Model output discussion - 1st December onwards

[bobbydog]

the 18.....Z ??

 

interesting to see where this goes. no ridge to split up the scandi trough from the atlantic on this run.

Edited December 26, 2015 by bobbydog

[Allseasons-Si]

Don't look past 144hrs if not sooner,you will be bold come the end of the run.....nuff said

we all know the score

[fergieweather]

27 minutes ago, chrisbell-nottheweatherman said:

Slightly O/T I know, though it does relate to the models.  Most of our seasoned experts here are showing a switch to a westerly/north-westerly stream into the New Year, yet I've just watched the BBC wek ahead forecast on their website, and the forecaster said that the flow would stay from the south west and exceptionally mild into the New Year, with no change of any sort in sight.  Indeed, they showed a jet stream chart with isobars and it showed those isobars forming a trough below Greenland, suggesting low heights there, and a ridge over Europe, indicating to me that they expect the Euro high to remain as is (presumably not Scandi high/WAA).  What do they know that we don't, or are they going for the percentages and just forecasting mild as a default?

No, it's because 12z ENS clusters, MOGREPS and GloSea5 prefer that (ultimately zonal) outcome. The NW flow signal actually appears more compellingly into late Jan (in eg latest EC Monthly). There remains scant support in 12z EC-ENS for any 'full-on' easterly, but as noted in my previous posts, that doesn't discount it. So, until such supporting evidence dominates (or at least becomes a noteworthy minority signal), then we have to run with consensus. Bear in mind GFS has shown very marked inter-run oscillations for a while, and in any event, is never followed as a 'trusted' guide post-T+144 because (unlike EC or MOGREPS, or GloSea5 for that matter) it's not a bespoke medium range tool. Yes: it *may* be right this time re easterly Op runs of late, but that's shaky ground to base a public forecast upon. What happens aloft stratospherically may be another matter.

The next few days look far more eye-catching in any case, forecast-wise. Given events already today, frankly whatever unfolds early Jan can happily sit on the back-burner for now....!!

[Allseasons-Si]

7 minutes ago, fergieweather said:

No, it's because 12z ENS clusters, MOGREPS and GloSea5 prefer that (ultimately zonal) outcome. The NW flow signal actually appears more compellingly into late Jan (in eg latest EC Monthly). There remains scant support in 12z EC-ENS for any 'full-on' easterly, but as noted in my previous posts, that doesn't discount it. So, until such supporting evidence dominates (or at least becomes a noteworthy minority signal), then we have to run with consensus. Bear in mind GFS has shown very marked inter-run oscillations for a while, and in any event, is never followed as a 'trusted' guide post-T+144 because (unlike EC or MOGREPS, or GloSea5 for that matter) it's not a bespoke medium range tool. Yes: it *may* be right this time re easterly Op runs of late, but that's shaky ground to base a public forecast upon. What happens aloft stratospherically may be another matter.

The next few days look far more eye-catching in any case, forecast-wise. Given events already today, frankly whatever unfolds early Jan can happily sit on the back-burner for now....!!

That's what i have just mentioned above

thanks Ian

Edited December 26, 2015 by Allseasons-si

[lorenzo]

8 minutes ago, blizzard81 said:

Wrong orientation of the high though and the start of that incredibly anoying baltic short wave that acts to block the high from advecting the brutal cold westwards.

I depends on what you are looking for in a run I guess, sorry am not focused on the dream time easterly, would love it to come through, yes, and am sure many more would.  Am more interested just now in the break from the controlling stratospheric regime, that is the uber cold vortex and what may or may nor disturb it, under it's own control it has been unperturbed, reached cold minimums and in the face of a strong additive Nino just rolled on regardless, colder and colder, 10hPa , 30hPa no matter where you look this thing has meant business.

Lots around today that tends towards the change in regime train of thought - increased polar cap height temps, meaningful trop blocks, which would not sustain in the rampant intensification period, the MJO moving from noise to coherent, the wave 2 pattern created by the Scandi block. The 100hPa flux is huge, it's our best chance yet, this block is not an artefact it's genuine, what is of interest in how it does the damage thereafter.

[TomDav]

What looks like a disintegration/split of the PV at the end of the GFS

[fergieweather]

I second Lorenzo's comments. Expand viewing horizons or risk missing wood for the trees...so to speak! 

[ukpaul]

As I'm up in the area worst affected at the moment it's very difficult not to focus on the one thing, that being to stop the rain. 18z I'm afraid is as potentially destructive a run in that regard as there's been for a few days. I hope it does stop the Atlantic down the line but the more time it takes the more people will be affected.

[Allseasons-Si]

1 minute ago, fergieweather said:

I second Lorenzo's comments. Expand viewing horizons or risk missing wood for the trees...so to speak! 

I third that,a few missing puzzles of the jigsaw starting to fill the rest of the gaps

at just 96 hrs,yes 96 hrs you can see WAA being pumped up toward the pole from Alaska and Scandinavia,not bad is it

[bobbydog]

as lorenzo and ian have said, while everyone is looking for the phantom easterly, we should be looking higher up. the previously solid 'dartboard' strat vortex is not looking too healthy by the end of this and previous runs-

 

[DAVID SNOW]

3 minutes ago, bobbydog said:

as lorenzo and ian have said, while everyone is looking for the phantom easterly, we should be looking higher up. the previously solid 'dartboard' strat vortex is not looking too healthy by the end of this and previous runs-

 

Phantom easterlies, and strat  charts @ 384 hours are very much the same.

[Allseasons-Si]

3 minutes ago, bobbydog said:

as lorenzo and ian have said, while everyone is looking for the phantom easterly, we should be looking higher up. the previously solid 'dartboard' strat vortex is not looking too healthy by the end of this and previous runs-

 

I see four sharks attacking the pv there but(not clued up on the strat)does that look like cold advancing toward America and Russia?

i stand corrected.

[bobbydog]

3 minutes ago, DAVID SNOW said:

Phantom easterlies, and strat  charts @ 384 hours are very much the same.

not really. the weather down here is much more fickle and prone to sudden change in detail. the strat is a much slower animal and the trend is for it to become a much less powerful beast than it has been...

[Allseasons-Si]

The gfs mean charts at 144hrs

12z mean at 162hrs(could not get the 144)as copied from earlier post

18z mean at 144hrs

pretty good consistancy there

[DAVID SNOW]

14 minutes ago, bobbydog said:

not really. the weather down here is much more fickle and prone to sudden change in detail. the strat is a much slower animal and the trend is for it to become a much less powerful beast than it has been...

 

So you are saying the strat animal is easier to predict than the weather down here?

Good luck with that one

[feb1991blizzard]

4 minutes ago, DAVID SNOW said:

 

So you are saying the strat animal is easier to predict than the weather down here?

Good luck with that one

Its a fact that it is, Recretos has done many posts on Strat verification in the past but just going off my own experience, Ive Never seen an SSW fail at T120 before but I have seen resultant Easterlies of those warmings fail at even less!

[DAVID SNOW]

5 minutes ago, feb1991blizzard said:

Its a fact that it is, Recretos has done many posts on Strat verification in the past but just going off my own experience, Ive Never seen an SSW fail at T120 before but I have seen resultant Easterlies of those warmings fail at even less!

Well lets get it down from 384 hours to 120 hours , and see where we stand then!

[feb1991blizzard]

Just now, DAVID SNOW said:

Well lets get it down from 384 hours to 120 hours , and see where we stand then!

Oh yes of course I agree a 384 is no certainty!! but the 2013 Jan SSW did count in very solidly all the way but remember all the uncertainty around whether it was actually going to deliver any cold or snow for the UK at even 120 - remember WTF!

[DAVID SNOW]

4 minutes ago, feb1991blizzard said:

Oh yes of course I agree a 384 is no certainty!! but the 2013 Jan SSW did count in very solidly all the way but remember all the uncertainty around whether it was actually going to deliver any cold or snow for the UK at even 120 - remember WTF!

[Allseasons-Si]

25 minutes ago, feb1991blizzard said:

25 minutes ago, feb1991blizzard said:

Oh yes of course I agree a 384 is no certainty!! but the 2013 Jan SSW did count in very solidly all the way but remember all the uncertainty around whether it was actually going to deliver any cold or snow for the UK at even 120 - remember WTF!

Oh yes of course I agree a 384 is no certainty!! but the 2013 Jan SSW did count in very solidly all the way but remember all the uncertainty around whether it was actually going to deliver any cold or snow for the UK at even 120 - remember WTF!

Yes that WTF moment,who said that?,let me know

the Jan 13 SSW produced a memorable snow event here in march with several feet snow drifts

1st March 2013 archives(gfs)

http://www.meteociel.fr/modeles/gfse_cartes.php?jour=1&mois=3&annee=2013&heure=18&archive=1&mode=0&ech=6&runpara=0&carte=0

you can fondle with the timeframes,but look what happened from a uk high and then trough disruption to the SE,who would of thought an easterly would come out of that

now,we have a bigger robust high in our visinity,what happens from now is anyones guess as we know,because the outcome will always be different.

 

 

Edited December 27, 2015 by Allseasons-si

[Allseasons-Si]

29 minutes ago, Allseasons-si said:

Yes that WTF moment,who said that?,let me know

 

 

 

was it ian brown

hoping for some stella runs tomorrow then

my glass is fuller than that

[Mucka]

4 hours ago, Geordiesnow said:

Too me the UKMO looks similar but having said that,  be careful of saying its a trend just because a couple of runs are showing that. Got to also be careful of not reading too much into the detail side of things which will vary. 

The main trends I see is a strong scandi block, atlantic looks like its going to weaken but likely to still affect the UK and potential for an easterly down the line but at this stage, an outside bet. The outlook whichever way does look like it will cool down also with some chillier air coming in from the west. 

 

I think people have misunderstood what I am talking about, UKMO is nothing like in that respect.

As said previously i am talking about the diving low that is NW of Portugal and heading South.

On UKMO it does nothing of the sort, it travels E/SE toward the UK.

As for a trend I mean within GFS output, 12z Op and control, 18z Op and control and some ensembles coming on board for the same track of that low that has not previously been modeled before - that Is a trend certainly.

Doesn't mean it is right, other models do not have a low diving South so far out in the Atlantic, trends can get dropped as well as picked up.

I tried to explain in basic terms the possible consequences because it could be an important development going forward. Unfortunately there are quite a few complexities and it would take a long post to try and convey those. Suffice to say the track of that low will have a baring on the pattern and we would likely be better served by it heading toward SW UK and disrupting SE into Europe under the block rather than head south as this will only reinforce heights over Europe at a time we want to lower them. On the other hand there are certain scenarios where if the WAA were such it could reinforce the Scandi block but that would require a deeper low travelling more SE than S and we would hoping for a second bite of the cherry. 

Wish I hadn't typed all that now because it is all hypothetical other than the track of the low being a new trend within GFS output and it being important to the upstream pattern as far as the weather our Island might receive is concerned.

Yes we can go into too much detail given it is not resolved I guess, but it was supposed to be a post about detail and how and why it matters not a post explaining the overall pattern - let's just wait and see I guess. 

 

 

 

 

Edited December 27, 2015 by Mucka

[Mucka]

GFS 00z sort of follows on nicely from my last post in that the low is a little deeper and travels more SE than S.

If i had wanted to draw a diagram by way of explanation of what I was saying in my last post it would of looked like the GFS op 00z at the point below.

00z last nights 18z for comparison.

That is much better as it can reinforce the block rather than just rebuild heights over Europe  as explained previously.

The low then disrupts with energy split N and S against the reinforced block.

It still might not be enough but look how much difference it makes to the air over the UK  just a day or so later. When dealing in such fine margins details matter, at least as far as the conditions we experience on our small Island which is ultimately what we are interested in.

Edited December 27, 2015 by Mucka

[Mucka]

GEM not that from GFS at 168, just a slightly stronger and better aligned high.

 

 

manages to get enough energy under the block to pull in some colder uppers - for a while at least. GFS was close to giving a breakdown snow event but didn't quite pull the cold air far enough West. I would take that for now.

[knocker]

I suppose the main significance of this morning's gfs is the number of bands of rain that cross the UK accompanied by strong winds at times courtesy of the Georgian express.  Of course the details regarding these will vary by the next run but one suspects not the basic idea.

Edited December 27, 2015 by knocker