Model output discussion - 16th Nov onwards

[nick sussex]

After 3 days the UKMO finally has moved to support the ECM/GFS. Better late than never!

 

Theres still that all important detail that's missing this far out, in terms of 850's and whether any shortwaves will run south in the flow producing more prolonged rain or snow.

 

The 850's currently predicted are marginal for snow away from higher elevations especially this early in the season with higher modification.

 

I think we'll have to wait till nearer the time to assess snow prospects.

 

After this north/nw flow its likely the high will topple but after this I'd be cautious of taking the outputs at face value. Upstream although the overall pattern is agreed on the amplitude of any low pressure systems is still the subject of some uncertainty.

 

I still wouldn't rule out a high pressure cell developing near the UK and stretching towards Scandi.

[Nouska]

Would never have thought we'd be seeing charts such as the hemispheric pattern in GFS 6z FI a week or two ago...pretty remarkable turn around, especially considering the signals we were getting at beginning of November. Good to see that some more seasonal temperatures are finally on the way and it would seem plenty of further opportunities for something colder down the line.

 

I remarked in another thread that the analogues we were looking at may be irrelevant for this winter as they were from before the onset of low solar activity and low Arctic ice. These are two teleconnections that are favourable to cold in Europe and may be playing their hand in what we are currently seeing. I wondered about the possibility of the conflict between them and which could be dominant.

 

Kara/Barents low ice extent: a precursor to a cold Europe according to recent research.

 

Low solar, particularly geomagnetic activity hinders chemical processes in the stratosphere that allow the strong vortex to propagate to lower levels.

 

Both are currently present and models are showing the type of NH patterns seen in the research relating to both subjects.

 

   

[Yarmy]

I remarked in another thread that the analogues we were looking at may be irrelevant for this winter as they were from before the onset of low solar activity and low Arctic ice. These are two teleconnections that are favourable to cold in Europe and may be playing their hand in what we are currently seeing. I wondered about the possibility of the conflict between them and which could be dominant.

 

Kara/Barents low ice extent: a precursor to a cold Europe according to recent research.

 

Low solar, particularly geomagnetic activity hinders chemical processes in the stratosphere that allow the strong vortex to propagate to lower levels.

 

Both are currently present and models are showing the type of NH patterns seen in the research relating to both subjects.

 

   

 

Hi, Nouska. Was it this paper, or is there something more recent?

 

http://onlinelibrary.wiley.com/doi/10.1029/2009JD013568/abstract

[SnowBallz]

I remarked in another thread that the analogues we were looking at may be irrelevant for this winter as they were from before the onset of low solar activity and low Arctic ice. These are two teleconnections that are favourable to cold in Europe and may be playing their hand in what we are currently seeing. I wondered about the possibility of the conflict between them and which could be dominant.

 

Kara/Barents low ice extent: a precursor to a cold Europe according to recent research.

 

Low solar, particularly geomagnetic activity hinders chemical processes in the stratosphere that allow the strong vortex to propagate to lower levels.

 

Both are currently present and models are showing the type of NH patterns seen in the research relating to both subjects.

 

   

 

I have to admit, space weather isn't my forte! Leaves me very

 

Some intriguing signals popping up in the seasonal modelling; I wouldn't say it's decidedly different to previous, but more a meander towards something perhaps a little cooler.  Whilst that is no doubt something to observe on the horizon, there is very much more immediacy - and focus on - our current dalliance with the wet stuff.

[Frosty.]

Yes Karl, Not really any change this morning for the weekend. A very cold Northerly shot continues to show for Saturday/Sunday and into Monday, As -7/8/9 850's push well South over the UK. And as usual in these cold dry Northerly set-ups it's Coastal regions that will be more effected by snow showers, Into next week by Wed a cool N/W Pm flow takes hold, So certainly not back to the balmy highs we have endured over the past Month, More average for the time of year from a more seasonal flow.

Yes PM and the 6z is an upgrade with more chance of snow, I'm wishing this week away to get the Arctic Blast.

Edited November 16, 2015 by Frosty.

[Nouska]

Yarmy: that is one of many but there's a much more recent paper looking at specific areas of ice loss in relation to NH atmospheric patterns - lost a lot of my links when my ancient Dell died but I'm sure it is in here somewhere in the climate section. 

 

Edit for this other link, not the one I refer to but similar topic.

 

http://www.nature.com/ncomms/2014/140902/ncomms5646/full/ncomms5646.html​

 

Abstract ....  Successive cold winters of severely low temperatures in recent years have had critical social and economic impacts on the mid-latitude continents in the Northern Hemisphere. Although these cold winters are thought to be partly driven by dramatic losses of Arctic sea-ice, the mechanism that links sea-ice loss to cold winters remains a subject of debate. Here, by conducting observational analyses and model experiments, we show how Arctic sea-ice loss and cold winters in extra-polar regions are dynamically connected through the polar stratosphere. We find that decreased sea-ice cover during early winter months (November–December), especially over the Barents–Kara seas, enhances the upward propagation of planetary-scale waves with wavenumbers of 1 and 2, subsequently weakening the stratospheric polar vortex in mid-winter (January–February). The weakened polar vortex preferentially induces a negative phase of Arctic Oscillation at the surface, resulting in low temperatures in mid-latitudes.

 

SnowBallz: abstracts from recent presentations at solar/climate conference.  http://scc.geomar.de/frontend/index.php?page_id=506&v=List&do=0&day=119

Edited November 16, 2015 by Nouska

[BLAST FROM THE PAST]

UKMO looks good but also it seems to be the only one with a pronounced LP over the UK before the cold moves in

 

 

 

GFS 06 for same time

 

 

 

 

I think the UKMO for me could be more on the money inasmuch I think more should be made of this feature

 

 

BFTP

Edited November 16, 2015 by BLAST FROM THE PAST

[mb018538]

Looks chilly on that chart for sure! I'd be very surprised if we only got to 1/2c here (Cambridge) on Sunday....I'd wager 4 or 5c is more likely. Either way it's still darned cold for mid to late november! Looking forward to what's coming after all these storms!

[jvenge]

GFS snow charts showing a fairly big upgrade on the 06z just covering for the Ski resorts hopefully after a slow start - 00z run on the right

 

 

 

For me it is hard to imagine how they get that for all but the hills in England. I just don't see how it will be cold enough, unless it is during the night.

[Mucka]

Looking beyond our cold snap at the big picture some better amplification upstream again and deeper troughing into Europe although Siberian high somewhat flimsy on this run.

 

 

Not sure about 144 to 168 upsteam at all, but doesn't push more WAA toward Greenland as I thought and just fills the low and shunts everything East.

Actually GFS seems totally clueless on what happens next and is floundering around.

 

ECM has been much more consistent with 6 to 10 day picture.

Edited November 16, 2015 by Mucka

[Methuselah]

Looking beyond our cold snap at the big picture some better amplification upstream again and deeper troughing into Europe although Siberian high somewhat flimsy on this run.

 

If 1050 mb is the worst-case scenario, the prognosis can't be that bad. Still strong enough to stall anything coming in from the west?

[Captain Shortwave]

Fair to say we still don't really have much clue about the coming weekend still aside from conditions getting colder. No real agreement on how the cold air pulls south with models throwing secondary features right, left and centre. Add to that difficulties handling a cut off low in the Atlantic embedded in the Atlantic ridge and also the background signals which seem to be at odds with each other. 

Day 5 charts

 

GFS

Northerly flow, showers down windward coasts, these a wintry mix, beforehand these will fall as snow to low levels in the north. A shallow low is present west of the Azores.
 

UKMO

 

North to north west flow, again wintry showers down windward coasts. The low as described on the GFS is off the coast of Newfoundland. Quite a difference, this is amplified by day 6.....

 

 

This is an interesting chart. Certainly a chance of another northerly quickly following as the low slides around the Atlantic ridge with re-amplification occurring behind it.

 

With regards to the Siberian high, it isn't the strength which is key, it is about how far north it is and hence how it interacts with the jetstream. You don't really want to see a mid latitude ridge interacting with this as the only result will likely be seeing the high sink towards Mongolia/China.

[Cheshire Freeze]

The most disappointing aspect of the 12z GFS for me is the orientation of the Siberian HP. Doesn't really impact the vortex in the same way as the 6z did so I'm not sure what direction we'll head in throughout FI.

Edited November 16, 2015 by CreweCold

[Mucka]

The most disappointing aspect of the 12z GFS for me is the orientation of the Siberian HP. Doesn't really impact the vortex in the same way as the 6z did so I'm not sure what direction we'll head in throughout FI.

 

Agreed. I don't trust that run at all though and GEM has a much more influential Siberian high, I think that is more in line with the sort of the thing ECM has been going for.

GFS is all over the place run to run so...

 

 

Actually GEM is a really nice run for coldies keeping us in a Northerly flow for longer and with some promise further down line.

Edited November 16, 2015 by Mucka

[Cheshire Freeze]

Agreed. I don't trust that run at all though and GEM has a much more influential Siberian high, I think that is more in line with the sort of the thing ECM has been going for.

GFS is all over the place run to run so...

 

 

Actually GEM is a really nice run for coldies keeping us in a Northerly flow for longer and with some promise further down line.

 

Interestingly, the amplification Pacific side looks stronger on the 12z GFS and as we head into deep FI we may actually see the vortex loaded towards the Eurasian side with heights lifting around Greenland once again.

[Ali1977]

Interestingly, the amplification Pacific side looks stronger on the 12z GFS and as we head into deep FI we may actually see the vortex loaded towards the Eurasian side with heights lifting around Greenland once again.

I agree Crewe, this looks interesting in FI...Hard to think it will happen as the last few FIs have been very different.

Keep an eye on strat warming though, this has reared its head over the last few days.

 

An update from Ian on the current METO models could show some different possibilities to theones from a week ago....Possibly more fluid outcomes rather than probable ones!!

Edited November 16, 2015 by Ali1977

[Methuselah]

Thanks chaps, for putting me straight on the Siberian HP situation.

[Mucka]

Interestingly, the amplification Pacific side looks stronger on the 12z GFS and as we head into deep FI we may actually see the vortex loaded towards the Eurasian side with heights lifting around Greenland once again.

 

Maybe but personally I'm giving up on GFS FI for now unless there is a proper signal rather than just noise. (at least the noise isn't variations of zonal though)

Really hoping ECM builds on earlier runs and we see something akin to the GEM solution.

Edited November 16, 2015 by Mucka

[Cheshire Freeze]

Maybe but personally I'm giving up on GFS FI for now unless there is a proper signal rather than just noise. (at least the noise isn't variations of zonal though)

Really hoping ECM builds on earlier runs and we see something akin to the GEM solution.

 

Even with only the Pacific side driving things we end up with a decentish result....attempted rebuild of Siberian high too. Though I agree we need the Paific and Siberian highs to work in tandem to help split the vortex.

 

 

Edited November 16, 2015 by CreweCold

[throwoff]

GFS 12z seems more confused than the 06. 

 

It seems intent on generating snow for the east coast of the UK all the way from Scotland down to Kent but I don't remember ever seeing such a thin line materializing all the way down the coast.

 

Right now my gut says we might see a few flakes even as south as Kent over the weekend but it will be incredibly marginal and turn to rain quite quickly after, the cold air just doesn't seem strong enough to push through and take over. 

[tight isobar]

As being noted'

And excluding the current upcoming colder shot.....

The gfs is in disorder' in all its suites 00zo6z12.

After mid range {+196 ish}

Its losing its foot notes.

And this is where in times past the ECM gained and

Walked the by then drunken gfs back frim tge pub and put it to bed!.

Maybe an thing of past times to be looking for....

[bluearmy]

I see that the 12z gem takes the 'wedge' I posted about this morning and builds a Scandi ridge with it. Anywhere from Scandi across to Greenland could end up with this wedge of higher heights though I suspect the further east it gets, the more defined it will become. If you are a coldie looking for good signs re the upcoming winter, you want to see the models playing with this wedge of higher heights and undercutting it with the Atlantic generating negatively tilted frontal incursions.

That would be a good pattern for the season ahead.

[Bullseye]

Intersting with latest GFS strat trying to produce a split and today Cohen updated blog indicates/hints at SSW mid-december using their very own AER model.

[nick sussex]

There are so many solutions on offer in the GEFS upto T168hrs that its difficult to look past the weekend with a lot of confidence.

 

The  low in the west Atlantic is causing lots of problems upstream because some GEFS phase this with the low pressure exiting the ne USA.

 

The UKMO looks like it might take this eastward and then subject to the amplification upstream this could head se, the good thing about that UKMO chart is that its hard to make a case for anything milder. With where the PV is located and the upstream pattern it does look primed for something more interesting.

 

I wouldn't be surprised to see the ECM this evening come out with a solution that would please most people  in this forum.

 

Not long to wait now!

[Mucka]

I see that the 12z gem takes the 'wedge' I posted about this morning and builds a Scandi ridge with it. Anywhere from Scandi across to Greenland could end up with this wedge of higher heights though I suspect the further east it gets, the more defined it will become. If you are a coldie looking for good signs re the upcoming winter, you want to see the models playing with this wedge of higher heights and undercutting it with the Atlantic generating negatively tilted frontal incursions.

That would be a good pattern for the season ahead.

 

I missed that post Blue but I think it was an astute observation.

If I had to predict the 8-10 day range I would say look for a MLB to reform most likely just NE of the UK but if not then for an Atlantic block to reform.

Those are the two most prominent signals other than a more unsettled outlook with deep trough setting up just North of UK and heights building behind again deeper into FI.

So half expecting (hoping) ECM comes up with something similar to GEM by day 10, perhaps even better.

End result of making such predictions is usually      but then I'm a masochist when it comes to second guessing the models.  

 

Edit (I see I'm not the only one with this affliction. eh nick?  ) 

Edited November 16, 2015 by Mucka