Model Output General Discussion

[johnholmes]

updated blog for rest of this week

http://forum.netweather.tv/topic/57953-the-predicted-pattern-change/page__st__34__gopid__1640713&

[snowmadchrisuk]

The Atalntic is really struggling to get back control at 168 ECM, If this cold spell lasts till the new year I will be most happytastical!

That has got to be Word of the week "Happytastical" Love it ECM has the break down somewhere between +168 and +192 but 850's look like a really heavy snowy breakdown for the Midlands.

[nick sussex]

For those hoping the ukmo is wrong in its later output heres a little good news, the ukmo verification stats have dropped sharply over the last few days.

http://www.emc.ncep.noaa.gov/gmb/STATS/html/acz6.html

The gfs 00hrs doing the best with the ecm just behind. I think this is the last update before the parralel run took over which is doing very well.

Edited December 15, 2009 by nick sussex

[Yeti]

Interesting precipitation amounts here at 144:

http://www.wetterzentrale.de/pics/Rmgfs144sum.gif

Given that most of that would fall as snow - particularly in the North - there are some pretty impressive totals there, especially in the NE.

Obviously only a very rough guide but I think it highlights roughly how the distribution of precipitation will fall.

[Harsh Climate]

I wouldn't say it was "inevitable" just possible, like the fact we could get another massive model flip in the next fews days that keeps us cold, just like the backtrack over the weekend.

As they say "more runs needed".

Mate, finding a run that shows no sign of a breakdown early next week is like trying to find a needle in a haystack.. The trend has been quickly growing over the last few days for a breakdown, but I do think most models are being a little progressive.

http://www.wetterzentrale.de/pics/Rtavn1921.png This chart illistrates nicely what would go wrong.

1. WAA across greenland GONE

2. Our greeny high slipped too far north west/loosing its grip over the uk.

3.The strength of the atlantic is unleashed, with no real block in the way there is nothing to stop it bursting through. If we had heights to our north, maybe it could undercut and cause a new block to re-establish itself or pull in a n eastery.

Chances of a breakdown tue to fri Id put at about 90%, there is still a small amount of time for a change but we need to start seeing that now..

Edited December 15, 2009 by Jed Bickerdike

[michail]

Interesting to see the jet still so far south at 180hrs, wouldn't this help to keep the heights to our north?

[Guest]

updated blog for rest of this week

http://forum.netweather.tv/topic/57953-the-predicted-pattern-change/page__st__34__gopid__1640713&

Thankyou for the update John, these synoptics are just amazing. I know I'm getting way ahead of myself but the similarites to Dec 1995 are becoming increasingly seductive for a wild ramper like me.

On balance how much of a chance of a complete downgrade do you think there is??

[Yeti]

Mate, finding a run that shows no sign of a breakdown early next week is like trying to find a needle in a haystack.. The trend has been quickly growing over the last few days for a breakdown, but I do think most models are being a little progressive.

http://www.wetterzentrale.de/pics/Rtavn1921.png This chart illistrates nicely what would go wrong.

1. WAA across greenland GONE

2. Our greeny high slipped too far north west/loosing its grip over the uk.

3.The strength of the atlantic is unleashed, with no real block in the way there is nothing to stop it bursting through. If we had heights to our north, maybe it could undercut and cause a new block to re-establish itself or pull in a n eastery.

Chances of a breakdown tue to fri Id put at about 90%, there is still a small amount of time for a change but we need to start seeing that now..

What's all this about WAA? As I understand it stands for Warm Air Advection - now that happened a few days ago up the Eastern Seaboard as the block was carved out, but for example by the time we reach 120 there's no warm air advection anywhere near GL...

http://www.wetterzentrale.de/pics/Rtavn1201.png

[Frosty.]

Just been catching up, reading all the posts with all the mood swings present and correct. Another cracking ECM run which is very similar to the 00z version by keeping the uk locked into a cold spell all the way through with the jet remaining well to the south of the uk and lows not being allowed to push milder air in. The GFS 12z seems to put a lot more energy into the atlantic with a very deep depression to the sw around xmas day, now if that low has been artificially boosted too much it might allow the cold block to remain intact until after boxing day but i'm sure the uk will be under constant attack by then with the atlantic desperate to take control. What could this mean...a snowy breakdown before milder air wins or for renewed heights to the north and northeast altering the jet in our favour and keeping us in the freezer.

[nick sussex]

Any chance of you or Steve M doing a summary of the next few days and a comparison with what the models were showing a couple of days ago? - just seems a tad of a downgrade for us here in BTL and the south west. Cheers

In terms of comparison we should remember that the pattern shown has been consistent for many days, in these situations however detail more than 48hrs out is very difficult, especially with easterlies where the exact flow ie ene ese can make a big difference.In terms of a summary I think i'll leave that to SM as he's the expert on those !

However I will be boring everyone with a look upstream to the USA to see how this impacts downstream in europe and also trying to pull apart the ecm ensembles, perhaps some renewed optimism regarding the Xmas period. I suspect a crucial day in the output tomorrow where hopefully the ukmo will enter the Xmas spirit!

For the moment I wouldn't get too downhearted, the key is the longer the cold spell lasts the more surprises often pop up.

Edited December 15, 2009 by nick sussex

[Harsh Climate]

What's all this about WAA? As I understand it stands for Warm Air Advection - now that happened a few days ago up the Eastern Seaboard as the block was carved out, but for example by the time we reach 120 there's no warm air advection anywhere near GL...

http://www.wetterzentrale.de/pics/Rtavn1201.png

There is look at the yellow colours, that highlights it well. But notice as soon as thats gone the atlantic starts to make inrodes through the block.

[swfc]

on the 240 ecm chart is there a slight rise in pressure to the north east or is it just a slack area of low pressure.thanks

[Tom D]

on the 240 ecm chart is there a slight rise in pressure to the north east or is it just a slack area of low pressure.thanks

It's a very slack, shallow low pressure.

Edited December 15, 2009 by Tommyd1258

[Yeti]

There is look at the yellow colours, that highlights it well. But notice as soon as thats gone the atlantic starts to make inrodes through the block.

The colours represent the geopotential heights though at 500hPa so that's not WAA; the yellow would indicate very strong heights whereas the blues show troughs and lows higher in the atmosphere than can be detected at sea level. But yes as you say later on the heights crumble and move west to give a -ve NAO that sets up too far W (current pattern subject to change).

[cyclonic happiness]

Mate, finding a run that shows no sign of a breakdown early next week is like trying to find a needle in a haystack.. :blink: The trend has been quickly growing over the last few days for a breakdown, but I do think most models are being a little progressive.

http://www.wetterzentrale.de/pics/Rtavn1921.png This chart illistrates nicely what would go wrong.

1. WAA across greenland GONE

2. Our greeny high slipped too far north west/loosing its grip over the uk.

3.The strength of the atlantic is unleashed, with no real block in the way there is nothing to stop it bursting through. If we had heights to our north, maybe it could undercut and cause a new block to re-establish itself or pull in a n eastery.

Chances of a breakdown tue to fri Id put at about 90%, there is still a small amount of time for a change but we need to start seeing that now..

I was putting all of my eggs in to the basket marked "reload", I'm hoping that the low at xmas will undercut britain and force a new easterly, I'm not at all convinced of this breakdown though, and feel there will be a continuation until just past new year.

the gfs show the Atlantic trying to break through in FI only for it to stall before it has a chance to get going and the ecm shows another attempt by the Atlantic to get going, but i think this will fail too and that we will stay in a mainly cold cyclonic rut until something comes along to change it.

there doesn't really seem a good enough marker to kick start the atlantic into it's default.

Edited December 15, 2009 by cyclonic happiness

[tinybill]

Jed, you've been talking about "the breakdown" since last Friday. Give it a break.

well any sign of a breck down you can look dep in to f1 to at least

dec 27 and that can change

[Nick L]

well any sign of a breck down you can look dep in to f1 to at least

dec 27 and that can change

It's FI - Fantasy Island

[swfc]

Does the lack of any real blocking to the north at the 240 mark not contridicte any kind of extended cold spell.?????

[Harsh Climate]

You're obsessed give the breakdown thing a rest!

Ok no more telling people what they dont want to hear.

If tommorow models have backed away from the idea of a breakdown, Il be the first person to comment on that!

And dont forget this is the model discussion, Im only discussing what there showing.

Edited December 15, 2009 by Jed Bickerdike

[Upgrade]

Ok no more telling people what they dont want to hear.

If tommorow models have backed away from the idea of a breakdown, Il be the first person to comment on that!

And dont forget this is the model discussion, Im only discussing what there showing.

but Jedward, you've been banging on about it since 5 days before the cold spell started.

[phil nw.]

For us snow lovers it`s good to see a short term improvement to the severity of the Easterly about to encroach fully by Thurs.

Here`s the fax for T60hr.

The cold air fully across the UK by then and with those minor troughs in the increased flow.

Here the 850 `s

http://charts.netwea.../h850t850eu.png

We can see why the Met. are now mentioning snow for later in the week.

http://charts.netwea.../uksnowrisk.png

These charts are never spot on but i think they close enough to show what is coming.

Even at this stage some places could even see more snow than expected.I have seen in the past where the showers can merge into longer spells of snow.It really is a fluid setup.

We just about catch our breath from the Easterly and at T96hrs. we look North

http://www.wetterzen...ics/Rukm961.gif

http://www.wetterzen...cs/Rtavn961.png

http://www.wetterzen...ics/Recm961.gif

Still very cold air as well

http://charts.netwea.../h850t850eu.png

More snow for many spreading south into sunday.

Much uncertainty after the weekend as low pressure starts to show to our SW,but certainly some parts could see more wintry weather in a battleground setup.

Certainly a very engrossing period of model watching at the moment.

Edited December 15, 2009 by phil n.warks.

[Optimus Prime]

Ok no more telling people what they dont want to hear.

Arghh don't start that! I'd be the first one to welcome in the mild as I'm not keen on the cold but going on about just gets boring. We KNOW there'll be a breakdown it's certain but hopecasting in hope you'll get it right (which eventually you will) is a bit like me saying we'll reach 20c at some point...no need to word the obvious.

[Yeti]

Im only discussing what there showing.

but that is surely in your opinion.i'm all for respecting peoples opinions,but at times this is becomming tedious.

an ignore poster option would be very handy at times like this.

There is an ignore poster function, it's somewhere in settings.

Jed - I think all people are saying is fair enough if it's what the models are showing but if you're going to comment on them then post the relevant charts/data. Posts without given evidence are difficult to follow, look rather too like opinion and are often less convincing as a result.

[Upgrade]

For us snow lovers it`s good to see a short term improvement to the severity of the Easterly about to encroach fully by Thurs.

Here`s the fax for T60hr.

The cold air fully across the UK by then and with those minor troughs in the increased flow.

Certainly a very engrossing period of model watching at the moment.

Phil - i agree. It is probably the most fascinating model watching since i first came to net weather in 2005. It has all the hallmarks of a really cold, potentially really snowy, spell in the making.

[Upgrade]

put the data up then.

i dont think it's offending people,more that it has become so bloody boring to read.

lets look at whats on the way for now.

And what's on the way is a snowy, cold easterly followed by a northerly, with a good chance of a reload, or even frontal snow at times. any further out we simply don't know. only that the set up looks amazing for a long continuation of the cold weather.