[Model Output Discussion - Cold spell ending - what next?]

Certainly mega mild after this week, for a bit ... Would be tempting to get the BBQ out if it wasn't for the small matter of the gales.

A week down the track and it's really much harder to see what is going on. There is evidence for extremely different possible outcomes and I don't think there is any clear way forward, despite a few fairly opinionated-sounding posts on here tonight that may claim to know for certain.

I think some interest still in the pipeline for February and the fact that we are at such an unknown juncture and potential fork in the road makes it pretty interesting regardless of the outcome.

 

[Model Output Discussion - Colder but how cold and for how long?]

1 hour ago, TillyS said:

I mean, strictly speaking the CET is above average. Has been well above average for the first third of the month: 

Met Office Hadley Centre Central England Temperature Data Download

WWW.METOFFICE.GOV.UK

 

It has felt really cold these past two days in the south, and in some cases and places has been cold, but empirically speaking not very. And temps are nudging upwards this week. So, no, not ideal ahead of the apparent snow event next week.

We need deep embedded cold. This isn’t that.

 

Unfortunately that's a misunderstanding as the CET on that tracker hasn't been updated since the 2nd January. Therefore I think it is deriving an 8.2 average from the 1st (8.0) and 2nd (8.4). The current CET is far closer to average and should be below average by some point next week. 

[Model Output Discussion - Into 2024]

16 minutes ago, AltonMatthew said:

Model Downgrades incoming as expected. Yet again too many got carried away with initial signs not understanding that yet again the models will flip or push the date out. Im holding no hope than a few days maybe of colder temps but nothing special as usual. 

appreciate this was an attempt to be provocative rather than a serious contribution, but it's almost certainly a bit more complicated than this. The solutions will wax and wane with the borderline of cold and less cold shifting around. On a global scale it's trivial but is obviously significant on the ground in the UK. This morning's solution seem to be more positive for those of a cold disposition and although it seems totally unscientific, it does seem that the overnight/morning runs are more 'cautious' about cold and the evening ones generally in favour of it! So I think signs are good for next week and you have almost certainly under-sold it.

[Model discussion - hunt for cold Christmas period 2021]

i've done a quick test on the September versus Winter theory, though I think it is only ever proposed fairly anecdotally on the twitter feed of the other main weather site.

I took 100 years of September CET data (1921-2020) and then did a correlation co-efficient to the following winter. This gave a correlation of 0.125 (i.e. negligible).

However, I appreciate this wasn't the question posed - i.e. it was whether mild Septembers lead to mild winters rather than whether September correlates per se.

So I filtered for Septembers with a positive average anomaly and then correlated them to the following winters. This gave a coefficient of 0.29.

So it is a slightly stronger coefficient but unlikely to pass a test of statistical significance. Anything below 0.3 is considered fairly irrelevant.

So I'd personally put the theory on the backburner!

[Model discussion - hunt for cold - Christmas countdown]

4 minutes ago, feb1991blizzard said:

Not enough energy diving and not far enough south, need a small low to dive rather than it just staying in Atlantic and ejecting a shortwave, the rest of this run will not deliver.

Netweather bingo card now completed for the evening!

[Model output discussion - closing in on Winter]

8 minutes ago, TSNWK said:

Thanks... 

Last night's 240 below..

We need the same at least. Otherwise the odds are really stacked against coldies for anything meaningful for December

you seem quite keen to write off the whole of December which seems a bit strange when it's a week before it even begins.

What will be will be for the winter. But looking forward to a nice little taster this weekend - hopefully ECM will continue the momentum behind this.

[Model output discussion - closing in on Winter]

5 minutes ago, sheikhy said:

Yup and lack of posts says it all!slowly becoming a non starter!over to the ecm to close this snooze fest!!!

or folks may be waiting for the run to come out, so as to present a balanced view rather than a slew of posts contradicting each other...

the bigger picture continues to look pretty interesting for next week. GFS fine in the grand scheme of things. 

[Model thread discussion - cold spell looming]

39 minutes ago, JimBob said:

The signs for milder weather have been appearing in the models for a few days now. 

 I don't think there have been any discernible trends in the last few days. Sure, certainly the possibility of the mild returning but loads of mixed and conflicting signals.

Would certainly agree that there does now seem to be a gathering trend towards a breakdown, but would prefer to consider it in the light of the 12s which are generally less progressive.

[Model thread discussion - cold spell looming]

quite a lot of low-flying toys in here this afternoon.

Someone said that the cold spell is over by Sunday - but when I checked GFS it is showing 850s of -7, gale force winds and a 2m temp of barely freezing.

so a lot of water (and ice!) to go under the bridge yet. Admittedly a further mega-easterly has perhaps reduced in chances after today's models but I think the cold should be here to stay for at least another week, and then plenty of further options on the table.

Hopefully anyone who does have snow can enjoy it without spoiling the mood?

[Model thread discussion - cold spell looming]

2 minutes ago, JoeShmoe said:

The GFS was woeful modelling the current cold spell so don’t see any reason to start backing it now it shows something good. I’ll wait to UKMO and ECM start going there ...

was it though? I think it picked it out even before last weekend. Yes it was then subsequently showing a micro-feature of low pressure just to our East, which for a time cast doubt on whether the Easterly would get going, but on a macro scale I think it is harsh to say it was "woeful"?

[Model thread discussion - cold spell looming]

29 minutes ago, DIS1970 said:

3 days ahead is difficult enough, yes, a very, very slight possibility of that occurring, yes, but this is the UK and there will another 60 runs between then and now.

Tim's point/question was a very pertinent one. No problem at all if you are only interested in 3+ days - same as the majority of the UK population! But for +72, most apps will give a good guide (except for specifics of snowfall in these sorts of setups etc). This thread has been at its most helpful when members have explained what is shown at longer timeframes and assessed the different probabilities of it. Longer term cold evolutions seem to be entirely within probability at the moment. It's much more difficult for a member to explain why/how etc than for someone to simply say it won't/can't happen.

[Model thread discussion - cold spell looming]

so it looks like pretty much cross model agreement, albeit with slightly different routes, towards an extension of the cold. These things can easily switch suddenly but quite a turnaround from yesterday. Seems a strong probability rather than a vague likelihood now. Someone should let the BBC week ahead forecast know!

[Meto Uk Further Outlook]

BBC week ahead forecast seems to be favouring a return to mild air by next weekend. Referring to 7 in London.

Doesn't look very likely when looking at the latest model data.

Louise was doing her best to wish away the cold - lost track of how many times she referred to "disappointing" temperatures this week!

[Model output discussion - deep cold inbound?]

2 minutes ago, Tim Bland said:

GEFS Ensembles still giving a firm ‘no chance’ to there not being at least a warm interlude after next week...

the mean is more than clearly going up. But wouldn't agree with "no chance" as it looks as though in 10 days time there is a 850s scatter of roughly - 12 to +12. To me it looks as though absolutely anything could happen!

[Meto Uk Further Outlook]

yes good update from the Met Office. I don't quite get this bit:

 

Quote

 

Outlook for Saturday to Monday:

Remaining unsettled with areas of rain, sleet and snow. Mild in the south initially, this being replaced by colder weather with snow showers in the east by Monday.

 

 

The models are clearly showing significant snow possibilities for Sunday, if not Saturday - and indeed the Met Office video forecast is showing widespread snow graphics on the Sunday - so much more than a vague possibility. So I'm not sure why Sunday barely gets a mention in the text forecast?

[Winter 2020/21 chat, ramps, moans and banter]

5 minutes ago, steveinsussex said:

Fergie believes the breakdown will be wed-thurs next week 

this is misinformation! He has said that there will be a "poss shift" on Weds-Thurs next week, but also acknowledged that models are often too keen to advertise this and the breakdown can be slower, snowier or just pushed back.

[Winter 2020/21 chat, ramps, moans and banter]

2 minutes ago, steveinsussex said:

So a 3-4 day cold snap

 

these sorts of posts are not terribly informative. Not sure whether it is trying to be provocative or merely a cry for help...

There are a range of options on the table next week with the "worse case" scenario a breakdown for Thursday. But of course this could lead to some spectacular snowfall for some.

I for one will be very happy to experience some real cold weather and possibly some significant snowfall, even if just for 4-5 days. A protracted cold spell may not be in the country's interest this year, but I am looking forward to experiencing some really interesting weather without obsessing over the breakdown.

[Model output discussion - deep cold inbound?]

The direction of travel looks pretty good to me.

GFS coming back in the right direction, so even a meeting point wouldn't be a disaster, albeit less memorable for the south.

But I remember seeing all the memorable spells evolve in the last 10 years: Dec 2010, Jan 2013, March 2013, Feb 2018 etc, and every time there has been much gnashing of teeth from doom-mongers who want to write it off before it's begun ("the -25 uppers won't reach Cornwall", "there won't be glaciers coming through East Anglia", "there won't be perma-frost in my bed" etc)

so we need to take these with a pinch of salt and broadly speaking things look good - with some absolute belting possibilities such as the GEM and, fundamentally, UKMO.

Fingers firmly crossed for the ECM

[Model output discussion - is the beast awakening?]

6 minutes ago, Anthony Burden said:

Morning all seems that the GFS is doing an ECM all change,Matt Hugo decided bin GFS 

very strong decision all credit to him for risking his reputation.Hope he is 100% correct 

my take he has my backing,might as well go down the drain together.

comes to something when somebody is "risking their reputation" for expressing a professional opinion in one specific area...

I can't remember such short term GFS divergence from such a solid-looking ECM mean. Fingers crossed for c.10am that the GFS retreats though I doubt it will be a sudden flip. Not sure if a halfway house even exists for this 'problem'....

[Model output discussion - is the beast awakening?]

4 minutes ago, sheikhy said:

Big big problems we got guys on this 06z!!!!all of a sudden we gona want ecm or ukmo to be correct!!!!

the GFS seems fine so far, albeit a slightly slower burner (or freezer - whichever way you look at it).

I'll reserve full judgement until a bit later in the sequence - I guess this is the problem with providing excessively dramatic commentary in real time as the run is emerging.

[Winter 2020/21 chat, ramps, moans and banter]

2 minutes ago, Johnp said:

Embarrassing from the beeb - and the presenter.  Shows they take no interest in the synoptics. 

Not sure you can suggest that the Beeb/Meteo "take no interest in the synoptics".

To be honest, the picture takes things completely out of context. Sarah did explain that the UK would be in the battleground between milder and colder air and colder air could push in from the East.

So that forecast is the worse-case scenario for us cold-lovers, whilst the 18Z tonight seems to present one of the best possible outcomes.

[Model output discussion 24/01/21]

7 minutes ago, NeilN said:

When was the last time a -16 / -20 upper hit the UK? 1986? 1979? 

i think -20 has clipped a few times historically - but i think even the famous Jan 1987 spell didn't quite achieve that - something like 19.

I think we got lower than -15 in the BFTE Feb 2018 spell, maybe a 16 or 17 on the EAst Anglian or Kent coast

[Model output discussion 24/01/21]

2 minutes ago, Frosty Winter said:

I hope that p6 is on the money on this afternoon.It’s not hard to find it on the ensemble graph unfortunately.

 

is that quite unusual to see possible solutions ranging from +5 to nearly - 5 on the 850s at around 72 hours hence?

[Model output discussion - into the last third of January]

41 minutes ago, mountain shadow said:

See post further up.

There is no MJO movement.  They're false signals caused by Kelvin waves.

With no MJO and a failed SSW, there is little cheer and we can maybe hope for an early Strat final warming to bring some late Winter promise into early March.

are the next 5-6 weeks all set in stone then, and is there no possibility of some interesting weather in February?

[Model Output Discussion - Snow for some, but what else is in store?]

10 minutes ago, Catacol said:

Will challenge this gently. The forecasts of a potentially severe end of January were/are built on impacts of the SSW. These were not premature. This has happened, and the stratosphere is significantly disrupted. However - as is said time and again with forecasting based on SSW impacts: specifics are a nightmare to pin down. All other drivers effectively go out the window when a downwelling response to a strong SSW are occurring and so all we can do is sit and wait to see where the vortex ends up. What I think you are referring to is disappointment that we ended up with a displacement, and disappointment too that (perhaps) the shape, position and temporary splits that have occurred have enabled some atlantic energy to reappear. 

It is far from certain what the last week of January will look like yet, but if "real" winter is delayed until February - or God forbid doesnt arrive at all - then I still dont think the forecast was premature. Those of us interested in the longer term forecasting game rather than the next 72h know that all we can do is try and get the broad brush mapped out. The broad brush has been mapped out here as many began to tout as far back as December....and in fact there were some suggesting that tropospheric precursors to strat disruption were very much in play before that despite the seasonal models sticking to a +NAO setup. I think amateur forecasting hacks looking at seasonal shape have not come off too badly this season so far. All we are really missing is the detail now - the fine elements coming together to give us a surge of deep cold. What did @chionomaniac say? Synoptic heaven, weather hell? Something like that. Spot on. We are still trying to find a bit of luck to get the vortex to align in the right way to allow cold to advect west properly. 

Time will tell. My calendar says 15 January - somewhere around the half way mark of winter (though I'd actually place half way at Jan 22 but that's just me....) What a lot has happened! Wow - a season of real interest and with so much still to go! And there are signs up top in the strat again that February could feature more stressed vortex behaviour and very uncertain weather. Some folk have been lucky already. I hope all of us can get into the action by winter's end - and ideally more than just 2-5cm of action. Gotta be 10cms+ to hit the proper snow index I reckon.........

this is such a fantastic explanation of the bigger picture and a nice counterweight to a few 'broken records' in the forums. Thank you for explaining everything so clearly to amateurs like myself.