Model Output Discussion - 30th November onwards

[bobbydog]

I maybe wrong but I believe this was relating to Robbie's observations with regard to the stratosphere given the attached charts and the only warming up Robbie would be talking about would be from within the stratosphere profile.   Please somebody correct me of I'm wrong.

 

not sure there, maybe robbie could explain what he meant?

 

they are pressure anomaly charts, which would put the average HP centre over scandi. giving us something like this for example-

 

(taken from the GFS 00z and the nearest i could find quickly)

 

 

certainly not warm by any means!

[Weather of Mass Disruption]

In terms of a longer-term output, I can see things calming down for Christmas and something abit more warmer than what we have at the moment.  A firm Scandinavian ridge till the New Year I believe is the more expected output.  

 

 

Looks like the green ghost from ghostbusters has taken over these images! Lol apologies mods...

[Frosty.]

This is the type of pattern which could evolve this month. GEFS 06z  Perturbation 19 would be perfect and there are others which are trending.

Edited December 3, 2013 by Frosty.

[Yarmy]

not sure there, maybe robbie could explain what he meant?

 

they are pressure anomaly charts, which would put the average HP centre over scandi. giving us something like this for example-

 

(taken from the GFS 00z and the nearest i could find quickly)

 

 

certainly not warm by any means!

 

 

Moreover, they only go out to the 17th/18th December. I suppose the pattern could persist into Xmas/New Year, but it's too early to say.

[lorenzo]

Nice post CH, the Scandi ridge certainly has support from the 100mb profiles, checked both ECM and GFS this time, reference ECM Berlin plots throwing us dodgy data earlier in the season. Well defined at 168.

 

Both ECM and GEFS provide the illustration of the Wave 2 Activity, some cross polar perturbations may indeed be kicking around soon.

 

30mb temp - encouraging signs but would love a Torque event to really test things.

 

Re - trailing segments of vortex, I know that these are complicated charts representing vorticity across an atmospheric layer, however without losing your mind to the physics involved provide an illustration of how the vortex is stretched.

 

Apologies for mixing the strat charts into the model thread, synoptics of the NH ridges are the key elements in play here, and trying to highlight the heights support.

 

On a bias front the ECM 00z ramps up Scandi blocks at 144-168, whereas the 12z is more moderate, something to also consider along with it being amped.

 

[Turnedoutniceagain]

Moreover, they only go out to the 17th/18th December. I suppose the pattern could persist into Xmas/New Year, but it's too early to say.

 

Ohh no, you mean the Mother-in-Law might not make it down for Christmas?? .................*sobs tears of joy*

[legritter]

if an easterly influenced pattern does set up ,it could disappear for xmas and come back again after ,there are so many options on the possibility side that it becomes mind Numbing and Prozack territory ,all very  interesting and if it does come to fruition a fantastic forum discussion with loads of  IMBY and Pram wars .so tonights ECM will be the one to watch ,only a thousand tickets for tonights show available ,booking recommended .JOE Laminate next i fear .

[Cheshire Freeze]

The current UKMO view is for a colder set-up to dominate again into the 10-15d trend period, with more progressive solutions in a minority. Possible net result is UK on western bounds of blocking with 'battleground' style issues in west thanks to periodic Atlantic incursions. Latest EC32 from yesterday is an interesting one; it also indicates a signal by Christmas for negative temp anomalies & HP to N; LP to S/SW, but the clusters do show a wide raft of potential outcomes. Anyway, very early days but tentative signs for something more blocked a bit further down the December diary.

 

Over 80 likes on this post. Awesome. Always good when the Metoffice start to pick up on a potential cold pattern change. 'Battleground style issues'........love it!

[The Northern Ramper]

Exciting update there from Ian!  Sounds like a step change from the Met office is on its way! Hopefully the lunchtime update of the long range forecast update will reflect this !

I have been watching the GFS ensembles over the last few days and what started with 1 or 2 easterlies showing there have gradually been more and more so we are now at nearly 50% showing some sort of scandi High. Hopefully this trend will continue. We still need to see some ridging up towards Greenland though otherwise we just watch and drool as Europe gets covered and we are on the periphery

I've been on nights so have not read the met update but i read yesterday that they base their further outlook on the ECM monthly output which Matt H has this morning gone for a Scandinavia block mid month. It is nailed on for a change in forecast with precautions.

[nick sussex]

Some things to look out for before the GFS 12hrs run. There is a clear correlation between how far south we see that mid Atantic troughing digging and its sharpness in terms of how the pattern moves forward after that.

 

Aswell as this the tilt of the troughing and how much energy spills east towards Iceland. I should also add that many easterlies start with a mild southerly because this is caused by troughing to the west of the UK sending warmer air north towards Iceland and Greenland, just as we see WAA causing pressure rises over Greenland the same situation often occurs with easterlies at the initial stage.

 

The tilt of the troughing needs to be at worst neutral but preferably negative so running at worst north/south but better nw/se.  Also look out for a low developing across the USA which runs ene towards ne Canada (circled red), this needs to be amplified as this approaches Canada it sharpens the pattern ahead this forces more energy to dig south, then as it engages the PV it helps to pull some of this away from eastern Greenland.

 

 

This was the ECM 168hrs from last nights 12hrs run, you need to see that sort of upstream pattern around the 144hrs mark today.

 

After this if things go well then you'd hope to see the troughing axis move round to a more favourable tilt.

Edited December 3, 2013 by nick sussex

[SW Saltire]

 

Re - trailing segments of vortex, I know that these are complicated charts representing vorticity across an atmospheric layer, however without losing your mind to the physics involved provide an illustration of how the vortex is stretched.

ecmwfpv475f240.gif

Great post Lorenzo, so the above chart would , in laymens terms, allow a Scandi high to form more easily (if it verifies) as there is little residual vorticity that has been left behind? Was it not mentioned a few days ago that the deep FI Greenland height rises did not come to fruition due to the models underestimating the amount of vorticity left behind.... if so, the above chart show be seen as encouraging but should not be taken as gospel

[SW Saltire]

The GFS 12z shows the powerful low, bringing strong winds on Thursday to many northern areas, with a central pressure of mid 970s mb

[Snowman.]

12z being very progressive as always, much flatter also.

[fergieweather]

 

The operationals this morning have not shown agreement regarding a future easterly (shock horror). This was to be expected and is simply part and parcel of the run variability that will definitely take place. The update by Ian F is very encouraging but obviously a long way from coming to fruition. It is also good that 11 GFS ensemble members develop some kind of easterly flow as add 2/3rds more amplification and.... if only it were that simple. This is of course the easy part, watching the Scandi high tentatively be brought into nearer FI. Once it reaches high res the real drama will start. If i was living on the east coast it would certainly seem like winter was upon me with temperatures seeming suppressed with the propensity for them to continue to lower, although the magical white stuff looks like a while off for the time being

UKMO view (just chatted with them) remains as before: i.e. for Scandinavian block to establish after next week's milder (for some, notably so) phase and a progressively colder return from SE/E thereafter.

[Mucka]

12z being very progressive as always, much flatter also.

 

 

It is very much in line with this mornings UKMO though which is probably the model to watch for mid term developments.

[Ali1977]

I wonder if there a chance this potential Scandy block could become established for a length of time, to bring in the cold it may have too ...

[Frosty.]

 

UKMO view (just chatted with them) remains as before: i.e. for Scandinavian block to establish after next week's milder (for some, notably so) phase and a progressively colder return from SE/E thereafter.

Fergieweather, any chance of pert 19 GEFS 06z please

[Mucka]

UKMO 120h

 

[adamgooner]

 UKMO view (just chatted with them) remains as before: i.e. for Scandinavian block to establish after next week's milder (for some, notably so) phase and a progressively colder return from SE/E thereafter.

fascinating update Ian.  What time frame we looking at here...10d-12d?  

[Mucka]

UKMO 144 better than GFS 12z at the same time 

 

[Weather Boy]

The most encouraging thing about recent output is Ian F's comments.

 

The Meto are taking a potentially easterly (that's what I construe as to his comments about cold spreading from E/SE parts) seriously and appear to be calling it the form horse.  We know that they more or less ignore the GFS at more than 8 days out, so I think we should do until that kind of timeframe.

 

Normally, though, the Meto are rather circumspect about these sorts of signals and with a minority of ensembles wanting the easterly, it seems to me that (as usual) they know more than we do, and therefore have something else to back up the pro-easterly view.

[Ian Brown]

A progressive 12z with less energy going South, could be a very mild and wet FI.

[Matty M]

Pretty dreadful outlook in the medium term with high pressure becoming banked over Europe steering up mild southerlies for most away from the far south-east of the UK.

 

Outlook rather poor for cold searchers this evening.

 

- A pretty disappointing run up to Christmas is likely, nothing worse than a mild run up to Christmas, i think most enjoy frost and snow around the festive season.

 

But the period beyond December 15th could still develop nicely. Fingers crossed.

 

-- Main event in short term, with a significant wind event for Thursday with risk of widespread gusts to 70mph with some extreme gusts to 90mph possible in parts.

Edited December 3, 2013 by Matty M

[adamgooner]

The most encouraging thing about recent output is Ian F's comments.

 

The Meto are taking a potentially easterly (that's what I construe as to his comments about cold spreading from E/SE parts) seriously and appear to be calling it the form horse.  We know that they more or less ignore the GFS at more than 8 days out, so I think we should do until that kind of timeframe.

 

Normally, though, the Meto are rather circumspect about these sorts of signals and with a minority of ensembles wanting the easterly, it seems to me that (as usual) they know more than we do, and therefore have something else to back up the pro-easterly view.

There appears a solid build up of cold air to the east to tap into now...rewind a month back and many of us were chasing signals for an easterly...with a lack of a cold pool to the east.  IMO any easterly incursion from mid month would be notable indeed.  exciting times...

[TSNWK]

UKMO 144 better than GFS 12z at the same time 

 

Would that be due to nice the vacum towards Swenden / Finland way for the our high to slip into, whereby on the gfs there is more low presure in the way of high ridging north east.