several segments and scattered all over the place - someone please explain to idiot here.

It might look that way but thats not really a proper split of the PV, it doesn't matter if the PV doesn't split as long as its not limpeted over Greenland, I've seen many easterlies with an angry looking PV but this has set up shop far enough to the west to allow that.

[kold weather]

I agree that GFS is the safest evolution into a cold spell, but I'm just mindful of the fact that a lot of people were disappointed during January 2011 because of the lack of snow in southern areas in spite of the month as a whole being near average to fairly cold. I'm also mindful of the fact that the winter of 1991/92 was arguably the most snowless of the twentieth century primarily because of these mid-latitude highs.

Indeed it can be boring but I'm also mindful of December 2006 when we had a strong blocking high over the UK. People wished zonality back...and we went on to have one of the mildest winters in history...so people need to be careful for what they wish for!!

Your not going to get anything other than cold zonality though from this run, cool but never much for those south of the border.