General Model Output Discussion

[Evening thunder]

Do you know I completely give up on some people suggesting it will be cold and dry. Look at the fax charts at T+60/T+72 for example. Imagine it was warmer than this to me it would look like there would be bands of rain and showers at times crossing most parts. Only this time, its going to be snow not rain. Also the bigger contrast in sea temps causes more instability. On Wednesday they show a low CENTERED OVER the UK with various troughs and fronts rapped around it. Even the GFS precipitation charts which underestimate ppn especially showers show precipitation over almost everywhere next week. In fact I've just looked at the GFS precipitation charts out to T+120 and it shows ppn crossing over every part of the UK at some point.

Also yesterday evening the GFS was forecasting just very small amounts of precipitation over the Irish sea let alone Wales, yet parts of Wales e.g. Pembrokeshire got about 3 inches in places! This was very well picked out by the MetO models yesterday and shown well by Ian Fergusson's great posts in the South West discussion thread.

I may be being just slightly over the top with my reaction here but I'm just a little tired of people constantly maintaining that it will be dry even though I see little evidence they can present to back this up.. some of it seems almost like a wind up to me! not saying anything is or is intended to be, just saying it feels like it.

Its not going to snow a foot everywhere! That would be extremely rare! But I would think nearly everywhere if not everywhere will see snow.

Yep - Northern East Anglia, and Far East Kent.

Really: that chart posted looked like more of the UK than not to me

Yup - OK let's look at the charts ... here's the ensembles which show very cold and dry weather for Kent:

Those ensembles only show 850hpa temps.

Just to add: sorry if this seems a slightly over the top or an at all argumentative post, I just got A bit fed up and felt I needed to say something.

This is coming from someone who has seen hardly anything in terms of snow in my area so far this winter.

Edited January 2, 2010 by StormMad26

[If Wishes made Weather]

The cumulative precipitation forecast for the SE is 10mm for the week: at best that means 10cm's snow for the entire week. So, as I said, it will snow.

Best accumulations will be North East England where the show will stop - they will accumlate, at sea level, nearly a metre of snow this coming week, and Eastern Scotland will be very similar.

As for the CET area - Birmingham and Manchester worst affected with, at most, 16 cms of snow over seven days - yes, peeps, that's a whopping 10mm/day.

I'm sure this discussion is about the conflict between the subjective and the objective. It appears that there are people who find that 10-20 cm of snow is extreme, and those who do not. Objectively, at present, for the reasons given the models currently predict around this amount of snow for the SE, over a week or so. And for the reasons given, VillagePlank has promoted an appropriate opinion that the models may be accurate owing to the dry nature of the airmass. The objections to this - and to yesterday's mails by someone (Snowballs?) were along the lines as to whether it is appropriate to make analogy to Biblical cataclism for such an event?

By the way, who is this JoeB person with the major snowstorm over Europe, starting in Italy and making a beeline for SE UK thing that is being quoted on the SE thread?

[TEITS]

Just been looking at the fax charts again and what interests me is Tues.

http://www.wetterzentrale.de/pics/brack2.gif

That cold front is really dragging its heals across the Midlands/Wales/E Anglia. Now its difficult to predict how active that front will be. However if the front is active then I would expect some fairly notable snowfalls from this due to how slow moving it is!

[TEITS]

As silly as this sounds but the ECM was one of the warmest runs as Nick rightly says.

http://www.knmi.nl/exp/pluim/vijftiendaagse/index.html

Fasinating how the extended ensembles are getting colder and colder.

[PB22]

Staggering extended ECM ensembles for Holland - look how low that mean keeps creeping:

http://www.weerplaza.nl/15daagseverwachting/default_pluim.asp?r=midden

[ChartViewer]

This thread is turning into a Snow watch.......Some of the Models suggest a warmer return to something

average and also late on the Models GFS go for something nearing average for the UK.....

Also nothing really cold compared to 87 or 91 and Id love someone to suggest otherwise as I loved

91 but this according to Model wise doesnt suggest that....Just cold and dry

Regards

[bluearmy]

been out most of the day (cold turkey just avoided!!). the two most significant things i notice about he 12z's are

i) ECM T240 shows the -AO being reinforced for a further spell. up till this run, we hadnt seen ecm showing a resplitting of the p/v in fi whereas GFS was repeatedly doing this.

ii) GEM is really not overly keen on the easterly. a year or so ago, this woudnt have bothered me but its been a pretty good model over the past year. i know TWS thinks the high will settle closer to us than scandi. keep your eyes on this if GEM still refuses to back down on its 00z run.

as for snowfall - forget it guys. it'll happen. get the cold entrenched. i travelled through plenty of rain in the eats midlands today. lets get the cold settled in first. from my perspective, where ever the models are predicting no snowfall more than 48 hours out - thats where you need to be looking. as VP said earlier - we'll all get some. impossible to predict with confidence so why bother - just enjoy the sypnotics - you may not see the like for another 30 years.

[TEITS]

This thread is turning into a Snow watch.......Some of the Models suggest a warmer return to something

average and also late on the Models GFS go for something nearing average for the UK.....

Also nothing really cold compared to 87 or 91 and Id love someone to suggest otherwise as I loved

91 but this according to Model wise doesnt suggest that....Just cold and dry

Regards

Evening CV hope you are well mate.

Based on the model output at the moment there does seem to be a trend towards blocking returning to Greenland in F.I. Now obviously this could change and it could turn milder. However the ECM extended ensembles are somewhat backing the GFS charts as the mean keeps dropping with every subsequent run.

As for Jan 87 and to be honest it will always be hard to compete against that. The Jan 87 E,ly was probably the coldest this country has even seen with regards to upper temps. I would say for severity it even eclipsed 47, 63.

By the way I will say my bias isn't affecting my judgement with regards to the models. I say this because come mid Jan I will probably be sick of it!

[cooling climate]

Staggering extended ECM ensembles for Holland - look how low that mean keeps creeping:

http://www.weerplaza...im.asp?r=midden

I was just looking at that myself. The mean only managing to reach -3c now which is quite amazing.

Certainly agree with Nick Sussex and others, many places will receive decent falls of snow over the

coming week or more with the brunt of the snow being down the eastern half of the country.

[Neilsouth]

Is this easterly/north easterly still on for late next week? , it looks to have tamed down some what from earlier models...

Please bare with me , with any spelling as i had a real nasty migrain today

[Hemlock]

VP theres no problem in having a difference of opinion, i was more highighting the se as thats the area that would be most effected by any easterly, before that theres still snow chances for other areas, of course more eastern and ne areas would always be favoured with the current pattern but as an example of how surprises pop up, i was speaking to friends in Cornwall today who woke up to snow this morning.

I have to say i'm not at all sold on that theory, from the last 4 easterlys i can remember Lincoln has only had notable snowfall once, the last easterly cold spell delivered less than an inch, the one before that brought sleet.

[Glacier Point]

been out most of the day (cold turkey just avoided!!). the two most significant things i notice about he 12z's are

i) ECM T240 shows the -AO being reinforced for a further spell. up till this run, we hadnt seen ecm showing a resplitting of the p/v in fi whereas GFS was repeatedly doing this.

ii) GEM is really not overly keen on the easterly. a year or so ago, this woudnt have bothered me but its been a pretty good model over the past year. i know TWS thinks the high will settle closer to us than scandi. keep your eyes on this if GEM still refuses to back down on its 00z run.

as for snowfall - forget it guys. it'll happen. get the cold entrenched. i travelled through plenty of rain in the eats midlands today. lets get the cold settled in first. from my perspective, where ever the models are predicting no snowfall more than 48 hours out - thats where you need to be looking. as VP said earlier - we'll all get some. impossible to predict with confidence so why bother - just enjoy the sypnotics - you may not see the like for another 30 years.

I wouldn't worry about the operational too much Nick - it ensemble mean is one of the best long range guidance tools. By day 10, the 12z suggests a huge +ve anomaly over Iceland:

http://raleighwx.easternuswx.com/models/cmcensemble/00zGGEMEnsembles500mbHeightAnomalyNH240.gif

which is very consistent with the GFS ensemble mean and operational ECM.

[johnholmes]

The reason i'm not giving possible snow amounts is we still don't know for sure how long the easterly will last and thats why i'm holding fire until we have a better idea, part of the uncertainty is exactly how much that southern european low deepens. In terms of the gfs i'm not just opposing its precip forecasts to be difficult! i've never trusted them and in convective scenarios they're even more out than in frontal precip situations.

on the post from VP as well

see my last blog which tries to explain with skew-t's how the cold air mass is unstable to sea temps, much more so than to the expected land temps. That is the key, cold upper air over what is a 'warm' sea by the air mass values flowing over it.

[bluearmy]

GP just posted on the in depth thread re upstream events supporting the re establishment of higher heights in greenland/iceland in 10 days time. also the northern arm which was expected to recover some strength is not now expected to do so. the southern arm is still where its at and from our perspective, with it in northern iberia and the med, we can expect the cold to go on for the next couple of weeks at least. (i'd say three now looking likely).

[ChartViewer]

Evening CV hope you are well mate.

Based on the model output at the moment there does seem to be a trend towards blocking returning to Greenland in F.I. Now obviously this could change and it could turn milder. However the ECM extended ensembles are somewhat backing the GFS charts as the mean keeps dropping with every subsequent run.

As for Jan 87 and to be honest it will always be hard to compete against that. The Jan 87 E,ly was probably the coldest this country has even seen with regards to upper temps. I would say for severity it even eclipsed 47, 63.

By the way I will say my bias isn't affecting my judgement with regards to the models. I say this because come mid Jan I will probably be sick of it!

Hi TEITS thanks for replying,

Can I first say the next 10 days will be cold. However im confused as -10 air isnt really

prevelant over the whole of the UK at any stage?

Also its interesting that people are comparing this to 87, 91 when we have no wind chill which

means no colder temps and about 2 degrees warmer than 87 at least.

Warmer air involved?

Regards

Edited January 2, 2010 by ChartViewer

[Rob K]

Can I first say the next 10 days will be cold. However im confused as -10 air isnt really

prevelant over the whole of the UK at any stage?

Say what? http://www.wzkarten.de/pics/Rtavn1622.png - from 12Z as I post, -10C over the whole of mainland UK! In high-res: http://www.wzkarten.de/pics/Rmgfs1622.gif -12s over many areas.

Will change as the 18Z rolls out though, but hopefully not much!

More snow around on the 18Z run... http://www.wzkarten.de/pics/Rtavn784.png

Edited January 2, 2010 by Rob K

[SMU]

http://91.121.94.83/modeles/gfs/run/gfsnh-0-102.png?18

First signs of a shortwave developing in the flow-

For the people commenting on how dry its going to be - ^^ thats about as unstable as it gets..---

http://91.121.94.83/modeles/gfs/run/gfsnh-0-114.png?18 STREAMER for the SE-

THe 18z is going to be Easterly heavon for the SE I think

S

Edited January 2, 2010 by Steve Murr

[Lewis]

http://91.121.94.83/modeles/gfs/run/gfsnh-0-102.png?18

First signs of a shortwave developing in the flow-

For the people commenting on how dry its going to be - ^^ thats about as unstable as it gets..---

http://91.121.94.83/modeles/gfs/run/gfsnh-0-114.png?18 STREAMER for the SE-

THe 18z is going to be Easterly heavon for the SE I think

S

Stunning chart Steve,

Very cold 850's, warm North sea SSTS, lovely tight flow, perfect ingredients for convective showers and troughs rattling in from the east across all parts. Certainly a winter wonderland to come.

Lewis

[PB22]

Another sensational run, what people would have given for this chart in Januaries gone by:

http://www.wzkarten.de/pics/Rtavn1261.html

http://www.wzkarten.de/pics/Rtavn1262.html

[on the coast]

Gale force easterly next Saturday. Should blow the snow round a bit! Very good 18z.

[PB22]

T+96 FAX: http://www.meteociel.fr/ukmo/fax/fax96s.gif

T+120 FAX: http://www.meteociel.fr/ukmo/fax/fax120s.gif

Cold and wintry!

[nick sussex]

The easterly looks a little better here and with the stronger flow would drive snow showers well inland, to be honest if you're in the east and se you'd want to bank this run and say thankyou very much. If it verified this would give huge snow totals to those areas, again though we're still not sure of exactly whats going to happen with this easterly until much nearer the time, the pattern looks agreed but small detail not yet.

[SMU]

Not working Paul

FORGIVE ME PEOPLE

OMG OMG OMG OMG

http://91.121.94.83/modeles/gfs/run/gfs-2-162.png?18

STREAMER ALL THE WAY BACK TO --- WARSAW---- SOMEONE FIRE UP THE WARSAW RADAR...

S

[sandstorm2]

Say what? http://www.wzkarten.de/pics/Rtavn1622.png - from 12Z as I post, -10C over the whole of mainland UK! In high-res: http://www.wzkarten.de/pics/Rmgfs1622.gif -12s over many areas.

Will change as the 18Z rolls out though, but hopefully not much!

More snow around on the 18Z run... http://www.wzkarten.de/pics/Rtavn784.png

Well it doesnt look like -10,s are covering the whole country to me, Scotland and East anglia are not under -10 air and same goes for -12,s, but hey we are splitting hairs here, its going to be very cold across the whole country with snow in many places.

SS2

[Geordiesnow]

I think one reason why PPN might not look as good is because of the fronts and troughs that are going to be embedded in the flow, it is not a clean easterly which means its not always going to be sunshine and convective clouds. GFS imo is the best model regarding PPN but it can more often or not underestimate PPN at times(although not as bad as the UKMO!)

For those worrying about PPN, there are some beefy showers in the North Sea just to the north of here and Edinburgh recieved quite alot of snow despite pressure rising so it is really watching the radar and see what you get.

If the easterly was a clean flow then i expect the GFS to of had more PPN on.