Model Output Discussion 1200 hrs 15/11/14

[ANYWEATHER]

Hi BA I wouldnt go that far out...

 

day 11 would be the earliest on the ECm type evolution

 

Whats the control saying 00z & 12z, both were very cold....

 

S

Steve , there is nothing in the pipe line at the moment that spells true cold maybe later but not yet    

[Nick F]

That's some long-draw southerly at T+216 on 12z ECM op, central Algeria to Norwegain Sea? Sahara dust anyone?

 

 

Anyway, as Phil nw mentioned earlier, some quite large broadscale differences apparent upstream over North America between 12z GFS and ECM at day 8, there were between the 2 models from their 00z operationals too. ECM drops another arctic cold pool down across the mid-west Plains while GFS dumps the cold across the east. This appears to have a knock on effect downstream, albeit not great on the broadscale, but still makes the difference for the UK, of 12z op GFS pushing the troughs and ridges a little further east than 12z ECM.

 

12z NH GFS vs ECM ops + ENS mean:

 

But despite these differences that are particularly notable upstream over NA, general large scale signal for Europe is that the Atlantic holding pattern looks set to continue for the foreseeable future and any cold pooling developing across W Russia and NE Europe kept annoyingly well out of reach ...

Edited November 20, 2014 by Nick F

[phil nw.]

A reminder to please include model output discussions when posting in here.

We keep having to move some posts over to the other thread here-

https://forum.netweather.tv/topic/81281-model-banter-moans-and-ramps-autumnwinter-2014/

 

.so if your post has gone it's likely to be found in the model moans/ramps thread.

 

Thanks.

[bluearmy]

Hi BA I wouldnt go that far out...

day 11 would be the earliest on the ECm type evolution

Whats the control saying 00z & 12z, both were very cold....

S

The 00z control showed a strong euro trough but even that didn't advect cold as far as the uk with the flow changing from positive to negative uppers and nothing particularly cold. De bilt with bit lower uppers but mainly cold due to a loner source continental feed.

Tbf, the 12z control does advect the cold pool over scandi as far as the uk by the end if the run

Overall the 12z ECM extended ens are not great for coldies. the trough trending back to the west of Ireland and away from Europe

Edited November 20, 2014 by bluearmy

[johnholmes]

And the anomaly charts continue to show the trough as the main feature, not mild looking at the heights shown over the UK but no sign of any deep cold as I posted earlier with even surface cold probably transient. My comment would be no sign of winter into early December at least. Could be wrong but based on the charts shown below which have shown consistency then no major cold.

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 

To stop upsetting folk I will not post these again until to me they seem to indicate a major change in pattern/wavelength that looks to suggest some kind of cold is within 15 days of t+00.

Edited November 20, 2014 by johnholmes

[shaky]

The 00z control showed a strong euro trough but even that didn't advect cold as far as the uk with the flow changing from positive to negative uppers and nothing particularly cold. De bilt with bit lower uppers but mainly cold due to a loner source continental feed.

Tbf, the 12z control does advect the cold pool over scandi as far as the uk by the end if the run

Overall the 12z ECM extended ens are not great for coldies. the trough trending back to the west of Ireland and away from Europe

does that mean more influence from the scandi high?

[Tamara]

upstream variation with the depression off the eastern seaboard T168. wouldnt be looking past day 6 at the moment on the ops. notice how much further sw ECM now is with the depression at day 6/7. remember 3 or 4 days ago when it first showed it diving se ans some of us mused that coem verification, it may well be further sw. the block keeps on batting the atlantic away and there is no sign that it is weakening. its support from the siberian ridge seems stronger than the upstream vortex can manage in support of the atlantic. which one of these two is likely to give way first ???

 

Yes  Deja vu model rinse and repeat and deja vu MOD post rinse and repeat.

 

Phase one cycle showed us this : 

 

 

 

Phase two cycle is starting to model converge closer on this type of thing although exact depth and position of the diving trough is open to question:

 

 

 

In terms of pattern backing west, the hemispheric anomaly pattern continues to reflect exactly the November analogue for the background factors..-QBO, -OPI, strong SAI , Aleutian low, Scrussian/Sceuro etc High and Atlantic trough. So no obvious change there then from the first half of the month it seems...

 

However, back to the charts above and the differences from a couple of weeks back. The orientation of the atlantic trough is taking on an increasingly negative tilt compared to 'cycle one' and the trough disruption bleeding out of the gradient infused US atlantic seaboard taking on incrementally adjusted fractions westwards. The High to our east/north east is encompassing increasingly cold air.....

 

Furthermore, each day news from the upper stratosphere takes on more and more of a truly loaded gun scenario and the available potential energy from the extreme stresses ongoing up there is primed to destabilise rapidly when  catalysts from the troposphere into the lower stratosphere come into play and become a forcing mechanism ....

 

That is where the present apparently frustrating pattern stalemate is quietly playing its 'boring' part. As long as the pattern stays like this and the models keep catching on that the atlantic lows hit a wall and sends shockwaves into the arctic then the chances increase down the line of the dam breaking open.

 

'Instant snow gratification' as repeated so often is not going to happen like that - and eventual reward, if it is going to happen in the UK, will not be this month and will certainly take us right into the heart of December too for sure, at the least.

 

The threat of disruptive cyclognesis preoccupies the METO thoughts as documented on here through official channels - but while a strong Jetstream is definitely primed to jettison out stateside, the evidence seems to be growing that this is destined towards France and Iberia rather than aiming a winter 13/14 type barrel at the UK 

 

There may be the same Canadian cold blower in operation as we saw last winter - but the polar field is a vastly different place and there is kidology attached to the (apparent on the ground) vortex strength this time around that masks the fact that it is flailing badly and quite conceivably could detonate quite spectacularly in the coming weeks...

 

@Knocker - PM explanation sent to you

Edited November 20, 2014 by Tamara תָּמָר

[knocker]

Sorry I must have missed this," The threat of disruptive cyclognesis preoccupies the METO thoughts as documented on here through official channels".

Could you point me where or just elucidate a bit about this disruptive cyclogenesis, please. Are we talking left exits of the jet regarding the UK?

Edited November 20, 2014 by knocker

[Polar Maritime]

The GFSP shows the Atlantic much stronger and early'r pushing the block away East from the N/W. Very unsettled possibly stormy turn of the Month.

 

Edited November 20, 2014 by Polar Maritime

[bluearmy]

Sorry I must have missed this," The threat of disruptive cyclognesis preoccupies the METO thoughts as documented on here through official channels".

Could you point me where or just elucidate a bit about this disruptive cyclogenesis, please. Are we talking left exits of the jet regarding the UK?

Ian has commented on this over the past couple days re the possibilities of deep depressions approaching the uk.

[ukpaul]

At 186h, things are relatively close by 144h but after that? It's anyone's guess.

 

ECM 12z
 

 

GFS 18z
 

[knocker]

Interesting evolution on the P. Would need to see the broader picture of this.

Charts courtesy weathell.com

 

 

[knocker]

Ian has commented on this over the past couple days re the possibilities of deep depressions approaching the uk.

 

Yes I was aware of the deep depressions possibility b but not the cyclogenesis angle. And talking of deep depressions...........

Edited November 20, 2014 by knocker

[Polar Maritime]

A nice chart to finish the run with the Jet way South and a cold N/W flow, Cold enough for snow in places. Way out in the run but nice to see all the same 

 

Edited November 20, 2014 by Polar Maritime

[Barry12]

Yes, it looks like we could get some snow from Polar Maritime air, Polar Maritime.

 

Edited November 20, 2014 by Barry95

[LomondSnowstorm]

A nice chart to finish the run with the Jet way South and a cold N/W flow, Cold enough for snow in places. Way out in the run but nice to see all the same 

 

 

Yep , ironically the coldest charts in the last day or two have been the ones with the troughing a bit stronger and further north. With the Sceuro-Russian ridge rather 'flabby' i.e. extending too far south into southeastern Europe, the scenarios where we get a cut off low to our south still don't manage to back much in the way of cold air westwards, so the best hope of cold air seems to come from the northwest for the next fortnight or so. As Tamara says the holding pattern is far from a hindrance long term and has definitely done its job this month but from an IMBY point of view for cold a more 'Polar Maritime' dominated start to December would probably be an improvement (although ideally with heights just being shifted a bit further northeast towards Svalbard/Novaya Zemlya deflecting the jet SE and still pumping wave activity into the strat rather than sinking altogether).

RE the MJO forecasts, I'm assuming given the lag time that we'd be looking for the phase composites to come into play a week or two after the event rather than immediately? In which case this for early December looks a plausible evolution:

followed by this towards week 2:

[Catacol]

Ian has commented on this over the past couple days re the possibilities of deep depressions approaching the uk.

 

Yep - but to my eye we are starting to see some of the effects of the stratosphere's discomfort in the model output. These depressions are stalling as they hit high pressure over scandinavia, or they are starting to dive SE. This is a very different scenario to last year - and at a time when the atlantic tends to be winding up towards its strongest. I have no doubt we will see plenty of rain still out of this - but in the long term the current pattern, and the trend of that pattern, looks pretty encouraging if it is snow chances that you are after.

[Duane S.]

Yep - but to my eye we are starting to see some of the effects of the stratosphere's discomfort in the model output. These depressions are stalling as they hit high pressure over scandinavia, or they are starting to dive SE. This is a very different scenario to last year - and at a time when the atlantic tends to be winding up towards its strongest. I have no doubt we will see plenty of rain still out of this - but in the long term the current pattern, and the trend of that pattern, looks pretty encouraging if it is snow chances that you are after.

Absolutely, my thoughts entirely CH. Right on cue the jet showing signs of wanting to head south (until we get into lo res of course), depressions diving SE to our SW at the time of year when the Atlantic will be at its strongest indicates a NH profile primed to deliver. We will of course need other triggers but this simply wasn't present last year. Just looking at the 'blues and purples' over Greenland and deriving it is similar to last year is plain wrong. The chances are we will have to endure some wind and rain (possibly a lot) but it will be a necessary evil to get to the pot of gold. Last winter V this winter = chalk and cheese. And let's not forget, we are not yet even in winter!

Even though not really showing on the charts yet I think strong wave2 activity will see the main vortex shift east across the meridian in a couple of weeks time. GEFS FI will be worth looking at shortly for signs of that.

[492]

And the anomaly charts continue to show the trough as the main feature, not mild looking at the heights shown over the UK but no sign of any deep cold as I posted earlier with even surface cold probably transient. My comment would be no sign of winter into early December at least. Could be wrong but based on the charts shown below which have shown consistency then no major cold.

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 

To stop upsetting folk I will not post these again until to me they seem to indicate a major change in pattern/wavelength that looks to suggest some kind of cold is within 15 days of t+00.

I hope you will keep posting these. I find that they are some of the most useful charts available and the fact that the pattern appears stuck is significant in its self .

[Catacol]

Absolutely, my thoughts entirely CH. Right on cue the jet showing signs of wanting to head south (until we get into lo res of course), depressions diving SE to our SW at the time of year when the Atlantic will be at its strongest indicates a NH profile primed to deliver. We will of course need other triggers but this simply wasn't present last year. Just looking at the 'blues and purples' over Greenland and deriving it is similar to last year is plain wrong. The chances are we will have to endure some wind and rain (possibly a lot) but it will be a necessary evil to get to the pot of gold. Last winter V this winter = chalk and cheese. And let's not forget, we are not yet even in winter!

Even though not really showing on the charts yet I think strong wave2 activity will see the main vortex shift east across the meridian in a couple of weeks time. GEFS FI will be worth looking at shortly for signs of that.

 

Agreed. I am becoming increasingly optimistic: not only is a blocking pattern starting to emerge earlier than I thought it would... but the wise old heads in the strat thread are making stronger and stronger noises about increased stress on the vortex as we approach the end of December and into January. In other words - the timing of much of this could not be better. I am starting to sniff the possibility of a shift to a blocked and frosty pattern into December and then increased retrogression of our scandy high with the chance of undercuts as we enter January. Within this we are bound to get some lows stalling and bringing rain.... but by January?? Hmmm. If the atlantic is relatively depowered this time around then one would expect the continent to cool down fairly quickly as we go into December, and cold air off the continent is gold dust in the undercut scenario.

 

Depending on just what happens to the shards of the vortex as and when a major strat event occurs (IF it occurs....) a significant northerly outbreak at some stage in Jan and Feb cant be ruled out either.

 

Last year was dull as dishwater. This year not so at all. Anyone that isnt reading the strat thread needs to do so - it will help you get a grip on why winter 2014/15 will be a totally different beast to last year. Steve Murr is quiet right now.... but I'll bet he's starting to feel properly excited - as if the fun and games surrounding the OPI didnt get him excited enough already!

[Nouska]

A little diigging around in the archives of the MJO to see if any years matched current forecast - it produced three matches - '75 - '84 and '93.

 

I suspect the winter that would most appeal among those three is 84/85 so a quick recap of the state of play on the first of December of that year.

 

http://cawcr.gov.au/staff/mwheeler/maproom/RMM/phasediag/pd.1984.12.1.gif

 

 

Looking very familiar? .....thought so.....

 

The archive - to have a look at the other options:-

 

http://www.meteociel.fr/modeles/archives/archives.php?mode=2&month=12&day=1&year=1984&map=0&hour=0

 

The MJO archive.   http://cawcr.gov.au/staff/mwheeler/maproom/RMM/phasediag.list.htm

[knocker]

One thing that is quite interesting this morning with both the GFS and (P) is the interplay of a complex area of low pressure over the UK and south and east over Europe with warm air being advected from way south. there is also the question of the ingress from the Atlantic. This dance of the lows starts around T132 but just an example at T192 from the  P

Charts courtesy weatherbell.com

Edited November 21, 2014 by knocker

[Captain Shortwave]

Another set of model output, same old stalemate

That is quite a southerly we are getting, shame it's late November and that would probably just squeeze temperatures into double figures for some. Rainfall could potentially become an issue if active fronts stall over areas of the country from time to time, though you would favour eastern areas to receive little rainfall during this period. The ECM overpowers the block by day 9 and 10, will that verify though?

GEM

The GFS and parallel offer some more widespread rain though as low pressure makes it closer to the UK

Edited November 21, 2014 by Captain shortwave

[Jason M]

Strong agreement within the GEFS this morning for the Atlantic to win out in terms of the UK. As others have said many of the charts on offer look very similar to last winter. That's not to say it will look like that for the whole winter!

With the Russian high in situ though we look like being stuck in a relatively mild set up for a good few weeks as winds will always be from a southerly quadrant over Western europe. I know people are expecting a change because of the strat, but anything cold seems a long way off to me. I've seen this pattern many times over the years and it takes some shifting.

[Nick F]

I'm beginning to wonder, for the sake of the sanity of those seeking for cold/wintry weather, if this stalemate malarky is really going to do us any favours in the short-term, because there's a continued signal for low heights toward the arctic and the block to our east is too far away to deliver deep cold. Unless there's some major pattern change upstream - I don't think that the current 500mb pattern over Europe/Atlantic/Greenland will get us anywhere nearer us seeing a snowflake for another few weeks unless you are up a Scottish mountain. Another thing that's lacking, which would be of great benefit, is an arctic high dropping down over Svalbard, this would help build a strong ridge closer to our N and NE. Instead we end up with a Russian High in retreat.

 

Mind you, the alternative, which seems to becoming more and more likely with each run, is a slow return to Atlantic mobility, which could set in for a while unless there is a big pattern change upstream to help dislodge the lobe of the PV over Greenland.and N Canada.

 

Still, we need to wait to see what happens when the Atlantic trough amplifies over western Europe big time day 8 as it hits the block to the east, but hard to see how it will work in our favour for cold/wintry prospects without height rises to our north.

 

But, as many have said, there are a number of signals (that were amiss last year) that point to this winter hopefully being different than last year pattern wise across the UK, depsite the prominent PV lobe across Greenland and N Canada. Think Chino maybe right with his preliminary winter forecast thoughts - Jan could be when the cold and wintry prospects really hit.

Edited November 21, 2014 by Nick F