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

[Ali1977]

UKMO and GFS at 144 actually look pretty good - if we didn't know what's showing beyond 144 I'd be happier!!  UKMO looks better with heights further North into Scandy.

[Singularity]

5 minutes ago, bluearmy said:

Does anyone fancy digging out the gfs op strat zonal flow forecast to see if it has a disconnect with the strengthening upper strat- could be a reason why the ops are so strong on the trop vortex development 

would also be worth seeing if the gefs are similar as they seem to manage a lot more amplification hemispherially 

I sense it may just be a case of the flatter pattern driven by the drop in GLAAM (as detailed by Tamara recently) naturally leading to a consolidation of cold air at the higher latitudes. This is why it should only be a short-lived affair, unless there really is unforeseen and unusually rapid downward propagation of the zonal wind anomalies from the upper stratosphere.

Update: Brief indeed on the 12z, and a strange configuration to the 30 hPa vortex emerged... the wave-2 attack remains evident from the previous 12z, but not nearly as strong. MJO forcing seems slow to take hold on this run. Alas, a mean that's keen doesn't mean that a particular det. run will be so pacy with the 6-7-8 propagation.

Still worth watching for any signs of that MJO influence - but don't worry about details beyond +168 (nod to Carinthian).

Edited December 9, 2016 by Singularity

[gottolovethisweather]

33 minutes ago, Ali1977 said:

If the high towards Scandy can hold and create a proper Scady high that would be a minor miracle, is that really where we should be looking "if" we can get something colder? Let's see how many ENS can do it, if any

 

 

I'm sure we will need more runs and also as I'm not a fan of the weekend outputs given their usual divergences, we need to bide our time. I do believe there will be a quick turnaround in fortunes, though, one which takes a fair bit of interpretation. Next week will look very different to how it's currently forecasted to look. If you had to put my head on a block (no pun intended) I see a spell of Northerlies incoming and shortly after the 13th.

Edited December 9, 2016 by gottolovethisweather

[carinthian]

1 minute ago, gottolovethisweather said:

The voice of reason, Thanks, Carinthian. The question is, is this the new favourite in our model output race of many runners? Sometimes, it's best to get your money on a second or third favourite in such races circumstances. There are no certainties in any of our computer generated pieces of meteorological guesswork, it is only as good as the data fed into in the beginning. And whilst I wouldn't mind betting tomorrow's little low feature might yet curtail some of our forecaster's projections, next week is ultimately more forecastable with heights rising to the North and East of the UK and a very slow trend downwards in terms of Temperatures from their currently exceptional highs.

Hi gottllovethis weather, yes its mind blowing reading all these different models and day to day changes. Sometimes we have to get back to old school forecasting techniques. I will dust off my old Met Office training manual from Shinfield Park days and look under ( forecasting Scandinvian High ) seems to be a rare feature these days but they did occur a lot back in the 60s and cropped up regularly in some 70s /80s winters. As you say a downward trend in temps should start next week as the block holds it own against the Atlantic.

 C

[Summer Sun]

Not good at all for cold just about as bad as it gets

Now the PV looks like it's suddenly going to wake up it could be some time until things improve

Today

Wednesday

Christmas day

[Mucka]

3 minutes ago, Ali1977 said:

UKMO and GFS at 144 actually look pretty good - if we didn't know what's showing beyond 144 I'd be happier!!  UKMO looks better with heights further North into Scandy.

It has been a feature of December thus far, promising ridges not producing the necessary trough disruption with all the energy going NE and flattening any amplification.

Rinse and repeat until FI where the Atlantic begins to take control ( on latest GFS Op runs anyhow)

The scope for any dramatic turn around would be around 120 14th/15th when Euro heights are a little lower and the ridge at its strongest, just the faintest possibility of some worthwhile undercut changing the picture but it is brief windown of opportunity and not one the models seem interested in at the moment. File under wishful thinking for now.

 

[Southender]

Well. Not a lot to say about the GFS 12z other than HP to our East/South, an angry PV, flat as a pancake, very dry particularly further South & East and temps average to slightly above at times, with the odd frost thrown in.

If that pattern verifies that is December wiped out cold/snow wise.

We really need a huge slice of luck. At least it looks dry I suppose, but festive it isn't.

Edited December 9, 2016 by Southender

[phil nw.]

Will have to view the ensembles later but based on what they have shown for the end of next week it may be a bridge too far for a northern block but hopefully a UK or favourably placed Scuero high could well give us a colder spell again.

The northern jet is pretty active right now so a mid-latitude block around these parts will at least hold back the Atlantic until hopefully a further amplification upstream develops.Yes GFS pushes the MJO into decent amplitude phase 8 today which is a better trend for this but the ECM still not seeing anything yet.

[knocker]

Not a great deal new to add to the GFS output in the ten days although the overall impression is that the HP is less effective on this run which means little without a lot more context. One quite interesting facet, after the latest trough deconstruction at T162 we  then have the next battle between  the cold, complex upper trough spewing out of Canada and the Azores ridging NE and a very strong thermal gradient transporting much energy NE.

This soon pushes the HP west and brings some wet and quite windy weather to Scotland whilst at the same time activating the cut off upper low to the SE. This has no surface significance as fronts sweep in from the west.

Edited December 9, 2016 by knocker

[Singularity]

  

Oh ARPEGE you tease!

Clean ejection of the shortwave from the parent trough on day 4 allows a wedge of higher heights to get in and let's just say it's looking a whole lot healthier at +114 hours than any recent det. run from the major models has shown.

If you want to spend Friday evening feeling positive - regardless of what ECM gets up to - tell yourself that the higher resolution of ARPEGE is allowing it to see an important detail that the other models are overlooking. I mean, you might as well, provided you can handle losing that hope again tomorrow, should it work out that way.

[Dennis]

 

[bluearmy]

1 minute ago, Singularity said:

  

Oh ARPEGE you tease!

Clean ejection of the shortwave from the parent trough on day 4 allows a wedge of higher heights to get in and let's just say it's looking a whole lot healthier at +114 hours than any recent det. run from the major models has shown.

If you want to spend Friday evening feeling positive - regardless of what ECM gets up to - tell yourself that the higher resolution of ARPEGE is allowing it to see an important detail that the other models are overlooking. I mean, you might as well, provided you can handle losing that hope again tomorrow, should it work out that way.

It never did before.................

Edited December 9, 2016 by bluearmy

[Ali1977]

Prob the best ENS member at 150, if we could keep this attempt going and somehow the PV weakens slightly could we get it holding the Atlantic back - maybe 

And slightly beyond this that set up could have a chance...interesting

Edited December 9, 2016 by Ali1977

[booferking]

Yep there it is a world record breaking 925mb.

[Summer Sun]

2 minutes ago, booferking said:

Yep there it is a world record breaking 925mb.

 

870mb is the current world record in 1979

[Mucka]

GFS 12z ensembles take another step away from blocking setting up any time soon after mid month.

If this becomes a trend it will be interesting to see what GFS comes up with in FI.

Whether we get a flat jet and zonal set up like the Op or we get the jet digging South and move back toward a mid Atlantic ridge setting up as some of the background signals have suggested may be possible.

Both those scenarios would seem to go against the current Meto thinking though.

Very hard to make any predictions at all for the holiday period at the moment.

Edited December 9, 2016 by Mucka

[chris55]

UKMO looking a lot better than GFS at 144 with a much more favourable tilt to the Atlantic trough and a lot less zonal progression away to the north. The evolution from 144 on UKMO could well have some cold potential!

UKMO

GFS

[booferking]

3 minutes ago, Summer Sun said:

870mb is the current world record in 1979

Haha i meant non tropical reading still mighty impressive.

[bluearmy]

5 minutes ago, Mucka said:

GFS 12z ensembles take another step away from blocking setting up any time soon after mid month.

If this becomes a trend it will be interesting to see what GFS comes up with in FI.

Whether we get a flat jet and zonal set up like the Op or we get the jet digging South and move back toward a mid Atlantic ridge setting up as some of the background signals have suggested may be possible.

Both those scenarios would seem to go against the current Meto thinking though.

Very hard to make any predictions at all for the holiday period at the moment.

Yes mucka - at day 8 when the resolution drops off, they are far closer to the eps than before with weaker upper ridging and anomoly to our east 

[swfc]

wow.after viewing the ukmo and 12z im pretty certain theres a drug induiced cult thing going on!!! theres nothing what looks anything like bringing any cold 850s or any serious blocking anywhere near the uk.enso outlook is up in the air and the pv is ramped up? 

[knocker]

The GEFS anomaly would indicate a movement of any ridging east to the southern Baltic and a zonal upper pattern. Rather supports the det. take on things within this time frame.

[karlos1983]

Watch the ECM throw out a stellar run for cold now 

[Mucka]

14 minutes ago, bluearmy said:

Yes mucka - at day 8 when the resolution drops off, they are far closer to the eps than before with weaker upper ridging and anomoly to our east 

Yeah not sure if its just a blip but the ensembles have tended to get a little flatter though the period.

Thus far the ensembles on face value are signalling what some here and Fergie et al have suggested, two clear but opposing signals. 

One for pressure to build once more to our NE as we enter last 3rd of December and the other for a period of zonality, still fairly well balanced between the two.

I'm just wondering if the ones that currently show zonal might actually amplify in the Atlantic sector after a short while though no sign of that as yet.

It would be nice to have the choice between a block to our E/NE or an Atlantic ridge

 

[NeilN]

I don't think it's over yet....me thinks we're gonna see a surprise  

[Summer Sun]

The mean still indicates high pressure through to the 25th