Model Output Discussion 12z 07/11/2012

[Mucka]

It all goes downhill in the lower resolution part of the GFS, the earlier timeframe was fine.

The UKMO however looks progressive with the pattern further east, normally the GFS 12hrs would be doing this but the UKMO makes even more of that low running east into the main trough.

Depends on how you project the UKMO would go, it is actually much more amplified to the East than GFS which did indeed push more energy NE and have a less southerly tilt to the jet in the crucial medium term so UKMO might better stall the Atlantic later as the trough to our NW drops SE and reinforces the Scandi ridge.

http://www.meteociel...44-21.GIF?13-17

http://modeles.meteo...nh-0-144.png?12

Edited November 13, 2012 by Mucka

[Continental Climate]

not that great a start from the 12zs too much energy in the northern arm and no sign of undercutting at all really, i personally think that this will be the correct solution this 'time' however there is still plenty of TIME left its only november

[Radiating Dendrite]

... and flow all the way from the North Pacific across the Arctic. Stunning run, tropospheric vortex obliterated.

Quite.

I would rather a pressure rise to the West early in Winter, A scandi would not deliver much at this time of year.

Once again a run shows strong northern blocking......the specifics are not required at this stage.

[Ian Brown]

A progressive GFS and the main theme is the low heights to the NW, essentially held in by the pressure patterns around them, though I suspect that sunsequent runs will take the northern arm of the jet further East.

... and flow all the way from the North Pacific across the Arctic. Stunning run, tropospheric vortex obliterated. This starts to get modelled t192 and is now starting to tick through the timelines. Look West !!!!!

I don't agree because with the -PNA you are not going to get High Pressure moving East from the seaboard to Greenland - simply not a practical synoptic evolution.

[johnholmes]

I am a bit puzzled at this almost obsession with 'undercutting'. I assume folk mean the surface low to somehow dive under the surface high east and NE of the UK?

Ignore the surface and look where the 500mb trough is, the major part of it, does it show any sign of moving beneath the upper high? If not then it is pointless looking at the surface charts as they stream out looking/hoping for that to happen.

Nothing in the NOAA, ECMWF and GFS has suggested that over the past 6-10 days, that is for it to be happening over the next 24-72 hours.

The NAEFS output for 12z does show the ridges (upper) east and west combining in the 24-60+time frame. But it then re establishes the main trough/low at 500mb and keeps it there from T+72 onwards.

[Eskimo]

not that great a start from the 12zs too much energy in the northern arm and no sign of undercutting at all really, i personally think that this will be the correct solution this 'time' however there is still plenty of TIME left its only november

With 2 weeks still to go until the potential arrives? A lot more twists and turns yet, a lot more than you think. Teeny bit of consistency in the GFS now.

[Met4Cast]

... and flow all the way from the North Pacific across the Arctic. Stunning run, tropospheric vortex obliterated. This starts to get modelled t192 and is now starting to tick through the timelines. Look West !!!!!

Exactly! To anyone thinking that this is a bad run, its anything but! Northern Hemispheric view to show that GP has alluded to above

[Tim Bland]

Not a bad 12Z! Low digging into Europe, Hights over greenland, PV is ripped to shreads... Wouldn't mind entering Dec with a set up like that! Could also be a lot of snow over hillier areas !

[johnholmes]

. Look West !!!!!

I was beginning to think much of the time I was a lone voice in the wilderness!

[UV-RAY]

A progressive GFS and the main theme is the low heights to the NW, essentially held in by the pressure patterns around them, though I suspect that sunsequent runs will take the northern arm of the jet further East.

I don't agree because with the -PNA you are not going to get High Pressure moving East from the seaboard to Greenland - simply not a practical synoptic evolution.

It may not be practical but it's certainly plausible Ian.

[chionomaniac]

I don't agree because with the -PNA you are not going to get High Pressure moving East from the seaboard to Greenland - simply not a practical synoptic evolution.

The PNA doesn't drive the weather in the same way as the NAO doesn't, Ian. It is purely another indice to measure pressure differentials.

[weatherguy]

Just a reminder to all....We still have >2 weeks to go until winter yet!

Yet another fantastic run from the GFS though, with the PV being split and heights building to our west. I've been seeing the charts showing exactly the same trends for a fair few days now...not sure what people are panicking about?

[Alan Medlock Valley]

Just a reminder to all....We still have >2 weeks to go until winter yet!

Yet another fantastic run from the GFS though, with the PV being split and heights building to our west. I've been seeing the charts showing exactly the same trends for a fair few days now...not sure what people are panicking about?

I think some people are just being cautious, nothing nailed on yet. There may be downgrades or upgrades yet, who knows before the last week of the month.

[Continental Climate]

Just a reminder to all....We still have >2 weeks to go until winter yet!

Yet another fantastic run from the GFS though, with the PV being split and heights building to our west. I've been seeing the charts showing exactly the same trends for a fair few days now...not sure what people are panicking about?

Maybe because these charts you talk about are way into FI and are not getting into the reliable, i keep reading about not trusting anything past 144 and here is everyone saying look at these great charts at t300 as though they are gospel. its all very confusing

[EML Network]

Mmmm ....shame the GFS doesn't go out another 24 hours, not too sure what would come after 384...looking at that chart I'd say it would be a brief northerly incursion , with the cold air being mixed out...still at least the charts are trending towards a cold spell so it's a little step in the right direction, but a step back from getting an easterly

still at 1.1.2: territory

Edited November 13, 2012 by EML Network

[J10]

Not as detailed as some but my two penneth,

If you look at the current synoptic pattern it is looking rather ominous with a Bartlett style High over Europe and Polar vortex starting to takes it annual trip into Greenland.

However moving into the Medium Term/FI there are signs that Pressures are building over Greenland coupled with that the Jet continuing to be a long way south, with Channel lows being forecast and at least there are opportunities. Hopefully these will move into the more realistic time frame, so currently the improvement over Greenland start around T+180 and T+200, hopefully this will make it to T+100, by the weekend.

So I am looking at the this more at the moment, than the eye candy at the end of the run. As an example yesterday, there was a Scandi High, today a massive low over Scandi.

Edited November 13, 2012 by Jackone

[offerman]

Well looks like my hopes for cold are dashed for the short term. Mind you winter hasn`t officallly started yet so get all the mild rubbish out the way now so when the real cold hits then let it be in winter so we can get the maximum depths out of it for that seasonal feel.

Just saw last 3 frames and improves things a little but to far out and charts up and down.If these charts start to show within a week projected ahead then i`ll start to take more notice rather than look to far ahead.

Edited November 13, 2012 by offerman

[weatherguy]

I think some people are just being cautious, nothing nailed on yet. There may be downgrades or upgrades yet, who knows before the last week of the month.

Oh of course, I'm just saying there's no need to get so worked up when we're so early on in the year! Yes it's exciting and the signs are all looking very promising IMO for something after 2 weeks, but no need to be nervous yet...plenty of time to chase the elusive cold spell

Maybe because these charts you talk about are way into FI and are not getting into the reliable, i keep reading about not trusting anything past 144 and here is everyone saying look at these great charts at t300 as though they are gospel. its all very confusing

You're right in saying it's unwise to look into FI as anything like gospel, rather just use it as trend watching. The trends indicate cold may be on its way, and it's good to grab the attention, but we won't know exactly until it starts getting within a more plausible time frame.

[weatherguy]

And sorry for the double post, but it's on a rather different theme...

Even if the possible easterly looked to come off, would it really deliver much in the way of cold at this time of year? Yes I know that surface cold may be more important when looking at an easterly than the upper air temps, but those uppers still look very mild over the continent.

[Isolated Frost]

Just had a peek at the GFS suite-

Off it's rocker! It's a beauty- tropo vortex completely dismantled- straight meridional flow- and a superb American stream/flow.

[Met4Cast]

And sorry for the double post, but it's on a rather different theme...

Even if the possible easterly looked to come off, would it really deliver much in the way of cold at this time of year? Yes I know that surface cold may be more important when looking at an easterly than the upper air temps, but those uppers still look very mild over the continent.

I see this same argument come up over and over again.

Last nights 18z is proof of how quickly things can change. Under the right Synoptic temperatures across Europe will fall very, very quickly

[bluearmy]

more evidence that we are possibly approaching a win/win situation (probably last seen in nov/dec 2010). the end result being blocking in the greenland area. we may get a block to our northeast before that but its not an essential part of the equation to get to a cold scenario. (though it would be preferable as it gives us a two pronged approach to get to the cold).

anyone (ian apart) want to suggest we get a two day toppler out of all this !!!!!

[chionomaniac]

Hi all,

We are trying to keep this thread informative and relevent to the models . If you see your post disappear then I apologise but it probably was a non specific comment without too much model comment.

Please try and keep on topic and with relevence. Thanks

[NorthernRab]

Well looks like my hopes for cold are dashed for the short term.

But none of the models were suggesting cold in the short term? Unless of course you're referring to the last week of November, in which case the fact that the GFS is still showing a disrupted vortex is indicative of the fact that it's still very much all to play for!

Take a look at this profile of the Northern Hemisphere:

No deep purples over Greenland / no large vortex and a northerly flow across the UK. Not a bad outlook for traditionally one of the most zonal periods of the year!

[offerman]

EML, A notherly might be better than an Easterly, The Easterlies of the 80`s were good , granted, but the 3 winters before last years bought good snow from lows running in or developing from the west or southwest and hitting in to the cold arctic air brought about by a huge Greenland High to Northeast Somerset.