Model Output Discussion 1200 hrs 15/11/14

[nick sussex]

So more drama this morning! We now see the generally more negative tilt to the troughing which helps, with a trend to colder conditions across the ECM, GFS P.

 

The UKMO/GEM look more complicated,.

 

In terms of the ECM ensembles very good support at least for De Bilt for an easterly flow over there from the 28th to the 2nd December before  more scatter.

 

http://www.weerplaza.nl/15daagseverwachting/?r=midden&type=eps_pluim

 

Will winter finally be gracing Europe? I can say for down here its been remarkable with temperatures here helped by a fohn effect hitting 25c yesterday.

Edited November 24, 2014 by nick sussex

[SLEETY]

certainly worth taking note of fergieweather said about no clear signals yet of what lies ahead,and they rarely look beyond 5-7 days .

 But it be interesting to see what mogreps is showing after its updates today,after this morning runs from the models.

[kumquat]

Oh my giddy aunt! It's all come good today. ECM 216

 

GFS 216

 

GFS (P) 216

 

 

However you look at it, the synoptic output is pretty stunning.

[legritter]

Morning ,one can look at todays output and see the sort of set up that many of us dream of ,but patience is the key untill we get to a more reliable synoptic possibility .we could finish up with high pressure sat over us in about a weeks time or in a favourable position for cold over NW europe or it could be a southern europe High trying to sneak in [with shares in Prozack ]But a very interesting and tantalising Model watching period coming up .Today all the roofs were a  glistening with frost ,bring it on ,out with the dog then a sausage Bap ,

[IDO]

ECM mean downplaying the op's heights as expected at D10: 

 

Subtle differences to the other model's means but in  line with the sceuro block, Atlantic to the NW, Azores to the SE and another cut off low in Iberia.

 

The GEM mean also showing the UK caught in the middle of those competing forces at D10: 

 

The pattern getting repeated and at D12 on the GEM control we are back to square 1 with another LP system from the NW trying to undercut the block and probably failing, expectantly sending another upper level low S/SE into S.Europe:

 

 

The outcome has consistently said no to retrogression despite the models churning out some cold charts in FI, as the models tend to do in these scenarios. There are subtle differences with the setup as each attempt is made but whether it will be enough to alter the outcome we will have to wait and see. 

 

 

[Paul_1978]

D10 and D12 aren't worth the pixels they're written on at the moment though.....

[bluearmy]

I'm not entirely with you here

Maybe I wasn't clear - things are taking shape going Into mid December but there is also the possibility of a coldish snap before then.

[nick sussex]

Both the GFS and GFS P improve their early output, the former has edged the pattern west and the latter looks even more favourable with a stronger push of positive heights nw towards Greenland.

 

The GFS still wants to push the troughing further ne and the GFS P after a good start takes longer to develop a shortwave to cut se through the UK.

 

Knife edge stuff really  ....

Edited November 24, 2014 by nick sussex

[492]

ECM showing more promise tonight in its later reaches with an expanding low pressure to the south cutting off the southerly feed and encouraging the cold pool to be dragged westwards.

00Z ECM continues the theme of expanding the area of low pressure to the south of the UK which has the effect of propping up the ridge and allowing cold air to flood over the UK from europe in a stiff northeasterly. 

http://www.meteociel.fr/modeles/ecmwf.php

Edited November 24, 2014 by 492

[summer blizzard]

GFS0z runs are glorious as we go into December, a raw and chilly start to December..

 

 

[nick sussex]

The phrase dogs dinner comes to mind as the NWP is about to implode with so many different things going on.

 

Arctic high trying to force the jet south, PV, low pressure over southern Europe, Azores high moving ne, Russian high. Trying to work out the interplay between all these features is going to be difficult.

 

The GFS P would need two trigger shortwaves to get to an easterly, one is bad enough so theres a new category to add to the one below.

 

Emergency Code Red Warning!

[SMU]

morning All-

 

Whilst all roads seem to arrive in rome today theres still significant divergence in the mid term.

 

the pick of the crop ( for possible long term cold ) are the UKMO & NAVGEM -

UKMO

http://www.meteociel.fr/ukmo/runs/2014112400/UN144-21.GIF?24-06

 

NAVGEM

http://www.meteociel.fr/modeles/navgeme_cartes.php?ech=6&code=0&mode=0&carte=1&archive=0

 

The 18z, 00z & now 06z which is overlayed in the link up to 144 is consistent like the UKMO of maximum amplification over Scandi as a result we get a cross polar ridge -

This is important as it blocks the NE progression of the atlantic fronts allowing that lobe of the vortex to align SW towards Europe. shown here-

http://modeles.meteociel.fr/modeles/navgem/runs/2014112400/navgemnh-0-180.png?24-06

 

As said this is the slowest most extreme pattern which leads to possible significant cold down the line-

 

the middle ground on the GFSp & ECM shown not enough amplification & negative tilt to allow that cross polar flow, however crucially the trigger low that starts the deep cold moving Sw is still in place & can become a factor post day 10.

instead we squeeze a flat wedge of high pressure over Scandi in the middle feeding in ever cold surface air from the Continent. Would certainly start December off on a cold note.

http://www.meteociel.fr/modeles/ecmwf/runs/2014112400/ECU1-192.GIF?24-12

http://www.meteociel.fr/modeles/ecmwf/runs/2014112400/ECU0-192.GIF?24-12

 

The most Easterly solution of the jet portrayed by the 06z shows equally the worst possible initial scenario-

http://modeles.meteociel.fr/modeles/gfs/runs/2014112406/gfsnh-0-150.png?6

 

This is unlikely at this stage bearing in mind the backdrop of the last 3/4 weeks of persistent over progression from the models.....

 

 

Things increasingly looking seasonal just as the opener to Winter arrives in 7 days....

S

[nick sussex]

Further to Steves post.

 

The UKMO because of that chunk of PV placed favourably to drop down would deliver the colder solution but its a bit more high risk and would take longer.

 

The ECM is quicker but you won't at that point tap into any significant cold. But thats still not  a shoe in, as ever with any easterly type set up its complicated.

 

Generally I prefer the easier solution and as long as heights remain low over northern Italy we might get another chance to develop something even colder later.

 

Of course others might feel lucky and want the UKMO to be the right trend.
 

[gottolovethisweather]

Well having not jumped on and over-analysed every run of late, I've left that to others but I am rather pleased that things over the last three days have remained rather consistent as to to developments in Central and Eastern Europe.

 

On Friday night I stated the following

 

• The NH Jet continues to dive on a NW to SE axis and be positioned ever Southwards out in the Mid-Atlantic at that juncture. This aspect gets pushed back progressively in time over successive 12z runs. Plenty to play for yet and the predominantly cooler uppers set to occur over central and eastern Europe during the middle part of next week, pushes ever slowly westwards should also aid to stave off the Atlantic until nearer late November at this rate, so yes the STALEMATE continues unabated.   Incidentally this last aspect has been dropped by the pub run, no worries there unless this eventually becomes the new trend.   

 

For the original post in full, see below.

 

https://forum.netweather.tv/topic/81842-model-output-discussion-1200-hrs-151114/?p=3073540

 

Two important things to take from this when investigating any changes in this viewpoint over the past three days are:

 

• The pub run new trend does NOT exist. 
•  
• Also, my most respected posters are on-board with this look East option as well, albeit something to trust only 50:50 wise, given the timescales involved. 

 

Overall, I would suggest we get Tuesday/Wednesday's low pressure system out of the way firstly and then see if the stalemate continues or as I suspect, a PATTERN CHANGE eventually arrives in time for early December.

 

By clicking on each successive day on the link below, you can watch the evolution westwards of any colder uppers as the week progresses. The important thing here is NOT to focus on our tiny patch in the NH but focus on the continental landmass of Europe at all points North and East.

 

http://www.weatheronline.co.uk/weather/maps/forecastmaps?LANG=en&UP=0&R=0&MORE=1&DAY=0&MAPS=over&CONT=euro&LAND=euro&TOFD=tag

Edited November 24, 2014 by gottolovethisweather

[IDO]

The GFS 06z run is more in line with my thoughts on the upcoming pattern. Compare the GFS control with this morning's:

 

 

 

I think Cohen's take on things is that we are moving into a period where the PV fires up the Atlantic. In that case I cannot see the block winning out in the next 2-3 weeks. I think the best we can get is that there is HP close to the south of the UK with maybe a N/S split. The mean at D10 suggests this is a possibility:

 

 

Not much change at D13:  D16 deja vu: 

 

So I am not really seeing a cold spell coming like others and looking at the GEFS at D14 the majority clearly favour the Atlantic taking at least temporary charge, with a small cluster showing heights to the N/NE: http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=324. The UKMO update today sees no clear signal but more than likely:

"

UK Outlook for Monday 8 Dec 2014 to Monday 22 Dec 2014:

There is no strong signal in weather pattern during this period. However, the most likely scenario is for a continuation of unsettled and, at times, windy weather, especially in western parts of the UK, with eastern parts seeing the best of any dry weather. Temperatures are generally expected to be around, or a little above, average for the time of year. There is a chance of some overnight and morning frost and fog in places - this will be more likely across northern areas where there is also a chance of some snow on higher ground."

Edited November 24, 2014 by i'm dreaming of...

[nick sussex]

IDO there is a problem when looking at the means in this type of situation because of the complexities around trough disruption and trigger type shortwaves.

 

In easterly set ups the GEFS ensembles in particular are normally the slowest to come on board as their lower resolution makes those more likely to send energy over the top of any blocking.

 

The NWP has already backed the pattern west over the last few days and there are so many different aspects at work that I'd keep an open mind about things.

[Man With Beard]

The GFS 06z run is more in line with my thoughts on the upcoming pattern. Compare the GFS control with this morning's:

 

gens-0-1-252.png  gens-0-1-264.png

 

I think Cohen's take on things is that we are moving into a period where the PV fires up the Atlantic. In that case I cannot see the block winning out in the next 2-3 weeks. I think the best we can get is that there is HP close to the south of the UK with maybe a N/S split. The mean at D10 suggests this is a possibility:

 

gens-21-1-240.png

 

Not much change at D13: gens-21-1-312.png D16 deja vu: gens-21-1-384.png

 

So I am not really seeing a cold spell coming like others and looking at the GEFS at D14 the majority clearly favour the Atlantic taking at least temporary charge, with a small cluster showing heights to the N/NE: http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=324. The UKMO update today sees no clear signal but more than likely:

"

UK Outlook for Monday 8 Dec 2014 to Monday 22 Dec 2014:

There is no strong signal in weather pattern during this period. However, the most likely scenario is for a continuation of unsettled and, at times, windy weather, especially in western parts of the UK, with eastern parts seeing the best of any dry weather. Temperatures are generally expected to be around, or a little above, average for the time of year. There is a chance of some overnight and morning frost and fog in places - this will be more likely across northern areas where there is also a chance of some snow on higher ground."

In years gone by, you'd look at the GFS / ECM / UKMO charts and think to yourself - the chances of the pattern being flattened a la GFS 06Z are over 50%. However, the persistence of the Scandi high recently suggests to me that the chances are probably less than 50%. The Azores high linking with the Scandi high is fraught with danger isn't it - it can either build the Scandi up more, or it can drag it down.  The trend of the last 6 months suggests the former - of course, that is not a given.

[Catacol]

To my eye the signs for cold are steadily growing. Some strat info first. Here are the temps at 30hpa that were mentioned a couple of days ago, As expected these are now climbing above average and look set to continue to climb

 

 

This means more pressure on the vortex... Then compare this day 9 chart at 100hpa

 

 

with this one at day 10 

 

A definite change in the angle of the vortex over the atlantic, suggesting rising pressure towards Greenland. Bear in mind this is just one run.... but it fits in with other signals too - wave 2 warming remains fairly constant out to day 10 

 

 

And all this feeds into this ECM chart this morning where by hook or by crook the model is determined to get high pressure building out west from Scandy.

 

 

It is dangerous of course to put one model and single runs out there as gospel, but I'm going to keep posting out these combined strat and trop model combinations because they help paint the bigger picture. At the moment ECM and strat signals are pointing to a gradual shift to more northerly blocking, low pressure over Europe and an easterly component to our weather. How quickly this might advect cold to our shores is impossible to know right now, and whether it is a sustained shift or just a blip is really hard to be sure of at this early stage.

 

But one thing is for sure - the chances of cold are there... and more strat vortex pressure is foreseen later in December. All good news.

[Bristawl Si]

The UKMO update today sees no clear signal but more than likely:

"

UK Outlook for Monday 8 Dec 2014 to Monday 22 Dec 2014:

There is no strong signal in weather pattern during this period. However, the most likely scenario is for a continuation of unsettled and, at times, windy weather, especially in western parts of the UK, with eastern parts seeing the best of any dry weather. Temperatures are generally expected to be around, or a little above, average for the time of year. There is a chance of some overnight and morning frost and fog in places - this will be more likely across northern areas where there is also a chance of some snow on higher ground."

That Meto outlook looks suspiciously similar to what they've put out over the last few days - almost, if not exactly, the same wording.

[Nouska]

The GFS 06z run is more in line with my thoughts on the upcoming pattern. Compare the GFS control with this morning's:

 

gens-0-1-252.png  gens-0-1-264.png

 

I think Cohen's take on things is that we are moving into a period where the PV fires up the Atlantic. In that case I cannot see the block winning out in the next 2-3 weeks. I think the best we can get is that there is HP close to the south of the UK with maybe a N/S split. The mean at D10 suggests this is a possibility:

 

gens-21-1-240.png

 

Not much change at D13: gens-21-1-312.png D16 deja vu: gens-21-1-384.png

 

So I am not really seeing a cold spell coming like others and looking at the GEFS at D14 the majority clearly favour the Atlantic taking at least temporary charge, with a small cluster showing heights to the N/NE: http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=324. The UKMO update today sees no clear signal but more than likely:

"

UK Outlook for Monday 8 Dec 2014 to Monday 22 Dec 2014:

There is no strong signal in weather pattern during this period. However, the most likely scenario is for a continuation of unsettled and, at times, windy weather, especially in western parts of the UK, with eastern parts seeing the best of any dry weather. Temperatures are generally expected to be around, or a little above, average for the time of year. There is a chance of some overnight and morning frost and fog in places - this will be more likely across northern areas where there is also a chance of some snow on higher ground."

 

Couple of points on this: - just as the ensembles blend out nuances, so do the composites that we look at when considering Cohen's hypothesis. There will be a variety of options possible - probably none exactly like the composite! 

 

The Met Office 15 - 30 day outlook is heavily weighted on the ECM monthly - it was last updated on Thursday of last week - a lot of water has flowed under the bridge (NWP output) in that time-span. If it is still the same on Wednesday, time to scratch the head and wonder where we are going.

[bluearmy]

Catcol - 100hpa strat charts are going to reflect the trop op chart and as such are only going to be approx 50% reliable. Strat charts above 50 hpa are more reliable at 10 day range but that drops off further out.

[nick sussex]

It's been a strange Autumn so far, certainly one feels something is brewing!

 

What really marks this Autumn out is the reluctance of low pressure to move anywhere past the UK, the models at times have been desperate in their longer range to break the defences but so far as the timeframe nears they've relented.

 

This stalemate has of course been frustrating for UK cold lovers as the UK is caught in between so little if any PM flows and no real cold continental air, so far.

 

Effectively the PV now will have one even bigger attempt as the pattern over the USA is set for a dramatic change, the deep cold is set to lift north as the PV rushes to meet the welcoming arms of the Greenland area. A place it knows and loves and which we hate to see.

 

I think we're reaching somewhat of a defining period so an interesting fork in the road coming up, normally this time of the year is when the PV will want to really gear up and rule the roost.

 

If it fails to break the defences this time I think that would be a positive signal for the rest of the winter, we await tonights output with both optimism aswell as trepidation.....

[nick sussex]

The first model out so far the GME looks okay, low heights over the southern Europe:

 

 

It's not a major model but still nice to see.

 

The GFS normal  upto T72hrs is also encouraging more favourable troughing to the west of the UK  better tilted, so far my optimism is increasing. Lets hope I haven't jinxed things now!

Edited November 24, 2014 by nick sussex

[MR EXTREMES]

The first model out so far the GME looks okay, low heights over the southern Europe:

 

gme-0-132.png

 

It's not a major model but still nice to see.

 

The GFS normal  upto T72hrs is also encouraging more favourable troughing to the west of the UK  better tilted, so far my optimism is increasing. Lets hope I haven't jinxed things now!

yep so far so good nice heights into scandi nice deep low plunging se into europe could be a trigger low moment.........

but will the zonal rain be to much for the mighty scandi block.......

 

look how far south the low is getting dont see this very often no wonder the models are all over the place....

 

Edited November 24, 2014 by emotional rollercoaster

[Bullseye]

https://twitter.com/MJVentrice/status/536898939413594112

https://twitter.com/webberweather/status/536900875655340032

New update from JAMSTEC today shows more in the way of colder conditions in UK although does state majority of Europe to be warmer than average. That's the good news. Bad news or more slight sign of concern is ECM showing lack of split in PV than recent. All this found over on Twitter(how wonderful and useful internet can be at times) and again I could have read these wrong.