Model Output Discussion - Tuesday 20:25 -->

[cooling climate]

One last post from me, the cpc charts are very bullish about a northeasterly airflow over nw Europe

in the 6-14 day frame.

In their synoptic discussions they also talk about a - NAO for next fortnight.

Something to chew on, night all.

[Guest North Sea Snow Convection]

Agreed

To be honest the 18z brings the colder air in much quicker, and obviously the uppers are generally -5 to -6 at best.

Forget about this chart, it might be the worst for snow lovers etc, but in modeling terms it's a very good run, as it will bring a different pattern of weather to our shores.

http://www.wzkarten....s/Rtavn2761.png

Thats the re-load point on that chart. The jet will be further south, there is a reason there's such bold predictions for deeply negative AO, the northern blocking will be more pronounced.

Another benefit is that nothing changes drastically in the stratosphere according to GP, so theres no reason the PV should reform as suggested in the 18z. I suspect the 18z will be one of the warmer ensemble members, the parallel looking much better.

Lewis

I totally appreciate that most of us want to see a snowfest agreement take place across the models in terms of the 'right sort of easterly'. But it is not ever going to happen day by day, run by run, in a nice cozy sequence that way.

Assuming the ideal basic pattern (as described) holds true and is consolidated in terms of agreement between the models over the next few days this week, then we can start to look at 'can it snow, will it snow, is it a stratoform easterly or a big fluffy cotton wool convective easterly nearer the time. Atm we are seeing a broad theme, with varying solutions within that theme in terms of weather type - that within each six/twelve hours changes radically - and then yet and another type is suggested. And people go through all the uneccessary bends and stretches with the rollercoaster.

No point in wasting breath and heart beat in terms of analysing what this or that model shows in terms of actual 'weather' at 7am or 7pm on whichever day it is, several days out ( like it is going to happen in reality that way)

This is all different of course to enjoying the output when it comes out and shows a blizzard at t174 - on the basis that is taken as a bit of cyber fun with a pinch of salt that is never going to happen like that

Edited December 8, 2009 by North Sea Snow Convection

[Mark Bayley]

GFS ensemble's are excellent if not slightly better than the 12z ones. As KW said the operational will have a better handle on the short wave situation being in higher resolution but its great to see the ensembles carrying on the trend towards much colder conditions.

Edited December 8, 2009 by mark bayley

[nick sussex]

The enembles still ging for the older style of shortwave direction, and in turn look pretty good overall...still can't ignore the fact that the op runs have higher resolutin and will deal better with short term shortwaves better.

Once again, it is very nice looking at very good northern blocking in December, but its all rather useless if it doesn't actually give much in the way of cold conditions, practically you may as well just keep a cold high over the UK for all the good such good synoptics give to the UK on the 18z.

Good grief KW did the dog chew up your winning lottery ticket

We've got days to go before knowing what exactly will happen, at least theres been no major drama with the gfs 18hrs run, if i'd have thought an air of gloom would decend on the place i would have had extra telephone operators manning the prozac helpline!

Lets just wait and see what happens in the morning, i'm sure there will be more twists and turns!

[Mark H]

Not looked through them all but there are some pretty cool looking ensembles tonight. I like this one!

http://91.121.94.83/modeles/gens/run/gens-11-1-192.png?18

[SP1986]

I have seen equally as strong patterns go down the drain, the prospects still look good at the moment, but even with good signals I doubt the rollercoaster has even started yet!

[Cecil Hogmanay Melchett]

Nice euro's this evening guys,

As long as ecm/ukmo look good i couldn't personally give a hoot what gfs operationals say.

As IB said earlier,gfs will make a song and dance and then come crawling in the end,i agree with him 100%.

All that said,i dont think its beyond the bounds of posibilty to wake up to a similar ecm to this morning although

tonights outputs must put that in the unlikely category now.

We are fast reaching the timeframe where we can be assured the high will ridge north but for me the next chapter

then opens and thats all to do with the shortwaves and their behaviour in advecting the cold air west.

Even if the artic based air doesnt reach us its still going to get cold and with a frigid continent by mon/tues

next week any feed at all from east will be cold,which,for now will do me nicely.

Anyone doing an all nighter?

[PersianPaladin]

I have seen equally as strong patterns go down the drain, the prospects still look good at the moment, but even with good signals I doubt the rollercoaster has even started yet!

We've entered the theme-park and yet to pay for the tickets, as far as I'm concerned.

[Geordiesnow]

The enembles still ging for the older style of shortwave direction, and in turn look pretty good overall...still can't ignore the fact that the op runs have higher resolutin and will deal better with short term shortwaves better.

Once again, it is very nice looking at very good northern blocking in December, but its all rather useless if it doesn't actually give much in the way of cold conditions, practically you may as well just keep a cold high over the UK for all the good such good synoptics give to the UK on the 18z.

To be fair Kold, UKMO 00Z, GFS 06Z, ECM 12Z and the smaller models has all shown what the ensembles are showing so all the big 3 suggested this could happen regarding the shortwave. I for one hope it will happen as colder air over us is a much bigger possibility than say what the GFS and perhaps the UKMO 12Z is showing.

I don't think it would take much shift in the pattern for the GFS 18Z to become a very good run though.

[Paul Sherman]

I have seen equally as strong patterns go down the drain, the prospects still look good at the moment, but even with good signals I doubt the rollercoaster has even started yet!

But equally Strong Patterns and near identical Set-Up do sometimes go right

4 days b4 "The Event" - Looks Similar you gotta admit

[Lewis]

Good news operational is on the warmer side but too much disagreement from day 3

Day 5 its ridiculous;

[smhouston]

I'm surprised no-one has commented on the ensembles! I think they're cracking with a mild outlier from the 17th

I still don't think it'll happen but it does get more encouraging as time goes by, especially with the ECM now on board.

[Mark Bayley]

If carlsberg made ensembles they would make them like this !

Just had a look a P7 and its outstanding Cold from T168 onwards, would certainly see some snow with that, those southerly tracking lows would be good as well

So we have a great ensemble set from both the ECM and GFS, very good UKMO and ECM, some good lesser models and an alright GFS op however the main cold doesn't reach. Another exciting model watching day tomorrow

Edited December 8, 2009 by mark bayley

[Guest North Sea Snow Convection]

Good grief KW did the dog chew up your winning lottery ticket

We've got days to go before knowing what exactly will happen, at least theres been no major drama with the gfs 18hrs run, if i'd have thought an air of gloom would decend on the place i would have had extra telephone operators manning the prozac helpline!

Lets just wait and see what happens in the morning, i'm sure there will be more twists and turns!

Actually the real models show a Bartlett, huge vortex over Greenland and tramline isobars from the Azores to Russia - but ssh don't want to spoil the mood!

Night all - sleep well and dream of big fluffy flakes against your window

Edited December 8, 2009 by North Sea Snow Convection

[kold weather]

Good grief KW did the dog chew up your winning lottery ticket

We've got days to go before knowing what exactly will happen, at least theres been no major drama with the gfs 18hrs run, if i'd have thought an air of gloom would decend on the place i would have had extra telephone operators manning the prozac helpline!

Lets just wait and see what happens in the morning, i'm sure there will be more twists and turns!

Yeah your right there will be more twists and turns, I've learned though over time when the GFS picks up such a trend with a shortwave others do tend to follow, I suppose thats why I'm little more worried about this whole thing. The basic framework looks solid though I grant you that and its a good thing at this stage. Just would be a shame to see stunning synoptics totally wasted, I think thats the most gutting of all set-ups...

Still things could be an awful lot worse and the ensembles looks solid with regards to cold and possible snow...and most of all they don't agree in general with the murky cloudy high situation we see on the GFS op runs. Fantastic European models, fantastic ensembles, just not quite the full works just yet!

18z run a mild outlier at the start of FI which is some good news. Op run is also upgrading the intial easterly shot.

Edited December 8, 2009 by kold weather

[Optimus Prime]

The thing that worries me most in the models is you never hear very cold easterly spells occuring in December like you do January and February. In fact has there ever been a really bitter and snowy E/NE in December?

[Paul]

Models, models, models!!

Please stay on topic folks - general chat and other threads are available elsewhere..

[Paul]

For those who may not have seen it yet, we have a new thread called 'My Model Summary', which is hopefully going to be a slower paced model discussion with the aim that people will post their (technical and non technical) summaries and overall opinions on run's as a whole (as opposed to the more fast flowing commentary and comments about smaller aspects of each run in this thread).

It's a new thread which has been created after the feedback from many members this week in the thread we started and we're really hoping it'll be a good addition, so it'll be great to see some summaries and overall opinions/thoughts on the run being posted in there to get it going from this evening's 18z

[weather eater]

Hi Tamara

Yes theres too much worry about detail which is likely to change many times. I remember many moons ago some great charts that showed almost -20 upper air getting close to the uk, each run changed this with one time northern areas getting the coldest , then the south, much debate about the 850's then the whole thing imploded! Theres no point of dreaming about the snow and the sledging and perhaps the odd day off work if you don't get past the first hurdle. For the timebeing for me the only thing that matters is events upto 144hrs.Once we have agreement from all the models then we can see whats in store, given so many previous let downs each run that goes by without major calamity is a big success!The things to concentrate on for me and not being too simplistic is this, block to the north, elongated atlantic trough running north/south over eastern us and canada, low pressure to the south extending into the med, as the gfs 18hrs still has this then great.

A spot on assessment Nick, all I'm worried about at the moment is that nothing scuppers the building blocks, past 144hrs the output will change and change again several times, sometimes nice to look at, other times less so, but pointless getting worked up over. As others have said the parallel run is another blinder, and right or wrong it has been remarkably consistent, in fact I would go as far to say, the most consistent modelling that I’ve ever seen over several days from any of the majors.

[Duane S.]

But equally Strong Patterns and near identical Set-Up do sometimes go right

4 days b4 "The Event" - Looks Similar you gotta admit

I've been marvelling at the similarites for a few days now. Very impressive.

My last post for tonight and I'll post what I have posted for the past few nights. Another day gone by, no major downgrades in 24 hours = an upgrade.

Getting closer...

[LomondSnowstorm]

I've been marvelling at the similarites for a few days now. Very impressive.

My last post for tonight and I'll post what I have posted for the past few nights. Another day gone by, no major downgrades in 24 hours = an upgrade.

Getting closer...

Well summarised. The dream cold spell is still feasable, and if charts like the 12Z ECM are still there by tomorrow, things start to look very good indeed.

LS

[Thundery wintry showers]

The thing that worries me most in the models is you never hear very cold easterly spells occuring in December like you do January and February. In fact has there ever been a really bitter and snowy E/NE in December?

There's been plenty over the years, but instances of large scale northern blocking, and particularly omega blocks, are hard to find prior to Christmas. December 1890- the coldest and dullest on record- had persistent easterly winds, and there were very cold easterly outbreaks in late Decembers 1927 and 1938. Christmas 1956 had a snow cover in many areas from an Atlantic vs continental air battleground. Late December 1970 had an easterly incursion that brought significant snowfalls in the south, albeit somewhat less so in the north.

There was some pretty impressive northern blocking earlier in the season, in Novembers 1965, 1985 and 1993, and also at the very end of November 1947. But as a general rule snowy Novembers and Decembers tend to be characterised by predominantly northerly winds, with easterly winds being recurrent features of most snowy Januarys and Februarys.

But whatever, we are staring at a pretty unusual synoptic setup for the time of year so past mid-December analogues aren't going to help much here. The GFS 18Z doesn't change my stance on the upcoming spell- it illustrates the main way in which we could end up cold and dry rather than cold and snowy, but I don't think its evolution is very plausible- this morning's 00Z ECM would be a more likely way to that scenario.

[kold weather]

Also providing we get that easterly airflow with high pressure over the top of it then the system won't just implode like the 18z op run does.

Anyway TWS, your right its pretty unusual, and the thing is we are very likely going to get some decent northern blocking, its impressivly early in the season for sure blocking. Should we get another big warming event in December then odds are we will have a very cold month before this winter is out.

The most pluasable solution if we do get an easterly will be an attack from the SW, the GWO charts at stage 4 would suggest low pressure in the Atlantic but if we have a easterly airflow and a high to the north it could be a very long process. In many ways I'd expect a breakdown similar to the 12z GFS...of course gotta get into the set-up first!

[Matty M]

The models are full of massive potential.

We must respect the intensity of the cold pool to our east.

http://www.wetterzentrale.de/pics/Rtavn1442.png

I strongly believe the power of this Arctic high is being underplayed by most if not all models.

I think by the end of next week we could well be shovelling ourselves out of our homes in an historic freeze.

Things will begin to move fast towards the weekend modelwise.

[TEITS]

I think by the end of next week we could well be shovelling ourselves out of our homes in an historic freeze.

Now thats the kind of ramping I like to see.

I haven't commented on the models this evening due to the fact that the I don't have much confidence in them at the moment, plus i've been too busy playing Modern Warfare 2.

Now im pretty confident of the block developing but I can't see the point of worrying about how cold its likely to be due to the continuing changes in the models even in the +72 timeframe.

At the moment im just enjoying the current output and taking each day as it comes.