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Paul

Model output discussion - winter proper underway

Paul

Please only post model discussion in this thread. 

For more general chat and banter, or moans and ramps loosely around the models, please head to the banter thread:
https://www.netweather.tv/forum/topic/86721-model-moans-ramps-and-banter/

For general weather chat including about the snow/cold chances around the country, please go to the regional threads:
https://www.netweather.tv/forum/forum/142-regional-discussions/

Thank you!

Message added by Paul

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28 minutes ago, Summer Sun said:

UKMO extended shows high-pressure building in

ukm2.2017121612_168_lant.troplant_prp_fcst.gentracker.thumb.png.aef6ec72a7230e079f3a319baa1bdb17.png

Those Ukmet168 charts are shocking, about as useful as the CMA.

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11 minutes ago, feb1991blizzard said:

Most striking point of note on the extended EPS is the re-emergence of the Euro -ve anomaly - expect a better London graph later.

Control goes off on one - big spread at end

ensemble-verwachtingen-detail10.thumb.png.5c164be5984dbbde82d16c4424f99638.png

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4 minutes ago, FiftyShadesofWine said:

Those Ukmet168 charts are shocking, about as useful as the CMA.

Disagree, the signal appears to be that the Azores / Atlantic ridge will build in during next weekend cutting off the Northerly airflow and pressure will then become higher generally across the southern half / third of the uk with night frosts and chilly bright mainly dry days although further n / nw may continue rather more changeable..that's how I see it.

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2 minutes ago, Frosty. said:

Disagree, the signal appears to be that the Azores / Atlantic ridge will build in during next weekend cutting off the Northerly airflow and pressure will then become higher generally across the southern half / third of the uk with night frosts and chilly bright mainly dry days although further n / nw may continue rather more changeable..that's how I see it.

Unfortunately your wrong, there's some verification on the the NOAA site for this, ukmet 168 is poor...ill check it out and post the link...l

 

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5 minutes ago, FiftyShadesofWine said:

Unfortunately your wrong, there's some verification on the the NOAA site for this, ukmet 168 is poor...ill check it out and post the link...l

 

I may be wrong about the ukmo 168 verification but the general pattern evolution I mentioned above may be similar to what I described with high pressure building in at least further south.:)

Edited by Frosty.

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1 minute ago, Frosty. said:

I may be wrong about the verification but the general pattern I described may be similar to what I described.:)

Don't want to move the thread off track, but if the verification is wrong your general pattern will be skewed lol...anyway we will see moving forward.

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26 minutes ago, feb1991blizzard said:

Most striking point of note on the extended EPS is the re-emergence of the Euro -ve anomaly - expect a better London graph later.

Indeed Feb - signs  of renewed mid Atlantic high anomoly and the euro low anomoly re established - the clusters will be worth looking at later 

we may not have seen the last of the slider this side of xmas 

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1 minute ago, FiftyShadesofWine said:

Don't want to move the thread off track, but if the verification is wrong your general pattern will be skewed lol...anyway we will see moving forward.

Actually the GEFS 12z mean goes along with what I said about week 2.:)..i.e..settling down, at least further south for a while with night frosts and chilly bright days, more changeable towards the NW.

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6 minutes ago, Frosty. said:

Actually the GEFS 12z mean goes along with what I said about week 2.:)..i.e..settling down, at least further south for a while with night frosts and chilly bright days, more changeable towards the NW.

Lol we were discussing uk met168 verification, not sure what gefs has got to do with it. Enjoy the snow :-)

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45 minutes ago, Man With Beard said:

Really quite incredible looking through the 12Z ECM ensembles - at just 18 hours away, the central front of the "slider" is forecast to stall just about anywhere between Guildford and Cambridge. London is hit by snow in almost all the ensembles now, especially north of the Thames.

Rapidly becoming an "on" the M4 event, rather than north of it.

Longer term - more and more charts stalling the Atlantic between 17th and 19th, will cold remaining in place. And with just 6 days until Christmas...

What is the resolution of the ecm precipitation charts you can see?

As far as I can tell, the 12z Hi-Res suite pads out as follows:

Significant snowfall South of Oxford for at least a few frames:

- AROME

- ARPEGE

- HIRLAM

- ICON (15z although only included due to heavy snow from undercut/wrap around in pm following rain)

- NETWX-SR

Significant snowfall only North of Oxford:

- NMM

-EURO4

Edited by The Enforcer

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4 minutes ago, FiftyShadesofWine said:

Lol we were discussing uk met168 verification, not sure what gefs has got to do with it. Enjoy the snow :-)

What snow?..it's mainly staying further south of where I am.

In answer to your other point about the ukmo 168, I was only agreeing with summer sun about the idea of high pressure building in from the end of next week onwards!:)

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1 hour ago, Joshua said:

Unfortunately, due to a data transmission issue we're currently not receiving the data for the Met-Office global model. We're hoping the data will be available again soon.

It seems they are currently offline. Never mind - they only show 72, 96 and 120 hours ahead as far as I can see.

UKMET-G charts for tomorrow:

P1_GZ_D5_PN_018_0000.thumb.gif.aa9d545c202cccae1b3019194f3b9296.gifP1_GZ_D5_PN_024_0000.thumb.gif.733dc93016cfa5097d9fa92953c1a5b1.gifP1_GZ_D5_PN_030_0000.thumb.gif.df232f4481e849eb49b0806550a94062.gif

ECMWF:

ecm0125_nat_msl_t850_6urk_2017120912_018.thumb.jpg.7308c10ba5f1f0fad5a0ece481dd7ac2.jpgecm0125_nat_msl_t850_6urk_2017120912_024.thumb.jpg.25ff36c407dfb95856ea38024a6fbe74.jpgecm0125_nat_msl_t850_6urk_2017120912_030.thumb.jpg.29d2c275bfffd1eca134b374f21e61fb.jpg

 

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Just looking at the 3 hour frames on ec 12z op and seems that the ridge ahead of the sliding trough manages to keep contact  with the Icelandic ridge and prevent any phasing at all of the sliding trough with the scandi trough. That keeps the sliding system that bit lower latitude and the little low at the front extension is now in s Kent before the slight pivot ne. The whole system now so flat that there is less advection north of the higher dp's (see Steve's post earlier). Would also note that gem was further south with the snow line last few runs without any clear reason as it wasn't as flat with the trough 

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44 minutes ago, FiftyShadesofWine said:

Unfortunately your wrong, there's some verification on the the NOAA site for this, ukmet 168 is poor...ill check it out and post the link...l

 

I think the UKME proviodes the sensible option for the MJO progression and imprint. GF is fast with the tropics and ECM over amplifies the solution we see. JMA also is a decent steer when MJO has influence over mid range patterns. Different lenses - NWP or teleconnections...

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1 hour ago, phil nw. said:

A lot of members now in the regionals i believe- where some of the posts that have been removed from here should have gone wrt the snow event chat.

Please only model talk in here.

Thankyou.:)

AN APPEAL FOR SOME SYMPATHY AND RESPECT TOWARDS THE MODERATORS

Before I start working on my next weekly report, which will appear late tomorrow (Sunday), I must get something off my chest and I feel that it might be better coming from a poster/reader like myself rather than from a moderator.

I strongly feel that some posters on this thread need to understand and respect what Paul and his team of moderators have been requesting repeatedly during the last couple of weeks in particular. Like the vast majority of posters and readers, I love cold and snowy weather and I can get as excited as anybody with much of the recent output but we must remember that this is a model output analysis and discussion thread. Yes, that does overlap with many related topics but it’s not really that difficult to know what is completely off topic. Just ask yourself, is what I’m about to post related to something about the model output. Think about the audience and what they expect to see on this type of thread.

For example, posting a chart (or charts) showing what the GFS 6z output shows is fine. Ideally, this needs to be backed up with at least a short comment like how it has changed from the previous run or how it compares to other model output or how it might result in a particular type of weather or a more general view about a perceived trend. This can include short term events such as potential snowfall when it bears a direct relationship to the model output. It does not include posts which only ask “will it snow in my location?” Even worse, some of the posts contained some quite nasty one liners about so and so getting the snow while they will miss out. Whether this was purely banter or something more sinister is not really the point, those comments simply do not belong on this thread. There are other threads for such things.  Sometimes we see some highly disrespectful and quite rude contradictions. If you really disagree with another poster's view(s) then politely explain why with a short and reasoned analysis or comment if it's relevant or send them a PM. I really sympathise with the moderators who have had their work cut out in deleting or transferring unsuitable posts. This is NOT a game of seeing just what you get away with.

I know that sometimes one feels that certain questions about the snow will only get answered if it appears on the model thread but some of the other threads have also been far busier than usual and the moderators and others from the NetWeather team do take the time to answer genuine questions. If posts consistently appeared on the correct threads then the usage and activity on those threads would increase accordingly. One can also send a personal message to any poster and many of these do get answered and now we have the “sticky note” option too. 

I was away on a short business trip from Thursday until today and I had to use my laptop instead of my normal desktop computer. The signal wasn’t very good and I really struggled to catch up with the latest analysis. Wading through so many posts that didn’t really belong on this thread made it particularly tough going. I skimmed through and only stopped where I saw a particular poster or where there were quite a few likes – which is not the best way to judge it all and I’m sure I missed a few really good posts that were buried in there somewhere.

One of the real positives about this thread is the huge diversity of posters. There is a whole spectrum and wealth of skills and knowledge from professionals, experts, scientists, technicians, many of the NetWeather team and also keen and/or experienced amateurs through to beginners and those wishing to learn more about this wonderful subject. We get some amazing reports on what is driving the models from the likes of @Glacier Point @Tamara @Catacol to name a few and we get great analysis of what the charts show and why with some thorough explanations from a whole hosts of posters.  A few, like me, usually prefer to do a longer analysis looking at particular aspects of the subject. All of the above is what this thread is all about. So, please let’s all make an effort to keep things on track so that we can all benefit from the experience.

Finally, things seem to be rather better this evening - perhaps as @phil nw. says the regional threads are being used for the forthcoming snow event. 

 

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37 minutes ago, Nick F said:

UKMET-G charts for tomorrow:

P1_GZ_D5_PN_018_0000.thumb.gif.aa9d545c202cccae1b3019194f3b9296.gifP1_GZ_D5_PN_024_0000.thumb.gif.733dc93016cfa5097d9fa92953c1a5b1.gifP1_GZ_D5_PN_030_0000.thumb.gif.df232f4481e849eb49b0806550a94062.gif

ECMWF:

ecm0125_nat_msl_t850_6urk_2017120912_018.thumb.jpg.7308c10ba5f1f0fad5a0ece481dd7ac2.jpgecm0125_nat_msl_t850_6urk_2017120912_024.thumb.jpg.25ff36c407dfb95856ea38024a6fbe74.jpgecm0125_nat_msl_t850_6urk_2017120912_030.thumb.jpg.29d2c275bfffd1eca134b374f21e61fb.jpg

 

That still looks brillaint for the midlands as a whole!!much further north compared to the ecm!!

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24 minutes ago, Nick F said:

UKMET-G, their global model, is not run to such a high resolution as the ECM as far as I'm aware, so may not verify aswell as EC det. - but we'll find out tomorrow.

Do you know the resolution of the ECM?

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Dreaming of a white Christmas?

image.thumb.png.96cc589cfb7d38e00f6c322fbe91e91a.png

image.thumb.png.e0fded473eaa941806b4c8f7d7f71d2a.png

image.thumb.png.1ca80ec856051842b285910aba5b2ba3.png

Then

image.thumb.png.371d24fd74d4978d9ee921ef8e269611.png

Nice to see - far off but a good trend we hope...:)

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19 minutes ago, The Enforcer said:

Do you know the resolution of the ECM?

0.125 or around 9km grid spaces: https://www.ecmwf.int/en/forecasts/documentation-and-support

Looks like UKMO global has now gone from 17km to 10km grid spacing, so should see improvements with this model: https://www.metoffice.gov.uk/research/news/2017/increased-resolution-of-global-forecast-models

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12 minutes ago, nick sussex said:

Very quiet in here which often happens when some snow is imminent for certain areas .

This slider low must surely go down in NW history as one of the  most microscopically analysed , with every jog south or north by a few miles met with panic or joy !

Putting aside this current saga which is drawing to a close we have seen some interesting trends over the last day on both the ECM and GFS trying to develop a ridge near Scandi towards day ten.

Looking at the De Bilt ensembles we’re beginning to see a small cluster developing some very cold conditions.

There are hints upstream that we could see a bit more amplitude developing after a relaxation of the positive PNA.

This would help as it will begin to pull back the PV and send a bit more energy se which you need to develop lower heights over Southern Europe to support any high.

It might be that we might need more than one attempt to get that Scandi high but perhaps it might arrive a bit sooner if the models are still slow at picking up the correct MJO signal . Singularity a few pages back made  an excellent post regarding that  and it does seem that the models forecasts were wrong and weakening the signal.

So after an initial suggestion that things might turn milder it’s possible we could see the mainly cold weather extended .

 

I dont know Nick, (To be fair, you should know...? I recognise the name from a long ago.)

Years ago this place would of been unbearable (10 to 20 posts every few seconds ) , lucky now its all split out more than it used to be so I guess better in a way.

- More in topic..

What i find most impressive is how the last few days its gone from being a very much midland and north snow event to being a midland and south snow event.
Time is ticking by and soon we will know for sure!

In times like this I always take GFS and METO with a pinch of salt. They work well for westerlies but as soon as we get the 1/10 setup's they suck! 
They just dont have the data needed to make a good guess and I see this year after year after year... As soon as its east, north or south, They cant handle it.  Coming from the west? They will nail it.

Edited by Lynxus

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