Model Output Discussion - moving into Winter

[weirpig]

8 minutes ago, Tidal Wave said:

I'm no expert but surely this is a extraordinary chart for December 5th from the ICON 12z:

Certainly unusual for December. Although uppers aren’t that cold. I’m certain some areas will see the odd wintry shower. Off that 

[Met4Cast]

3 minutes ago, lorenzo said:

Awful outlook really..

I was about to post this - About as clear cut as it's possible to get for a -NAO outlook. If this were to fail it would surely be a bigger model bust than when the 2012 easterly failed.

Detail re: UK less clear cut than the broader picture of course but given the monumental amount of blocking we're seeing it's surely only a matter of time before deeper cold (& thus snow) reaches our shores.

[Ali1977]

Icon is epic at T180 , follow that GFS 

[nick sussex]

The cold pooling to the east changes between each run so nailing down what the UK could tap into initially is difficult .

The ICON overall is very encouraging for coldies so we await the GFS to hopefully keep the feel good factor !

As I’m in Cyprus at the moment I’m looking for some nice warm conditions which just so happens to correlate at this time of year with wintry prospects for the UK.

Troughing over Scandi or a nice Genoa Low often throws up high pressure to its east and se so we all win then !

 

Edited November 28, 2022 by nick sussex

[bluearmy]

6 minutes ago, lorenzo said:

Awful outlook really..

Ooh Tony - where did you get access to Decider ? 

[northwestsnow]

23 minutes ago, sheikhy said:

Very good start to icon!!150 hours iberian low squished!!

Yup..

Want that low waaaaaay outta the way.

[lorenzo]

5 minutes ago, bluearmy said:

Ooh Tony - where did you get access to Decider ? 

It just popped up onto Twitter feed Nick - if only !

[Met4Cast]

I don't suppose anybody knows what GLOSEA is currently showing, do they?

[That ECM]

2 minutes ago, Met4Cast said:

I don't suppose anybody knows what GLOSEA is currently showing, do they?

I’m guessing the high not going as far nw as we may wish. But without much confidence?

Edited November 28, 2022 by That ECM

[sheikhy]

Ibe low squised at 138 hours on gfs 12z!!!well im hoping it dont resurrect from here on !!

[That ECM]

T144 Ukmo and gfs. 

[Rain All Night]

26 minutes ago, northwestsnow said:

Yup..

Want that low waaaaaay outta the way.

Another poster pointed out that it would reduce the chance of frontal snow if we didn't have waves of mild air coming up from the south. Although I assume the same mild air would melt the snow quickly once it hit the ground.

[sheikhy]

1 minute ago, That ECM said:

T144 Ukmo and gfs. 

Very very good start to the 12zs!!!thats ukmo and gfs now!!

[Singularity]

40 minutes ago, Mike Poole said:

One thing that has struck me looking at the countless model runs over the last week or so, is how resilient both the formation of the initial block, and its eventual evolution to a Greenland high is, to whatever obstacles in the form of badly placed shortwaves, low pressures etc. the models deign to throw in the way on each individual run.  

It is as though the destination is known and the models will find a way - and on some runs that has even meant in extremis, the Azores high ridging west of the whole caboodle and shoving it onto the Asian side.  

This might be down to teleconnections, but it seems a much stronger influence than I can recall seeing before.  I’ve mentioned before the possibility that all roads lead to Rome on this, but why is another question?  It could be the +AAM, and MJO - I guess, but are we seeing some unknown driver at work? There is the wild card of the volcanic eruption, which we know affected the strat in the southern hemisphere, so it could be that, perhaps.

This is one reason why I’ve been less keen to look for ways it might go wrong than some.  I feel that the pattern, in the broadest terms, may, partly at least, be set.  That does not mean that here in the UK, on our small island, we will not contrive to mess it up locally, of course!

On to the 12zs!

Just tried isolating runs of days since Jan 1958 (start of records) with sustained high AAM in Nov (as we've seen lately) & the result was... interesting. 

I'm now waiting to see what's produced for Dec.

A less organised low to our southwest on the 12z GFS compared to 06z as of Sunday. There's also less of a break being maintained in the high pressure to our west.

Both should mean less northward advance of milder air across the Low Countries going forward.

[Allseasons-Si]

Next stop,...better heights S tip of Greenland  on both the op and parra than on the 06z 144hrs>

[Mark wheeler]

Looks decent to my untrained eye . UKMO 144

Edited November 28, 2022 by Mark wheeler

[iceman1991]

47 minutes ago, lorenzo said:

Awful outlook really..

What does this mean please someone ? 

[Captain Shortwave]

I have to be honest regarding the UKMO, At day 6 it doesn’t look like we would get the window to build that high properly to the north west as the jet stream appears to be much stronger than any other output. On the other hand it is probably another rather erroneous day 6 chart.?

 

The fact that the Siberian/Canadian vortices are fully connected is the reason as cold air will transfer to the Canadian side. The GFS/ICON are nowhere near this though.

The easterly at day 4-7 is still uncertain in terms of how clean and cold it will be. There is still a chance of some flakes of snow if the airmass is cold enough.

Good effort from the GFS

 

Cold air pushing westwards through Europe.

Edited November 28, 2022 by Captain Shortwave

[Met4Cast]

2 minutes ago, iceman1991 said:

What does this mean please someone ? 

It's a regime chart based on the latest UKMO, ECM & GFS runs. It's showing rock solid support for a -NAO pattern through the entire first half of December. Doesn't say much about UK detail though in terms of mild/cold.

[Singularity]

For the heck of it as I don't usually find much time for this these days... here's more detail on the key 06z v 12z GFS run differences for what happens next weekend to the west & southwest of the UK.

The 06z slide a low SE from the S tip of Greenland to merge with another to the W of the UK. The 12z slides the low later and less emphatically, preventing that merger and allowing high pressure to bridge the gap.

Meanwhile, the low to the SW of the UK is far less consolidated on the 12z run. This appears unrelated to what goes on to its north - a bit of internal variability from GFS - it just happens to be a less efficient baroclinic process on this run. Reality does tend to be toward the less efficient end of the spectrum (as many will attest to in their daily lives).

[Ice Day]

At 174 on the GFS Op, some decent cold advancing towards us from the east!

  

[northwestsnow]

1 minute ago, Captain Shortwave said:

I have to be honest regarding the UKMO, At day 6 it doesn’t look like we would get the window to build that high properly to the north west as the jet stream appears to be much stronger than any other output. On the other hand it is probably another rather erroneous day 6 chart.?

 

The fact that the Siberian/Canadian vortices are fully connected is the reason as cold air will transfer to the Canadian side. The GFS/ICON are nowhere near this though.

The easterly at day 4-7 is still uncertain in terms of how clean and cold it will be. There is still a chance of some flakes of snow if the airmass is cold enough.

I was thinking it looks good and expecting low heights to drain away from S Greenland at 168 

Eeek.

 

[snowsummer]

4 minutes ago, iceman1991 said:

What does this mean please someone ? 

Negative NAO 

[Downburst]

The Iberian area low is very flabby on the 12z compared to the 06z. Certainly, very far from the climatic norm this entire setup playing out, that's for sure. I am loving it, not least the dry (ish) air incoming.

 

Edit, it gets it act together around 200 hrs. This will be very interesting as to how far north it gets of course. It's our kind of steering low as this plays out.  

Edited November 28, 2022 by Downburst

[TSNWK]

West based option this time.