Model Output Discussion 26/11/2012 18Z onwards

[Southender]

The 120 fax is NOT yesterdays for goodness sake. 5 days from midday today is midday Saturday. Jeez.

[Weathizard]

I have now reached an complete state of confusion with the charts, I think I need to chill out and await the mornings output, The fax chart looks alright though, solid. Thanks for the fun and good night!

Edited November 26, 2012 by Weathizard

[etched Chaos]

no it is rather different from the 2208 issue on 25/11/12

It had updated after i posted.

[LomondSnowstorm]

UKMO rationale re this weekend, or at least the part I can abstract (I cant routinely share all the EC stuff for example). Hopefully this makes position clear from their perspective. All seems prudent science to me:

" 1. Amplifying Remarks : The main uncertainty through this period is to what extent cold air floods SW’wards towards the UK during Saturday. The GM has shown good consistency in the last few runs in bringing this cold airmass from Scandinavia across all parts of the UK over the weekend (fig 1). EC, both the deterministic (fig 2) and a large number of its ensemble are less keen and run a surface depression over eastern Europe further north into Scandinavia, which in turn restricts the very cold air reaching UK shores. This solution has more support from other model centres and modifications have been made in this direction. Given the consistency from the GM though and support it has from JMA (fig 3), we cannot be too confident about the extent of wintry ppn by Saturday."

Thanks for the update. Very clear reasoning, can't argue with any of it.

[karlos1983]

The 120 fax is NOT yesterdays for goodness sake. 5 days from midday today is midday Saturday. Jeez.

There has to be an easier way, I'm doubting myself over simple Math now for christ sake, I'm off before I lose the plot!!

[chris55]

UKMO rationale re this weekend, or at least the part I can abstract (I cant routinely share all the EC stuff for example). Hopefully this makes position clear from their perspective. All seems prudent science to me:

" 1. Amplifying Remarks : The main uncertainty through this period is to what extent cold air floods SW’wards towards the UK during Saturday. The GM has shown good consistency in the last few runs in bringing this cold airmass from Scandinavia across all parts of the UK over the weekend (fig 1). EC, both the deterministic (fig 2) and a large number of its ensemble are less keen and run a surface depression over eastern Europe further north into Scandinavia, which in turn restricts the very cold air reaching UK shores. This solution has more support from other model centres and modifications have been made in this direction. Given the consistency from the GM though and support it has from JMA (fig 3), we cannot be too confident about the extent of wintry ppn by Saturday."

Brilliant Ian, thanks for that, very clear. Kind of sums up many peoples thoughts on here including mine.

[SMU]

http://weather.noaa.gov/fax/otherfax.shtml

Here people use my LINK for the fax charts- shows what time they updated.

S

[Buzz]

Tell you what though guys, i and many others will of wasted alot of time model watching if nothing happens! thats why when it does snow i am out in it ALL day!

Hopefully you (and others) won't have wasted any time at all - hopefully you will have learned something from the experts that also post here.

[Jan_Bromley]

Thank you very much Ian. Very difficult problems to solve

regards

Jan

[Panayiotis]

The 120 fax is NOT yesterdays for goodness sake. 5 days from midday today is midday Saturday. Jeez.

Yes they have been updated now,but fax charts posted on here showed that 120hrs was Friday, which as you stated is not. But everything is now sorted.

[fergieweather]

Brilliant Ian, thanks for that, very clear. Kind of sums up many peoples thoughts on here including mine.

Yes: proper (unbiased!!) assessment. The last sentence is crucial and it's for exactly this reason that I, for one, didn't go into weekend charts in a tv week ahead summary this evening. I'm leaving it until we see proper continuity between UKMO-GM and EC.

[Staffordshire]

Hopefully you (and others) won't have wasted any time at all - hopefully you will have learned something from the experts that also post here.

Yes i hope! and i as im sure many others are extremely greatful for that! the cold is coming just as i hope it wouldnt - i have to submit my A level options!

[igloo]

the fax charts have been updated and dont look to bad to my eye.its always the same in this type of setup the models underestimate blocking either from the north or east

Edited November 26, 2012 by igloo

[Jack Wales]

The cold spell keeps getting downgraded in the more reliable time frame, the main reason seemingly being the tilt / angle of the HP Cell to the west of the UK. Now we see a more North-to South elongated HP cell, (rather than the SW to NE tilt linking into Scandi), the upshot of this being a shortwave trough / cut-off low forming to the north of the uk and restricting the westward advection of the cold past Norway, here is Tuesdays chart (T+24)...

The second attempt for the real cold to move in is at the weekend, but here is the GFS chart for Saturday (T+102) which shows the shortwave being the spoiler again.

I can't help but think that GFS have over-egged the jet on this run but as we move nearer to the reliable timeframe, the forthcoming cold spell does appear to be somewhat less of event than expected a week or so ago.

Edited November 26, 2012 by Jack Wales

[peterf]

time for some peeps.

[Cloud 10]

http://weather.noaa..../otherfax.shtml

Here people use my LINK for the fax charts- shows what time they updated.

S

Cheers for that link Steve,i lost that one about two computers ago!

btw,in my post about the ecm ensembles earlier,i was referring to the -20 scale being used.

[PubliusEnigma]

looks ok to me

And the UKMO would make the next Fax frame a logical follow on ??

[Alex]

Yes: proper (unbiased!!) assessment. The last sentence is crucial and it's for exactly this reason that I, for one, didn't go into weekend charts in a tv week ahead summary this evening. I'm leaving it until we see proper continuity between UKMO-GM and EC.

Thanks Ian, another decent analysis from the top of the tree. One thing I would like to know though is how much thought goes into teleconnections? I visited the Met Office on an open day this year and when I asked forecasters about teleconnections they seemed rather unknowledgeable?

I'm guessing most of the work is really upto 5 days ahead, but would be interested in finding out what's happening at the top of the tree and whether the 6-15, 16-30 and seasonal forecasts are more based on ECM 32 dayer and other ECM outputs / CFS rather than really looking deep into MJO / angular momentum / stratospheric conditions etc.

[lorenzo]

Here is another link for the fax charts, thank goodness for time stamps saves mental arithmetic.

Nice and easy open here then click on the chart to move through the cycle. http://www.weathercharts.org/ukmomslp.htm#t24

[Mucka]

GFS ensembles still show promise in the long run.

http://modeles.meteociel.fr/modeles/gens/graphe_ens3.php?x=239&ext=1&y=42&run=18&runpara=0

[Panayiotis]

GFS ensembles still show promise in the long run.

http://modeles.meteo...un=18&runpara=0

Sorry but what is the location?

[TEITS]

So the plot thickens because despite some saying the Met O aren't supporting their own model, we have the latest fax charts which are an exact copy of the UKMO raw output.

A couple of things I want to say before I retire to bed because despite my post yesterday, some are still making the same mistake.

Many are just assuming that the return of the Atlantic means mild, rain but you are missing one important aspect of the model output. Despite all the model differences we continue to see blocking over Svalbard region. Due to this any less cold weather is likely to be temporary and depending on the angle of attack from the LP, some locations may even remain cold with snow on the N flank of the LP.

Finally my observation of the GFS over many years is that it won't suddenly back the UKMO. What you will find is each run will make a slight correction and then after many runs it might resemble the UKMO.

[Mucka]

Sorry but what is the location?

Central UK but they are much the same for the SE only maybe with some colder runs showing more clearly

http://modeles.meteo...un=18&runpara=0

Click the map for your location

http://www.meteociel.fr/modeles/gefs.php

Edited November 26, 2012 by Mucka

[Panayiotis]

Central UK but they are much the same for the SE only maybe with some colder runs showing more clearly

http://modeles.meteo...un=18&runpara=0

Thank you, from that i dont see any mild weather coming for the foreseeable and from the 30th its showing a lot of chances for snow (small chance but still good to see)!

[NickR]

Central UK but they are much the same for the SE only maybe with some colder runs showing more clearly

http://modeles.meteo...un=18&runpara=0

Click the map for your location

http://www.meteociel...odeles/gefs.php

Is there a clickable map somewhere for ens for parts in the N of Eng and Scot??