Model Output Discussion:

[karyo]

I am back after an interesting afternoon driving in the snow! What a pleasant surprise to view the 12z output and nice to see the UKMO ending it's love affar with that stupendous Atlantic low! Interesting that the models have gone cold as soon as the MJO moved to phase 7 again!

Since Saturday, the models have shown the most volatile output with the largest swings, since I started following them, back in 2001/2! Caution is still needed of course, but let's hope there will be no more drama!

Karyo

[Frosty.]

Karl, well the thing is if we have a cold upper flows to our east any decent drag back westwards on an easterly airflow then as I said earlier odds are quite decent of getting a very potent cold airflow. Whether or not it'd go that cold I'm not sure but we shall see. The key is also as much about how quick we can drag in the cold air as whether we get the flow in. to get a severe shot (which whilst somewhat unlikely still, its plausable) we really need the flow being quite strong and occuring as soon as probably 120-144hrs. any longer and that cold pool wiil become to moderate somewhat, and whilst still obviously decently cold we probably have a 48-72hrs time window to get the real severe stuff to our part of the world before it starts to moderate upwards in terms of temps.

Yes Darren I think there is potential for a severe spell but as you say, the window of opportunity is only 2-3 days but as nick said in a recent post, lets get the cold in first and then the details will take care of themselves, we have come a long way in just the last 24 hours and another setback in the morning will be hard to stomach. With Glacier Point saying we are now at a very similar phase to mid december is very encouraging although the likely duration this time looks rather less than back then.

[Glacier Point]

Thanks GP! I wonder what makes the GWO spends time in phase 5 & 6? Is there any chance the GWO will spend some time in phase 5 & 6?

The GWO is a function of relative angular momentum:

http://www.esrl.noaa...m.sig.90day.gif

(which is governing the amplitude)

and tendency in relative angular momentum:

http://www.esrl.noaa...d.sig.90day.gif

(lateral movement)

Tropical wave analysis suggests that the westerly wind burst has another few days left in it (potential velocity potential anomaly 200 hPa field):

http://www.esrl.noaa...d.sig.90day.gif

Whilst analysis of the December evolution the GWO suggests around 10 days allowing for a greater amplitude event this time round:

http://www.esrl.noaa...gcm/gwo_90d.gif

Solid 8-14 day anomaly pattern forecast from the CPC tonight:

http://www.cpc.ncep.noaa.gov/products/predictions/814day/814day.03.gif

Battleground UK and no ridge over Iberia.

Edited February 3, 2010 by Glacier Point

[kold weather]

Not really mild at all though qseghj6, its actually fairly cold out there compared with average I'd imagine, esp further east you go towards Scandinavia.

ECM ens still don't look that impressive really, its a very much a scattered look, though there is a stronger cluster in the cold solution then the mild solution, but obviously shows a certain amount of uncertainity with regards to the evolution still.

[DAVID SNOW]

Do you think from a true blown easterly it would be possible to predict potential snow depths or streamer likelyhoods purely from sea surface temperature ?

Do the models take this into account ?

Its looking relatively mild out there !

If i may answer your question, sea surface temps in the north sea are at present 1 to 2 degrees below average

[lobbox]

Indeed. And what's all this slightly combative nonsense appearing in certain posts about supposed "competitors", etc, in the mid/long range forecasts??? It did make me chuckle.

I mean come on...... it's science discussed on this thread, I hope, not soccer.

Good, evolving science is about embracing shifting ideas and well-proven outcomes - irrespective of the supposed 'competition'. And if the folks at the likes of NOAA and UKMO can embrace this basic notion and attend symposia together in Exeter (and they do) quite happily without having to wear respective GFS/GM scarves and shout abuse at each other, then that says it all, surely.

Robust, non-preconceptual science (of ANY discipline) isn't about what you wish for, nor what you wish against.

'Wishing' is the unique human emotion that distinguishes well-judged scientific analysis from religion and voodoo.

So let's await the scientific consensus and leave wishful thinking / ill-judged notions of 'competition' on the sidelines..... please?

Lol Ian, surely by now you have realised that most one line posters (about 70% of all the posts) switch their pc off when the footy is on! I think they have some duty bound misguided loyalty that they have to 'know' what happended last night when they get into work in the morning! Seriously good post though, Science is learning and I love that.

[bluearmy]

NOAA cpc charts are consistent with yesterdays offerings although the nuances are good for us. the trough to the south is more elongated so draws a mean se flow in the south of the uk and an easterly to the nothern half.

http://www.cpc.ncep.noaa.gov/products/predictions/610day/610day.03.gif

http://www.cpc.ncep.noaa.gov/products/predictions/814day/814day.03.gif

you will note that the 6/10 looks bit better than the 8/14 re the flow. i think at this kind of range, small differences arent worth pondering. the fact is the trough alignment today is better than yesterday although not as far south as some might have expected. the southern half of the uk could be looking at a very unsettled period - if we can advect the cold quickly enough to undercut the trough as it moves in and out (it wont just sit there), could be very very interesting.

what does interest me is the prose on offer for the 8/14 day period - wonder how close to the coast of w europe they are talking about?:

MOST OF THE HEIGHT ANOMALY FORECASTS DISPLAY A WELL PRONOUNCED ANOMALY COUPLET OVER EASTERN NORTH AMERICA AND THE ATLANTIC, WITH A POSITIVE HEIGHT ANOMALY CENTER NEAR NORTHERN HUDSON BAY/BAFFIN ISLAND, AND A NEGATIVE HEIGHT ANOMALY CENTER OVER THE CENTRAL ATLANTIC NEAR 40N/50W. THE LONG WAVE PATTERN IN GENERAL OVER THE WESTERN HEMISPHERE SEEMS

REMARKABLY STABLE, AND THE RIDGE ANTICIPATED OFF THE COAST OF WESTERN EUROPE

MAY BE HELPING TO FURTHER ANCHOR THE FLOW PATTERN. IN ADDITION, THE ATLANTIC

PORTION OF THIS PATTERN PROJECTS WELL ON THE NEGATIVE NORTH ATLANTIC OSCILLATION (NAO), AND IN A BROADER SENSE, A NEGATIVE AO.

i am intrigued to see if the 12z NAEFS anomolies looks better than these charts as the tendency is for them to be pretty well reflective of each other.

[DaBrigg]

I've just seen the ECM. Certainly some lovely charts for cold lovers, but they are some of the oddest winter charts Ive seen in the 10 years Ive been model-watching. The jet stream swings south, with southerly tracking lows, but the pressure remains relatively low over Scandi, particularly around 120-144 hrs. I will be very surprised if there aren't more adjustments over the next few runs, though hopefully for the better.

A fascinating pattern nonetheless. I know many people despair at the wild swings at close range, but I have found it quite refreshing. If the models ever became 100% accurate, it would mean a lot less discussion on here, thats for sure!

[Bobby]

There's a fair scatter in the ECM and GFS ensembles which shows the uncertainty still. Looking pretty good though but still some caution still needed.

GFS 18z probably a be a stinker now, would be typical.

[Snowyowl9]

Another day of model madness.Models are excelent tonightECM 9/10GFS 8/10UKMO 8/10 breathtaking stuff.

Agree with that.

The is IMO the best chart on ECM tonight,it could produce something very snowy.

http://www.wzkarten3.de/pics/Recm1201.gif

[Jason T]

Cant look at 18 run. waiting for the post that states good news.

[Mrsf16]

Cant look at 18 run. waiting for the post that states good news.

They're obviously all checking them out.... or passing out!! lol

[DAVID SNOW]

Agree with that.

The is IMO the best chart on ECM tonight,it could produce something very snowy.

http://www.wzkarten3.de/pics/Recm1201.gif

Ok

In MY OPINION i have to agree with ian brown with regard to the latest ECM output

and that snow is only likely in eastern and more likely south eastern areas.

Just my OPINION though.................

testing testing 123

[londonsnow]

18z rolling out now. convinced that our ne block will win through this run. the 12z tomorrow is the crucial one, and hopefully the big 3 will be absolutely on side by then

[cowdog]

18z seems to be pointing so far that its going to undercut even lower. So looks like game on still.

[wee]

Nail bitting stuff now

[Jason T]

Nail bitting stuff now

STILL CANT LOOK LOL....

[Weathizard]

18z seems to be pointing so far that its going to undercut even lower. So looks like game on still.

Would you mind giving me a link mate?

[MartUK]

Is it really going to happen ?

[bluearmy]

the NAEFS 12z is pretty consistant with the 00z. 'battleground UK' as GP referred earlier. FI paints a pretty strong rex block to the west of the uk with troughing devoloping over scandi. will be interesting to see if NOAA cpc pick up on this rex block over the next few days. the mean uppers arent heading into serious negative territory (ie around -5/-6c) which does show that even with the jet over northern iberia, we look to be 'close to the action'.

the caveat is that despite the NAEFS being keen on an fi rex block to the west for the past fortnight, it isnt much closer - yet.

[Bolton67]

Upto T+54 at the Moment.

Dont think i can watch anymore LOL

[Ben_Cambs]

Ok

In MY OPINION i have to agree with ian brown with regard to the latest ECM output

and that snow is only likely in eastern and more likely south eastern areas.

Just my OPINION though.................

testing testing 123

To be fair though in January, when it was said Northern and Eastern areas were most favoured for snow, it happened to an extent, but places like Cambridge didnt see anything significant fall, while parts of the north west saw quite a lot, so snow cant be ruled out anywhere yet, let alone this Easterly/North Easterly is not fully guaranteed yet.

Back to the models, I expect more of the same from GFS from earlier, and confidence in this Easterly will grow if the Big 3 models can keep the trend going and keep agreement with eachother. I wish the UKMO went further than T+144, as it would of been interesting what it showed past this timeframe.

There was quite a big scatter on the ECM ensembles earlier, of course more were opting for cold but the general outcome is still way off being certain.

Let the model watching continue....

[wee]

STILL CANT LOOK LOL....

No i cant either,lets keep everything crossed now,let me know the outcome lol,just cant bear it anymore.lol

[conor123]

I think if this Easterly comes off a setup like 11-18th March 2006 seems possible, obviously it would be much much colder than then being much earlier in the year but it seems a rather realistic setup.

The 18z for Friday has added an extra low suddenly, could potentially slow the process down somewhat?

[Skyhi]

Oh please!...I'm down to quicks on my fingers now, this is agonising!!!