Model output discussion - Closing in on Christmas

[cyclonic happiness]

That is a nice GFS run this morning, and it must be on to something as the 0z is usually the party popping hangover model after the 18z pub run's stunner, the night before.

One thing seems almost set, we should see some sort of northerly over the Christmas period, but where it goes from there is still up for grabs :-)

Fingers crossed everyone!!

[Rocheydub]

Fair enough

[Tim Bland]

Cold enough air on the west side of that low at the end for some proper snow I’d imagine...

Edited December 18, 2020 by Tim Bland

[Rayth]

5 minutes ago, Tim Bland said:

Cold enough air on the west side of that low at the end for some proper snow I’d imagine...

And if the white stuff did fall

 

Blizzard fans rejoice 

 

 

[Sky Full]

Here is this mornings very promising GFS (0z) evolution from Boxing Day to New Years Eve....

                          500s.                                                             850

   

 

VERY seasonal!   Quite a few wouldn’t need a lockdown to make them stay at home if this happened.   Pity it’s in the land of make believe...   

[sheikhy]

Fantastic output this morning!!gfs and ukmo take the shortwave further west again but ecm wants to play scrooge at 120 hours and take it over the uk!!you feel massive moment coming and shall probably set the trend for the rest of the winter?

[West is Best]

The first properly exciting model run of the winter. The first one to make me sit up. Notice the all-important Greenland High. Upstream blocking is the key, which wasn't present in previous flashes of cold. 

It doesn't have great support but neither is it an outlier. Something to watch.

[Roger J Smith]

The uppers on the day 10 ECM panel appear a bit reluctant to follow the surface evolution, but if all elements further north phased in a little faster, that would be quite a dynamic change to the pattern locking in a very cold northeast flow from a rapidly building north Scandinavian block. The unseen day 11 and day 12 of that ECM run would probably look very frigid indeed. 

The GEM shows the obstacle to full phasing that is created by only weak ridge formation from Greenland to mid-Atlantic high. That keeps the flow relatively mild from the w.n.w. recycling old arctic air rather than allowing it all to break through. 

GFS as people mentioned is quite a stunner too.

All things considered, these are the kinds of charts you would want to have at 8-10 days if in fact there was going to be a pattern shift. The first problem to overcome is getting the approaching Atlantic storm to do one of two things (Monday-Tuesday), either weaken and drop southeast, or stall over the North Sea and lose contact with the main jet stream. Then it can be more helpful than harmful to the later prospects for cold. 

Cautionary note, there is probably about a 30% chance that none of this is real and the outcome will be just a slight interruption in the mild Atlantic regime. But those are way better odds than we had a week ago. 

[SnOwFeSt]

Fascinating output this morning which will surely keep me hooked on here over the coming days.

If it comes off it does feel like quite a locked in pattern which could last for a good couple of weeks at least. And occurring at a colder time of year than dec 2010, March 2013/2018 etc!

[mb018538]

6 minutes ago, West is Best said:

The first properly exciting model run of the winter. The first one to make me sit up. Notice the all-important Greenland High. Upstream blocking is the key, which wasn't present in previous flashes of cold. 

It doesn't have great support but neither is it an outlier. Something to watch.

Believe me - I've seen many major outliers in my time here.....this isn't one of them! 

[West is Best]

3 minutes ago, mb018538 said:

Believe me - I've seen many major outliers in my time here.....this isn't one of them! 

Which is presumably why I stated that it is not an outlier. Or did you rush to reply before reading properly? 

Edited December 18, 2020 by West is Best

[mb018538]

4 minutes ago, West is Best said:

Which is presumably why I stated that it is not an outlier. Or did you rush to reply before reading properly? 

I probably just phrased my answer wrong - I was agreeing (in a rather unclear way) ! 

[Matt H]

Brilliant model runs overnight, don’t know where to start this morning. Something is going on here...

Edited December 18, 2020 by Frosty Winter

[West is Best]

7 minutes ago, mb018538 said:

I probably just phrased my answer wrong - I was agreeing (in a rather unclear way) ! 

Haha no worries! If this kind of model run appears with 72 hours to go this place will be chaos and we'll all be posting and replying in a febrile state!

Fingers crossed, although John Holmes may need to remind us that we should be careful what we wish for. A 1947 or 1962-3 would be a sucker punch for a lot of people after this year. Not for most of us on Net weather model output discussion though 

Edited December 18, 2020 by West is Best

[The PIT]

A bit more interesting this morning but still far out to be really confident in it. After a few days moving in the right direction don't be surprised if they move in another in the next few days. The cool/ rather cold start to December at one point looked likely to last longer before the models suddenly flipped.

[Chesil View]

Well that's a nice surprise this morning GFS keeps up with its wintry mode from late yesterday and the ECM moves towards it in the medium term.  If we can keep this medium range model agreement through the weekend then it really could be game on for an Xmas/new year wintry spell.

[Vikos]

4 minutes ago, BARRY said:

It would sum up this year, and lead to chaos around the country

Hmm...

I know those snow cover outpouts from a global model aren't worth a lot but, I don't see a lot of snow coming in midterm...

[Vikos]

If smbdy noticed...

+4

There is something going on

Edited December 18, 2020 by Vikos

[West is Best]

14 minutes ago, The PIT said:

The cool/ rather cold start to December at one point looked likely to last longer before the models suddenly flipped.

I didn't think it looked at all likely. Why so? Because there was no upstream blocking: people were relying on the high pressure in Russia / Scandinavia to turn into sustained blocking here and that's a fraught pathway to cold in the UK. Looking east not west is like beginning a book on the last page and reading backwards to the start. It can be done but it's sub-optimal .

This time there's upstream blocking showing up: a proper Greenland High which is very different.

Doesn't mean it will happen, mind you (so I agree about that), but at least the starting position is on much firmer ground. Damn the flow upstream first and watch the results. This is a cracking chart:

Edited December 18, 2020 by West is Best
Insertion of chart

[Tim Bland]

GEM worth a mention. No sign of any PV left to our North west with a massive block !

[Griff]

8 minutes ago, Tim Bland said:

GEM worth a mention. No sign of any PV left to our North west with a massive block !

Always have to admire a massive block... Time for  

[bluearmy]

6 eps clusters in the extended ...... hello Shannon !

[Skullzrulerz]

GFS looks absolutely stunning! 

ECM is still good but hoepfully it can improve in the medium term 

[Iceaxecrampon]

1 hour ago, West is Best said:

The first properly exciting model run of the winter. The first one to make me sit up. Notice the all-important Greenland High. Upstream blocking is the key, which wasn't present in previous flashes of cold. 

It doesn't have great support but neither is it an outlier. Something to watch.

Fantastic Chart....!

But -  first it was the 22nd 23rd then 24th and 25th........

Now the 28th.

Same old GFS.

[BLAST FROM THE PAST]

ECM

UKMO

 

GFS

All at t72.  Pretty consistent stuff there. So evolutions on from each are plausible.....and pretty cold surface temps from all of them are coming....GFS brings frigid set up, ECM knocking on that door....I believe UKMO would too as it’s pretty cold at t144.  We had 2 days of ‘wobbling’ but the chances of the cold Xmas week didn’t disappear, just in what form it’ll play out.  I suspect more altering to come....but at t72 it’s looking good to be in position

 

BFTP  

 

 

Edited December 18, 2020 by BLAST FROM THE PAST