Model Output Discussion

[nick sussex]

lOOK AT THE COLD building up north in FI.

If we get the right synoptics we'll get a proper freeze with all that to tap into.

Please HD don't be seduced by the dark side of the force! If it's wrong at T-120hrs then theres no hope of it being remotely right later.

[Cecil Hogmanay Melchett]

Please HD don't be seduced by the dark side of the force! If it's wrong at T-120hrs then theres no hope of it being remotely right later.

Yes,i dont think gfs is correct but one may as well comment on whats on the monitor nick.

Is anyone else beginning to wonder if gfs is really becoming a cannon fodder model?

[reef]

Please HD don't be seduced by the dark side of the force! If it's wrong at T-120hrs then theres no hope of it being remotely right later.

But how can you say its wrong when the charts in question are 5 days out? Surely the time to say whether it is correct or not is when the time has arrived!

[Mark H]

Link to the parallel run.

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=6&code=code&mode=0&mode3h=&carte=0&runpara=1

A little different to say the least.

[SP1986]

I imagine with the general trend consistency in patterns that the GFS is showing, it will probably be correct but who knows, it's an evolving scenario so it will change as and when it comes

[cooling climate]

I know its computer generated at the weekends but....

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

http://www.cpc.noaa.gov/products/predictions/814day/500mb.php

Edited November 29, 2009 by cooling climate

[nick sussex]

But how can you say its wrong when the charts in question are 5 days out? Surely the time to say whether it is correct or not is when the time has arrived!

Because no other global model backs it, its basically the ecm, ukmo, gem and together with this even the cannon fodder no gaps, gme and jma say no to its view of things, on top of this its verifying 4rth behind the first 3 i mentioned and is the one major model known to continue with a wrong prognosis well into what would be the normally reliable timeframe, so with this in mind and my general experience of the gfs especially the 18hrs and having been viewing it for a very long time I'm quite happy to call its 18hrs run a pile of nonsense and wrong, that is the case for the prosecution! please state your closing arguments for the defence?

[Duane S.]

A few one liners and off-topic posts have been removed. Please try to avoid this as it clutters the thread and makes it difficult for people to understand whats happening.

Thanks

Back to the models and I have to say that they are more confused about where we are heading early-mid December than most of us. Tonight's 18z is for sure to be consigned to the bin. My gut feeling is that we are going to be in for a coolish couple of weeks but I struggle to see a repeat of the 1980 scenarios many have akined this upcoming spell to. Still can't decide whether or not we are going to see any decent heights building to our N as well . I really thought the models would have started to settle on a trend by now but it appears not.

Edited November 29, 2009 by grab my graupel
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[weather eater]

18z resembles last nights box of frogs, mind, you could say that for all recent GFS output, it jumps around like a cat on a red hot poker. We are still no nearer seeing a clear path, past 120hrs.

[damianslaw]

Hope is fine of course, if you have this opinion then I cant fault it.

I have however this week seen references to 1981 and 1982 - so basically I've developed a little cynicism along the way but I get what you mean - In my virtually short lifetime though winter often goes through a few patterns, rather than continues the same throughout.

I would expect during December a milder pattern to take hold - obviously I may be wrong but it's a good bet based on previous years (although we havent, other than last year, really seen a cold start to winter).

We'll see anyhow.

I just hope people dont get disappointed

Taking the past 4 Decembers, a colder pattern developed in each of these as the months were on - as follows

2005 - generally average conditions until christmas week when it turned rather cold thanks to an easterly

2006 - very mild start but a fairly cold middle only turning mild in the final few days

2007 - a very mild start but like 2006 high pressure developed by mid month and again fairly cold weather held through until just before christmas

2008 - a very cold start became milder in the lead up to christmas but then cold towards end.

Not sure where you get your based on previous years from statement. In fact early december is usually the mildest part of the month often very mild indeed, colder spells tend to arrive mid month..

Back to the outlook, general theme is for unsettled weather in the short term with slow moving low pressure anchored over the country mid week, by Friday signs of pressure rising to the NE and a ridge developing, beyond this difficult to call, probably low pressure will once again push in over the country on a southerly track, mmm a pattern is beginning to emerge here - a southerly tracking jet and height rises to the north which goes against what you normally expect to see in early December - bodes well for cold as we head further into the month I feel.

[Stu_London]

Most of the colder runs on the ensembles have disappeared.

Nothing to see here - move along

As expected normal service resumed - the most severe the weather will get in the next fortnight will be over the next 36 hours.

[SP1986]

Damian I'm not saying it will go milder indefinitely, I'm just saying that that if there's a cold spell in early December, the chances are that the step after that will be a milder one (as in most cases cold pattern doesn't last 3 months except in exceptional circumstances) - that's not to say that there will be many different patterns this winter..

[SP1986]

Heres the latest ensembles (Ive chosen Cheshire because it's pretty central and I just pick this without thinking now)

After the 6th it completely loses any trend and becomes a complete mess.

Before that though it's fairly stable, and although slight cooling at 850's it shows a flattening off somewhat of the trend.

[Cecil Hogmanay Melchett]

WOW Thngs appear to be going downhill looking at the 0z runs and ens.

Bck to square one?

[Iceberg]

Yep HD I think we were back to sqaure 1 yesterday in all but name, but after the 00Z it looks like being official.

The GFS is probably a bit too blow torch, but atm cold weather is not progged, I still think there might be a pattern change to something more settled and colder come the second half of December though.

[nick sussex]

Overall not much change from yesterday evenings output with the euros and others except for the gfs bringing in lots of rain, temps average trending cooler in the north, the jet still looks reasonably south so a chance for something a little wintry on higher ground in the north.

The gfs continues to look out of place earlier on and i would dismiss it's output, if a model has picked a new trend the others would normally follow very quickly, the fact they haven't after several days suggest we'll be seeing another climbdown from the gfs later, the ability of this model to continue on the wrong path well into what would normally be the reliable timeframe still surprises me.

The gfs operational will be replaced by the current parrallel run sometime in December so lets hope this improves the model although I have my doubts.

We have seen over the last few days the models draw back from their colder scenarios with the easterly ensemble members dropped from the gefs ensembles, just one cautionary note on the output, upstream across the Pacific we are expecting some changes, this will have effects downstream in western europe, at the moment the models suggest this will release alot of colder air into the eastern and central USA and fire up the jet, this in part is responsible for the changes in output, there could still be some variability but I think at best we might see lows tracking slightly more favourably with weak height rises to the ne, there is no sign however of any prolonged colder or snowy weather but perhaps the odd colder shot of air behind these lows.

Edited November 30, 2009 by nick sussex

[Frosty.]

Disappointing GFS 00z in the longer range with mild weather returning early next week with a strong sw'ly flow and remaining unsettled with further spells of rain, especially in the north and west with drier, brighter conditions in the south & east. At this range it could of course still change and the ecm 00z has the PFJ further south next week with a rather colder but still unsettled pattern for the uk. This week looks like slowly turning less cold from the south but remaining chilly across scotland all week with snow over the hills/mountains, most areas will just have rain, heavy at times from tues night onwards but tonight is going to be frosty and tomorrow looks sunny and crisp for most of the day away from the west.

Edited November 30, 2009 by Frosty039

[Nick F]

I think the upper trough re-establishing to the W of the UK and ridging over SE Europe is the most likely outcome as we head into medium range of early December ... never really taken the potential thrown up by the models recently for a Scandi high or northern blocking with easterlies too seriously (though easy as it is to be drawn in!), as much as it would be a welcome change from wet and windy weather of late.

Still ... looks like the jet will stay to our south which will allow some frosts where skies clear and always potential for snow over higher ground. The Atlantic rain conveyor looks set to continue for a while yet unfortunately ...

[cooling climate]

The positive signs of height rises to the north seem to have imploded somewhat

this morning, the reason for this seems to be how long the ridge thrown across

from Canada can build heights to our north and over Greenland before being cut off

by a cross polar vortex from Russia into Canada.

Things could still change of course but for now it looks like the cold will stay locked

up in the north.

Edited November 30, 2009 by cooling climate

[mushymanrob]

a pretty average looking set of runs again with nothing too extreme. i might get the first 'proper' frost tonight, not bad going for me, a 'frostophobe'.

[Cal]

One for the more experienced here, with the MJO heading into phase 7 what implications may this have on our weather?

http://cawcr.gov.au/bmrc/clfor/cfstaff/matw/maproom/RMM/phase.Last40days.gif

[BLAST FROM THE PAST]

We have seen over the last few days the models draw back from their colder scenarios with the easterly ensemble members dropped from the gefs ensembles, just one cautionary note on the output, upstream across the Pacific we are expecting some changes, this will have effects downstream in western europe, at the moment the models suggest this will release alot of colder air into the eastern and central USA and fire up the jet, this in part is responsible for the changes in output, there could still be some variability but I think at best we might see lows tracking slightly more favourably with weak height rises to the ne, there is no sign however of any prolonged colder or snowy weather but perhaps the odd colder shot of air behind these lows.

I think that is pretty spot on. Nick, I think the plus will be that the jet will continue to barrel LPs over us maintaining its more southerly position. Particularly for northern locations the colder shots will be cold enough but agred that prolonged blocking/cold isn't the favoured course....yet. I should say too that there will be further likely flooding episodes in December with heightened risk as we enter the second week on as we build to a peak energy period mid month and so I think middle/northern England in particular should be on 'watch'.

BFTP

[nick sussex]

One for the more experienced here, with the MJO heading into phase 7 what implications may this have on our weather?

http://cawcr.gov.au/bmrc/clfor/cfstaff/matw/maproom/RMM/phase.Last40days.gif

Normally this indicates height rises over Scandinavia but these will probably be weak, it still hasn't got to phase 7 and the nearer it is to the inner circle the weaker its impact, you also have to take into account other teleconnections.

Regarding BFTP post, upstream there is the chance that the pattern might retrogress slightly further west and then much depends on whether theres a decent height rise to the ne to help the jet track more nw/se.

Here from NOAA they discuss this on the morning discussions.

RECENT MODEL/ENSEMBLE TRENDS SEEM TO INCREASE THE

POTENTIAL FOR THE POSITIVE ANOMALY CENTER TO DRIFT NWD INTO AK

WHICH WOULD BRING THE MEAN NOAM TROF AXIS FARTHER NWWD AND

INCREASE UNDERCUTTING SRN STREAM FLOW OVER THE ERN PAC

And finally we see the gfs as expected backtrack to the euros, yet another humiliating climbdown for the gfs.

The gfs 06hrs run upto 168 hrs looks far more likely given the pattern upstream, its important to remember that if the pattern edges west this will take the troughing in the atlantic westwards, to remain at least with average temps with chances of the odd colder shot more especially for northern areas its imperative to see at least some height rise to the ne to deflect the jet on a more favourable track through or just to the south of the uk.

Edited November 30, 2009 by nick sussex

[cooling climate]

The 06z at t144 has much better heights and ridging across the pole with the main vortex

held back over Russia. This has the potential to be a very good run.

How accurate it is I don't know.

[BLAST FROM THE PAST]

Regarding BFTP post, upstream there is the chance that the pattern might retrogress slightly further west and then much depends on whether theres a decent height rise to the ne to help the jet track more nw/se.

It seems a bit like last year that in spite of northern blocking not being prevalent/strong in our region the jet reamins further south by some margin than what we became accustomed too. This is important and will win or lose the winter. I mean if the southerly track continues, any reasonable northern blocking and 'hey presto'. The potential wetness ahead over coming weeks is a concern for me.

At short range i prefer the 06z to the 00z so I'm glad its backtracking

BFTP