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The hunt for cold - Model discussion (late November)


Paul
Message added by Paul

If you're hunting for cold potential in the model output, this thread is for you. But if you'd like to look more widely at the models, please head over to the general model discussion thread.

This is a model related thread, so a general, frequent theme of the model output is a given, but it will not be strictly enforced:

  • Some topic drift, humorous responses etc are fine
  • Posts likely to lead the thread off on an entirely off topic tangent are not ok. For example (but not solely limited to): Posts entirely or mainly about Met Office, BBC or media forecasts with little or no model context, and posts solely asking for a weather forecast in a specific location.
  • Posts which start with something like 'I know this is off topic but ...' are not ok.
  • Posts which break the forum guidelines are not ok (eg trolling, troll-hunting, weather guilt tripping, overly defensive/aggressive, abusive, disrespectful to others)

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Posted
  • Location: Near King's Lynn 13.68m ASL
  • Weather Preferences: Hoar Frost, Snow, Misty Autumn mornings
  • Location: Near King's Lynn 13.68m ASL
42 minutes ago, seabreeze86 said:

GFS p goes for it this morning giving a white Christmas for many. Nice to look at but needs support to take seriously 

Screenshot_20181213-075444.png

It's been consistent with the pattern of throwing up a significant ridge in the mid-Atlantic around the T240 mark (it was there at T264 yesterday). How successful it has been in ultimately advecting cold air to us has varied though. If it's still appearing at T216 tomorrow, then it will start to get interesting.

Edited by Yarmy
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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.
49 minutes ago, Frosty. said:

Potentially i see plenty of potential for some wintry weather in the run up to crimbo!:santa-emoji:

Just as long as the building blocks don't a 'Jericho', the chances are there for a rather special winter, Karl...Please God!??

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Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
6 minutes ago, SLEETY said:

Complete   garbage from Ecm this morning,the way that low pressures just  expands and smashes through the whole of Europe at t192 onwards.Model produces junk sometimes.

Still some big differences between the EC and GFS operationals in the upper patterns over N Atlantic in the 8-10 day range looking at them side by side:

test8.thumb.gif.9aa73f6a95344e7f70574e0224a055a7.gif

GFS, on the right above, holds back the 500 hPa trough further west off the eastern seaboard of N America, whilst the EC spreads the trough out further east across the N Atlantic and near the UK, which keeps the flow flat and doesn't allow for amplification in the flow nor blocking over GIN corridor like GFS, though does have a stronger ridging signal over Scandi still. 

A look at the GEFS and EPS mean similar to their respective operational runs really ...

gfs-ens_z500a_nhem_33.thumb.png.678665cf721350347d255b916f555162.pngecmwf-ens_z500a_nhem_9.thumb.png.752399a0c6c048c59ca7282425581c63.png

... so quite a contrast continues between the two models, like T May's leadership - a vote of no confidence past day 6 with the models from me.

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Posted
  • Location: Home :Peterborough Work : St Ives
  • Location: Home :Peterborough Work : St Ives
26 minutes ago, matty007 said:

Sorry, but you're wrong. 

Weather models are an amazing tool and are generally very good for short term forecasting, but that can not be said for long term. Sure, on occasion they may predict something in the long term, but that can mostly be attributed to an accurate or lucky prediction. Make enough predictions and you are bound to be correct eventually. 

All weather models are is a computer generated environment that analyses the current situation and then predicts the most likely outcome in relation to that current situation. Unfortunately the weather isn't that predictable and a slight change in wind direction, speed etc can turn a cold snap into a mild snap etc etc. Or a December 2010 into a  December 2015. 

How many times has a credible forecaster touted a significant spell only for it to turn into nothing?  How many times has a hot summer been predicted only to become a washout? If the weather models long term meant anything, there would be no need for forecasting. 

Anybody forecasting past the end of this week (myself included) is putting it in the hands of the gods. 

In summary, models are a vital tool for sub 5-6 day forecasting or there about. Past that, we are all predictors, not forecasters. 
 

Probably being pedantic but the weather models do not predict anything let alone the most likely outcome , which seems to imply that the model has a choice.

Current observations are loaded into a computer model and using proven scientific formulas and mathematics , present the results. The reason why they appear to be inaccurate over the longer term is called Chaos Theory. For this reason there is ensemble forecasting which attempts to even out the chaos theory but at the cost of resolution .ie the results will be less specific to a particular region.

The ensemble forecasting allows forecasters to give broad forecasts and allow contingency planning which along with seasonal forecasting allow for preparedness.( these forecasts use the terms such as "likelyhood","possible" and "on average" which are compared to seasonal averages)

The prediction (forecast?) comes from human intervention which will use his/her skill and experience to identify the most likely outcome. It is for this reason that they are professionals and do that for a living. The biggest problem is that "us" amateurs take what is often a somewhat vague analysis by the professionals or look at the computer generated outputs and allow our own internal bias for weather preferences to "cloud" our judgement and then hold that initial analysis as being wrong. 

 As you have correctly pointed out the weather has the ability to make fools of anyone ,including the professionals ( October 1987 and BBQ summer are the most obvious examples) , especially if they predict anything with 100% certainty beyond the 5/6 day period but then again where would the fun be in this forum if everybody only stated what was 100% certain and not what was possible 

 

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Posted
  • Location: Banbury
  • Location: Banbury
40 minutes ago, matty007 said:

No no no. 

I came to say that I have a 'feeling' that this winter will be very mild. You know, the same way many are saying it will be cold? Whose right? God knows. 

I then went on to say that looking at the models NOW affirms this. We have had very little in the way of cold and the models in the reliable timeframe  continue this trend. Of course, that may change. 

This is being taken way too seriously. 

I totally see your point and yes of course we all have opinions which on many occasion will differ but by saying we have had little in the way of cold on December 13th is a tad early , if this were the end of Jan or into Feb I get your point. We had cold weather at the very end of Autumn which gave good frosts and chilly days. And as  I say the reliable is only at 120 if we are being honest , I think giving what the very knowledgeable on here say as well as other outlets we will get some of the white stuff this Winter ………………..just my opinion of course . 

Edited by Banbury
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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.

The GEFS ensembles: 

GEFS Ensembles Chart Op clearly suggests a cooling trend, at 2m.

GEFS Ensembles Chart And the 850 ensemble, an enormous divergence, post Xmas.

 

GEFS Ensembles Chart And a possible rise in pressure, after the 19th...

All adds up to monumental uncertainty, regarding the position of any block, I feel...?

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Posted
  • Location: sheffield
  • Weather Preferences: cold ,snow
  • Location: sheffield

Morning.id like to apologise for my ramblings  yesterday.Had some bad news and headed for the pub. Anyway il leave it be .

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Posted
  • Location: Hernia Bay
  • Weather Preferences: Heavy Snow
  • Location: Hernia Bay

Oh will someone please answer my question from earlier. Its like trying to muscle in with the big boys in a rugby scrum when you're half their size..... Cmon lads..... Let's play nice.... Strat?   

Edited by snowfish1
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Good morning people

Hope everyone is doing ok. Well I am back again after a few days since I done my last post. Those who recall my thoughts last time were that we would get a dry period and then we would be looking at the Atlantic to take over, and to some extent that is what will happen currently. I did also think that this setup would not priduce the goods we are waiting for and any wintriness down here south would be very minimal if any.

i have to say that it does sadden me when people start bickering about what is going to happen in the longer term. To be to the point I personally take anything beyond 5 days with a pinch of salt and it has proven several times to be different  to current output. Whilst I admire all the knowledge our kind experts kindly share, the weather is something that will always change and any high knowledge will not be enough to defy this. We can make assumptions from the facts but we cannot change what the atmosphere will process. For this reason my take would be not to take anything serious outside the reliable timeframe to avoid disappointment. 

Anyway back on the current situation I think as it stands out in reality we are facing the barrel of the Atlantic after this weekend. What happens in a weeks time is something to watch and focus on. As some have pointed out this morning there are very mixed signs on the models and also cold weather by Christmas is in the equation. How this pans out who knows if we will be lucky and Santa will throw a Easterly present our way is to be seen. 

Lets not get dishearted I know this easterly did not come to anything, but there is still a long journey to go and we are in this together. We will get there but patience will be required.

i did also say in my last post it would be worth keeping an eye on temperatures in the Far East and see how the cold is building up. Good news is for eg in Moscow temperatures have dropped to minus ten and below which is a good sign if our Easterly was to come but will carry on watching in the week ahead. 

Our wait for the Siberian Express continues 

wishing you all a lovely day

kind regards

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Posted
  • Location: Loggerheads, Staffs
  • Weather Preferences: Hot and sunny summers, cold & snowy winters
  • Location: Loggerheads, Staffs
15 hours ago, I remember Atlantic 252 said:

this was a very good 'runner', heaviest snow I think I've seen, daytime lying snow

archives-1998-1-5-12-0.png

I remember this - rain to snow event in south Lancashire, resulted in c. 3" of wet snow before it melted overnight. It just started to sleet as I was leaving school for the day, and was a snowfest by the time I got home.

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Posted
  • Location: Live in NW Kent by the Thames & work in SE London
  • Weather Preferences: Snowy November to March and Sunny and warm April to October
  • Location: Live in NW Kent by the Thames & work in SE London

How accurate are these 10HPA zonal winds forecasts? I don't want to sound negative but that's a dramatic change from previous days. With the CFS showing the majority much closer to average through much of the winter now after the initial drop in December 

Screenshot_20181213-092813_Samsung Internet.jpg

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Posted
  • Location: Home :Peterborough Work : St Ives
  • Location: Home :Peterborough Work : St Ives
17 minutes ago, snowfish1 said:

Oh will someone please answer my question from earlier. Its like trying to muscle in with the big boys in a rugby scrum when you're half their size..... Cmon lads..... Let's play nice.... Strat?   

I think the issue is that a chart can show favourable conditions but cannot guarantee cold but if you goto this thread 

then you will probably find what your looking for and will help in your learning.

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Posted
  • Location: Saffron Walden, near Cambridge.
  • Weather Preferences: Sunny and hot.
  • Location: Saffron Walden, near Cambridge.
9 minutes ago, Snowman. said:

No nothing to do with your mild prediction it's your attitude towards forecasting itself. There are plenty of people in here who have spent years learning and researching the drivers of the world to try and understand how are weather funtions where they then form a forecast. Then you come in say anything past day 6 isn't worth looking into because no one gets it right.

Do you understand how rude that it is? You basically discredit those who work hard and base their forecast on actual science rather than a 'gut' feeling?

I never implied that. 

Yes, there are people that know a lot more than me. They have far more knowledge of the weather than myself and of the models. That puts them in a better place to judge how the weather will develop, but outside of the reliable timeframe it is still wide predictions at best. That is solely down to the nature of weather, regardless of the amount of expertise evaluating it. Yes, more often than not it's wrong, you can't argue with statistics. 

I just made a casual comment that outside of the 6 day timeframe, the models are largely unreliable. That is fact. Why people are taking it as an insult is beyond me.

And I still stick to the notion that if I had the opposite opinion, nobody would be calling this into question in the first place. Because my opinion goes against there's, they suddenly pick holes that can't exist. Long range forecasting is patchy, extremely unreliable and approaching guesswork even with some guidance, interpretation and extensive knowledge. Get over it. 

Edited by matty007
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Posted
  • Location: Scouthead Oldham 295mASL
  • Location: Scouthead Oldham 295mASL
8 minutes ago, carinthian said:

Good news from the UKMO extended at 168t. Shows Atlantic trough sinking SE and mid Atlantic ridging. Looks more akin to GFS model at this stage. ECM out on its own. 

C

ukm2.2018122000.168.lant.troplant.prp.fcst.gentracker.png

Nice one C..

Trouble is knowing our luck EC will be correct with its flatter Atlantic profile..

 

168 UKMO actually looks really promising the more i look at ..

Edited by northwestsnow
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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.
2 minutes ago, matty007 said:

I never implied that. 

Yes, there are people that know a lot more than me. They have far more knowledge of the weather than myself and of the models. That puts them in a better place to judge how the weather will develop, but outside of the reliable timeframe it is still wide predictions at best. That is solely down to the nature of weather, regardless of the amount of expertise evaluating it. Yes, more often than not it's wrong, you can't argue with statistics. 

I just made a casual comment that outside of the 6 day timeframe, the models are largely unreliable. That is fact. Why people are taking it as an insult is beyond me.

And I still stick to the notion that if I had the opposite opinion, nobody would be calling this into question in the first place. Because my opinion goes against there's, they suddenly pick holes that can't exist. Long range forecasting is patchy, extremely unreliable and approaching guesswork even with some guidance, interpretation and extensive knowledge. Get over it. 

Hi Matty.

It's sometimes odd that so many folks cite, for example, 'model bias' whenever a predicted 24-hour-long blizzard gets watered down to an annoying wee sleet shower, and then go on to criticise others for doing the very same thing, when the forecast is different...IMO, model-predictions are either accurate or they are not; the type of weather being forecast should be irrelevant?

Anywho, onto a much more egregious matter: you can choose your friends and your family, but you cannot choose your football team...COYS!:yahoo::santa-emoji:

 

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Posted
  • Location: Essex Riviera aka Burnham
  • Weather Preferences: 30 Degrees of pure British Celsius
  • Location: Essex Riviera aka Burnham
7 minutes ago, northwestsnow said:

Nice one C..

Trouble is knowing our luck EC will be correct with its flatter Atlantic profile..

 

168 UKMO actually looks really promising the more i look at ..

You don't see the full picture here though...no doubt a primary low to the north west towards Iceland and yet another feature brewing from off the Eastern Seaboard so I'm not sure that digging trough will change the pattern that much.

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