Model Output Discussion - Deeper into Autumn

[johncam]

The Parrallel is going to be the main model soon so why is everyone cherry picking the best one every alternative run , human nature I suppose 

[BLAST FROM THE PAST]

1 minute ago, johncam said:

The Parrallel is going to be the main model soon so why is everyone cherry picking the best one every alternative run , human nature I suppose 

Was Supposed to have been the main model ages ago?

 

BFTP

[TSNWK]

1 minute ago, johncam said:

The Parrallel is going to be the main model soon so why is everyone cherry picking the best one every alternative run , human nature I suppose 

Correct. Why would any right minded coldie not do anything differently

[Anthony Burden]

55 minutes ago, Nick F said:

12z GFS is an improvement - as it doesn't have the Azores High muscling in at the critical point when the trough sinks south down the North Sea and opens up the cold floodgates from the northeast.

Instead the Azores heights build north to the west toward Greenland rather than NE towards the UK.

All to do with modelling the jet stream differently over the Atlantic and northern Europe. Stronger omega poleward ridge developing out west on the 12z compared to 06z

06z                                                              12z

Hi Nick 12z GFS looks low pressure oriented all in the unreliable time frame of course over the U.K. 

[Ali1977]

Been offline all day, come back to loads of posts - things are certainly looking better than this morning. Blocking everywhere

[BLAST FROM THE PAST]

GFS picking up on the trough digging south down the North Sea like the ECM. 

timing and the movement NNW/SSE is looking right to me.

Big freeze?  Not expecting it to crash in, but a chilly continental flow to develop hot fav

 

BFTP

 

 

Edited November 22, 2022 by BLAST FROM THE PAST

[minus10]

No split vortex on the parra, bit of a monster actually..

[ANYWEATHER]

Gfs at day ten shows the developing theme of high pressure over the Scandinavia region, and low pressure over the Mediterranean and southern Europe. .....what possiblycould go wrong

[BlueHedgehog074]

1 hour ago, CreweCold said:

Believe you me, I’d take sleet all day long over 11c and torrential rain

At least with sleet you still get some white stuff mixed in. 

Sorta a shame about the 850 hPa temperatures that get drawn over the UK not being particularly cold. But then, to be fair, the Easterly/North-Easterly setup is quite far away, plus there is more than the 850 hPa temperatures which determines whether snow will fall to low levels. 

Synoptically, the 12Z GFS is certainly impressive.

 

The Polar Vortex being held captive on the other side of the Northern Hemisphere

 

[phil nw.]

The models so far are all showing the Atlantic ridging and being held at bay by day 7 which is getting close to the reliable.

I think i would take that for a start we already have the block around Scandinavia so it will be a case of how the whole area of heights develop from there.Modeling will of course show various ways forward but a change of pattern now looks odds on now as the chain of Atlantic lows gets broken.

Whichever way the new pattern goes it looks the vortex is getting a hit and we should see temperatures fall away as the westerlies are stopped. 

[Duane S.]

Anyone finding fault with the current output is very much missing the point and will just lurch all over the place with the models.

As always, forget the detail, see the bigger picture and potential. We will never get a cold spell without going through having potential initially . And this is the first opportunity of the season so far, so I'd say not bad a start.

Warm air advection, backed up by background signals / jet profile, leading to blocking in and around the right sort of area is all we can ask for really?  Of course, what can go wrong probably will go wrong... but as always, I'm coming along on the crazy train for the bumpy ride.

[carinthian]

The UKMO extended looks quite a bit different to the latest GFS op. UKMO going for a surge of pressure build over the British Isles , whilst GFS  going for some form of trough distruption . ICON sort of in between. Really, all sorts of model interpretations in the mix as the models come to terms with the solid North Russian high. Overall , I think by this time next week we could be looking at some rather dramatic developments towqrds a colder outlook in one form or another.

C

[Eagle Eye]

Long term and this has been on the cards for a few runs now. Significant strat warming. I would take that. Way beyond the normal range though but the trend is there. As a general rule, the amount of EHF in the mid term coming up from the troposphere should warm parts of the Stratosphere up to those values. As a general rule of thumb this is what can be expected in a way.

This is shown well by today's GFS cross-section so we're not in a bad position right now but of course it's still too far away.

Just another case of the waiting game in the Stratosphere, let's hope its worth it.

Surface modelling looking good for cold, Stratosphere modelling looking good for a potential split or SSW. It's only the last few runs but if you're a coldie, I wouldn't complain about the latest few runs.

Edited November 22, 2022 by Eagle Eye

[Mike Poole]

I can see something of a clown’s face in this chart, anomaly at day 16 on the 12z GEFS:

This is looking very good for a mean chart at T384:

Clear signal for Greenland whether you look at the anomaly or the actual heights.  

[Cold Winter Night]

EC Op at 168h also drops the trough South across the North Sea, just like GFS 12z.

The Low off the coast of Newfoundland is much shallower than GFS and its own 0z.
Interesting to see what that means for WAA later on.

[Mike Poole]

Given all the recent model shenanigans, ECM and GFS similar in some ways at T192: 

Edited November 22, 2022 by Mike Poole

[minus10]

9 minutes ago, Mike Poole said:

I can see something of a clown’s face in this chart, anomaly at day 16 on the 12z GEFS:

This is looking very good for a mean chart at T384:

Clear signal for Greenland whether you look at the anomaly or the actual heights.  

Lets hope the weather isnt 'clowning' around this time. Good looking anomaly charts from gem12z also day 8 and 10.

 

[MattH]

No fancy graphics and no significant changes in this update, and @s4lancia sums up the situation well a few posts back...

While, as will always be the case, an interest in each model run it is about keeping focus on the trends and overall developments as the days progress. The overall evolution remains unchanged and as highlighted a few days ago, the AAM profile is/has changing and clearly there are reasons for that but, finally, after numerous weeks of the Atlantic trough that will degrade and amplification to the pattern will arrive. Clearly there has been amplification in recent weeks, but that's a different period of weather to what is coming up.

The key things to remember right now are;

1) We are within the RI (Rapid Intensification) period for the strat vortex and this can often quickly connect to the trop vortex, there's no clear signs for that

2) Model data both seasonal and sub-seasonal and consistantly indicated early winter-time blocking patterns, that is now falling into 'short-term' NWP time frames

3) The "standard" UK pattern at this time of year is for a +ve NAO pattern and an Atlantic dominated regime with wind storms, that clearly isn't the outlook

4) Models and evolutions are often more tricky to gauge when amplification occurs, especially at this time of year, so caution over individual model runs

We could, in theory, look beyond the next 2 weeks or so and there remains some clear evidence for the MJO to return through mid-to-late December. There has always been evidence too for the MJO to often be a frequent visitor to phases 5-6-7 this winter, with the main VP200 anoms firmly over the W Pacific/Maritimes and, at times, getting into the central PAcific too, especially as the La Nina weakens. A quick example of that is below from the EC46 Control overnight and the CFS. This kind of MJO evolution through mid-December would, without question, spike interest in bringing further potential amplification of the pattern and also perhaps have some stratospheric implications as well before the end of the year.

 

All that aside and we are rapidly saying goodbye to autumn and saying hello to winter in a regime that wouldn't really be expected across NW Europe. It remains pleasing to see that many long range forecasts (mine included!) have constantly signaled early winter-time blocking and is especially of significance this year to have both teleconnections and seasonal models generally signing from the same hymn sheet. Often there is a disconnect and that provides further uncertainties.

As usual there are many wild cards; global warming influences that are, without question, unknown, the impact of the massive volcano earlier in the year and the huge amount of gases and moisture it sent up into the stratosphere, so we never know the full story, but coming back to the here and now, follow the trends, keep tabs on the broader amplifications and see where we go. Yes, we may not get a 'screaming' NE'ly of epic proporations, we may end up with high pressure that brings dry, settled cold, seasonal and crisp early winter weather and, for me, that'll do for now.

Cheers, Matt.

[Mark wheeler]

Slowly slowly , patience.

[That ECM]

What a pleasant change this would make.

[Eagle Eye]

Definitely not a bad start to the crossover between Autumn and Winter. MJO phase 6-7, a faily good looking AAM, weak zonal wind. We've seen worse positions,in fact you could argue we haven't seen a better starting position for quite a few Winters as I don't think 2020/21 started like this. If we keep the up for a month or two and don't get decent cold, we'll have to have been really unlucky.

We've already got 1 possible setup and we aren't even in December yet. With the MJO phase 6/7 lag, WAA is pushed up towards Greenland and possibly flips us to a -NAO style pattern over us and some early season colder air.

It's very weird considering the time of year and the oceanic La Nina phase. Like I said, there are worse positions to be in. @MattH a few posts above tells the story a lot better than me, as I'm just an interested 15 year old and I'd advise listening to him this Winter.

Edited November 22, 2022 by Eagle Eye

[Cheshire Freeze]

The trop PV is done by D10 on the ECM. Amplification waiting out again in the Atlantic and there’s no easy way back for the PV by that point.

[cold snap]

5 minutes ago, CreweCold said:

The trop PV is done by D10 on the ECM. Amplification waiting out again in the Atlantic and there’s no easy way back for the PV by that point.

Yes absolutely. 

But we need to remember we may never go any further than a high pressured holding pattern. 

 

[Methuselah]

Well, the GEFS 12Z temperature ensembles are not exactly world-beating. But, hey, the winter-weather rollout is only just beginning!

    

[phil nw.]

It's starting to look more like Winter and just as we enter December so timely output tonight.

Gefs 2mtr temperatures for C.England and C.Scotland.

confirming surface temperatures dropping off next week as high pressure builds.Another thing of note is the much drier outlook on the graphs as we would expect.

ECM at day 7 going the same way as the others

continuing the trend to a blocking pattern.

At that stage the pattern change is just getting underway and based on past experience it will quickly get colder under high pressure as long as the Atlantic flow is cutoff as modeled currently.

We then have to see if the high orientates in a favourable position to draw cold uppers to the UK.We don't usually switch to bitter cold in the UK straight away,oftenit takes some days before this happens whilst the setup evolves.

For me the best outcome would be the link up of the Scandinavia and Siberian high which will brings the coldest air from the north east.The ecm at day 10 is a close thing but not far enough north for perfection.Even so it still brings a cold flow from the east. 

Promising charts but even better if the blocking gets further north in time.