Model output discussion - The run up to Christmas

[Matt H]

As @That ECM said the uppers do look marginally better on this run which is brilliant, but I’m going to reserve judgement until terrier drops in later. Fingers crossed!

Edited December 22, 2020 by Frosty Winter

[sheikhy]

Welll lets just countdown  now folks!!!whose gona get the snow first is the only question i got?850s better on the 06z and this all starts 2 days from now!!!christmas eve is just a taste of whats to come!!funny thing is the colder 850s are on christmas eve/day but the snow comes with less cold 850s a few day later!!!gota love the weather

[TSNWK]

Whole of uk under at least -5, pressure raising again to the north west and slider heading in I think...and the air with slider looks colder...

[Howie]

Looks like the low that's about to dive from Greenland has much colder air within it as well

[Methuselah]

Not too bad; getting colder alright... But still nae cold enough for tracking Bigfoot through the streets of London? 

    

[BarometerCat]

One trend standing out on the 6z GFS run so far, it is not mild.  Pretty much colder weather after +24.   As many have said, this is nothing like where we were last two winters at the very least! Devil is in the detail as always and closer to the time.  

Looking forward to the next few runs.... 

[mushymanrob]

1 minute ago, sheikhy said:

Good to see you on the cold wagon mate!!when your mentioning cold and snow then something is defo stirring up!!!❤

Its interesting , these synoptic charts are the most interesting for a weather enthusiast like myself.

[Day 10]

I like the look of the way this low is dropping south.

[ALL ABOARD]

The system moving down from Greenland at at 216 would produce snow quite widely on new year's eve. 

 

[Kasim Awan]

GFS 06Z is much weaker with the development of shortwaves / slow movers, and resultantly drives down the snow risk slightly 27th 28th. Mainly because the low centre is placed over the midlands, and here is slightly less unstable. Only before a surface easterly warms the air 0 to 960hpa. This will be a factor to an extent it may be that we see snow chances on both the more unstable southern and northern margins of the low centre as it drops south as here these factors are reduced. The best few frames are 27th for northern hills and 28th is optimal for central UK as a light surface easterly develops reducing local low core warming & onshore wind impacts, this under a very unstable airmass before easterly winds produce a surface moderation.

We then slowly build a more decent surface easterly and if clean enough could drive in conducive conditions again later 29th. Given the GFS' tendency to perform ok as well as this synoptic evolution being common sense in this set up this is a fair shout.

What would otherwise be zonal energy is being forced north cooling only to dip over the UK again. I've seen these repeated patterns before and this is one. The chances with this next northerly are even greater. 11th Jan 2013 springs to mind. That was a good trough disruption / dive SE.

Edited December 22, 2020 by Kasim Awan

[Howie]

Gfs drops that low a bit too far west i think, obviously it will change closer to the time 

[Battleground Snow]

Here we go again, usually you wouldn't take to much notice of the GFS at this range, but the way it's consistently modelled the area around the ESB and Greenland has been very impressive recently.

 

[SnOwFeSt]

Fantastic looking runs this morning. Gfs has a great slider coming in from Greenland. Lots of moisture and cold air wrapped up in it and coming into the existing cold air sat over us. 

Yes it’s not a deep freeze type of cold spell (maximas will scrape above zero), but could be extremely snowy, particularly more northern areas with a bit of elevation. Fantastic stuff from an imby perspective and looking like more reloads to come from it, each progressively colder.

We’re in the cusp of a classic cold spell I think. Another couple of days to firm up on the post Xmas reload..

[Day 10]

Is this going very cold from the north east soon?

[Matt H]

Looks like a Greenland ridge joining forces with a Scandi high with the trough sinking south... FI should be brilliant!

[Craig84]

GFS 234, a huge block is being created here east to west. Is this the sort of setup that will drag in the really cold air from Russia

[festivalking]

3 minutes ago, Portsmouth Sun said:

Instead of looking for cold rain chances in la la land, the amount of rain modelled to fall in the SW and Wales over the coming 48hrs is a concern.  Apart from a slight downturn in temperatures for Christmas Day it all looks very average moving forward.

Certainly south of the M4!

[Guest]

13 minutes ago, Skullzrulerz said:

I have to agree with what you are saying 

It's been awfully quiet here unlike the pages that we use to have over a set of runs? 

So I decided to have a quick look at the models this morning ICON (which has strangely disappeared into thin air) as well as the ECM

Unless you're living on a hill somewhere or live in Scotland you might be for a snowy day or two 

For the most of us we're going to be seeing some lovley rain (cold on the plus side) which everyone was expecting unfortunately 

In this case silence can speak a lot louder then words here and this is the case today 

If you were expecting a cold "spell" with snowfall expected across large parts of England then you might as well go and play the lottery and have a better chance of winning that 

And please don't get yourself too excited regrading snowfall charts especially a week out they have been proved to be unrealistic and unreliable as in reality it will be snowfall for higher ground and more favourable parts of northern England and Scotland 

 

I agree with your analysis of the ECM snowfall charts. They are nice eye-candy but often grossly overestimate snow amounts. I think many on here take them with a pinch of salt.

However, the rest of your post I have issue with, it comes across as IMBYism laced with pessimism. A cold spell IS incoming for the majority - temps below average and the 'chance' (certainly better than lottery odds!) for many to see some of the white stuff over the next 7-10 days with longer term prospects looking more encouraging than we ever could have believed when reading winter forecasts earlier this month.

As has been mentioned countless times now, trying to pinpoint where and how much snow might fall is a futile exercise when looking at charts +48hrs, as small disturbances won't show until high-res output is available. Naturally some will be disappointed, it is the nature of our weather and at no point has anyone forecast 'large parts of England' under snowfall. Having perused these pages when the modelled cold spell was in its infancy, most posts have been talking up the blocking potential and how our cold might prolong and eventually intensify should conditions align favourably, rather than touting widespread snow potential.

I will be happy to revisit both our posts in the New Year to see if it is indeed only the tops of the hills and Scotland that have seen snow  Merry Christmas.

[sheikhy]

Gota say didnt see that coming on 216 hours!!hopefully a mild outlier and gone on the 12z!!

[Howie]

Pressure starts to build over iberia and the low stalls to the west, typical. West based -nao

[Drifter]

2 minutes ago, sheikhy said:

Gota say didnt see that coming on 216 hours!!hopefully a mild outlier and gone on the 12z!!

I wouldn’t worry - there’s no real consensus yet on what happens after the initial ridge. Models will continue to play around with solutions for the next couple of days. 

[Tim Bland]

Are we allowed to call this a Greenland High PS..90% of the time the pattern shifts east so no panic from me 

[Davegwarn]

2 hours ago, IDO said:

The gefs at d12 are not yet conclusive for how the pattern develops from the third ridge post-d7. Certainly the op is the most progressive by d10 with the Greenland wedge, but it is not until d12 it gets a solid cluster in the ens. There are however maybe two more options with similar support...

d12 gefs> London> 

...the Atlantic high (rebounding at times) and the NW>SE flow. This still needs to be resolved. Still a solid 850's mean running through to d16 in my area, so an extended seasonal flow, with maybe after d12, some signs of a few members moving colder. There are the usual humbug runs mixed in of course.

Looking an interesting 10 days from Thursday and the door remains open in FI for further possibilities.

 

 

Can anyone tell me where I can input my own longitude and latitude to view the same GEFS as above? I tried Google and looking on metrociel but couldn't find the same charts.

Thanks in advance

[sheikhy]

I just checked the 850s and i dunno how we managed to keep -4 850s around the uk between 216 and 258 hours!!got away with one i reckon!could have been worse!!

[Man With Beard]

Well if you can't get snow at the end of December on a chart like this ... when can you?