Model Output Discussion - 1st - 7th January

[Cheshire Freeze]

As Steve has pointed out, a stunning NH profile on this run.....a definate positive when coupled with the ECM run. Not too bothered that the UK is shown to stay in a disturbed Atlantic pattern this run because it's in a completely different context of developing a more favourable Arctic profile. Not a bad run to end the day, could have been much worse.

[Brum Watcher]

18z changes from 240+, hopefully upgrades to heights on later runs, still better seeing yellow all the way thru....

[ITSY]

The tail end of 18Z FI on the op has serious potential IMO - it has heights rising to north, south and west of Greenland with favourable orientation on a displaced PV over scandinavia. Obviously lala land with a positive spin but not all doom and gloom

[Zakos]

AO looks set to head at least slightly negative.

NAO could go either way.

[summer blizzard]

18z has the jet stream far too strong near the UK with a 945mb low east of the UK (unlikely).

ECWMF is far better in the longer term.

[kold weather]

it would be a few days later though. i cant believe that if we get a massive distortion in the polar field such as the 18z shows, we wouldn't be the recipient of deep cold at some point in the fortnight that followed that run.

I'm trying to remember when it was but I've seen archived charts which had a very strong -ve AO but because the upper low set itself up to our SW/W, it constantly pumped up milder WSW/W airflows and prevented us from ever really tapping into anything other then the very tail end of the cold flow once it all finally moved on, so it can happen, though you'd be unlucky to get nothing...I think the 18z wouldn't end up giving anything that impressive as by the time it shifted eastwards it'll be much weaker and have little cold air left flowing round the circulation.

Anyway a far more believable run from the GFS in terms of how the Arctic responds, indeed this run may even be somewhat overdoing things on that front.

The set-up and building blocks are great on the 18z, the actual outcome is pretty poor considering.

Some TASTY ensembles by the way, some make the ECM look poor!

[damianslaw]

lol goodbye america...

http://www.meteociel...&mode=1&carte=1

A stunning NH run for indexes like the AO- heading to the lower values of -4, however nothing special for the UK_

S

Those temp profiles for Egypt are astonishing!!! - the cold plunge into the middle east- whilst southern england retains a warm blob - no chart better conveys our temperate climate better than that before..

What is encouraging with the profile shown is the deep cold entering NE Canada with WAA up the west side of greenland this is often a precursor to a cold northerly feed across our shores - it would only be a matter of time before the bottled up cold over the arctic makes it our way.

[SMU]

Almost universal Agreement from the 18z ensembles that Day 9/10 is the crunch time for a Northerly & at the same time a sustained cold spell with the polar height field around greenland-

85% of members have a sweeping arctic front at around 228 that sets up the Northerly- after that its anyones guess-

the best MOST consistent set of coldish GFS ensembles for a long time & all inline with the ECm OP-

S

Edited January 4, 2012 by Steve Murr

[Cheshire Freeze]

A very good set of ensembles from the 18z around the day 10 timeframe. A lot of support for the ECM 12z op there.

[summer blizzard]

Almost universal Agreement from the 18z ensembles that Day 9/10 is the crunch time for a Northerly & at the same time a sustained cold spell with the polar height field around greenland-

85% of members have a sweeping arctic front at around 228 that sets up the Northerly- after that its anyones guess-

the best MOST consistent set of coldish GFS ensembles for a long time & all inline with the ECm OP-

S

Do you still think that height rises over Scandinavia are likely over time or do you feel that northerlies are more likely to repeat?

[SMU]

Do you still think that height rises over Scandinavia are likely over time or do you feel that northerlies are more likely to repeat?

Depends on how amplified the jet gets & whether that arctic front goes South & encourages height rises over the top-

S

[feb1991blizzard]

Control run an absolute rasper again, seems to be a theme lately.

[Ladyofthestorm]

And the Ecm has shown something very interesting by T+216 onwards with a pattern change, I love how the T+240 chart finally squashes that high to the south and it pops up again but much further to the southwest. The Gfs 12z op run is flat mild zonal but also attemps a change at the T+240 range but soon defaults back to the familiar pattern. All my hopes are pinned on the ecm being right and the gfs jumping onboard in the next few days.

wasnt that what the GFS came up with yesterday in two of its runs? The 12Z and 18Z?

[Jack Wales]

Yet again we are being teased in FI with the GFS control run destroying the PV over Greenland. Interestingly, if you look at the whole NH run, this is facilitated by strong heights progged to develop over the Canadian Rockies (SLP 1056mb+) advecting warm air polewards.

Therefore it will be interesting to observe the upcoming runs to see if this key building block is a prominent feature over the next few days. One word of caution though is that according to the 18z ensembles, FI starts at T+96hrs!!

Edited January 5, 2012 by Jack Wales

[Duane S.]

Interesting I'd say the GFS 18z op is a bit of a deep outlier regards the SLP, around my neck of the woods at least...

A change is looking more likely by the day and I suppose looking at the NH charts the smart money may well be on a fairly negitive AO thanks to the ridging of the Canadian high into and around the pole and with us not being on the sharp end of the cold. That really is the fine detail though at this stage and as long as there are continuing signs of the sort of longwave pattern change that we are looking at, then I'm more than happy to see us sat in the 'warm sector' for now. A) That could change overnight down to +96 & B) if the sorts of charts we have seen do verify themn even if we miss out initially it will only be a matter of time before we get our turn.

Bottom line is I think we are now heading into a period of very diverse model interpretations, day on day expect severe chopping and changing for at least a week. It'll be 'fun'...

[winter watcher]

Please forgive me for being well ' Not to clued up ' But i thought we was more likely to see a cold attack from the N/E - E direction and not directly from north? Or could it be a northerly attack then with a chance of a easterly outbreak?

[feb1991blizzard]

Best GEFS suite of the winter so far, FI and i would urge caution but caution with a touch of optimism.

Flatter ecm run this time though.

Edited January 5, 2012 by feb1991blizzard

[Isolated Frost]

00z

12z

I know I shouldn't really compare the 0z to the 12z output, but it's interesting how promising both charts are, but from a very different perspective. A strong svalbard block moves into scandi and that pv centres itself over scotland.. what 264/288 would deliver would be so interesting..

[feb1991blizzard]

ECM 240 not bad though, could a full on scandi high develop from there i wonder.

[Radiating Dendrite]

Is this getting any closer though? Seems to have been at 240 on ecm for a few days now.

[feb1991blizzard]

Is this getting any closer though? Seems to have been at 240 on ecm for a few days now.

True, and i will stick my neck out now and say its very unlikely to verify but at least it shows background signals are showing up, still a long way to go and i think if we do get a potent blast, its more likely at the end of Jan or feb than mid jan because i would think by now that the Met office would at least be mentioning the possibility of a cold spell if one was likely in the 15 day timeframe.

[Alex]

It does seem that any northern blocking or colder weather is kept almost or in FI and Meto obviously aren't too convinced, they have hinted more settled and cooler but not some of the evolutions showing here.

If I was sticking my neck out, I would go for a more cooler outlook with an anticyclone residing over southern parts and maybe this will track back to the Atlantic over time introducing a more northerly flow but it is definitely straw clutching. The teleconnections are looking favourable but the models aren't playing ball as ppl want!

[Alex]

It does seem that any northern blocking or colder weather is kept almost or in FI and Meto obviously aren't too convinced, they have hinted more settled and cooler but not some of the evolutions showing here.

If I was sticking my neck out, I would go for a more cooler outlook with an anticyclone residing over southern parts and maybe this will track back to the Atlantic over time introducing a more northerly flow but it is definitely straw clutching. The teleconnections are looking favourable but the models aren't playing ball as ppl want!

[mountain shadow]

Stick with the GFS ops run. it may only be right by default but at least it's being right and not continually leading us up a garden path like the ECM,

[Nick F]

Is this getting any closer though? Seems to have been at 240 on ecm for a few days now.

No, the stalemate continues between low heights to the N and NW and a stubborn high over Europe. Still no realistic signs yet of the 'change' on the table, despite the interesting scenarios ECM evolves around t+240.

The GFS operational sticks fairly close to the GEFS mean (Manchester and Aberdeen) throughout too, with a tailing off of T850s by mid month as the jet shifts south a bit, the control goes pretty cold towards the end.