Model Output Discussion 18th Nov.2013-12z onwards.

[johnholmes]

Didn't SM say these are global rankings ? How they 'perform' in our patch maybe very different.

 

Couldn't GFS have a inherent bias in our region ? but be better on a NH scale ?

the checks are for the northern hemisphere, SM did I think last winter have a European area model check but is unable to find the link this winter

[johnholmes]

I copy this, although it has no model output in it, another case of someone getting fed up of folk point scoring!

welcome to the site, PLEASE post your views as someone has posted after your input, the more positive posting the less the squabbling will show up.

My outlook is per my pdf just posted-It does not look like a mild wet south west flow but other than that most options seem possible.

 

fat chad, on 22 Nov 2013 - 18:41, said:

Been watching from the shadows for 3 years now and am getting bored of all the petty squabbling. I did want my first post to say thank you to all the regular posters who post and pass on their knowledge to the rest of us. The posters who do contribute know who they are and make this place fantastic. Its just a shame that the forum is now turning into a tantrum chamber full of hacked off moaners...... I'll come back in a few days I think when the toys are put back in the Pram and adults can be adults. (sorry for being a nag, but I like this place. Keep a lid on it I'm not happy, in fact I'm quite sad. The weather Will do what it does. Whether we like it or not.) FATCHAD

[johnholmes]

looking again at the AO and NAO they do show rather more inclination towards zero or below than above, both of them, and the PNA shows zero or above more than below. So for what it is worth they do tend to support, at the moment, the idea of the Atlantic not powering up.

[Someone from the South]

the pdf I promised

 

What might the upper air pattern be as we move into December-22 nov 13.pdf

I very rarely actually post in here but I do spend a worrying amount of time reading through the threads (particularly the MOD thread) trying to understand and learn more, whilst looking forward to the next bout of interesting weather. I know its not strictly on topic but wanted to specifically say thanks for the time and effort you put into the forum - the PDF you uploaded a little while ago being a prime example of what I'm talking about. I'm sure I speak for many newer members and lurkers alike when I say lots of your posts like this are very helpful and very much appreciated! Keep them coming!!

[yorkieblade]

Hi , Sorry for this in advance mods, I noticed some educational links posted on here a while ago on how to read the models , I wonder if anyone has the links to hand - much appreciated in advance

[Mucka]

GFS 18z looks more likely to provide some FI fun than the 12z did as the high is displaced West and the trough sinks into Europe. how amplified the pattern is behind is anyones guess but I wouldn't mind being in this situation at 192h or at least I would much prefer it to the 12z

 

 

Oh

 

 

Didn't see that coming.

 

Another delay.

Edited November 22, 2013 by Mucka

[yorkieblade]

the pdf I promised

 

What might the upper air pattern be as we move into December-22 nov 13.pdf

Just echoing what many others probably think JH - very informative and concise to us novices, your posts are never agenda driven, just how you see it . Thank you JH, keep up the great work

[gottolovethisweather]

Well, further to my rather sarcastic but realistic posting from earlier and having now read JHs input (very helpful indeed) I feel it is a case of being stuck in a rut somewhat I'm afraid.  The only slight changes witnessed could be showers skirting the East of the UK on Monday then a day or two blip of something slightly milder by next Wednesday and Thursday as stressed by Summer Sun. Friday looks to be a possible changeover date at this range, at least according to my least favourite run, the GFS 18z. Early December is where its at for something different right now, given some upheaval starting to show up in the Stratosphere forecasts (if I'm reading them correctly?). Anyway it's all good fun and the thrill is often in the chase, if you ask me.

Edited November 22, 2013 by gottolovethisweather

[johnholmes]

Hi , Sorry for this in advance mods, I noticed some educational links posted on here a while ago on how to read the models , I wonder if anyone has the links to hand - much appreciated in advance

 go to the Guides and just spend time going through the very long list of information, you are sure to find what you want in there. If not please ask. If you feel unsure about asking on the open forum then please pm me and I will try to help.

thank you for your kind post above, it is much apprecaited and for the others who have 'liked' your post-thank you

 

link to the Guides area

http://forum.netweather.tv/forum/24-learning-about-weather-and-meteorology/

Edited November 22, 2013 by johnholmes

[nick sussex]

Behind the initial differences between the longer range models upto 144hrs re the upstream disagreements concerning  the amplitude and depth of that eastern USA low there does seem a trend after this to develop a more favourable NH pattern. The detail is murky at the moment but we could be looking at a briefish nw/n flow, then a flattening of the pattern then a bit more amplification with that ridge pushing towards the Arctic from the Pacific side, basically throwing a few punches at the PV. I don't think we're going to see a knock out blow though but perhaps a better chance of a more potent northerly towards day 10. Still problems to get a sustained pressure rise over Greenland.

 

Whats heartening if you were unlucky to be subjected to that run of dismally mild winters is that we don't see the PV wanting to stick to its normal winter hideout, generally the PV reforming to the north would send us all running to the travel agent to book an emergency trip to Lapland!

 

So overall then nothing too wintry showing in terms of detail at present but it could have been so much worse so I think we just have to keep our fingers crossed and see what the coming days bring re a better chance of a northerly towards early December.

[Ian Brown]

Ian i think we have to agree to disagree

Notably though seeing as you follow the GFS theres been a high correlation of failed westerly forecasts from the keele area - must be GFS HQ

Lol, well we were talking about something that was at day 8 plus anyway and is subject to the usual caveats at those timeframes.

 

The ECM tonight ends up back at square one and what I said last month about taking HLB for granted after the change of the last few winters is relevant, though of course very early days yet.

[TSNWK]

Morning. My take on the gfs and met 00:00, appear to have dropped the northerly next weekend, high then bouncing around and for a few days its south east of uk....yuck.

Vortex waxes and wanes throughout the run, with no split.

Pretty poor runs for coldies this morning.

[tight isobar]

Overnight runs leave a lot to be desired, in terms of cold.HP seems obsessed with UK atm,with any retrogresion via north west(Greenland) looking decidedly shabby at present!!!!

[bluearmy]

The interest remains towards the end of the first week dec. this is dependant on so many factors falling right for our part of the NH. The most important being the polar profile and we know how poor the modelling tends to be there. The vortex looking to leave a fair chunk over n Greenland/e Canada and struggling to convincingly detach it. Gem and ECM both hint at Canada becoming a low height free zone with cold blocking evident. However, until we see the vortex not dumbelling energy back towards Greenland, we will struggle to get our block to move anywhere advantageous re advecting low uppers our way. Patience required to see a model concensus of sorts. At least we aren't stuck under a zonal train whilst we wait.

[IDO]

Another GFS op outlier (four in a row), compared to the mean this morning; pressure:

The mean and most of the ens still go for the toppler next Saturday, not the op. The late stages of FI has the mean pressure falling steadily, with precipitation spikes suggesting the HP may be sinking. This ties in with the mean at T300:

Gem: Navgem:

None of the above are really zonal, it is a blocked NH profile with the PV moving west to east and stalling.

ECM keeps HP close to the UK throughout the run, T240:

Also the op says no to the toppler; too far east this run. Last nights ensembles show no clear pattern emerging yet:

Yesterday's JMA update for week 3 & 4 mean:

Still showing Higher heights close to the UK.

Interesting model watching but difficult to say where it is all going.

[Frosty.]

GEM 00z is bang on track and is still showing amazing continuity from day to day, high pressure pushed well west and ridging north, 1060 mb high across Greenland and a super trough across scandinavia with progressively colder air sweeping southeastwards across the uk.

[tight isobar]

GEM 00z is bang on track and is still showing amazing continuity from day to day, high pressure pushed well west and ridging north, 1060 mb high across Greenland and a super trough across scandinavia with progressively colder air sweeping southeastwards across the uk.

Yes frosty, the GEM is(has) been showing great consist with north west arming of HP and getting good HPA (850) into east euro. Un underated model perhaps ???!!!

[bluearmy]

Gem is good at two things. It's short term modelling pre day 4 and spotting odd trends late in its run when the other models haven't. Comparing with the ECM polar profile over the past few runs, it may well be broadly in the right area but the detail is probably out. pressure rise over Canada, yes - but has it modelled the eastern seaboard and n of Greenland right?

Edited November 23, 2013 by bluearmy

[Newberryone]

Really is a rollercoaster ride at the moment with some models toying with the idea of mid Atlantic pressure ridging north.  

Only problem being this trend seems to be forever in the far flung reaches of never never land.  

[nick sussex]

Looking at the ECM ensemble mean and spreads together with the other outputs theres a solid signal for troughing to the east/ne and cold heading into that region. The main chunk of the PV remains over Siberia. The problem is whether we'll see any remnants of this hanging around to the nw, as long as you keep the main PV to the ne/e of the UK you have a chance to get some cold south but need the trigger upstream by way of more amplification.

The ECM attempts to get some cold south between 168 and 192hrs but fails as theres not enough amplification to help pull the high further to the nw. In terms of the possible northerly toppler suggested earlier by some of the models for around the 144hrs timeframe the deep low heading out of the ne USA is too flat and the energy just spills east so for the timebeing I think this brief window has closed.

What we have seen over the last few weeks is the models overdoing upstream amplification in their later outputs so should bear this in mind, until any more favourable synoptics survive to well within 144hrs then I'd be cautious about them verifying especially if they suggest a northerly.

Edited November 23, 2013 by nick sussex

[bluearmy]

Looking at the ECM ensemble mean and spreads together with the other outputs theres a solid signal for troughing to the east/ne and cold heading into that region. The main chunk of the PV remains over Siberia. The problem is whether we'll see any remnants of this hanging around to the nw, as long as you keep the main PV to the ne/e of the UK you have a chance to get some cold south but need the trigger upstream by way of more amplification.The ECM attempts to get some cold south between 168 and 192hrs but fails as theres not enough amplification to help pull the high further to the nw. In terms of the possible northerly toppler suggested earlier by some of the models the deep low heading out of the ne USA is too flat and the energy just spills east so for the timebeing I think this brief window has closed.What we have seen over the last few weeks is the models overdoing upstream amplification in their later outputs so should bear this in mind, until any more favourable synoptics survive to well within 144hrs then I'd be cautious about them verifying especially if they suggest a northerly.

 

the trend on ecm/gem is to raise the n american heights overall and form a  block over e canada. that should draw our block northwest. should that happen,  if we are left with a greenland lobe of p/v,  i suspect cool/cold 'zonality' will ensue with the troughing digging to our se. the alternative is a proper cold spell as the pattern really amplifies to our west.  an above average return on temps through the first week or two of dec seems very unlikley.

Edited November 23, 2013 by bluearmy

[jgunn01]

Frosty you make me buzz..."Supertrough" is a different level though..

[Summer Sun]

ECM isn't interest as much this morning for a full on northerly with high pressure clinging on to our west we have a short live north westerly instead before the high gets back in control

 

 

The 850's are not overly low either

 

 

GFS has also removed the northerly

 

Edited November 23, 2013 by Summer Sun

[draztik]

Moving forward, there is now a consistent trend from the ensembles showing heights rising to our NW and troughing to our NE. The EPS ens highlight this by day 12 on this mornings run.

Heights & temp anomaly / ECM EPS ens 0z

[Summer Sun]

Latest from Gibby on the 00z models

 

All models show High pressure the dominating factor to our weather centred down to the West or SW. As a result dry weather will ensue for most areas with the exception of isolated showers near coastal areas. Frost and fog patches will be commonplace over the coming days but will be tempered in amounts for a period towards the middle and end of next week as winds back more towards the NW and strengthen somewhat carrying cloud and some rain towards the north and East midweek, clearing again by the weekend with a return to similar synoptics as we have now with High pressure well in control likely to be centred over or close to Southern Britain.

 

GFS shows very little change through it's latter stages this morning. As our High declines SE'wards later then a new one takes control near to the SW separated by a spell of rain on a cold front. This means that frost would then return late in the run as the weather settles down once more for most away from the far North.

 

UKMO closes it's run this morning with High pressure close to the SE and to the West with a weakening trough dissecting the two. So some cloud and a little rain looks like moving East or SE late next week to be followed by a return to High pressure based weather with frost and fog patches.

 

GEM shows a much more aggressive NW flow developing later next week with gales and rain at times in the north and East while the South and West hold on to largely dry and breezy conditions with plenty of cloud hence little in the way of frost and fog later.

 

NAVGEM also highlights a strong NW flow late next week and the weekend with rain reaching Northern areas with the South staying dry, breezy and rather cloudy with average temperatures.

 

ECM too shows a short spell of NW winds when the North and East in particular might see some rain but this becomes quickly replaced by High pressure building across the UK from the Atlantic with a return to fine and dry conditions with frost and fog patches night and morning.

 

The GFS Ensembles continue to show largely normal conditions for this time of the year with temperatures never straying far from either side of average. However, with High pressure around especially in the South frost and fog is possible at times as well as some rain later as Low pressure to the North allows front to cross the North in particular in the second half of the run.

 

The Jet Stream remains to the North of the UK and shows that the main core of the flow remains there for the foreseeable future with the direction turning SE over Europe as it sinks down on the far Eastern flank of High pressure near to the UK or in the Atlantic.

 

In Summary very little has changed today with a High pressure dominated pattern persisting. There are short intervals when weakening troughs could cross down over the Uk from the NW with a little rain but the pattern is always favoured to reset once passed to maintain the anticyclonic theme with any meaningful rainfall held well to the North and NE. Frost and fog will continue to be a feature especially early and late in the period with a milder interlude midweek lessening this risk for a time as increasing winds and cloud in association with one such trough crosses SE later next week.

 

http://www.norton-radstockweather.co.uk/Model-Analysis%282859336%29.htm