Winter Model Discussion 18Z 12/2/13 onwards.

[nick sussex]

Still no resolution to the model drama. It's amazing how the handling of shortwave energy to the north can lead to such different outcomes.

As we've seen this needs to clear cleanly from the troughing to the west , this really is the crucial part of the output because if you get to T96hrs on the ECM/UKMO then you've overcome the first major hurdle.

It's going to be a long wait now till the 12hrs because we really need to see the models agree on that first part, whilst the GFS refuses to join the party you'll continue to have those nagging doubts especially given the timeframes involved.

At the moment you'd side with the Euros given they both agree within T96hrs and for them both to be wrong at that timeframe would be extremely rare.

[frosty ground]

You can post as many charts as you want, the reality is that the ECM has on 4 separate occasions this Winter shown (for several runs in a row) an Easterly feed developing, in it's output between +168 and + 240, and the reality is that only once has that come to fruition.

I would love the ECM to be on the money as much as anyone else on here that loves cold...would.

Come back to me next Thursday when we're under a cold feed and snow showers are feeding in off the North sea and then tell me how wrong I am

Just a point that needs to be raised...... The GFS has also shown Easterlys this winter, usually around the same time as the ECM.

[swilliam]

GEFS definetely now on board with an easterly if somewhat delayed compared to the Euros

Mean t192

and at t240

with the cold fast approaching

[Pennine Ten Foot Drifts]

Referring back to the stat charts posted by Snowking (thanks)

What really strikes me is that when you look at the trend, apart from the GFS being consistently the worst performer on an overall basis (as compared with UKMO, ECM) is that when the GFS is wrong it really is horribly wrong - or put another way, the statistical gap between GFS and ECM when ECM is performing best is much worse than when GFS is performing best.

Whilst yes it's true the GFS does appear to lag behind the ECM and UKMO more than it leads them, I think what Snowking's verification charts actually show is overall how unreliable any models beyond T72 still are, (at least in terms of detail for our little neck of the woods). Which is why I often smile when things get so heated in here. Most of the commentary on any model beyond that timescale can only be treated as conjecture, and as such subject to light-hearted debate at most. Detailed analysis in terms of what those charts are showing for local weather conditions (especially at T144 plus) - comments such as 'that would bring ice days and frequent snow showers' - is really of no more value than just the fun factor of imagining it coming true, because the verification stats show that the chance of it actually happening are pretty low, whatever the model might be..........

[cobbett]

Looks like Exeter have discarded UKMO and ECM based on latest update..

UK Outlook for Tuesday 19 Feb 2013 to Thursday 28 Feb 2013:

Predominantly dry weather is likely to prevail over the UK through to the end of the month. Cloud cover will vary from day to day, but most areas should see at least some sunny periods. Western and southwestern parts have the greatest chance of seeing any rain as weather systems try to push in from the west at times. There may also be some wintry showers in eastern counties too. It now seems increasingly likely that there will be little change in this pattern through to the end of the month. Temperatures in most places will be close to normal at first, with no more than patchy frost by night, but a downward trend is likely later in February, with frost becoming more widespread and daytimes feeling rather cold.

[fergieweather]

Update: MOGREPS now agrees with EC on scope and onset of blocking with longevity well into trend period (10-15d): cold & frosty; dry/largely dry for most with exception of E districts initially & showers tending to migrate progressively to more central districts with time.

[kent]

All this debate about whether the ECM or GFS is the more superior model is superficial at modelling a possible cold spell on the horizon. The simple truth is that they are all useless at the current time spell of expectancy. Sitting on the fence as usual until much nearer the predicted outcome.

[Average Joe]

Latest update on the met office website:

UK Outlook for Tuesday 19 Feb 2013 to Thursday 28 Feb 2013:

Predominantly dry weather is likely to prevail over the UK through to the end of the month. Cloud cover will vary from day to day, but most areas should see at least some sunny periods. Western and southwestern parts have the greatest chance of seeing any rain as weather systems try to push in from the west at times. There may also be some wintry showers in eastern counties too. It now seems increasingly likely that there will be little change in this pattern through to the end of the month. Temperatures in most places will be close to normal at first, with no more than patchy frost by night, but a downward trend is likely later in February, with frost becoming more widespread and daytimes feeling rather cold.

So again, as I mentioned several days ago, they are still suggesting it will be predominantly be dry and settled for the foreseeable, and have even suggested "increasingly likely".

[Captain Shortwave]

Update: MOGREPS now agrees with EC on scope and onset of blocking with longevity well into trend period (10-15d): cold & frosty; dry/largely dry for most with exception of E districts initially & showers tending to migrate progressively to more central districts with time.

That's good news, I shall take their update on the metoffice site with a pinch of salt for now as of course the usual issues apply with forecasts for wintry precipitation only given in the long term when there is a reasonable to good degree of certainty on the event which of course there isn't at the moment. But things are looking good for us coldies.

Edited February 14, 2013 by Captain shortwave

[frosty ground]

Update: MOGREPS now agrees with EC on scope and onset of blocking with longevity well into trend period (10-15d): cold & frosty; dry/largely dry for most with exception of E districts initially & showers tending to migrate progressively to more central districts with time.

A classic easterly incursion then..... slowly building. Not seen one of these for a while....

[Coast]

All this debate about whether the ECM or GFS is the more superior model is superficial at modelling a possible cold spell on the horizon. The simple truth is that they are all useless at the current time spell of expectancy. Sitting on the fence as usual until much nearer the predicted outcome.

[BLAST FROM THE PAST]

fergieweather, on 14 February 2013 - 10:14 , said: Interesting, as UKMO continue to talk of a "marked waning" of cold anticyclonic signal into 10-15d period and transition to S/SW type into that timeframe with signal for some recovery of temperatures.... another update due within the hour, so will see how it compares.

fergieweather, on 14 February 2013 - 11:51 , said: Update: MOGREPS now agrees with EC on scope and onset of blocking with longevity well into trend period (10-15d): cold & frosty; dry/largely dry for most with exception of E districts initially & showers tending to migrate progressively to more central districts with time.

Well there's one for the books, a probable switch in outlook from UKMO from major waning of block to strengthening block?

Well time will tell, and it ain't that far ahead as it all looks like making its way from T96.

I may be being picky here but why the change now? UKMO model and ECM have been on board 24-36 hrs haven't they? And many have been 'reading' blocking conditions for longer than that.

I know they have MOGREPS so I assume that model in their eyes supercedes all others? If it is the uno numero, why has it changed and taken so long?

Reasonable questions if you ask me.

BFTP

Edited February 14, 2013 by BLAST FROM THE PAST

[Tamara]

A classic easterly incursion then..... slowly building. Not seen one of these for a while....

Taken at face value, it doesn't suggest circa or sub -10 uppers and snow showers. Essentially they perceive the best synoptics as suggested on the ECM as something much more modified, much as I commented earlier might be the case perhaps. However time will tell - this assessment is based on the best available consensus the METO have at this time

[MR EXTREMES]

Still no resolution to the model drama. It's amazing how the handling of shortwave energy to the north can lead to such different outcomes.

As we've seen this needs to clear cleanly from the troughing to the west , this really is the crucial part of the output because if you get to T96hrs on the ECM/UKMO then you've overcome the first major hurdle.

It's going to be a long wait now till the 12hrs because we really need to see the models agree on that first part, whilst the GFS refuses to join the party you'll continue to have those nagging doubts especially given the timeframes involved.

At the moment you'd side with the Euros given they both agree within T96hrs and for them both to be wrong at that timeframe would be extremely rare.

the only worry i have now is ian f post about the return of west southwest flow i sopose the pros have the tec to see this outcome would be a shame if this failed im climbing back on the fence for now until its nailed.

[legritter]

IM pretty sure we will see a big turnaround from GFS over next 24 hrs .a good run from other modells for cold if thats what you are after .but caution needed ,we just need a fair run from ECM AND uk met LATER ,NOT NECESSARILY A stella Run but a consistant run .latest MET office update is with caution as areas of precipitation would be hard to forecast at this range ,and we all know ,get the cold in proper and the snow could turn up later ,whether frontal or showers from the east or north it will please us coldies ,last nights fax at 120 looked good ,lets hope we can build on that .

[chris55]

Absolutely fair assessment from Ian and the Met update, based on the Euro runs, and considering the colder weather builds the more into FI you get, these charts can not be taken at face value solely from the Operational's (ECM). However a very good trend and with some luck we could see an exciting end to the winter (well the meteorological winter anyway)

[Yarmy]

Off-topic, so move if necessary mods, but is MOGREPS likely to make it into the public domain at some point, or will it remain a commercial offering?

[mountain shadow]

So, given the Met update we can only assume they are not going with the ECM and expect the colder unstable air to go South of the UK.

Tonights runs take us to around T+168, so not much time for change

[feno13]

So, given the Met update we can only assume they are not going with the ECM and expect the colder unstable air to go South of the UK.

Tonights runs take us to around T+168, so not much time for change

I would ignore the met update, have you not read ian f latest update from the met .

Update: MOGREPS now agrees with EC on scope and onset of blocking with longevity well into trend period (10-15d): cold & frosty; dry/largely dry for most with exception of E districts initially & showers tending to migrate progressively to more central districts with time.

[fergieweather]

Off-topic, so move if necessary mods, but is MOGREPS likely to make it into the public domain at some point, or will it remain a commercial offering?

It's not really even used outside UKMO as a commercial product per se. Note my first update was based on yesterday 12z output (iissued midnight); the second based on 00z (issued 11z) and characterised by the turn-around we'd been led to expect in tone for trend period.

[tcc]

So, given the Met update we can only assume they are not going with the ECM and expect the colder unstable air to go South of the UK.

Tonights runs take us to around T+168, so not much time for change

Funny cos I read Ian F's update and the Meto update to suggest that initially dry and cold, and then as the HP moves further north to allow more convective potential further inland? And/or possibly a deeper cold pool to come across us?

[Purga]

the only worry i have now is ian f post about the return of west southwest flow i sopose the pros have the tec to see this outcome would be a shame if this failed im climbing back on the fence for now until its nailed.

My first post on NW after a lengthy period 'lurking' - very impressed by the wealth of knowledge available and especially like the 'sage-like' musings of John Holmes!

Regarding the above post, I believe Ian F was referring to an earlier stance this morning by UKMO regarding the possible 'return of W / Sw regime and was awaiting the latest which he has now recently advised. It reads to me as though the latest MGREPS output now supports the EC N blocking / cold scenario an so supercedes the earlier position. I stand to be corrected of course.

[Ian Brown]

Well if the ECM proves to be wrong, it wouldn't be the first....or second..or even third time this Winter that ; as a model it will have egg on it's face.

The ECM and GFS have been at loggerheads with each other post 144 since the beginning of the year and for that time frame at least, I think the GFS has performed much better than the ECM has.

if by this time next week, we are not under the influence of colder air from the East, or ESE, then I think it would be fair to say that the ECM had got it completely wrong, yet again.

this the ECM chart for + 144 (which should be the very end of the ''reliable'' time frame)

After all we're not looking at charts at +240 here, so for me, this is a big test for the ECM V's the GFS, I suspect as has been mentioned by others, a half way house will ensue, with the cold air ending up just out of reach...echoes of Last Feb !!

I don't think the GFS has performed better than he ECM, yes the ECM has progged a few easterlies that have not happened, but the GFS has handled the colder spells badly, oftern going for Atlantic victories at T96/120 that have not happened.

[Tim Bland]

Great to see the 06z GFES ensembles are smelling the coffee! OP was almost a mild outlier. wish I could go to the bookies and put money on the 12Z OP looking more like ECM / UKMO. Especialy as the Controll run now almost follows the ECM route!

Re Below I would Echo the need for realism here. This set up is great for Kent / East Anglia and the North East (near to coast) of England and Scotland. If you are in the Western half of the UK then it looks cold and dry. The SW and South could see snow if a low crosses through the Channel and the NW could see snow if the atlantic creeps in. I know they are not just looking at their own locations but its worth noting that both TEITS and Steve M both live in districts to the east that would get lots of snow showers and snow cover from this set up. If your in the SW / NW / Wales etc then I would hold back on telling the world that snow is comming back soon!

Edited February 14, 2013 by Tim Bland

[Jason M]

Following on from the above posts and Ian's in particular I think its worth just setting out what current expectations are for this cold spell (if it happens) for the benefit of any lurkers. All my opinion of course and others may differ in their views.

1. It looks like a potentially cold to very cold period of weather

2. Snow showers would probably occur in the East / South East and maybe more widespread

3. As shown at this juncture it does not look a 'severe spell'

I think point 3 is important here to manage expectations. This looks like a decent end of winter cold spell. Daytime temps in range of zero to plus 3C i'd imagine. Places would get snow cover others would stay dry and cold.

This isnt a Feb 91 scenario or anything of that ilk. It would be better than the last week though with better uppers and low dew points.

Also, things could yet evolve for an even stronger cold shot. So in summary, cold or very cold with snow cover in favoured places but as yet not in the severe category.

Jason