Model Output Discussion - cold spell to end Autumn

[snowbob]

16 minutes ago, Frosty. said:

Not for all those in southern England it isn't, they look like missing out on Sunday..a damp squib for the south / southeast if the 18z is right.

Yep not looking great from the pub run down here frosty but ,

its not mild, il still need a coat on sun,and can’t cook burgers on the bbq with all that rain so not like most decembers

hoping the over night runs may bear a little more fruit for us down here.

Although not such a done deal yet Aperge does not agree with the pub run

exciting times

Edited December 7, 2017 by snowbob

[The Enforcer]

A full set of comparisons for the various models' outputs today can be found here:

http://www.meteociel.fr/cartes_obs/comp_panel.php?mode=10&ech=54&size=3

There are a few that are more S&W-aligned than GFS, like the aforementioned Arpege and there are several that have moved S&W with each output - ICON being the most dramatic example.

[steveinsussex]

7 minutes ago, captaincroc said:

Hi Shaky, have you got a link to it or a screen shot?

[Man With Beard]

18 minutes ago, CreweCold said:

Low heights remain over Europe?

Doesn't look that bad to me as we've still got one of the ingredients necessary for the foundation of a future cold spell. Upstream is flat, granted, but I suspect this *may* be temporary.

I didn't post what comes next

still a bit going on with heights to the north but generally west looking less settled.

I do agree with your sense that this may not be "it" for cold, it's still a long way out and "breakdowns" often go wrong, so I'm not resigned just yet, not by a long chalk.

[Man With Beard]

25 minutes ago, Danny* said:

One cluster at T240 with 100% support? I feel like something has gone wrong with the clusters, there's no way that's right.

Does seem strange - I'm always a bit sceptical when they give us one cluster - though to be fair a lot of individual members are similar on weather.us.

Of course we don't know how they decide on clusters - it could be to do with similarity on a global scale - or even just outcomes for Iceland?

Edited December 7, 2017 by Man With Beard

[Frosty.]

4 minutes ago, snowbob said:

Yep not looking great from the pub run down here frosty but ,

its not mild, il still need a coat on sun,and can’t cook burgers on the bbq with all that rain so not like most decembers

hoping the over night runs may bear a little more fruit for us down here.

Although not such a done deal yet Aperge does not agree with the pub run

exciting times

Hopefully the 00z runs will be better for you snowbob, good luck.  

[The Enforcer]

And for a comparison of FAX chart progress - look no further:

T+120:

T+96:

T+84:

T+72:

Analysis: Fronts making faster progress, more negatively tilted and further south on each output.

[Man With Beard]

53 minutes ago, bluearmy said:

It's pretty clear from the eps clusters this evening that something isn't right when they go for one cluster post day 10. The cluster looks nothing like the ens mean/anomoly! 

Have to say I'm baffled by those colours again - blues in the middle of a ridge!!

I wonder if they pick one solution that seems to best represent the runs?

All guesswork!! I suppose we can see the clusters as another tool - have to say they've been really good at spotting trends or understanding the mean at times - but without a complete understanding of how they are formed they need to be treated with a little caution.

[karlos1983]

12z ens in the extended trending milder..

[The Enforcer]

14 minutes ago, snowbob said:

Yep not looking great from the pub run down here frosty but ,

Although not such a done deal yet Aperge does not agree with the pub run

Neither does 18z ICON,12z GEM, 18z NAVGEM or 12z CPTEC.

[damianslaw]

Today was always going to be one of the days to skip model wise - I've refrained from looking at them all day - expecting various output, will be looking at them more in earnest tomorrow evening - with this in mind, take them with large margin of error today as they continue to struggle with a complex set up that will come down to sudden short-term developments. 

[Paul_1978]

3 minutes ago, karlos1983 said:

12z ens in the extended trending milder..

Yes on closer inspection, the "milder" (less cold?) trend starts around the 17th.... that's 9/10 days away yet!

A lot of water to pass under the bridge before then.

[karlos1983]

4 minutes ago, Paul_1978 said:

Yes on closer inspection, the "milder" (less cold?) trend starts around the 17th.... that's 9/10 days away yet!

A lot of water to pass under the bridge before then.

Yes that’s true, but I look at these twice daily and it has been a trend over the past few runs increasing the number of milder members. It is what it is. Long way off and hopefully it changes, but can’t just be ignored!

Edited December 7, 2017 by karlos1983

[NickR]

33 minutes ago, snowbob said:

Yep not looking great from the pub run down here frosty but ,

its not mild, il still need a coat on sun,and can’t cook burgers on the bbq with all that rain so not like most decembers

hoping the over night runs may bear a little more fruit for us down here.

Although not such a done deal yet Aperge does not agree with the pub run

exciting times

From what I can tell the Arpege is stalled at 60hrs, and shows a shift further north from its earlier run.

[lewis clark]

Just a quick question if anyone can help, does anyone know which model xc weather use for their forecasts, i use them alot for winds and they are normally always spot on 3 or 4 days out, just curious?  Anyway interesting watching the last few weeks  i havnt a clue on charts and models  but love cold weather and am sure this winters going to be different....

[sausage]

unfortunately ive refrained from posting in here atm because its aĺl about the midlands rather than anywhere else. we dont exist up here.

the gfs 18z is fantastic and i sincerely hope it comes true. the midlands AND north england get snow.

#cumongfs

[snowbob]

4 minutes ago, NickR said:

From what I can tell the Arpege is stalled at 60hrs, and shows a shift further north from its earlier run.

I said it wasn’t as north as 18zgfs not from its own previous run

[NickR]

1 minute ago, snowbob said:

I said it wasn’t as north as 18zgfs not from its own previous run

I know.

I was just contextualising by pointing up the trend.

[Panayiotis]

Just a quick look at some of the high res models for the feature we have currently stretching across the country. Radar below just so everyone knows what feature I am talking about:

Now a look at the EURO4, NMM 2km, AROME 2.5km, ICON and ARPEGE at 3am:

ICON and the ARPEGE dont make much of the feature however the other models seem reasonable with the extent of the PPN band but have it shifted north compared to the realtime radar. 

I feel as though this really puts a real sense into how difficult it will be to forecast the slider for this weekend and where the associated snow risk will be...

 

Edited December 8, 2017 by Panayiotis
AROME was for 4am not 3am which puts it inline with the other models which have the band to the north.

[CanadaAl]

4 minutes ago, Panayiotis said:

Just a quick look at some of the high res models for the feature we have currently stretching across the country. Radar below just so everyone knows what feature I am talking about:

Now a look at the EURO4, NMM 2km, AROME 2.5km, ICON and ARPEGE at 3am:

ICON and the ARPEGE dont make much of the feature however the other models seem reasonable with the extent of the PPN band. Looking at these models it seems that the EURO4 and NMM have it too far north, with the AROME closest to reality (still a touch north though).

I feel as though this really puts a real sense into how difficult it will be to forecast the slider for this weekend and where the associated snow risk will be...

 

Completely agree, goes to show how it's all to play for until Saturday eve at least.

[Cheshire Freeze]

ICON take on the Sunday front-

Snow depths up to Sunday evening

The GFS 0z take on proceedings..

and associated snow depths

Edited December 8, 2017 by CreweCold

[Cheshire Freeze]

GEM slightly further S than the GFS

Shows it still snowing 12 hours later

[CanadaAl]

Interesting, looks like the GFS is falling more inline with the ECM with that "super low" coming off canada at 174h. Hoping it's not a trend for a renewed Atlantic onslaught. A lot to enjoy in the shorter range though! 

[Cheshire Freeze]

ARPEGE on Sunday low

https://modeles7.meteociel.fr/modeles/arpege/run/2017120800/arpegeeur-2-60.png?0

Fairly broad agreement across the models so far (may not stay that way obviously).

GEM seems furthest S, GFS furthest N with the likes of the ICON, ARPEGE taking the median track.

Edited December 8, 2017 by CreweCold

[Cheshire Freeze]

19 minutes ago, CanadaAl said:

Interesting, looks like the GFS is falling more inline with the ECM with that "super low" coming off canada at 174h. Hoping it's not a trend for a renewed Atlantic onslaught. A lot to enjoy in the shorter range though! 

0z GFS is actually colder for us at day 9 than the 18z was

You can see the issue that bit of Canadian vortex is going to have in exerting authority..

Height rise out Russia way means that the Scandi troughing is trapped, it can't go east due to rising pressure there...

It'll (the Canadian vortex) eventually have no option but to spit bits of energy off rather than moving wholesale into the N Atlantic sector. Every it turns so far this year, the trop PV is being pushed about.

Edited December 8, 2017 by CreweCold