Model output discussion - 5th December 2016 - Into Winter we go

[tight isobar]

Also worth noting' that a feasible cross model agree' for colder insurgé is pretty good atm via 1/01/2017..03/01/2017..

But there should be a cut off point..for a decent degree of sureties that follow from +5days from that juncture. 

I'd say this evening s 12z ecm will be near the money around these time frames. .I'll make a valid point via (this point ) of saving 12z frames for compare for mentioned above!!!..

 

[NorthYorksWeather]

Speaking of higher resolution models don't forget NMM has a Europe view that goes out to 120hrs.

No idea of its verification details but I used it a lot last winter to track details of potential colder spells as they move closer to the present.

Here's the 6z view for the same time as the Arpege chart posted above.

The only issue I find with it is we have no idea what is happening upstream.

Here's the link anyway.

http://www.meteociel.fr/modeles/wrfnmm.php?ech=3&mode=2&map=20

[booferking]

Going through the GFS ens there is support and its more than 1 ens there are about 5 or so.

Edited December 27, 2016 by booferking

[Daniel*]

24 minutes ago, Kieran said:

Back edge snow for most parts (except for the far south) on New Years Day shown on the GFS. Something to keep an eye on....

                 

 

 

Ian flagged it up on that 'wintry update' I believe, correct me if I'm wrong? - which was later deleted due to the flaming Facebook folk - there is quite some support for a low to the nw, tracking southeastwards down the country engaging with cold front sweeping south. Some transient snow possible even for London.

[london-snow]

2 minutes ago, Mucka said:

let's hope ECM backs UKMO rather than GFS which is pretty much a worse case scenario for snow chances through 1st week of January from where we are.

If we can just back the pattern West a few hundred miles it will make all the difference in lowering pressure to our S/SE, raising pressure to our NW and of course opening the gate to an Arctic flow which even with toppler scenarios would give much better depth of cold and snow chances between ridges and better Easterly chances further down the line.

It is on a knife edge between a standard cold/frosty spell with short milder interludes and a prolonged cold spell with better snow chances IMO.

Great post and those underwhelmed at today's output thus far need to take note of the above. 

As I stated yesterday it will be turning colder into the new year period. How prolonged is up for debate and snowy (which is pretty much a day to day forcasting situation) unless you have a high slap bang over us is also up for debate.

All the cards are on the table but most if not all are showing colder weather into the new year period so what's to be dispondant about at this juncture if you're a coldie? 

[radiohead]

3 minutes ago, vizzy2004 said:

Speaking of higher resolution models don't forget NMM has a Europe view that goes out to 120hrs.

No idea of its verification details but I used it a lot last winter to track details of potential colder spells as they move closer to the present.

Here's the 6z view for the same time as the Arpege chart posted above.

The only issue I find with it is we have no idea what is happening upstream.

Here's the link anyway.

http://www.meteociel.fr/modeles/wrfnmm.php?ech=3&mode=2&map=20

NMM gets its boundary conditions from GFS data.

[Catacol]

3 hours ago, TEITS said:

Radiosonde data is tiny eh? Some disagree.

http://www.greatfallstribune.com/story/news/local/2015/04/02/weather-balloons-still-critical-forecasting/70861502/

Instead of clinging to some kind of conspiracy argument regarding data acquisition please can you explain why you think we are set for a potentially severe shot in week 2 of January. Far more interesting than a pointless debate on the workings of Christmas Day.

[Banbury]

Be happy with this ......................if only

[doctor32]

Still alot of scatter from around 2/3rd jan.

majority still trending on the colder side

[Weathizard]

5 minutes ago, doctor32 said:

Still alot of scatter from around 2/3rd jan.

majority still trending on the colder side

The clear trend after the 2nd is for no real sustained cold though, though there is still some scatter in my opinion the trend is still away from any long lasting cold spell. The mean was -5 yesterday it's now between -1 and -2.

[TEITS]

1 hour ago, johnholmes said:

Come on TEITS, the only time this theory is trotted out is when there is no sign of cold weather. So yes it is fairly often with our run of relatively mild spells around Christmas. Odd though, don't you  think, that this theory is absent if 'cold' seems likely and even less so if it is cold and some get snow over Christmas. Like a hundred and one other factors taken into account by forecasters the period of data absent, for whatever reason, is ALWAYS factored in to any professional forecaster when assessing all the data available. In truth there is a larger number of aircraft over the Atlantic on Christmas Day in the past few years than say 10 years ago. Have a look at the IATA data for these days if you do not believe me.

Also a bit rude of you to suggest for a professional to go back to basics. Can you tell us what your meteorological qualifications are please?

Sorry for this post not having any model data in it but as an ex forecaster this red herring every year when it is not cold gets on my nerves.

 

Go back and read my posts and you will see I make no connection with lack of data and no sign of cold weather. I always believe the NWP is erractic at xmas regardless of whether its showing a heatwave or a big freeze.

The reason I said "Back to basics" because I find it incredible when some seem to disregard the importance the chaos theory has on numerical weather predictions. This remains the sole reason why weather forecasting remains very challenging beyond 5 days.

As for you professional comment. The professionals can get it wrong as you very well know.

[doctor32]

1 minute ago, Weathizard said:

The clear trend after the 2nd is for no real sustained cold though, though there is still some scatter in my opinion the trend is still away from any long lasting cold spell. The mean was -5 yesterday it's now between -1 and -2.

Agree, but this is just another run with a few differences, come tomorrow it well be back to more colder solutions once models get an idea on things from the first cold plunge.

Or it may well go the same way again with less cold uppers showing, but in my opinion i think there will be many more shots at the cold/snow chances during the month.

[Grimsby Snow Lover]

9 minutes ago, Weathizard said:

The clear trend after the 2nd is for no real sustained cold though, though there is still some scatter in my opinion the trend is still away from any long lasting cold spell. The mean was -5 yesterday it's now between -1 and -2.

 

The average temperatures look to remain below 5 degrees which to my knowledge is below average if nothing else. I do get what you mean though as things could be a lot colder if those Stella runs from yesterday were to verify.

Edited December 27, 2016 by Grimsby Snow Lover

[Banbury]

8 minutes ago, Weathizard said:

The clear trend after the 2nd is for no real sustained cold though, though there is still some scatter in my opinion the trend is still away from any long lasting cold spell. The mean was -5 yesterday it's now between -1 and -2.

There is nothing clear after the 2nd full stop

[radiohead]

4 hours ago, TEITS said:

Radiosonde data is tiny eh? Some disagree.

http://www.greatfallstribune.com/story/news/local/2015/04/02/weather-balloons-still-critical-forecasting/70861502/

The amount of data from radiosondes that is collected for weather models is indeed tidy.

GFS data from 2012 for example.

Satellite data amount each day:

00z: 3,179,834

Radiosonde data amount each day:

00z: 2,333

Source: https://www.americanwx.com/bb/topic/43144-why-do-people-dismiss-6z-and-18z-model-runs/?do=findComment&comment=2864317

Weather balloons are launched every day including Christmas Day, as far as I know all over the world . So there shouldn't be any missing data from them anyway.

They are still important for sampling the atmosphere more accurately during high impact tropical cyclones etc. Extra balloons are often launched and radiosondes will be dropped by aircraft around and inside a storm. So they still have an important place in weather forecasting. But they do make up a tiny percentage of the data that goes into a global model. 

 

 

[london-snow]

9 minutes ago, feb1991blizzard said:

There were lots of GEFS members showing uppers very cold for days a few runs ago, they are fast disappearing and with the Met Office outlook not suggesting much PPN after some very insignificant back edge snow on the weekend, it looks like another garden path job again, mind you the background signals never really suggested HLB in the first place. Well at least we can look forward to some frosty clear days and interesting weather  .zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz.

Ok so background signals like in early Dec is that what you're basing you're outlook on now (false dawn) springs to mind..

And I'll love to know how you have inside info re the outlook being frosty clear days and a snooze fest when the diffrence into the first week of Jan which is atm at least 5+ days away may well be a few hundred miles away from white flakes falling south of let's say reading in a long while.

Dismiss at you're peril but I'm a believer..

[TEITS]

44 minutes ago, Catacol said:

Instead of clinging to some kind of conspiracy argument regarding data acquisition please can you explain why you think we are set for a potentially severe shot in week 2 of January. Far more interesting than a pointless debate on the workings of Christmas Day.

Before I do read this post of mine 5 days ago. Far more accurate than these silly teleconnections which people use only to make their posts seem more technical. Quote has gone wrong. Read my prediction on page 188 on this thread!!

As for week 2. I have never said severe but possibly swinging towards a NE,ly. Following the tame N,ly a brief less cold period followed by a reload from the N which shall eventually veer NE,ly.

Edited December 27, 2016 by TEITS

[snowray]

Oh dear, wheres our topler going, can we salvage something at T144?

 

[frosty ground]

14 minutes ago, london-snow said:

Ok so background signals like in early Dec is that what you're basing you're outlook on now (false dawn) springs to mind..

And I'll love to know how you have inside info re the outlook being frosty clear days and a snooze fest when the diffrence into the first week of Jan which is atm at least 5+ days away may well be a few hundred miles away from white flakes falling south of let's say reading in a long while.

Dismiss at you're peril but I'm a believer..

The same poster was writing winter off last week what else is there to say.

Even by the poster admissiononly a few GEFS run where showing somthing a bit more severe..... and that's the point the info has only really shown a toppler then high pressure with a second go at it a week later. 

 

It just happens to be the high will be a cold one rather than a usual south westerly that follows a high toppling south east

[snowray]

+T144.....gone!

[london-snow]

1 minute ago, frosty ground said:

The same poster was writing winter off last week what else is there to say.

Even by the poster admissiononly a few GEFS run where showing somthing a bit more severe..... and that's the point the info has only really shown a toppler then high pressure with a second go at it a week later. 

 

It just happens to be the high will be a cold one rather than a usual south westerly that follows a high toppling south east

 

Sorry did I write it off?

[stewfox]

37 minutes ago, TEITS said:

The reason I said "Back to basics" because I find it incredible when some seem to disregard the importance the chaos theory has on numerical weather predictions. This remains the sole reason why weather forecasting remains very challenging beyond 5 days.

As for you professional comment. The professionals can get it wrong as you very well know.

Chaos theory can apply for any day of the year and xmas day is not the only national holiday on the planet.

Given we have twice as many aircraft crossing the Atlantic from USA in summer then we should  get much better forecasts , we don't. 0.002% influence but cant find the reference

Edited December 27, 2016 by stewfox

[Ben Sainsbury]

2 minutes ago, snowray said:

+T144.....gone!

Can you please explain what you mean? It would be valuable to those who want to learn and myself!

Edited December 27, 2016 by Ben Sainsbury

[northwestsnow]

Really frustrating seeing the high sink on the ecm, not entirely sure how ir can be saved at 144.

[frosty ground]

2 minutes ago, london-snow said:

 

Sorry did I write it off?

I was referring to the poster you where replying too