Model Output Discussion - 30th November onwards

[johnholmes]

Just so people realise, the EC 32 day forecast model is virtually experimental, forecasts at week 3 and 4 are pretty much the same as climatology. IE they have no skill. Occasionally they can show some skill, an example being the cold spell in 2010,but this was a exception to the rule. 

 

That comment is not correct Matty, they are based on the ECMWF longer term model which has nothing to do with climatology

Of course it is wrong at times and you are correct to say it is experimental but not that it follows climatology.

for those interested in what ECMWF say about the model, see link below

http://nwmstest.ecmwf.int/research/monthly_forecasting/Introduction.html

Edited December 3, 2013 by johnholmes

[That ECM]

But it's quite rare for the met to be forecasting this, it's not like the express have been telling us. I think these updates are massively encouraging. Normally the met are very cautious when it comes to long range forecasting

I think some may need to re read what IF posted. Colder from a position of fairly mild. Yes I get the possibility of an eastward direction of weather but he has said half of what people maybe are thinking. The problem with the written word and I could be miss interpreting myself.

[Summer Sun]

GEM is not interested in any cold infact it becomes very mild +14 850's for some with +12 widely at the end before that we have +8's widely

 

Edited December 3, 2013 by Summer Sun

[Frosty.]

Matt Hugo on Twitter:

 

"CFSv2 supports EC32 in terms of pressure patterns with a really strong signal for high pressure to the N/NE of the UK"

ooooooo nice..January 13th 1987 here we come...what a christmas present that would be

[Yarmy]

Always good to have the view from Ian F, but a Scandinavian block is most unlikely from the synoptic set-up we find ourselves next week even if the GFS 12z is wrong. The High may migrate Northward but that can only be temporary with the jet over the top.

 

Inclined to agree. Any residual PV over the pole and it's hard to see how the high can get far enough N. The PV either has to completely migrate to Canada or split with a larger chunk going S into Russia. Not much margin for error, but fingers crossed.

[Smiler1709]

GEM is not interested in any cold infact it becomes very mild +14 850's for some with +12 widely at the end before that we have +8's widely

 

At least we're be saving on the heating bills

[Mucka]

Always good to have the view from Ian F, but a Scandinavian block is most unlikely from the synoptic set-up we find ourselves next week even if the GFS 12z is wrong. The High may migrate Northward but that can only be temporary with the jet over the top.

 

 

Obviously it is in the balance but I disagree with the assessment it is most unlikely from here for example - although there could be improvements to better our chances for sure.

 

 

You say the jet is blasting over the top in this synoptic, which is not strictly true. It is firing South to our West and the weaker arm of the jet is over the top, While that will result in the ridge flattening at first (bad news) the jet firing South on the Western flank will tilt the axis back SW/NE - we see that from 120 to 144 on UKMO. We then have competing forces with the energy over the top wanting to sink the ridge but the energy to the West wanting to push WAA NE and reinvigorate it because the trough to East of the ridge through Eastern Europe prevents it simply being shunted East and flattening.

There is no reason this synoptic can not create a block over Scandinavia but its orientation, latitude and Westward influence are all up for grabs.

 

I think we are much more likely to see a mid lat block somewhere to our NE than anything flat and zonal toward the end of next week but where we go from there is anybodies guess, If the high migrates Northward or retrogresses as you suggest it might then that implies the jet is not over the top and we are getting some undercutting so I am not sure on your reasoning with that part of your analysis. Perhaps you are saying the high can't migrate North or retrogress because the jet will be over the top? Too far out to call that, maybe, maybe not. 

Edited December 3, 2013 by Mucka

[johnholmes]

the actual text from Ian F as some are quoting differently

UKMO view (just chatted with them) remains as before: i.e. for Scandinavian block to establish after next week's milder (for some, notably so) phase and a progressively colder return from SE/E thereafter.

[pip22]

Its not all bad, In fact we may see a north-westerly blast coming from Canada if the low pressure ever goes to the east. Then we will see the high pressure (shown at the very top left) moving in to greenland.

 

otherwise it be full on British equivalent of Pineapple Express.

 

Edited December 3, 2013 by pip22

[fergieweather]

 

After viewing todays GFS 12Z from a coldies perspective one would be forgiven for reaching for the medicine cupboard, but alas, Ian F has given the UKMO's take on how some sort of blocking pattern 'could' become established later on this month. So for now at least, the prozac is staying firmly locked away. 

 

GEM 12Z finishes with +14 uppers  

 

Here's hoping for a much better ECM in an hour's time.

Yup, 'could' being the key phrase given the timescale ahead. However, the notion of the colder block (with UK somewhere to western edge of it) remains the form horse they favour currently. I've not seen the DECIDER output behind it, but have perused the EC32, so can see the rationale being employed. Anyway, we watch with interest. The polarization of solutions past next week is very striking currently and it would be foolhardy to wholly write-off any solution (including the NCEP 'Winter Blowtorch') at this juncture, albeit the seemingly contractually-required return to a more zonal or Atlantic-dominated status-quo is a known GFS trait and one often highlighted by the senior forecasters at Exeter, as a note of caution for those perusing stuff progged out past T+240. But that doesn't mean it's wrong. We just don't know... Edited December 3, 2013 by fergieweather

[Matty M]

That comment is not correct Matty, they are based on the ECMWF longer term model which has nothing to do with climatology

Of course it is wrong at times and you are correct to say it is experimental but not that it follows climatology.

for those interested in what ECMWF say about the model, see link below

http://nwmstest.ecmwf.int/research/monthly_forecasting/Introduction.html

John I performed a verification study of the model. The model at week 3 and 4 is  the same or marginally better than a forecast based on climatology (based on RMSE & ACC). Even at week 2 it is only marginally skilful.

Edited December 3, 2013 by Matty M

[forecaster]

 Yup, 'could' being the key phrase given the timescale ahead. However, the notion of the colder block (with UK somewhere to western edge of it) remains the form horse they favour currently. I've not seen the DECIDER output behind it, but have perused the EC32, so can see the rationale being employed. Anyway, we watch with interest. The polarization of solutions past next week is very striking currently and it would be foolhardy to wholly write-off any solution (including the NCEP 'Winter Blowtorch') at this juncture, albeit the seemingly contractually-required return to a more zonal or Atlantic-dominated status-quo is a known GFS trait and one often highlighted by the senior forecasters at Exeter, as a note of caution for those perusing stuff progged out past T+240. But that doesn't mean it's wrong. We just don't know...

 

What exactly is "DECIDER"?

John I performed a verification study of the model. The model at week 3 and 4 is  the same or marginally better than a forecast based on climatology (based on RMSE & ACC). Even at week 2 it is only marginally skilful.

 

Very interesting. Did you cover the globe or just Europe? Was this a dissertation? Is it available anywhere?

[Frosty.]

In the meantime, watch out northern scotland, it could become very snowy up there through thursday and into the first ½ of friday with frequent snow showers and NNW'ly Arctic Gales. Friday looks bitterly cold for most of the uk.

[MR EXTREMES]

and the gem is not the be all and end all its a trend that also could lead to better trends futher on.

as fo +14 upper I suspect that's not really a reality.

 

as could this easterly but the models do tend to be pointing towards blocking into scandi area.

[fergieweather]

 

What exactly is "DECIDER"? Very interesting. Did you cover the globe or just Europe? Was this a dissertation? Is it available anywhere?

 (1) See, for example, http://www.metoffice.gov.uk/media/pdf/l/f/decider.pdf(2) I'd also be interested to see this paper - I've seen a few (mostly EC-based, non UK) published studies using retrospective analysis of EC32 but none UK-based. I've seen no recent ones (and EC32 has seen varied tweaks since some published papers were written).

[Matty M]

What exactly is "DECIDER"?

 

Very interesting. Did you cover the globe or just Europe? Was this a dissertation? Is it available anywhere?

 I actually just covered Ireland grid points, but the literature from other papers i read for Europe etc. were in-line with my results.

 

Literature published by the ECMWF back this up. There are a few papers from Frederic Vitart, if you search him which show this.

Edited December 3, 2013 by Matty M

[Gael_Force]

What exactly is "DECIDER"?

 

http://www.ecmwf.int/publications/member_states_meetings/Forecast_products_users/Presentations2011/PDFs/Mylne_Parker.pdf

[SE Blizzards]

 

Yup, 'could' being the key phrase given the timescale ahead. However, the notion of the colder block (with UK somewhere to western edge of it) remains the form horse they favour currently. I've not seen the DECIDER output behind it, but have perused the EC32, so can see the rationale being employed. Anyway, we watch with interest. The polarization of solutions past next week is very striking currently and it would be foolhardy to wholly write-off any solution (including the NCEP 'Winter Blowtorch') at this juncture, albeit the seemingly contractually-required return to a more zonal or Atlantic-dominated status-quo is a known GFS trait and one often highlighted by the senior forecasters at Exeter, as a note of caution for those perusing stuff progged out past T+240. But that doesn't mean it's wrong. We just don't know...

 

Thank you for the info Ian 

 

Sounds like many options currently on the table then for the 10+ day period.

[MR EXTREMES]

infact the gem at t240 is what you call a good trend indeed with heights into eastern Greenland and deep lows that would most certainly be going southeast.

but its unlikely we will see Greenland blocking anytime soon but scandi block is a very realistic trend.

[East_England_Stormchaser91]

GEM is not interested in any cold infact it becomes very mild +14 850's for some with +12 widely at the end before that we have +8's widely

 

That would not be mild Gav. Infact, it could feel quite cold with the surface wind off the continent.

[Captain Shortwave]

infact the gem at t240 is what you call a good trend indeed with heights into eastern Greenland and deep lows that would most certainly be going southeast.

but its unlikely we will see Greenland blocking anytime soon but scandi block is a very realistic trend.

Worth noting the GEM despite having uppers in double figures, the surface temperatures look average at best. Sign of the times, kind of need to save that chart for next summer

So the options for the major part of December look to be honest to be either a Scandi high and cold easterly winds or a Euro high on steroids which will have most summer sun-seekers on the phone to complain about why we can rarely get charts like those during the summer 

Edited December 3, 2013 by Captain shortwave

[fergieweather]

 

I actually just covered Ireland grid points, but the literature from other papers i read for Europe etc. were in-line with my results. Literature published by the ECMWF back this up. There are a few papers from Frederic Vitart, if you search him which show this.

Cheers Matty - very helpful.

[MR EXTREMES]

_{navgem wants ago at scandi heights and broadly across nearly all models the good and the bad they all want to send heights into eastern north eastern Europe.}

 

_{yesterdays jma also wants heights into scandi area looking at the over all model outputs I can see why theres interest in perhaps an se or easterly flow cant wait for the ecm.}

 

_{although im a little worried about model fright lol}

Edited December 3, 2013 by emotional rollercoaster

[garbagebags]

A lot of brave faces in here at the moment and my hat goes off to you.If I am being honest? I haven't seen such a poor run of winter charts in quite a few years. Particularly if you go by the 850's. Looking mild or "warm" for pretty much everywhere for the whole GFS and ECM runs, including FI. If that kept going we could see an exceptionally +ve Dec CET and that's not an exaggeration.Having said that. Am I too bothered? Nope, the weather can entirely flip on its head in the space of 10 days, models completely turning around. So, the hope lives on.

Edited December 3, 2013 by garbagebags

[JK1]

GEM is not interested in any cold infact it becomes very mild +14 850's for some with +12 widely at the end before that we have +8's widely

 

What a nice chart, wish it would happen