Model output discussion - 21st Jan Onwards

[Derbyshire Snow]

What to make of  outputs so far today

Low pressure still dominant across Greenland locking in the cold air across high latitudes, jet stream showing no sign of easing. To save this winter we need a SSW event to split the PV and allow this cold air to filter in to mid latitudes i.e UK and Northern Europe. There are signs of minor stratospheric warming in early February which hopefully will displace the PV east or smash it in two.

The other large factor is the huge Bartlett high but if we can get a SSW there is a possibility that these heights could be pushed out of the way very quickly with a trough from the North

Some interest for the far north of Britain with occasional incursions of polar maritime air. Wintry showers particularly on the hills... probably feeling quite raw in those winds as well.

8.30pm downloaded image off my satellite showing US blizzard

[Singularity]

8 minutes ago, nick sussex said:

Singularity yes I agree the ECM is an improvement however I don't trust outputs with the jet projected south with the PV still in that location.

Model bias re southwards jet placement has to be factored in at longer range in this type of set up. For this reason I'll be more confident when its shown within T168hrs.

As I mentioned earlier the ECM looks quite amplified in the east Pacific at day ten and yes the ECM after that point could develop more favourably but I'd like to see a consistent signal for this.

If the jet does get further south then theres a chance of some interest more especially for northern areas as low pressure runs east but I've been reluctant to overplay this until the jets southwards projection is shown within T168hrs.

Looking at the ECM ensemble spreads the main one relevant to the UK from T192hrs to T240hrs is the track of low pressure in terms of how far south this gets.

 

Hi Nick,

Just to clarify - with the vortex in what location? Essentially it is northeast, going on east, of the UK days 7-10 which surely favours the jet moving south? Admittedly the pace is open to question and that's where I'm hoping trends continue going forward from today.

I suspect, though, you are referring to the residual lobe as it moves Canada/Greenland. Development as that engages with the Atlantic jet is bound to pull the jet north again for a time but in a shorter wavelength with a move back south soon afterward. So I kind of see where you're coming from, I think?

 

I expect to see a bit of spread in the southward movement of the jet in the ens. as there's still a fair range of MJO 'kick-off' timing and consequential addition of amplification to the pattern as the AAM is shot upward.

 

[Singularity]

3 minutes ago, IDO said:

The GFS has the same wave from the Pacific as the ECM around the same time and also deepens the US trough, however after D10 it flattens the ridge as the Asian PV lobe pushes east and this kills the meridional flow before it can work its magic downstream (Atlantic). We do not see D10-15 from ECM but we do the GFS and GEfS and the latter currently says that the Pacific wave will generate some residue heights towards the Arctic but will not sustain any EPO. Remember the models played with the U.K. to Scandinavia ridge several days ago at that sort of range and backed off, and ECM at D10 where heights are concerned is notoriously unreliable. Not saying it cannot happen but until evidence says otherwise I am not holding my breath.

Well as I keep saying (making me sound like a stuck record!), this faliure to develop the pattern further I put down to GFS reading the tropical signals incorrectly. It is admittedly an assumption, but one made on very recent observations (the model's predictions compared to what actually happened Dec to mid-Jan).

[nick sussex]

Just now, Singularity said:

Hi Nick,

Just to clarify - with the vortex in what location? Essentially it is northeast, going on east, of the UK days 7-10 which surely favours the jet moving south? Admittedly the pace is open to question and that's where I'm hoping trends continue going forward from today.

I suspect, though, you are referring to the residual lobe as it moves Canada/Greenland. Development as that engages with the Atlantic jet is bound to pull the jet north again for a time but in a shorter wavelength with a move back south soon afterward. So I kind of see where you're coming from, I think?

 

I expect to see a bit of spread in the southward movement of the jet in the ens. as there's still a fair range of MJO 'kick-off' timing and consequential addition of amplification to the pattern as the AAM is shot upward.

 

Thanks for the reply.

In terms of the MJO forecasts well if we're going on what happened recently then the UKMO in terms of the initial bullishness to move the MJO was proven correct, the GEFS/GFS was an abject failure, the ECM in between.

Indeed the GEFS was still on holiday in the COD as the UKMO had packed its bags and boarded the flight home!

 

[Singularity]

1 minute ago, nick sussex said:

Thanks for the reply.

In terms of the MJO forecasts well if we're going on what happened recently then the UKMO in terms of the initial bullishness to move the MJO was proven correct, the GEFS/GFS was an abject failure, the ECM in between.

Indeed the GEFS was still on holiday in the COD as the UKMO had packed its bags and boarded the flight home!

 

Yep I remember it well. I remember any chance to laugh at GFS very fondly indeed 

To be honest, I am starting to place a slightly dangerous amount of hope on UKMO being the leader of the pack again the time and bringing about the quickest achievable route to 'proper winter' in lowland southern England. It's a big ask, but I have enough experience to survive a let down... I think 

With the movie 'Oblivion' (on C4 for those interested) seeming a reasonable way to take a break from all this, it seems like a good time to sign off for the evening with my new favourite phrase;

May The Forcing Be With Us.

[bobbydog]

just thought I should mention; ok, the output we can see is not showing much in the way of cold and this has been a rubbish winter - so far.... however, there has been much talk on the strat thread of 'favourable developments'. we still have a few weeks left of winter. there are no rules regarding winter, or any other season for that matter. if i remember correctly, many early forecasts were going for a 'back end' winter due to el nino etc. the strat is definitely warming. we dont know to what extent yet but it is. more importantly, the Met Office are forecasting height rises in the atlantic in mid-feb leading to a cold northerly flow. this would tie in with the strat forecasts etc. they have access to vastly more information than we do and they dont make statements without some confidence.

there is hope yet...

[blizzard81]

2 minutes ago, Singularity said:

Yep I remember it well. I remember any chance to laugh at GFS very fondly indeed 

To be honest, I am starting to place a slightly dangerous amount of hope on UKMO being the leader of the pack again the time and bringing about the quickest achievable route to 'proper winter' in lowland southern England. It's a big ask, but I have enough experience to survive a let down... I think 

With the movie 'Oblivion' (on C4 for those interested) seeming a reasonable way to take a break from all this, it seems like a good time to sign off for the evening with my new favourite phrase;

May The Forcing Be With Us.

Thanks for the heads up there S. Will watch it as I need a break from this weather lark too  

[marksiwnc]

Surely even at +24 the models were wrong as none said that this Snowmageddon over in the states would reach ny to the progress it has made. Would this not mean that there would be a bit more amplification in the models even in the short-term??  I'm only asking btw and would appreciate any professionals response.  

[bobbydog]

in fact.....

(further to my earlier post) based on the information presented to me by professionals and (well informed) amateur enthusiasts alike, i am confident that the UK WILL see a major snow event before the end of February.

"you don't believe me?.... you will Dr Jones.... you will..."

[damianslaw]

Differences between GFS and ECM, GFS maintaining a very strong zonal flow with the jet locked in a position that prevents and polar air from making inroads... mmm how often do we see this signal from GFS... all too often and to be expected really.

ECM suggesting a bit more amplification allowing the jet to dig further south as we end the month, meaning northern parts see polar air and temps around the norm.

In the days ahead I firmly expect GFS to show more of the same (for this reason - I won't be bothering to look at it), whereas I suspect the ECM will show more of a meridional flow for the first week of Feb in response to predicted changes in the upper atmosphere.

UKMO performed excellently during the recent cold spell, GFS was left floundering.. Given the Met office forecast for perhaps colder conditions mid month with a mid atlantic high, I'll be surprised if it follows GFS suite in the days ahead. So expect the default ECM/UKMO vs GFS performance, with the usual wild GFS 18Z swings to add a bit of spice to things.

As for any more winter over posts - I make a plea please can these be deleted until winter has actually ended. In weather terms we are roughly at mid point of winter (first half of March statistically is colder than the first two thirds of December and often far snowier.. despite the added heat from the sun).

[nick sussex]

As the GFS 18hrs run comes out the T168hrs timeframe onwards will be interesting to see whether this can edge the jet further south.

Its likely lows will develop and run east in towards the UK.

Just looking at the ECM De Bilt ensembles theres an increase in snow spikes for the 31st January/1st February timeframe. Because of the set up any lows effecting De Bilt will be effecting the UK first.

Currently the main uncertainty is in relation to how far south the jet might get upto T240hrs. Theres a chance that within the overall rather underwhelming outputs that a snow event might pop up within that range if the jet can get sufficiently south.

Just a chance at present and this would be a bonus given the overall pattern, the ECM hinted at this but the ECM ensemble spreads do show that the track of these lows could change.

 

 

[damianslaw]

2 minutes ago, nick sussex said:

As the GFS 18hrs run comes out the T168hrs timeframe onwards will be interesting to see whether this can edge the jet further south.

Its likely lows will develop and run east in towards the UK.

Just looking at the ECM De Bilt ensembles theres an increase in snow spikes for the 31st January/1st February timeframe. Because of the set up any lows effecting De Bilt will be effecting the UK first.

Currently the main uncertainty is in relation to how far south the jet might get upto T240hrs. Theres a chance that within the overall rather underwhelming outputs that a snow event might pop up within that range if the jet can get sufficiently south.

Just a chance at present and this would be a bonus given the overall pattern, the ECM hinted at this but the ECM ensemble spreads do show that the track of these lows could change.

 

 

Yes you can never discount a snow event popping up even when we seem locked in a mild atlantic flow. 12 December a good case in point, parts of Scotland and far north of England saw a surprise snow event, as low pressure tracked further south.. it came in the wettest and warmest Dec on record.

[nick sussex]

1 minute ago, damianslaw said:

Yes you can never discount a snow event popping up even when we seem locked in a mild atlantic flow. 12 December a good case in point, parts of Scotland and far north of England saw a surprise snow event, as low pressure tracked further south.. it came in the wettest and warmest Dec on record.

Yes these things can pop up out of a seemingly poor pattern. I think the key thing is the main PV chunk does get into Scandi, that would at least help in tracking low pressure in at a more favourable angle for that.

[lukemc]

Nick before we get to any more amplified pattern do you think that we could get some cold zonality that could deliver for some northern parts of England (as well as Scotland/Ireland of course)? Zonality does not always have to be mild actually when we get a very strong polar vortex it can happen like in December 2012 we had some "turbocharged" zonality that provided some good snowfalls for the setup in North West England.  If we can't have a blocked pattern at least we could have some cold zonality - it even delivered in March in 1995.  But Nick, if I got just one decent event with snow on the ground on my patch I would be happy - last weekend Manchester got snow on the ground - Liverpool mainly did not - but at least I got to see snow on the ground as I was at Manchester Airport last Saturday.

Maybe a bit OT but is Manchester on average slightly snowier than Liverpool even though they are 30 miles apart? Been a few times I remember raining in Liverpool and snowing in Manchester - talking the city not higher areas like Oldham and Rochdale

 

Luke

Edited January 23, 2016 by lukemc

[nick sussex]

26 minutes ago, lukemc said:

Nick before we get to any more amplified pattern do you think that we could get some cold zonality that could deliver for some northern parts of England (as well as Scotland/Ireland of course)? Zonality does not always have to be mild actually when we get a very strong polar vortex it can happen like in December 2012 we had some "turbocharged" zonality that provided some good snowfalls for the setup in North West England.  If we can't have a blocked pattern at least we could have some cold zonality - it even delivered in March in 1995.  But Nick, if I got just one decent event with snow on the ground on my patch I would be happy - last weekend Manchester got snow on the ground - Liverpool mainly did not - but at least I got to see snow on the ground as I was at Manchester Airport last Saturday.

Maybe a bit OT but is Manchester on average slightly snowier than Liverpool even though they are 30 miles apart? Been a few times I remember raining in Liverpool and snowing in Manchester - talking the city not higher areas like Oldham and Rochdale

 

Luke

Proper cold zonality is a rare thing, that's normally when many parts of the UK stay in the cold throughout but you'll see from the ECM that it tries to run low pressure in further south.

The GFS 18hrs run is the best its delivered in days in terms of the overall pattern, a bit further south and that Atlantic low could prove interesting!

Putting aside the Euro limpet high the GFS 18hrs run is encouraging and better than the ECM in terms of the PV splitting and the orientation of the Scandi troughing.

Edited January 23, 2016 by nick sussex

[Eskimo]

Will this little feature in the Atlantic cause the breakdown of any prolonged meridian flow at +192h?

 (Anyone else having problems copying and pasting meteociel images?)

[Derbyshire Snow]

Interesting split in the jetstream over the US behind the snowstorms, will this be enough to allow heights to develop over the west and north atalantic. Certainly encouraging heights to develop over Greenland on this run. is this a chink of light

Edited January 23, 2016 by Derbyshire Snow

[Nouska]

48 minutes ago, lukemc said:

Nick before we get to any more amplified pattern do you think that we could get some cold zonality that could deliver for some northern parts of England (as well as Scotland/Ireland of course)? Zonality does not always have to be mild actually when we get a very strong polar vortex it can happen like in December 2012 we had some "turbocharged" zonality that provided some good snowfalls for the setup in North West England.  If we can't have a blocked pattern at least we could have some cold zonality - it even delivered in March in 1995.  But Nick, if I got just one decent event with snow on the ground on my patch I would be happy - last weekend Manchester got snow on the ground - Liverpool mainly did not - but at least I got to see snow on the ground as I was at Manchester Airport last Saturday.

Maybe a bit OT but is Manchester on average slightly snowier than Liverpool even though they are 30 miles apart? Been a few times I remember raining in Liverpool and snowing in Manchester - talking the city not higher areas like Oldham and Rochdale

 

Luke

Looking at the ECM ensemble mean at +174 hours it is definitely zonal but it will not be mild zonal if chart verifies.

     

People are in too much of a rush to make assumptions.

Edit to add the +168 jet stream chart.

Edited January 23, 2016 by Nouska

[Derbyshire Snow]

Once again in FI the jet stream is winning out but i believe the trend is for some sort of change showing  in a week or two. At least we are now getting polar maritime incursions and that mass of  cold air to the north is slowly slipping south at times. PV is still very reluctant to move far though but cold zonal is better than mild zonal. Its a start

Edited January 23, 2016 by Derbyshire Snow

[BLAST FROM THE PAST]

What we are seeing is the Uk getting ever more affected by deep systems and less Euro HP influence as mentioned the other day as we head through last week of Jan to months end and more inroads of pM air.  As we get to month end we start looking at air from our NNW/N. I have and still anticipate we look there for real cold conditions to dig in from the North as we enter Feb and not have to wait until mid or late Feb.  Don't expect major N blocking but enough amplification to bring very cold air from our north with potential interaction of the cold air from an Atlantic influence forced on a more southerly track. I mentioned a couple of days ago one or two runs hinted at this, and today we see further hints of this.

 

BFTP

[Derbyshire Snow]

7 minutes ago, BLAST FROM THE PAST said:

What we are seeing is the Uk getting ever more affected by deep systems and less Euro HP influence as mentioned the other day as we head through last week of Jan to months end and more inroads of pM air.  As we get to month end we start looking at air from our NNW/N. I have and still anticipate we look there for real cold conditions to dig in from the North as we enter Feb and not have to wait until mid or late Feb.  Don't expect major N blocking but enough amplification to bring very cold air from our north with potential interaction of the cold air from an Atlantic influence forced on a more southerly track. I mentioned a couple of days ago one or two runs hinted at this, and today we see further hints of this.

 

BFTP

Exactly as i see it. Unfortunately looking east and relying on a Scandinavian/ Siberian high stretching west  may be  a lost cause this year. I believe sustained cold of any sort will have to start from these polar maritime incursions and if the teleconnections are good causing a jet stream break   then just maybe we can get a trough to swing down in to Europe with heights developing over Greenland

Edited January 23, 2016 by Derbyshire Snow

[Rollo]

Your optimism is sorely needed at the moment BFTP, and somehow I begin to think you are onto something.

[mulzy]

The ECM ensemble mean at day 10 is slightly encouraging (all relative ofc).

FWIW the extended ECM mean does show the negative height anomaly move from the Scandinavia locale at 10 day to North West Scotland at day 15 maintaining the very strong zonal flow (caveats as ever at this range!)

 

Edited January 23, 2016 by mulzy

[ukpaul]

GFS ensembles for the Pennines, 2 m temps.

There's an awful lot of rain there in the search to have some of it fall as snow but the lack of temperatures close to freezing suggest that if any does fall as snow it will be only transitory. The highlands of Scotland would be much better positioned though.

[IDO]

9 hours ago, Singularity said:

Well as I keep saying (making me sound like a stuck record!), this faliure to develop the pattern further I put down to GFS reading the tropical signals incorrectly. It is admittedly an assumption, but one made on very recent observations (the model's predictions compared to what actually happened Dec to mid-Jan).

Hi

Yes GFS was slow with that MJO forcing. However I am not sure that the MJO signal would have been much help to the UK, I put the cooler spell more down to Storm Frank and its forcing of the Atlantic Ridge and subsequent Kara Block. Without that I suspect the EPO ridge and block would not have been sufficient against a strong trop PV to make a significant meridional flow in the Atlantic, and in my opinion the colder trough would have then been even further east, due to the omnipresent Euro heights; a bit like the D10 GEM:

GEM D10:  GFS: ECM:

The upcoming Pacific forcing IMO will not be sustained as the PV still has too much energy and we can only hope that the residue EPO block will meander to somewhere useful. As you can see from the current D10 charts nothing has changed and for days members have been suggesting the D10's will start to show changes, yet those D10 charts to me look hopeless for any change to cold within D15? Until the trop PV wanes, forcing from any MJO wave will probably be not much use for the Atlantic sector. The D15 GEFS mean:

D16 mean: London T850s: 

No real consensus from members as to how the EPO block is handled but the vast majority suggest it is of little help to the UK. There is a tendency after D13 for the zonal flow to slacken allowing the ridge-trough combos to be slightly more amplified so the temporary NW flow(s) may last a bit longer and have more bite, though early days for any conclusions there.

Overall no sign of any changes on any model, all backed up by the LR varients. A major SSW maybe our only hope of changing what is a locked in pattern as another Storm Frank looks unlikely.