Model discussion - hunt for cold Christmas period 2021

[TheJCInsights]

In a more close up hunt for cold, seemingly depending on which model you trust determines what happens in South England tomorrow afternoon with regard to that front coming south.
GFS seems to think a couple of cm snow fluries
ECMWF seems dry
Icon and Aperge think rain.

Nowhere seems to say anything other than "Light rain" in their forecasts though so assuming GFS is messing with me.

[MJB]

27 minutes ago, Jeremy Shockey said:

you 2 are just wild boys !

More like Notorious 

[knocker]

14 minutes ago, Climate Man said:

To be fair my main point was that the Pros are pretty much at the mercy of the vagaries of the weather as we are. Their performance can be appalling at times and you should not always bow to them over experienced members here. The big difference is that the Pros interpretation has to be cautious whereas we can put our necks on the block. 

You are such a wag CM. The big difference is that they are trained meteorologists with years of experience and are privy to much more detailed charts. And of course the option of taking a wild punt, the raison d'etre of this thread, is not on the table.

[LRD]

26 minutes ago, Climate Man said:

To be fair my main point was that the Pros are pretty much at the mercy of the vagaries of the weather as we are. Their performance can be appalling at times and you should not always bow to them over experienced members here. The big difference is that the Pros interpretation has to be cautious whereas we can put our necks on the block. 

Look, I don't want to derail the thread but you picked up on something I said in my original post (the Xmas-cold model fail) that wasn't even anywhere near central to what I was trying to say and said 'this argument doesn't hold water' - an argument about modelling and pro-forecast failures/successes that I wasn't even making! From what you've said here, you still continue to misinterpret/misrepresent what I was getting at. 

I'm not going to comment on your point about believing people on here more than professional meteorologists because a) that's a bizarre thing to say and b), as I have said more than once now, it's not even a point I was anywhere near making in my original post. I am baffled how, after reading my post, you think that's what my point was - which, to repeat yet again, was I'll call cold when I see model evidence for it (like last month, even though it failed) and I'll go against cold if model evidence is pointing that way (which it is at the moment despite some overly-optimistic assessments on here supporting a cold outlook). 

Edited January 3, 2022 by LRD

[Cambrian]

The 0z ECM operational run starts mild, turns cold, then very mild and ends cold and frosty. 

This afternoon at 15h, with the cold air appearing over Scotland, Ulster and northern Connacht, but further south holding on to the mild air for a few more hours.

By 54h, Wednesday morning, the whole of the UK and Ireland is in the cold air, with potential for some lying snow as far south as the southwest moors.

 

Looking at the charts for 6am each day, still widely chilly on Friday morning, fleetingly milder going into Saturday, before a colder start again on Sunday. 

  

The oscillation continues with an exceptionally mild night in southern and central areas as we begin day 9, in a gentle southwesterly as high pressure pushes up from the south…..

 

…before turning quite sharply cold and frosty under the high pressure by the end of day 10.

 

So some seasonal weather to come over the reliable and semi-reliable timeframes, along with some milder interludes too, about average overall as we continue undeterred in our hunt for cold!

If the high does move north as speedily as this, and incidentally this movement northeast was supported by the ensemble means for 192h and 240h……

 

that’s a quite firm shoving of the PV north, we’ll lose our westerlies and northwesterly shots for a brief southwesterly followed quickly by frosty anticyclonic weather for a few days. And then if the high continues to migrate further north, well, who knows?!

[Tamara]

On 03/01/2022 at 10:43, mushymanrob said:

Sorry but i strongly disagree with that!

Someone with little knowledge can post up a "boom" chart (dreadful statement) and says "look at this" - gets 40 "likes" and back slapping, yet a detailed, explained, technical post that doesnt promote cold gets next to nothing.

Thats the problem i have with the "likes" system, and it feeds those on an ego trip. Personally, id bin it.

Yes - the perennial problem is the lack of promotion of the most probabilistic outcomes.      If this was set up as an objective weather pattern discussion thread that sought to provide the sort of detailed, technical post you describe (to find the most likely outcome and not ANY preference bias whatever that might be) then the site would not get the traffic it requires. Next to impossible to achieve objectivity with the title of the thread having the word 'hunt' inserted in it.  A word that invokes tribalism and x vs y divisiveness in itself (and somewhat Neanderthal in nature) so further augmenting the ridiculous factionalism. 

By way of balancing that - there is a separate thread devoted to detailed technical impartiality but no surprise that so few people go to the trouble of posting in it, despite its very creditable aim - as it is rendered futile and a waste of time and energy when the majority on this site are more interested in preference indulgence than observing  how t0 arrives at the correct solution and not always the preference solution. 

By observing the correct solution, and analysing how that came about it provides a basis to learn more. There was an excellent technical discussion on this thread several years back, which was inhabited by a plethora of very informed posters - both amateur and professional. At the time it succeeded in getting quite a wide audience from within the standard model thread with people eager to learn from it. I for one learned so much from this and lead to the example I try to follow these days, (allowing for so many complexities to attempt to fathom out).  However the drive for quantity over quality in the way I have tried to describe has resulted in the loss of quite a few of these regular contributors. That, and the parallel drive towards twitter and social media outlets (which bring problems of their own due to brevity of messaging/misrepresentation and clickbait popularity issues)

So no surprise that my own view of the outlook within this thread, will probably have a 'bland' unpopular perception to it.    Baroclinically induced Pacific forcing is leading to strong westerly inertia off equator - and has driven atmospheric angular momentum much above average (especially related to the base state).

Equatorward fluxing ( rather than poleward) is creating anomalous Hadley cell strength ridging, rather than amplifying high(er) latitude ridging -  dovetailed with an organised polar vortex associated with upper cooling. Wave trains continue to point to such anomalous ridging into mid latitudes while a shift of vorticity within the Canadian sector drives an increased thermal gradient exiting the US.

The abundance of orange shaded AAM anomalies within the tropics (westerly inertia) identified clearly within the relevant GSDM plot as posted:

 

This is where clarity in respect of poleward AAM anomalies is required to avoid apparent contradiction in terms. Momentum transport c/o rising AAM through the tropics into the extra tropics is very much governed  by the vector of directional flux. Equatorward flux will restrict the amplification of sub tropical ridges that might otherwise transport poleward to become extensions of arctic height rises, (if the polar field is unstable enough to allow these). The current situation continues to see extensive wave breaking and significant Pacific jet extension c/o large East Asian Mountain torque - but directional flux and a well organised polar profile (vortices) restricts amplification of the associated rossby wave eddies to anomalous mid latitude Branstator ridges.

 

I suggested that the outlook into the early part of 2022 would be interesting and fascinating either way, irrespective of preference, and that is proving very much the case (for me at least). The precise directional fluxing of these amplified westerly wind eddies in accordance with the ongoing tropospheric/stratospheric interaction proving the fine line and highly disparate outcomes that can result - depending on such relationship between them. Open mindedness comes with lack of the burden of bias intrusion and distraction, and has its rewards

Muitos cumprimentos e respeitos

 

[Climate Man]

Anyway, back to the models. There does still seem to be greater levels of uncertainty, particularly at a micro scale. The form horse seems to be a wintry mix for the rest of this week with most weather types possible at times. Next week the signal is for high pressure to build close to the UK and,as in December, exact location will be vital - frost, fog, cold, snow.....several days needed for any clarity. 

[Kasim Awan]

1 hour ago, TheJCInsights said:

In a more close up hunt for cold, seemingly depending on which model you trust determines what happens in South England tomorrow afternoon with regard to that front coming south.
GFS seems to think a couple of cm snow fluries
ECMWF seems dry
Icon and Aperge think rain.

Nowhere seems to say anything other than "Light rain" in their forecasts though so assuming GFS is messing with me.

Wrf is a nice middleground - light mixed precip, mostly light rain pushing south producing a local dusting over 100m asl in midlands & a few mins of wet snow locally further south in the heavier bursts.

Edited January 3, 2022 by Kasim Awan

[Cold Winter Night]

Apparently the subtitle of the model thread has a large impact on some posters, tbh I hardly ever take note of it.
I've always thought of that title "Hunt for cold" as a light hearted illustration of this thread in winter, not as a solemn charge or something.
The model output is the model output, the weather is the weather, whatever this thread is called.

So, about that model output, just before the 12 z's start rolling out, we are currently in a slow descent from very mild to average by the end of the week. And average in the first week of January means that some may see wintry precipitation, white surprises here and there are possible.

The EPS up to 192h is not as enthusiastic as it was 2-3 days ago about bringing back Atlantic amplification and Scandi troughing (BLO-), as the regimes chart shows:

The ensemble follows the edge of the central circle towards more BLO+, in this case associated with an increase of heights over the UK, which the clusters illustrate well:

Expect conditions to be generally calmer Day 6-9, not really cold, with milder temps towards the NW and closer to average nearer the SE, all depending on the exact location and alignment of this High.

The clusters from 192h-240h do increase heights West/Northwest/North/Northeast, but heights to our SE are not low enough in most members to set us up for real winter weather. This is because that Scandi trough is not as pronounced earlier on as modelled before. Still there is a minor possibility of cold coming in through the Scandinavian gate in this lead time.

In the extended, 264h-360h, unfortunately less is made of that Ural High feature we saw before. Still, heights in higher latitudes are played with, this time to the Northwest, forcing the tPV away from its favourite place, lowering European heights too.

This leaves open all sorts of colder options. Tonight's EC46 would be interesting, because the way the clusters end this morning is different from the anomalies it had on Thursday for that period.

A move towards a NAO+ picture, with endless mild Southwesterlies is not in the output up to day 15, despite what some seem to suggest over and over again.

[Updated_Weather]

Maybe some interest or maybe some hope but those who haven’t seen some snow yet.. *MAY* get a chance as the low clears south, as harmonie suggests some may see some wintriness.

but my bet is it’ll be either rain or at best sleet.

no covering expected.

[Ali1977]

20 minutes ago, Updated_Weather said:

Maybe some interest or maybe some hope but those who haven’t seen some snow yet.. *MAY* get a chance as the low clears south, as harmonie suggests some may see some wintriness.

but my bet is it’ll be either rain or at best sleet.

no covering expected.

GFS has similar areas down for, can’t see many of any getting a coating though - be a nice surprise if we do

 

Although the totals say maybe some will be lucky

Edited January 3, 2022 by Ali1977

[Updated_Weather]

On 03/01/2022 at 15:47, Ali1977 said:

GFS has similar areas down for, can’t see many of any getting a coating though - be a nice surprise if we do

Yep it’s a long shot but surprises happen.. and I’m not just hoping because I’m in with a chance but,

nothing to get excited about imo

[Lukesluckybunch]

will be interesting to see how this 12z develops,hope we can have a similar run to the 6z.looking for heights to build in around the 180h mark

[swfc]

12 minutes ago, Lukesluckybunch said:

will be interesting to see how this 12z develops,hope we can have a similar run to the 6z.looking for heights to build in around the 180h mark

Looks pretty similar at 216 hrs ie PV and high to the wsw.

[phil nw.]

Looking just at the next few days some places will see snowfall.

As i posted in the other thread given it's quite a mobile Atlantic driven setup we do get short periods of polar air coming through.

Over the next 48 hrs Scotland in particular will see snowfall in those cold northerly winds and as the cold front comes south overnight further south may see some back edge snowfall.

A look at late Thursday and into Friday another burst of polar maritime air heads in, sourced from a deep cold pool over Canada as it rushes across behind the next low.There will be of course some modification by the time it arrives but given the time of year surprise snowfalls are quite possible especially for those further north.

The above snow chart not be taken as gospel at this stage but indicates the possible in such a cold westerly.

 

[That ECM]

Gfs is being consistent with the high. Slightly further west. Which is good as  I “ look out for cold”  looking out for something is more caring than hunting?  

[Battleground Snow]

Day 10

trop vortex just starting to drain from North East Canada,

[swfc]

1 minute ago, Battleground Snow said:

Day 10

trop vortex just starting to drain from North East Canada,

Indeed. Be great to get that high pulling nw and maintain the low heights to the south 

[Lukesluckybunch]

pretty identical out to 240h! as the 6z

[KTtom]

Just now, Lukesluckybunch said:

pretty identical out to 240h! as the 6z

The overall set up tho is screaming out for a northerly....ill tempt fate, watch the high regress north west and that vortex sink into Scandinavia

[BLAST FROM THE PAST]

7 minutes ago, Battleground Snow said:

Day 10

trop vortex just starting to drain from North East Canada,

And a real draining after that.  This is a slowburner and more of the same please 

 

BFTP

[Ali1977]

This looks great, PV moved to Russia - height rises to Greenland now very possible. 

[BLAST FROM THE PAST]

Just now, KTtom said:

The overall set up tho is screaming out for a northerly....ill tempt fate, watch the high regress north west and that vortex sink into Scandinavia

That is my idea going forward.  But we are looking way way ahead. I like what I’m seeing though 

 

BFTP

[Don]

3 hours ago, Tamara said:

I suggested that the outlook into the early part of 2022 would be interesting and fascinating either way, irrespective of preference, and that is proving very much the case (for me at least). The precise directional fluxing of these amplified westerly wind eddies in accordance with the ongoing tropospheric/stratospheric interaction proving the fine line and highly disparate outcomes that can result - depending on such relationship between them. Open mindedness comes with lack of the burden of bias intrusion and distraction, and has its rewards

Muitos cumprimentos e respeitos

 

Hi Tamara

Do you see much hope at this stage for more sustained cold for the UK later in winter i.e late Jan/Feb? (yes I'm a coldie! )

Apologies if you've already covered this and I've missed it!

[Lukesluckybunch]

a pretty non eventful run so far from the 12z,high is just lurking around over the country doesnt want to move north at all