Model Output Discussion - cold spell to end Autumn

[NickR]

3 minutes ago, snowbob said:

The rate this is moving north don’t bode well for the cold to sweep down the uk

surely we need south corrections 

Or continued corrections north, if you're not down south...

[snowbob]

Yep this is true

was just hoping for a nationwide cold spell.

if south is cold from this, north would be colder there fore a better cold for all

[Thunder Snow]

8 minutes ago, Frosty. said:

The Gfs 18z shows persistent heavy snow for some areas on sunday which would make for a very snowy drive to work next monday..potentially severe weather on the way for somewhere across the central swathe of the uk..plenty of snow showers piling into western and northern areas before then with sharp frosts, especially over the snow fields..hope I get to say that plenty more times this winter!!

just alittle more further north please 

[blizzard81]

A positive tonight for the medium term - 120hr fax chart goes with ukmo and not ecm. Gfs 18z almost identical to the 120 fax chart. 

[blizzard81]

Easily the most exciting start to winter model watching for 7 years. Absolutely compelling stuff! This is what we are all here for isn't it. 

[bluearmy]

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! 

[bluearmy]

Pub run going for renewed +PNA by day 10

much better over the Atlantic than ecm 

[blizzard81]

2 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! 

Very strange! This seems to have been a problem for the last few days. Let's hope the ecm is having a technical glitch so we can bin the 12z suite

[igloo]

a super storm starting to brew south of greenland at 240h the NAO looks to be going positive on this run to see out december i hope this trent does not continue

[ICE COLD]

Evening 

Could someone please post some off the later stages of GFS 18z . My GFS is stuck on 153 hrs ?. Probley something to do with the heavy settling snow outside ?.  

Thanks 

[blizzard81]

I wonder if we are heading into a battleground scenario as we approach Christmas. There is clearly some signal for some form of blocking from the north east but also spasmodic cranking up of the pv lobe to our north west. Could make the xmas period very interesting. 

[Man With Beard]

Clusters T240: confirmation of the flatter prognosis with little variance between members

 

[Catacol]

36 minutes ago, Singularity said:

There is one possibility though; I have noticed that the MJO propagation to phase 7 has gained a bit of a stall in the model predictions, particularly those from ECM, before a resumption of eastward motion. This may have widened the window of simulated time (i.e. what the models go with) during which a more zonal flow is able to get going before the push toward the new HLB phase kicks in. Worth watching out for any sign of HLB gaining support late in the EPS over the coming day or two.

Thing is though, that MJO stall may well be erroneous in itself, in which case the output will backtrack toward what runs such as yesterday's 06z depicted i.e. a quicker transition to HLB near to the NE with the attempt to increase the zonal flow across the N. Atlantic derailed. Not sure it will ever be quite as quick as that run showed though, but you get the idea.

Agree. Schiraldi plots with 5 days hindcast capability over on the albany site continue to show the models are underestimating the pacific signal. In addition visible checking of MJO forecasts also shows a tendency to pull them back towards the COD and orbits 1 - 4. Clearly we have a Nina with a difference here... with warmth in the western pacific doing much to counter the trades... and for whatever reason the signal is not being correctly modelled. Leads me to repeat what I said a day or so ago - take all model runs forecasting any return to a flat pattern in the atlantic with a pinch of salt, though at some stage the Canadian trough is surely likely to throw more at us than a splinter/slider.

Ensemble signal for very low heights over the UK over the next 7 days is rock solid. A relaxing then of the cold as the mid atlantic ridge fades a bit and more of a westerly component from end of next week... before we wait to see just how quickly heights might rise to the NE. GP put it far more clearly than I ever could in terms of north pacific links and a pattern retrograding the Canadian trough and likewise the Russian high more towards Scandy.

In the shorter term the snow is now a certainty even if the location is less than clear. Snow chances via showers tomorrow, the low on Sun/Mon and I reckon again perhaps on Thurs/Fri next week from the next pulse of cold uppers. Not bad. It wont be December 2010 in terms of depth of cold, but some places will see some big falls. Beyond T+168 I wouldnt like to call the specifics.... 

 

[Johnp]

GEM now out on meteociel - slider further south!

http://www.meteociel.fr/modeles/geme_cartes.php?ech=6&code=0&mode=0&carte=4&archive=0

Edited December 7, 2017 by Johnp
add link

[Cheshire Freeze]

1 minute ago, Man With Beard said:

Clusters T240: confirmation of the flatter prognosis with little variance between members

 

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.

[markw2680]

With regards to this slider there will be plenty more changes north south east west etc. We won’t really get it nailed until sat and even then it will still have a bit more room for manoeuvre, all my opinion of course 

[Catacol]

2 minutes ago, Johnp said:

GEM now out on meteociel - slider further south!

http://www.meteociel.fr/modeles/geme_cartes.php?ech=6&code=0&mode=0&carte=4&archive=0

A huge variation at only t+80. Shows that the weekend track is still uncertain. Dont forget what happened in March 2013. I never will - and others mentioned it earlier too. Forecast of trajectory was wrong by a good 50 miles at only t+24 back then...

[Met4Cast]

6 minutes ago, Man With Beard said:

Clusters T240: confirmation of the flatter prognosis with little variance between members

 

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

[Vortex3929]

13 minutes ago, igloo said:

a super storm starting to brew south of greenland at 240h the NAO looks to be going positive on this run to see out december i hope this trent does not continue

Presuming it's gfs  18z- t240 is laughable. Fantasy island..  more chance at that range of the sun turning to chocolate 

[Justin Miller]

Does this mean the snow boundary has become a little further south again?

[Frosty.]

25 minutes ago, blizzard81 said:

Easily the most exciting start to winter model watching for 7 years. Absolutely compelling stuff! This is what we are all here for isn't it. 

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.

[shaky]

Arpege is full on snow for midlands and wales again!!plot thickens!!

[captaincroc]

2 minutes ago, shaky said:

Arpege is full on snow for midlands and wales again!!plot thickens!!

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

[mother nature rocks]

3 minutes ago, shaky said:

Arpege is full on snow for midlands and wales again!!plot thickens!!

Yup anywhere from M4 to M62 as someone mentioned earlier. Sticking to its guns the good old Arpege.

[ianmm94]

7 minutes ago, shaky said:

Arpege is full on snow for midlands and wales again!!plot thickens!!

Looks a little further north than the previous run to me?