Model output discussion - 5th December 2016 - Into Winter we go

[Frosty.]

The GEFS 12z mean shows increasing high pressure influence for the southern half of the uk from around day 9 / 10 onwards with our weather becoming largely settled, even for the north with more in the way of frost and fog returning which would lower daytime maxima

Edited December 5, 2016 by Frosty.

[nick sussex]

It goes downhill quickly on the ECM with energy spilling over the top at T168hrs. Upstream its flat as a pancake at T192hrs, pretty awful output from the ECM so far with little festive cheer. The hope window at T144hrs has been firmly shut!

[karlos1983]

Got to be honest, I'm struggling....

 

[Ali1977]

1 minute ago, karlos1983 said:

Got to be honest, I'm struggling....

 

Yep, I was hoping tonight may give us some hope - this ain't helped with that!! 

[nick sussex]

1 minute ago, karlos1983 said:

Got to be honest, I'm struggling....

 

You're not the only one! utterly dire. This looks like verging on catastrophic for the ski resorts unless theres a major pattern change quickly. The Euro slug high is going nowhere with that upstream pattern at T192hrs.

[Frosty.]

Actually the weekend cools down quite a bit on the Ecm 12z but most of this week will be much milder than we've been used to recently.

Edited December 5, 2016 by Frosty.

[knocker]

In one sense I think we can be thankful that the HP hangs in there because the way the upper trough is configured around T180 we could well have been clobbered by a nasty low. Still could be of course; it's always a danger in this sort of mobile set up. More likely to be Scotland in the firing line if the worst came to the worst. Anyway all very speculative.

[Summer Sun]

Nothing really for coldies from tonight's ECM with winds continuing from the west

As I said yesterday we've reverted back to chasing cold in FI and even that's proving hard at the moment!

[Frosty.]

The Ecm 12z doesn't end mild or cold

Edited December 5, 2016 by Frosty.

[gottolovethisweather]

Everything is as expected over the next few days with us all seeing a weakish Westerly regime taking over. The resultant Jetstream profiling forecast by the GFS 0z on the 2nd December, some three days ago was this.

It matches closely to the corresponding ECM chart for t+72 hours which is replicated below,  not many differences between the two if you were to overlay the NH Jetstream profile over today's ECM. However, two key regions to watch for upcoming developments are highlighted in red.

 

 

 

Bear in mind, my watch period was and still covers the period between the 10th and 13th December, which should see a relatively small yet still significant pattern change after three or four days of unseasonal warmth by day and night.

Why am I so confident in this being a crucial timeframe, well because it has been showing hints of it across all model suites (particularly the 0z and 12z suites) for a number of days now. Additionally, take a gander at the GEFS ensembles spreads which further back up my suspicions of a pattern change of sorts.  

The greatest divergence on the above GFS 0z spreads begins around the 10th and 11th December in all instances, so I suggest this is precisely when our confidence in any given prediction should start to wane. We will clearly know more as to which direction we are heading in beyond the 10th/11th by this Thursday or Friday.

To which pattern change, I hear you ask and that is as yet, unanswered. We have option one of an increasing ridging influence up from the south again. Option two being an outside chance of a brief (duration unknown at this range) period of Northerly-based winds, it's a 50:50 chance, either way, IMHO.

Beginnings of a split vortex as early as D4 (9th December) which ties in with other outputs and those previously mentioned confusing NH Jet Stream differences.

 

D5 (9th December) chart shows first hints of an incoming Northerly flow, but equally, increasing heights up from the south-west approaches looks just as feasible. By then, however, the unseasonal warmth will have likely departed our shores towards Europe.

 

Any point in me second guessing what mid-December might look like, nope. For fun I'll throw in one of tonight's ECM operational suggestions.

The following ECM D8 chart respresents the end of my watch period and shows a NH profile in turmoil, so I have very little confidence in that chart verifying, however it does illustrate the great uncertainty past next weekend if you ask me. 

 

All the best then, my advice is to step back, have a good few hours off our personal attempts at cross-model analysis and give things another day or two. Have a mince pie or three, a class of prosecco or beer and come back for tomorrow's model rollercoaster ride. A pattern change (NOT an entrenched cold delivery version) but a change of sorts is a-coming before the third week of December begins from what I can tell. 

Edited December 5, 2016 by gottolovethisweather

[winterof79]

1 minute ago, igloo said:

your wrong no amplification even at day 10 the worst ECM run for a long time lets hope its just a outlier otherwise the met office will have to ditch there forecast for christmas big time

Day 10 takes us to the 15th a full 10 days before Christmas Day. I think the Met have it covered.Settled probably the best bet over the start of the Christmas period but lots of time for that to change

Those hoping for a pattern change may have to stop looking at every run to avoid a major headache.

I have read and looked between the lines, and we all have seen posted,that it will probably be the last week in December before a real shot at colder synoptics can be expected.

[SMU]

Sadly the upgraded ECM has been pretty spot on since its release, - for example all those phantom Greenland highs depicted by the GFS - the ECM didnt want a bar of it ( not like the fun days of the day 10 fantasy GH on the old ECM )

more recently that little wedge of high pressure over iceland was plucked by ECM at day 10 & the GFS caught up today-

Other than that statistic the rest of tonight is poor- theres no chance of cold from that wedge at 144 with the best case scenario a cool 1 day NW flow- after that all pressure rises do far are located at an unfavourable location for cold so outlook wise

wet & very mild moving to dry ( poss ) & mild-

we are almost breeching Dec 15th in the main output now with nothing to show- we could be a sixth of winter down before we know it -

Lets have some lady luck for a change, not the fat lady singing like 2015...

Edited December 5, 2016 by Steve Murr

[nick sussex]

My advice go into a denial bubble! Overall this evening there were a few crumbs for us on the GFS and to a degree the UKMO. The ECM throws too much energy ne'wards at T144hrs and from there it was downhill.

Ordinarily that set up of two elongated PV lobes one either side of the UK leads to some pressure rise in the gap. The problem is we can't carve enough energy se'wards at the critical timeframe.

The upstream pattern is going to become flatter , this means that we only really have one window of opportunity and that was with a low chance of a Scandi high.

Its hard to see where that amplification is going to come from , the MJO isn't really moving anywhere fast. Last week there were issues with conflicting signals. The latest NCEP update will be tomorrow.

 

 

[blizzard81]

Not much sign of the much vaunted mid month atlantic height rises on the ecm. Quite the polar (no pun intended) opposite in fact.

[winterof79]

While everyone is writing early winter off.

Could I please have clarification as to the whereabouts of the so called "Euro slug" that is quoted in many posts?Was it on the ECM because I see an Azores high this evening so its quite a quick slug

[phil nw.]

Pretty uninspiring for cold this evening.Some signs of ridging in the Atlantic in the T144/168 range but the main vortex is determined to re join hands across the pole at the vital time and continues to scupper any blocking attempts.

Looking through tonight's gefs stamps there are 2 or 3 with cold patterns after mid month with Greenland highs and around another 12 out of 20 with highs near or over the UK.Certainly fewer ens members with any high latitude ridging for the same date,so a step back for cold chances in the next 2 weeks.

These for day 12 just after mid-month where the temp ens have been showing a fall for some days.This is where i have been counting down day to day following these.

I should add i do this sometimes when things look a bit grim in the near term and it keeps me interested!

A look at the clusterings and the overwhelming majority go for a euro high maybe extending into the south of the UK.

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=euro&MODELL=gefs&MODELLTYP=2&BASE=-&VAR=cslp&HH=276&ZOOM=0&ARCHIV=0&RES=0&WMO=&PERIOD=

It seems a mid-latitude form of blocking is the likely evolution going forward based on these.It's just a case of where it settles which would affect the wind flow direction and therefore the surface conditions,ie chances of cloud,frost etc..

Eagerly seeking some amplification in the NH pattern to move that high modeled in week 2 further north.

 

 

Edited December 5, 2016 by phil nw.
Added larger image

[karlos1983]

Really interested to see what the update is later from EC. I keep saying to myself look at the ensembles, not the op. But surely this consistent reluctance to build heights to our north can't be ignored. Not a decent run for ages. 

[nick sussex]

12 minutes ago, winterof79 said:

While everyone is writing early winter off.

Could I please have clarification as to the whereabouts of the so called "Euro slug" that is quoted in many posts?Was it on the ECM because I see an Azores high this evening so its quite a quick slug

It was there for the whole run, the chart you posted just shows one Euro slug about to be replaced by another. Euro slug or displaced Azores high they all suck!

[Banbury]

You can look at all the long range forecasts all you like BUT there isn't a thing on the horizon, you can look at means and ENS as well they mean nothing after 168  .

Ive clutched straws for years and until we see something consistent across the big boys I wont be getting that interested , of course I will look at the charts each day but we continue to chase i'm afraid

Edited December 5, 2016 by Banbury

[NeilN]

Can an Azores high actually cause some cold? We've still a long way to go and December isn't a good performer

[karlos1983]

4 minutes ago, nn2013 said:

Can an Azores high actually cause some cold? We've still a long way to go and December isn't a good performer

Yes, if it does one!

Edited December 5, 2016 by karlos1983

[Banbury]

5 minutes ago, karlos1983 said:

Really interested to see what the update is later from EC. I keep saying to myself look at the ensembles, not the op. But surely this consistent reluctance to build heights to our north can't be ignored. Not a decent run for ages. 

And Karlos  what if the EC update is a Winter wonderland?? It really doesn't mean a thing ......apart from its got another idea.........another

[Allseasons-Si]

10 minutes ago, karlos1983 said:

Really interested to see what the update is later from EC. I keep saying to myself look at the ensembles, not the op. But surely this consistent reluctance to build heights to our north can't be ignored. Not a decent run for ages. 

I hope it's something like this.....goodness me,Merry Christmas and a happy new year every one

run it through

http://www.meteociel.fr/modeles/cfse_cartes.php?ech=354&mode=0&carte=0&run=10

it could happen

Edited December 5, 2016 by Allseasons-si

[Frosty.]

9 minutes ago, nick sussex said:

It was there for the whole run, the chart you posted just shows one Euro slug about to be replaced by another. Euro slug or displaced Azores high they all suck!

I hate the term Euro slug, isn't there a better name for it..like Eurotrash High or Bartlett

Anyway, it's what the models are showing which is the name of the game after all!

 

Edited December 5, 2016 by Frosty.

[Chris K]

4 minutes ago, nn2013 said:

Can an Azores high actually cause some cold? We've still a long way to go and December isn't a good performer

It would ideally need to retrogress up towards mid-Atlantic/Iceland/Greenland, but the jet seems too strong for this to occur. Generally it means a SW/westerly or a slight NW feed at best on occasion. In other words, get rid of it.

Edited December 5, 2016 by Chris K