model discussion Model output discussion - the final third of Autumn

[Anthony Burden]

Evening all,charts lost the wintery theme tonight but in reality 5 6 days is the absolute max for any reliability 

at present.Pressure looks to be high is perhaps the only thing to have some reliability on,northern blocking 

at present showing to the northeast and then drifting east.My take cooler/ colder temperatures next week

with some cold nights in places where skies stay clear,certainly nothing to be depressed about for cold lovers.

Lots going on with the charts that are likely to change very quickly due to lots of uncertainty.

 

[LRD]

One very small crumb is that the GFS 12z op run was at the top of the ensemble suite - from Day 10 onwards

But a lot of the very cold runs have disappeared too

Edited November 9, 2021 by LRD

[Frosty.]

Looking at the Gfs 12z operational, the rest of this week is looking pretty mild…however, the daily mirror says we will be blasted by snow and cold this week with temperatures plunging to as low as 0c!

 

 

[carinthian]

Hey folks this chart below is from November 1981. Looks familiar ? Yes, November that year was high pressure dominated , especially for the south of the UK with sporadic incursions' of Arctic air mass into the far north but was predominantly dry and mild.  I remember well at my time working at Gatwick Airport that period and the Met Office super computer at Bracknell provided charts out to 5 /7 day range . Wow, you may think, but at the time that was something to behold ! Never in a million years would you expect what was to come  in early December 1981 and last until mid- January 1982. A cold wave developed over the UK  and produced one of the coldest  and snowiest Decembers on record with some record low temps.  In the the words of the great Sam Cooke song , " a change is a coming " but sometimes you can never tell when !

C

[E17boy]

Evening peeps

hope everyone is well

I think I have got a headache now after catching up with all the posts today and to end the day on a dismal note. Alas we have been through this do many times. This is seriously like the Bermuda Triangle in here today Fantasy charts that have suddenly mysteriously disappeared.

No matter how downbeat we get at the end of the day there is nothing we can do unfortunately, we can’t unplug the models or reboot them.  
 

The strangest laughable thing is that those of you who read my post on Saturday I did refer to the Met office changing their extended outlook and taking out the Northerly and Northwesterly wind element out of their forecast . Now they have changed their extended outlook again and bright back northerly winds and wintry weather and the models don’t want to know.

Wednesday 24 Nov -Wednesday 8 Dec

Towards the end of November and into early December there are signs of an increased likelihood of north to northwesterly winds. This means that overall temperatures are likely to be near or slightly below average, although some milder spells cannot be ruled out. In such patterns the most unsettled, wetter and windier conditions are often found across northern areas, while the most settled, driest and brightest conditions are predominantly across the south. There is a slightly higher than normal chance of some wintry conditions, especially across the north.

Updated: 15:00 (UTC) on Tue 9 Nov 2021

The only piece of comfort is that it’s only 10 days into November, we have got a long way to go for models to change again. Let’s see where we are tomorrow.

Have a  great evening all 

regards

[bluearmy]

And as quickly as it all appeared …….puff, and it was gone …..

Until it returns ! 

The ens suites are all pushing the troughing further east ….

[Kirkcaldy Weather]

Whilst it’s just two ensembles currently, this is the first part of a pattern I mentioned in my post yesterday with low pressure through UK and being far enough south that an easterly is brought in  we can see if it’s picked up more in upcoming runs

[Mike Poole]

Just a comment on the 12z runs in context of the wider picture.  

My view of the current situation is that we are in (and have been for months) a meridional pattern in the NH, one which would allow height rises into Greenland to the extent we could see a true block here.  That hasn’t changed.  The potential is there, it was yesterday and it is still today, and will be tomorrow.  We can see the potential is there because op runs and ensembles are showing it.  

This place can’t half be a rollercoaster at times, and (crap analogy coming up) that reminds me of  a JPM fruit machine of the 90s:

These machines used to show potential - outside of winning spins, the high low reel would spin 1 or 12 very regularly if there was potential in the machine, and not if there wasn’t.  Unlucky if you played it and didn’t know that! But you still needed to be lucky or skilful to take that value out.  We’re in a similar situation right now, the NH is spinning 1 or 12 regularly.  It is primed to pay out!

But to actually deliver a proper Greenland block, needs more than potential.  It needs a lot of luck, in terms of a well placed low pressure to deliver highly directed WAA into Greenland.  That is happening on some runs and not on others, and on those where it is happening, it is happening at different times.  

This is the one area that GFS models well, lows coming off the eastern USA, which is the key trigger here, to initiate  that WAA, so if it is ever going to happen, no surprise the GFS is showing it more than the others.  

But this period of potential won’t last forever, we have a period of a few weeks I think, and if a blocking scenario doesn’t arise, if we don’t drop lucky, the strat and trop vortex will couple and it is game over, for the front loaded winter idea, anyway.  Clock’s ticking, but watch the GFS - if it carries on throwing out Greenland highs, one will probably happen!

Edited November 9, 2021 by Mike Poole

[Cheshire Freeze]

About as grim as it gets for wintry weather- conveyor belt of mid lat HP

 

On the plus side, I'm not perturbed by this synoptic showing up now...very rarely will we see this type of pattern last Nov through to March. Just the same as wintry conditions in November have often preceded a mild winter (think '88/'89).

[MATTWOLVES 3]

12 minutes ago, Uncertainy said:

@MATTWOLVESI would normally totally agree with you and you’re absolute correct with what you say…

but…

Just look at this absolute garbage 

GFS 324

GEM 240

ECM 240!!!

Three horrific long fetch atmospheric river events (which very much do verify) when the GFS said for days we’d get a screaming northerly.

We could end up more settled than the above but the last few days the early winter cold boat has started to sink. 

If the vortex does connect with the trop then I’m afraid the above is far more likely than a Greenland high and it’ll be back to checking river levels rather than lampposts. 

It’s amazing how often this happens, the over amplification bias across the modelling in the medium range happens time and time again. But to go from a Greenland high to a long fetched southwesterly with purple over Greenland really stings.

We have so much in our favour this winter, and many I’m still confident we’ll get one at some point, but a cold spell won’t  matter much to me if Cumbria gets sunk before that happens. The above charts indicate that, against all predictions, that is once again the spectre again, perhaps even next week

I realise this is a rant, and feel free to ignore it, but just about every prediction (EC46/JMA subseasonal/Low res GFS/ vast majority of pro/amateur forecasters(including myself) / most background forcing) have indicated this early winter period would be absent of such horrors. But alas, the strengthening SPV appears to be changing all that. 
 

Hopefully the models back off tomorrow. If I could shout at the models, tell them how cross I am with them then I would, but that’s a bit like shouting at a cup of Tea. And there’s just no point in that.
 

Yes mate that looks poor...but look at the timeframes! All we are seeing is output that goes from fantastic to diabolical in 24hrs! If we are seeing output like that in 4 or 5 weeks time,I may get concerned...but for the here and now,I'm not in the slightest bit concerned..

Life has taught me one major thing....the more you stress and concern yourself over any kind of task or anything out of your control,the harder the said task becomes!

But yeh mate it's a long haul,and we've barely stopped off for refreshments just yet...and your rant is fine by me...your actually a very good insightful poster...like I said know disrespect to any posters on here....hopefully the new iceage will be back come the 18z..

[Chesil View]

20 minutes ago, carinthian said:

Hey folks this chart below is from November 1981. Looks familiar ? Yes, November that year was high pressure dominated , especially for the south of the UK with sporadic incursions' of Arctic air mass into the far north but was predominantly dry and mild.  I remember well at my time working at Gatwick Airport that period and the Met Office super computer at Bracknell provided charts out to 5 /7 day range . Wow, you may think, but at the time that was something to behold ! Never in a million years would you expect what was to come  in early December 1981 and last until mid- January 1982. A cold wave developed over the UK  and produced one of the coldest  and snowiest Decembers on record with some record low temps.  In the the words of the great Sam Cooke song , " a change is a coming " but sometimes you can never tell when !

C

Excellent analysis Carinthian.

That Nov 9th 1981Chart in no way suggests what was to come for the following December. 

The same as today's Nov 9th chart and the op running forward from in no way suggests  what the coming December might deliver.

[LRD]

Not much to get excited about in the ECM ens graph:

Op was an outlier right at the end but no sign of anything much

I speculated, earlier today, whether the GFS picked up on the right signal but just modelled it far too early. A couple of others (northwest snow included) also commented that the cold might not be cancelled, just delayed. I wonder if that's what will transpire. We've seen it before on the models pretty regularly. A pattern changed predicted, dropped, then brought back again at a later timeframe and ending up verifying. The Met Office might be wrong with their latest 30-dayer but they're obviously seeing something. We shall see

Edited November 9, 2021 by LRD

[bobbydog]

Just a snapshot from November 1962...

 

You just never know.... 

[carinthian]

18 minutes ago, Broadmayne blizzard said:

Excellent analysis Carinthian.

That Nov 9th 1981Chart in no way suggests what was to come for the following December. 

The same as today's Nov 9th chart and the op running forward from in no way suggests  what the coming December might deliver.

Aye, back in those days we never had model charts out to 15 days and beyond. The Met Office had a Long Range Forecast team that produced a monthly forecast and from what I can remember was probably better produced/ documented than whats on offer today. Even today with advanced super powerful computers at hand, many charts post 10 days hardly verify, however, back in the Bracknell days when Dr Mason was in charge of the Met Office , the advent of the super computer produced some amazing results in the shorter time span out to 3 and 5 days. I am sure the accuracy success has not greatly advanced as quickly in the medium to long term forecasts. 

c

Edited November 9, 2021 by carinthian

[Frosty.]

The GEFS 12z mean is looking pretty benign with high pressure generally the dominant feature…unless I’m reading it wrong..? 

[Cambrian]

I know that the last 24 hours has shown us that looking ahead more than a few days can have its ups and downs, but I just wanted to show a couple of today’s 12z operational charts for day 11 (yes, we never learn) that show how finely balanced it all can be. 

On the left, the highly uncelebrated GFS 12z op for 264h - shallow Aleutian low (1005mb), fairly flat into Western Canada, broad trough down into the Great Lakes, out through Newfoundland, low to the south of Greenland, UK and Ireland basking under what might in the event be a rather pleasant high. Yes, chin up, GFS, that’s not so bad really.

 

On the right, in a sign of the times this evening (any port in a storm) the JMA 12z op for 264h - slightly deeper Aleutian low (995mb), sharper ridge up into Western Canada, less broad trough doesn’t make it to the lakes or out to Newfoundland, high building to the south of Greenland, UK and Ireland looking set for something unsettled and chilly from the northwest and another taste of that NW-SE aligned jet stream across the Atlantic that we’ve been tracking on and off for the last few weeks.

The early winter cold spell is dead.  Long live the early winter cold spell ! 

[Staffmoorlands]

46 minutes ago, carinthian said:

Aye, back in those days we never had model charts out to 15 days and beyond. The Met Office had a Long Range Forecast team that produced a monthly forecast and from what I can remember was probably better produced/ documented than whats on offer today. Even today with advanced super powerful computers at hand, many charts post 10 days hardly verify, however, back in the Bracknell days when Dr Mason was in charge of the Met Office , the advent of the super computer produced some amazing results in the shorter time span out to 3 and 5 days. I am sure the accuracy success has not greatly advanced as quickly in the medium to long term forecasts. 

c

I find the 10 day Met Office forecasts on Youtube to be fairly accurate these days. Usually, uploaded on a Wednesday and they show the probabilities of high/low pressure at day 10 and also temperature trends. Its the best forecast available in the UK  

[damianslaw]

It's been a rollercoaster ride with the models last 24 hours, GFS going up and down at turbo speed it seems, with highs and lows swapping places - putting credence in the statement often used, stick to the reliable 120 hrs usually, sometimes 144hrs, often though 96 hrs, and you will save yourself alot of frustration. Try it and you might feel a whole lot better..

I would not at all be surprised to see future GFS runs bring back a screaming northerly again at the 300hr mark or whatever.

Its trends and watching short term developments that can give you clues for longer term prospects. Right now we have an interesting evolution, a low pressure breaking off from the main trough riding over the UK with heights building in behind by the weekend and anchored to scandi - this is not a normal pattern, and indicative of the rather abnormal base state we are in right now, with a very weak atlantic - but at the same time rather slow moving pattern.

 

[Weather vane]

As others have said, a few bad runs today mean very little when we're looking at charts past 5-6 days. Why make conclusions on 8-9 day charts, over the promising 9-11 days charts the past 2 days? Both sets are not even in the semi reliable so still all to play for. Seems obvious, but small alterations in the many things I don't understand can flip the current scenario very easily.

[Mike Poole]

ECM 12z clusters, first T192-T240:

Nothing really into Greenland, but cluster 4 has a massive Scandi block.  I’m actually sceptical of all of that, but before commenting, here on to T264+

Now we get the massive Greenland block (cluster 4) and something not dissimilar (cluster 5).  No euro heights apart from cluster 1.  

So it is still there…breathe…and as I have said before, ridging into Greenland is a difficult scenario for the models, and the GFS is best at it…that doesn’t mean the lower resolution GEFS, by the way.  I mean the GFS op run, if it doesn’t show a Greenland high within the next 8 runs, it is probably a bust, if it does, very much game on…we will see…

[Frigid]

November 1978 was a very mild one, look at these synoptics! Who knew at the time one of the coldest winters of the 20th century was about to commence. This is why I'm not all too worried of todays sudden changes.  There's enough time for things to change

   

[booferking]

Icon update stronger high 120hr could see more energy go underneath if this continues one to watch.

[damianslaw]

11 minutes ago, Frigid said:

November 1978 was a very mild one, look at these synoptics! Who knew at the time one of the coldest winters of the 20th century was about to commence. This is why I'm not all too worried of todays sudden changes.  There's enough time for things to change

   

November 2009 another great example, one of the mildest and wettest on records, long fetch south westerlies, look what happened in December. Not saying we will see a 2009/2010, just worth noting how what may seem entrenched spells can suddenly flip.

[ICE COLD]

JMA looks pretty good at the end

[tight isobar]

getting into real synoptic conflict/confuse territory now, the La Niña consequence now filtering through the upper middle latitudes, and conflicting model signals will begin exactly what is being perceived!.   The only way until late November - to gage imo will be through overall consensus , through 24 hr suites.. it’s just pick 1 and go with it.. then 24 hrs later compare. Then run through the same sequence on all other available avenues @other mods and there supporting.. mid month should open that door wide.. and the 11th is global review/- probable impact day/discussion.. for the winter ahead.. hold tight .. this could be our year..@the axe falling on the correct tree,?!??... 

Edited November 9, 2021 by tight isobar