Winter Model Output Discussion 01/02/2013 12z onwards

[Iceni]

Similar to late jan 03 and 04

http://www.wetterzen...00120030130.gif

http://www.wetterzen...00120040128.gif

03 saw the M11 brought to a standstill due to an unexpected snowfall during Thursday evening's rush hour

04 was the infamous thundersnow event - some very heavy snowfall rates that day!

Such a flow is always prone to unexpected disturbances

SK

A foot of snow on my car when I finally got back to Whittlesford that night (31/1/2003).

The M11 closure saved my bacon as the un-gritted motorway was clear of traffic north of Stansted and I could skid about on it in safety. Wishbone effect is always a gamble, but one that sometimes pays off big time from an EA IMBY point of view.

PS "Deja vu" French for 'Already seen" Deja - already. Vu - seen.

Edited February 1, 2013 by Iceni

[StretfordEnd1996]

Personally I'm underwhelmed by the pub run. The ensembles currently rolling out look a huge upgrade to me though.

In the 5-8 day range I'd expect the opp to be one of the milder runs.

Jason

Trust me, you cannot really ask for better than that op run

[bradymk]

Trust me, you cannot really ask for better than that op run

only post 192, low res though. The high res is still pretty poor compared to ECM but an improvement. 18z op a clear mild outlier in short term ens though.

[Snowman.]

I think it is safe to say that the Atlantic is pretty dead in FI on this run lol

http://www.wetterzen...s/Rtavn3601.png

Best about that?

Shows that you can get cold and snow with a reluctant Canadian PV.

[StretfordEnd1996]

only post 192, low res though. The high res is still pretty poor compared to ECM but an improvement. 18z op a clear mild outlier in short term ens though.

Depends if you want to compare the GFS 18z to some of the GFS 18z's from 1997-2002

My take on things today, generally output held steady, perhaps even a few improvements especially with the GFS.

Ensembles looking decent though and that's my biggest savoir

[Mucka]

GFS continues to stumble in the dark out to the medium term.

But a very interesting MetO 144 chart which seems to back recent ECM runs in keeping the Azores high to the West.

Even with a flatter opa

Even with a flatter pattern and the azores high further west and poorly aligned by 144 GFS Op still comes up with this at the end of hi res.

Naturally it tried to break down the block and flatten things again from there but things still trending the right way this morning.

Could be a tasty ECM, hope I haven't jinxed it!

Edited February 2, 2013 by Mucka

[Captain Shortwave]

ECM T192 is excellent, slack north-Easterly winds across all areas with -8 uppers for the majority

http://www.meteociel...1-192.GIF?02-12

Edit - -8 uppers across all of Great Britain and Northern Ireland by T216

Edited February 2, 2013 by Captain shortwave

[Mucka]

Some very weird GFS worship when it has proven it isn't handling the pattern well and desperately peeking over the Euros shoulder for the answer.

If you can't understand the potential in UKMO then ECM should help you out. It is not out of the blue either, I was calling the possibility of this pattern a long time ago but it hasn't verified yet so still some caution needed.

[bluearmy]

superb ecm op run which we know will verify as it has found a norwegian shortwave at day 9!

[MattH]

Morning...

We are getting to that point again where some model is likely to flip or change suddenly in the coming days. Within the ECMWF ensembles there have been numerous members that support this rather consistent ECM Det run which supports a greater risk of height rises to the NE and a potential E or NE'ly flow. The latest EC32 day run, without question, signals a general mean flow from the NE as we progress further into Feb with clearly below average temps by around 2C or 3C.

Somewhere along the lines the ECMWF solution is either going to become the dominant type in other models and confidence will then slowly increase in a potential NE'ly scenario, as per 00Z ECMWF at 192hr this morning, or the ECMWF will back away from the idea and clearly more of an Atlantic influence will develop, as per the GFS. Both models are consistent in their own solutions, which is all good and well, but from a forecasters perspective is a nightmare.

Clearly further model runs will determine this outcome and the 00Z EC ENS will be interesting to see if there is any support for the Det model.

M.

Edited February 2, 2013 by chionomaniac
Tidying - as you duplicated your post, Matt.

[winterof79]

I must be missing something here? All looks very underwhelming to my eyes,GFS 0z is again poor,even when we eventually get some kind of easterly influence there is little or no cold pool to tap into and by mid Deb thats exactly what would be needed.

UKMO looks OK at 144h but again,where is the freeze coming from on ukmo?

All in all im ready for spring now,the one thing that will be remembered from this 'winter' is the PV sat like a limpet to our NW,its runied our chances of something prolonged from a coldies POV.

Prepare to be dissapointed.

http://www.meteociel...0-240.GIF?02-12

http://www.meteociel...1-240.GIF?02-12

UKMO at 144 http://www.meteociel...44-21.GIF?02-06

ECM AT 144 http://www.meteociel...1-144.GIF?02-12

Before then we have a littlewinter storm to contend with

http://www.meteociel...fax84s.gif?01-0

http://www.meteociel...ax96s.gif?01-12

http://www.meteociel.fr/ukmo/fax/fax120s.gif?01-12

That is nasty.

Edited February 2, 2013 by winterof79

[bluearmy]

note the weather front on the tuesday fax just over scotland

see it has cleared the south on the wednesday fax

its the bit in between we need to see

looking at the models, it appears that the precip inland from that occlusion is very muted and it picks up energy again over the channel.

[Cecil Hogmanay Melchett]

In the interests of balance i have to say ecm 0z run is superb!

Obviously i hope it comes off!

[Jason M]

Looking through the models this morning we really are in high stakes territory now. ECM is a great run, GFS is poor, METO is good.

The GEFS on balance support the opp run although the ECM scenario does have have support within the suite. The control run is dire.

GFS opp and control runs have been resolute really in saying no and whilst too much weight can be given to This model because it runs four times a day I think we discount it at our peril. It was GFS that first signalled an Atlantic victory this last week and I think most people on here, myself included ignored it for a long time because what it showed didn't link with the teleconnections etc we were being told about.

I think from this point anyone who states with certainty a particular outcome is very brave indeed. From what I can see its coin toss territory this morning. I'm slightly siding with GFS, but only because I see more data from GFS whereas with ECM its literally just the opp run.

Jason

[TEITS]

Well some superb output from the ECM & UKMO. If the UKMO went out further it would certainly show a similar pattern to the ECM. What I especially like from the ECM is with each output the signal for an E,ly with blocking to the NE is getting stronger.

GFS although poor is beginning to lose agreement with the GEFS ensembles.

http://cdn.nwstatic.co.uk/ensimages/ens.20130202/00/t850Cambridgeshire.png

So my prediction of NW,lys veering N then NE,ly with the 10th Feb being a pivotal day is looking quiet promising at the moment.

[Long haul to mild]

Looking through the models this morning we really are in high stakes territory now. ECM is a great run, GFS is poor, METO is good.

The GEFS on balance support the opp run although the ECM scenario does have have support within the suite. The control run is dire.

GFS opp and control runs have been resolute really in saying no and whilst too much weight can be given to This model because it runs four times a day I think we discount it at our peril. It was GFS that first signalled an Atlantic victory this last week and I think most people on here, myself included ignored it for a long time because what it showed didn't link with the teleconnections etc we were being told about.

I think from this point anyone who states with certainty a particular outcome is very brave indeed. From what I can see its coin toss territory this morning. I'm slightly siding with GFS, but only because I see more data from GFS whereas with ECM its literally just the opp run.

Jason

I wouldn't give too much credit to the GFS getting things right re the recent Atlantic breakdown. I remember it continually try to bring in the Atlantic way too early and in the meantime it was proved wrong with snow events cropping up all over the country. In fact, if GFS had had its way, the cold spell would barely have started at all, let alone last well over a week!

In the UK, eventually the Atlantic is going to win out but it engenders no more kudos for the GFS for predicting that than saying that at some time over the next ten years, Man Utd will win the Premiership!

It may be right this time, who knows, but consistency is a long way from reliability.

Edited February 2, 2013 by Chalk Serpent

[SMU]

The GFS is way out of its depth again overrunning the pattern, where as the ECM has had it nailed for 3/4 days.

The only real question is how far west does the cold get. The day 10 ECM has the -10 isotherm across the whole of the Uk and snow showers.

All in all a continuation of yesterday, don't worry about the rogue ECM outliers and Gfs they will come into line.

S

[Ice Day]

A bit after the event, but the ECM at 192 is a superb chart (within a superb run) so thought I'd post it up again! Regarding the GFS, as Jason M said earlier you discount it at your peril, however I believe it's performed very poorly since the beginning of January, and was outperformed by the UKMO/ECM on the lead up to the previous cold spell. It may well be proven to be right this time, but I'd rather be seeing UKMO & ECM vs GFS. As always, only time will tell!

[Ian Brown]

I'm not surprised we are now seeing the ECM show the loop over of HP that brings an easterly, the UKMO is very similar to the ECM at T144 and you would have to think it would go the same way.

The GFS obsession with getting the Azores High over us continues, and on the form of this winter alone, you wouldn't back what the 0z shows coming off. However we are talking trying to get winds from to use SM's phrase 'East of North' to the UK so it won't be a straightforward process...

Edited February 2, 2013 by Ian Brown

[Methuselah]

This from Ian Ferguson (SW thread) might lend a little perspective:

"I fail to see the hyperventilating about Tuesday versus any genuine winter extreme in strict sense of the term. Yes, a decidedly v cold feel thanks primarily to windchill rather than very low ambient temperature. But crucially, at this juncture, ensemble analysis offers little extra useful insight towards Tuesday, certainly none to support notion of a 'severe event' under accepted definition (Daily Express excepted). For example, through Tuesday, latest MOGREPS has no signal anywhere in UK for more than 5cm of snow. It then has a signal for more than 1cm, transferring from western Scotland across to the North Sea by Wednesday, coupled to a signal also for NW Wales. Conversely, the 12z ECMWF EPS does have a strong signal for more than 5cm of snow for western Scotland on Tuesday (but nowhere else at that amount), which it steadily reduces to a low probability for the whole of Scotland by Wednesday. If these combined ensemble signals were much more compelling, a warning would have been flagged as likely already... but whilst gale/severe gales are progged as well as snow showers, nothing I've heard in UKMO briefings, nor read in their latest analysis (issued 40 mins ago) screams of a 'severe event' versus accepted use of the term in a historical sense."

[nick sussex]

Oh no! we're back to a shortwave drama between 144hrs and 168hrs! My nerves are shredded already! Great ECM and the UKMO looks like backing it but GFS, oh dear! Still flat and uninspiring later on.

I'd advise people to hang back from getting too excited, its not like early next week with a simple nw/n flow and a pattern the models can cope with easily.

A shortwave dropping south from Iceland isn't a bog standard winter synoptic and for that reason I'll believe it when its modelled at T72hrs.

[bluearmy]

the ecm ens still not supportive of the op in a convincingly 'mean'ingful sense.

from a cold perspective, just have to hope that the ecm op with its higher resolution is resolving a tricky evolution better than the american models and the ens .

[SLEETY]

the gfs was a complete joke in the last cold spell.It kept wanting to bring the cold spell to an end days before the other models

In the meantime many places were being hit by snow

Why then do some people here still swear by what it shows time after time.

Its always below the ecm and ukmo in the verification stats as well!

[Gibby]

Good morning folks. Here is the morning look at the 00z output from GFS, UKMO, GEM and ECM for today Saturday February 2nd 2013.

All models show reasonable agreement this morning on proceedings up to 144hrs but diversify beyond. The cold Northerly flow shown by all models for today will weaken and back West through tomorrow, Any sleet and snow showers affecting more Eastern coastal counties will die out later to leave all areas dry and sunny today but cold in a moderate Northerly wind. A frost will develop widely tonight before cloud and less cold air moves into the West early tomorrow and on Eastwards over the day tomorrow with some rain at times. Through Monday a strong WNW wind develops for all chasing any cloud and outbreaks of rain away from the South first thing so that all areas come under an increasongly cold and showery flow. As winds turn through NW and eventually Northerly over Tuesday and Wednesday it will become very cold generally with showers turning to snow for all with accumulations likely for areas exposed to the wind in the North, East and West while somee inland Central and Southern parts see few showers and stay largely dry with frost by night. Thereafter the models split in the following ways.

GFS takes us through the latter end of next week with the Northerly flow weakening as a weak front moves slowly in from the West with a little rain and sleet. High pressure will be very close to SW Britain so any precipitation here will be quite light and intermittent. A more active trough then moves into the UK from the West late in the weekend with rain moving East followed by a further round of rather cold NW winds and wintry showers for a time. FI today shows a flattening of the pattern briefly with a milder interlude with Westerly winds and occasional rain before further cold and unsettled conditions return with rain, sleet or snow at times in association with Low pressure moving SE over or later to the West of the UK and pressure building to the NE.

The GFS Ensembles show a rather cold spell for a time next week before the general consensus between the members still show an overall recovery to more normal values with rain at times. Conditions at the surface may well be rather colder than these values suggest determined by the wind flow direction at the surface later in the run.

The Jet Stream shows a continuation of the pattern currently held of the flow ridging over the Azores High and down over the UK to Southern Europe. Late in the reliable timeframe of a week there are indications the flow will buckle sufficiently North of the UK to break the flow leaving one arm travelling East over the South of Europe with the Northern arm hitting the buffers to the NE of the UK and returning SW as it hits developing High pressure to the NE over Scandinavia.

UKMO for the middle of next week shows the cold Northerly flow with snow showers gradually weakening later in the week. A front is shown to be edging in from the West then and with cold air in situ a messy transition of snow, sleet and rain looks like gradually moving East over the UK late in the week.

GEM shows the cold flow too being modified by Atlantic troughs sliding SE late next week with rain and sleet for a time before winds back West then SW with mild and unsettled weather shown over the UK by Day 10 with rain at times.

ECM keeps a feed on NW or North winds for later in the week with the midweek snow showers giving way to a period of rain, sleet and snow for a time. Then winds turn north or Northeast with sleet and snow and cold temperatures returning SW across all areas as pressure builds from the Atlantic NE to the NW of Scotland. late in the run the pressure pattern becomes complex but good for maintaining cold over the UK with High pressure having built strongly over Scandinavia with also High pressure in the Atlantic keeping UK winds from a NE or Easterly direction. With various troughs and disturbances in the air pattern sleet and snow could occur almost anywhere with frost at night.

In Summary today the general pattern looks like seeing cold Northerly winds to move down over the UK early next week with sleet or snow showers in places and frosty nights. Its longer term that things become more complex with GFS showing further SE moving Low pressure and a trend to colder synoptics late in its run while ECM is still bullish about keeping the UK locked in a generally cold pattern with some snow right out to day 10 and beyond aided by a strong pressure build to the NE. This is the third consecutive ECM run that has come up with a High pressure build to the NE in a week or so time so one has to begin to take the point seriously that the model has picked up on a trend with some latter agreement from GFS too albeit deep in FI.

[Timmytour]

Thw way the GFS is so easily dismissed by some for its "Atlantic bias" bemuses me. personally I'm convinced the ECM is the model with the bias, junmping at whatever opportunity it can get to bring in an Easterly. That said, I'm sure the GFS was the one that led it into the December Easterly that never was....and when the ECM joined in only for the GFS to pull out, the GFS was mocked for its Atlantic bias until the ECM started bringing it in as well!

It's true the GFS was quicker than most to look to break down the recent cold spell...but i see this as a matter of timing only. Nothing wrong in the trend it picked up early on despite the declarations of some in the early days that the cold spell was set to endure and the "Atlantic bias" of the GFs should be ignored.

I've been very hopeful of something a little but special popping up next week, perhaps along the lines that ECM has been producing. And I've been waiting for the GFS to climb aboard, believing I could make out small improvements in its output throughout a series of runs. But though the improvements are there, they are not on a big enough scale to turn things around for me. Devoid of overwhelming support from the GFS, my optimism is draining now and I now think we are destined for a period of one or two short-lived cold incursions in an otherwise unremarkable spell of weather.

perhaps the 6z could turn things around....but even if it did, we all know what we are supposed to do with its output!

Edited February 2, 2013 by Timmytour